https://w140.com/tekwiki/index.php?title=545/Repairs&feed=atom&action=history
545/Repairs - Revision history
2024-03-29T09:11:06Z
Revision history for this page on the wiki
MediaWiki 1.40.0
https://w140.com/tekwiki/index.php?title=545/Repairs&diff=69952&oldid=prev
Vintage dave: termination network not delay line
2021-10-21T00:14:05Z
<p>termination network not delay line</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:14, 20 October 2021</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Vertical Amp Fuse==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Vertical Amp Fuse==</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Late-production 545A (S/N 29960) adds F1054 to protect the <del style="font-weight: bold; text-decoration: none;">delay line and/or 350V regulator </del>in case a vertical amp output is shorted to ground. If the fuse opens, all fourteen 6DK6's will draw the usual current, but through the screen grid instead of the plate. A long time ago someone (Stan Griffiths?) worried this would fry them. I did the math. The 130mA combined screen current drags it down to 220V which is 35V above cathode which inputs 0.35W of heat which is safe. However, the 5W R1218 will see 17W and fry, and then 6DJ8's V1033/V1043 will fry trying to pass 130mA to the 6DK6 control grids. Unless you turn off the power within about ten seconds, which you probably would do since you're the one who shorted it poking around and you know you did it. So, just the fuse.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Late-production 545A (S/N 29960) adds F1054 to protect the <ins style="font-weight: bold; text-decoration: none;">termination network </ins>in case a vertical amp output is shorted to ground. <ins style="font-weight: bold; text-decoration: none;"> (Also any instrument fitted with Mod Kit 040-227.) </ins> If the fuse opens, all fourteen 6DK6's will draw the usual current, but through the screen grid instead of the plate. A long time ago someone (Stan Griffiths?) worried this would fry them. I did the math. The 130mA combined screen current drags it down to 220V which is 35V above cathode which inputs 0.35W of heat which is safe. However, the 5W R1218 will see 17W and fry, and then 6DJ8's V1033/V1043 will fry trying to pass 130mA to the 6DK6 control grids. Unless you turn off the power within about ten seconds, which you probably would do since you're the one who shorted it poking around and you know you did it. So, just the fuse.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Add a note inside: TURN OFF POWER IMMEDIATELY IF VERTICAL AMP IS GROUNDED EVEN BRIEFLY</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Add a note inside: TURN OFF POWER IMMEDIATELY IF VERTICAL AMP IS GROUNDED EVEN BRIEFLY</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>If you don't think that's enough, upgrade R1218 to 15W.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>If you don't think that's enough, upgrade R1218 to 15W.</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Ohmite TUW15 ($1) or B20 ($7).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Ohmite TUW15 ($1) or B20 ($7). <ins style="font-weight: bold; text-decoration: none;"> Then the instrument will survive open F1054 indefinitely. (It won't work, but it won't eat itself either.)</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>These mods can be retrofitted to any 541/543/545/541A/543A/545A/551/555.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>These mods can be retrofitted to any 541/543/545/541A/543A/545A/551/555.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td></tr>
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Vintage dave
https://w140.com/tekwiki/index.php?title=545/Repairs&diff=69849&oldid=prev
Vintage dave: Fuse/resistor mod also applicable to 551 and 555
2021-10-12T15:06:57Z
<p>Fuse/resistor mod also applicable to 551 and 555</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 08:06, 12 October 2021</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Ohmite TUW15 ($1) or B20 ($7).</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Ohmite TUW15 ($1) or B20 ($7).</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>These mods can be retrofitted to any 541/543/545/541A/543A/545A.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>These mods can be retrofitted to any 541/543/545/541A/543A/545A<ins style="font-weight: bold; text-decoration: none;">/551/555</ins>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td></tr>
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Vintage dave
https://w140.com/tekwiki/index.php?title=545/Repairs&diff=69810&oldid=prev
Vintage dave: Turns out moving R1218 to F1054 fries V1033/V1043 - R1218 must hold!
2021-10-11T16:58:28Z
<p>Turns out moving R1218 to F1054 fries V1033/V1043 - R1218 must hold!</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 09:58, 11 October 2021</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Vertical Amp Fuse==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Vertical Amp Fuse==</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Late-production 545A adds F1054 to protect the delay line <del style="font-weight: bold; text-decoration: none;">when </del>a vertical amp output is shorted to ground. If the fuse opens, all <del style="font-weight: bold; text-decoration: none;">twelve </del>6DK6's will <del style="font-weight: bold; text-decoration: none;">try to </del>draw the usual current, but <del style="font-weight: bold; text-decoration: none;">all in </del>the screen grid. A long time ago someone (Stan Griffiths?) worried this would fry them<del style="font-weight: bold; text-decoration: none;">, but </del>I did the math. The 130mA combined screen current drags it down to 220V which is 35V above <del style="font-weight: bold; text-decoration: none;">the </del>cathode which inputs 0.35W of heat which is <del style="font-weight: bold; text-decoration: none;">under the maximum rating</del>. However, R1218 will fry <del style="font-weight: bold; text-decoration: none;">at 17W</del>. <del style="font-weight: bold; text-decoration: none;">I think we can head this </del>off <del style="font-weight: bold; text-decoration: none;">by rewiring R1218 so </del>it <del style="font-weight: bold; text-decoration: none;">too is downstream from F1054</del>. <del style="font-weight: bold; text-decoration: none;">Then V1033 saturates sending about 100mA to </del>the <del style="font-weight: bold; text-decoration: none;">control grids, I guess </del>that's <del style="font-weight: bold; text-decoration: none;">okay</del>. <del style="font-weight: bold; text-decoration: none;"> The mod </del>can be retrofitted to any 541/543/545/541A/543A/545A.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Late-production 545A <ins style="font-weight: bold; text-decoration: none;">(S/N 29960) </ins>adds F1054 to protect the delay line <ins style="font-weight: bold; text-decoration: none;">and/or 350V regulator in case </ins>a vertical amp output is shorted to ground. If the fuse opens, all <ins style="font-weight: bold; text-decoration: none;">fourteen </ins>6DK6's will draw the usual current, but <ins style="font-weight: bold; text-decoration: none;">through </ins>the screen grid <ins style="font-weight: bold; text-decoration: none;">instead of the plate</ins>. A long time ago someone (Stan Griffiths?) worried this would fry them<ins style="font-weight: bold; text-decoration: none;">. </ins>I did the math. The 130mA combined screen current drags it down to 220V which is 35V above cathode which inputs 0.35W of heat which is <ins style="font-weight: bold; text-decoration: none;">safe</ins>. However, <ins style="font-weight: bold; text-decoration: none;">the 5W </ins>R1218 will <ins style="font-weight: bold; text-decoration: none;">see 17W and </ins>fry<ins style="font-weight: bold; text-decoration: none;">, and then 6DJ8's V1033/V1043 will fry trying to pass 130mA to the 6DK6 control grids</ins>. <ins style="font-weight: bold; text-decoration: none;">Unless you turn </ins>off <ins style="font-weight: bold; text-decoration: none;">the power within about ten seconds, which you probably would do since you're the one who shorted it poking around and you know you did </ins>it. <ins style="font-weight: bold; text-decoration: none;">So, just </ins>the <ins style="font-weight: bold; text-decoration: none;">fuse.</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Add a note inside: TURN OFF POWER IMMEDIATELY IF VERTICAL AMP IS GROUNDED EVEN BRIEFLY</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">If you don't think </ins>that's <ins style="font-weight: bold; text-decoration: none;">enough, upgrade R1218 to 15W.</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Ohmite TUW15 ($1) or B20 ($7)</ins>.</div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">These mods </ins>can be retrofitted to any 541/543/545/541A/543A/545A.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td></tr>
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Vintage dave
https://w140.com/tekwiki/index.php?title=545/Repairs&diff=69588&oldid=prev
Vintage dave: copyediting
2021-10-10T22:28:05Z
<p>copyediting</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 15:28, 10 October 2021</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Vertical Amp Fuse==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Vertical Amp Fuse==</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Late-production 545A adds F1054 to protect the delay line when a vertical amp output is shorted to ground. If the fuse opens, all twelve 6DK6's will <del style="font-weight: bold; text-decoration: none;">continue </del>to draw the usual current, but all in the screen grid. A long time ago someone (Stan Griffiths?) worried this would fry them, but I did the math. The 130mA combined screen current drags it down to 220V which is 35V above the cathode which inputs 0.35W of heat which is under the maximum rating. However, R1218 will fry <del style="font-weight: bold; text-decoration: none;">dissipating </del>17W. I think we can head this off by rewiring R1218 so it too is downstream from F1054. Then V1033 saturates sending about 100mA to the control grids, I guess that's okay. The mod can be retrofitted to any 541/543/545/541A/543A/545A.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Late-production 545A adds F1054 to protect the delay line when a vertical amp output is shorted to ground. If the fuse opens, all twelve 6DK6's will <ins style="font-weight: bold; text-decoration: none;">try </ins>to draw the usual current, but all in the screen grid. A long time ago someone (Stan Griffiths?) worried this would fry them, but I did the math. The 130mA combined screen current drags it down to 220V which is 35V above the cathode which inputs 0.35W of heat which is under the maximum rating. However, R1218 will fry <ins style="font-weight: bold; text-decoration: none;">at </ins>17W. I think we can head this off by rewiring R1218 so it too is downstream from F1054. Then V1033 saturates sending about 100mA to the control grids, I guess that's okay. The mod can be retrofitted to any 541/543/545/541A/543A/545A.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td></tr>
</table>
Vintage dave
https://w140.com/tekwiki/index.php?title=545/Repairs&diff=69586&oldid=prev
Vintage dave: 6DK6 screen fry DEBUNKED but mod still desirable
2021-10-10T22:27:02Z
<p>6DK6 screen fry DEBUNKED but mod still desirable</p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 15:27, 10 October 2021</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l13">Line 13:</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Vertical Amp Fuse==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Vertical Amp Fuse==</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Late-production 545A adds F1054 to protect the delay line when a vertical amp output is shorted to ground. <del style="font-weight: bold; text-decoration: none;">However, if </del>the fuse opens, all twelve 6DK6's will <del style="font-weight: bold; text-decoration: none;">fry due </del>to screen grid <del style="font-weight: bold; text-decoration: none;">overheating</del>. <del style="font-weight: bold; text-decoration: none;">This </del>can <del style="font-weight: bold; text-decoration: none;">be avoided </del>by <del style="font-weight: bold; text-decoration: none;">rerouting screen resistor </del>R1218 so it's <del style="font-weight: bold; text-decoration: none;">powered by F1054</del>. The <del style="font-weight: bold; text-decoration: none;">fuse and resistor mods </del>can be retrofitted to any 541/543/545/541A/543A/545A.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Late-production 545A adds F1054 to protect the delay line when a vertical amp output is shorted to ground. <ins style="font-weight: bold; text-decoration: none;">If </ins>the fuse opens, all twelve 6DK6's will <ins style="font-weight: bold; text-decoration: none;">continue </ins>to <ins style="font-weight: bold; text-decoration: none;">draw the usual current, but all in the </ins>screen grid. <ins style="font-weight: bold; text-decoration: none;">A long time ago someone (Stan Griffiths?) worried this would fry them, but I did the math. The 130mA combined screen current drags it down to 220V which is 35V above the cathode which inputs 0.35W of heat which is under the maximum rating. However, R1218 will fry dissipating 17W. I think we </ins>can <ins style="font-weight: bold; text-decoration: none;">head this off </ins>by <ins style="font-weight: bold; text-decoration: none;">rewiring </ins>R1218 so it <ins style="font-weight: bold; text-decoration: none;">too is downstream from F1054. Then V1033 saturates sending about 100mA to the control grids, I guess that</ins>'s <ins style="font-weight: bold; text-decoration: none;">okay</ins>. The <ins style="font-weight: bold; text-decoration: none;">mod </ins>can be retrofitted to any 541/543/545/541A/543A/545A.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td></tr>
</table>
Vintage dave
https://w140.com/tekwiki/index.php?title=545/Repairs&diff=69491&oldid=prev
Vintage dave: Vertical amp fuse warning and fix
2021-10-10T20:10:10Z
<p>Vertical amp fuse warning and fix</p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 13:10, 10 October 2021</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div></blockquote></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div></blockquote></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">==Vertical Amp Fuse==</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Late-production 545A adds F1054 to protect the delay line when a vertical amp output is shorted to ground. However, if the fuse opens, all twelve 6DK6's will fry due to screen grid overheating. This can be avoided by rerouting screen resistor R1218 so it's powered by F1054. The fuse and resistor mods can be retrofitted to any 541/543/545/541A/543A/545A.</ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Instrument repair reports]]</div></td></tr>
</table>
Vintage dave
https://w140.com/tekwiki/index.php?title=545/Repairs&diff=49191&oldid=prev
Peter at 18:39, 16 July 2019
2019-07-16T18:39:52Z
<p></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 11:39, 16 July 2019</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Fan mounts==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Fan mounts==</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>''See also the general article on [[Fan mounts]]''</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">''' </ins>''See also the general article on [[Fan mounts]]'' <ins style="font-weight: bold; text-decoration: none;">''' .</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Ken Chorney says:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Ken Chorney says:</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><blockquote></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><blockquote></div></td></tr>
</table>
Peter
https://w140.com/tekwiki/index.php?title=545/Repairs&diff=49190&oldid=prev
Peter: Created page with "==Fan mounts== ''See also the general article on Fan mounts'' Ken Chorney says: <blockquote> Just wanted to add an alternative supplier for replacement fan mounts for the..."
2019-07-16T18:39:33Z
<p>Created page with "==Fan mounts== ''See also the general article on <a href="/tekwiki/wiki/Fan_mounts" title="Fan mounts">Fan mounts</a>'' Ken Chorney says: <blockquote> Just wanted to add an alternative supplier for replacement fan mounts for the..."</p>
<p><b>New page</b></p><div>==Fan mounts==<br />
''See also the general article on [[Fan mounts]]''<br />
Ken Chorney says:<br />
<blockquote><br />
Just wanted to add an alternative supplier for replacement fan mounts for the Tektronix 545 oscilloscope fan.<br />
Digi-Key currently stocks two part numbers which fit and work perfectly: RPC1597-ND and EAR1345-ND.<br />
Both are 1/2" length (same as original) and both have 8-32 male threaded ends (same as original).<br />
Both are slightly smaller in diameter (0.4" vs. the 0.5" originals) but this does not affect their fit at all and likely does not affect their function appreciably.<br />
I have installed three of the RPC1597-ND standoffs in my 545 and they fit and work perfectly.<br />
</blockquote><br />
<br />
<br />
<br />
[[Category:Instrument repair reports]]</div>
Peter