ChuckA:
OK, I believe you are correct in determining that T601 is likely not the
problem.? I did not pay as much attention as I should have to your
original email where you already mentioned that the +500VDC line is
solid; my apologies.? I probably have some "tunnel vision" as I've seen
likely T601 failures discussed in several Tekscopes group threads over
the years.
Mike Dinolfo N4MWP
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On 5/2/24 19:20, ChuckA wrote:
I've pretty much verified that the LV supply (T601) is good. When the
T602 voltages drop the +500V output from T601 doubler
stays constant, as do the filament voltages.
ChuckA
On 5/2/2024 6:13 PM, Mike Dinolfo wrote:
The voltage breakdown of the CRT heater winding, which can indeed be
resolved by installation of a new 6.3 VAC filament transformer, is a not
uncommon failure mode for many 500-series scopes.? But it applies to the
60 hz power transformer (T601 in the 503), rather than the ~25 khz
transformer (T620 in the 503).? The original poster (ChuckA) indicated
the failure was in T620- ????? Several years ago, I myself fixed a 504
(similar power supply) which had the same power supply, and the same
symptoms that ChuckA described (i.e, erratic voltages derived from
T620).
I prepared a writeup of the process that I went through to identify the
problem area (T601 vs. T620) and posted the results to the Tekscopes
site, but I don't recall where I put it on the server.
Mike D? N4MWP
Mike Dinolfo