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A common problem with 7000-series scopes | A common problem with 7000-series scopes are the sockets in the mainframe that accept the | ||
plug- | plug-ins. The fingers of the connector are springy metal. The fingers are supported by a flat piece | ||
of plastic on either side of connector. This piece of plastic tends to crack, which causes the connector | of plastic on either side of connector. This piece of plastic tends to crack, which causes the connector | ||
fingers to be unsupported, which causes bad electrical connection with the plug-in, which typically | fingers to be unsupported, which causes bad electrical connection with the plug-in, which typically | ||
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Bought the nice 7504 Ebay 112036180730 recently, which after some cleaning was | Bought the nice 7504 Ebay 112036180730 recently, which after some cleaning was | ||
nearly as new from its cosmetic appearance, but as many of these had the connector | nearly as new from its cosmetic appearance, but as many of these had the connector | ||
problem. This made the operation on all | problem. This made the operation on all plug-in places useless with random uncorrelated | ||
faults. | faults. | ||
</blockquote> | </blockquote> | ||
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are not the problem, but the deterioration of the plastic covers on the sides of these | are not the problem, but the deterioration of the plastic covers on the sides of these | ||
connectors. If they loose their strength, the contact pressure is gone. In order to apply | connectors. If they loose their strength, the contact pressure is gone. In order to apply | ||
the procedure below, the plastic covers must still be | the procedure below, the plastic covers must still be in place and not broken. Sorry for | ||
bad pictures, I was in a hurry. | bad pictures, I was in a hurry. | ||
</blockquote> | </blockquote> | ||
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I had boards of what we call Pertinax, synthetic resin paper, of 5 mm strength, the width | I had boards of what we call Pertinax, synthetic resin paper, of 5 mm strength, the width | ||
of the boards was 75 mm and it may not be much more - if you cut it, it must be shorter | of the boards was 75 mm and it may not be much more - if you cut it, it must be shorter | ||
than the connector itself, have a look at the other side. I had to cut eight pieces of 23 mm. | than the connector itself, have a look at the other side at the plug-in itself. I had to | ||
cut eight pieces of 23 mm. | |||
</blockquote> | </blockquote> | ||
<blockquote> | <blockquote> | ||
For the raw material see picture 0 below. It surely is possible to use a different non conductive | For the raw material see picture 0 below. It surely is possible to use a different non | ||
stiff material instead. | conductive stiff material instead. | ||
</blockquote> | </blockquote> | ||
<blockquote> | <blockquote> | ||
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four-plugin unit. On one place the distance was only 4 mm, but the piece was easy to | four-plugin unit. On one place the distance was only 4 mm, but the piece was easy to | ||
file down. At some points additional rasping is necessary due to wires or components, | file down. At some points additional rasping is necessary due to wires or components, | ||
but most of the gaps are clear of these. | but most of the gaps are clear of these. The Pertinax is easily treated. | ||
</blockquote> | </blockquote> | ||
<blockquote> | <blockquote> | ||
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On the outside, the two remaining pieces must be fixed to the connector side in a different | On the outside, the two remaining pieces must be fixed to the connector side in a different | ||
way. I used two metal bars for this and carefully made screw holes to the edges of the | way. I used two metal bars for this and carefully made screw holes to the edges of the | ||
connectors. See picture 1 with | connectors. See picture 1 with plug-in; here you can see also why the strips may not | ||
have the same length as the connector. | have the same length as the connector. | ||
</blockquote> | </blockquote> | ||
<blockquote> | <blockquote> | ||
It was useful to take the main board off the instrument to perform this work | It was useful to take the main board off the instrument to perform this work, but I did not | ||
remove the fixed wiring. It took few hours to do this, but was worth the effort. The | remove the fixed wiring. It took few hours to do this, but was worth the effort. The plug-ins | ||
have a tight fit now and the scope is working perfectly well. | have a tight fit now and the scope is working perfectly well. | ||
</blockquote> | </blockquote> |
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