547: Difference between revisions

547 (view source)

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 The 547 uses the Tektronix [[154-0478-00]] CRT.
-A common problem with 547's is the [[hv_transformer|HV transformer]]. Rather than the wax used in older designs,
+A common problem with 547s is the [[hv_transformer|HV transformer]].
-the transformer was potted in a new epoxy resin, which turned out to absorb moisture over time when used in humid
+Rather than potting the HV transformer in wax,
-climates.  Excessive leakages requires the regulator to drive the [[6AU5]] input oscillator tube (V800) harder.  Eventually, the drive circuit can not supply enough power to keep the supply in regulation.
+as was done up to that point,
-The usual solution is to scavenge a replacement from another scope.
+the 547's HV transformer was potted in epoxy.
+Unfortunately, this epoxy turned out to absorb moisture over time,
+particularly when used in humid climates.
+The moisture causes increases losses in the transformer.
+Excessive losses requires the regulator to drive the [[6AU5]] input oscillator tube (V800) harder.
+Eventually, the drive circuit can not supply enough power to keep the supply in regulation.
+The usual solution is to scavenge a replacement transformer from another scope.
+As a labor of love, hobbyists have been known to rebuild the HV transformers.
+This is discussed from time to time on the Yahoo TekScopes forum.
 The 547 has a five-stage BJT vertical amplifier that is fully differential from the plug-in