Quote:
Originally Posted by VintagePC
Still twiddling my thumbs.
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The only issue I could see is with the set's floating ground- Would it cause an issue if I plugged in an audio source with a hard-wired ground?
Anyway, once I've recapped, what would be the best way to power up the set? I don't have a variac (alas) but I'd thought to pull all the tubes, check the transformer output voltages, and then put the tubes back in one by one, testing voltages (indicated on the schematic) as I go.
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No problem with ground floating ground, it will just cease to be floating
when connected to a grounded source. This is not really a hot chassis,
the power transformer does provide isolation. You can ground the chassis
to earth if you make sure you have the correct power line polarity as
discussed before, end even with incorrect polarity, the leakage will
be small and tolerable as long as the line filter components (one
resistor and two capacitors) are OK.
Do not plug the tubes one by one! Instead, install all the tubes
except the rectifier. It would be best to start up with a variac
(do a bit of research with this word), or with an incandescent
bulb in series, but in a pinch the line fuse will do. With power
applied, tube heaters should light up (not very bright, but visible
in the dark). Let the set run (while watching) for maybe 30 minutes.
The power transformer should get mildly warm, but not any hotter.
Without rectifier, no DC will be generated, so no voltage measurements
to be done at this point.
You may use your old tubes for this test (hope you did not discard
them), many or all are likely to be good. Bad tubes would be
detected later by measurements and substitutions.
Now with power off, install the rectifier tube. The time for the
full test is approaching. Securely hook up your DC voltmeter to C23 and
ground. Turn on power, and watch the meter. The situation
is now the same as before, so no sparks are expected, but as
the rectifier warms up, the correct DC voltage (275) should appear.
If the value is substantially lower, it means you have a short somewhere
down the road from the rectifier, HIT THE POWER SWITCH. Otherwise,
listen for some hum in the speaker, etc. You may start doing the
voltage measurements you suggested.
This should get you going for a while. Good night.