It means the diode may be shorted of have leakage, checking with meter show reading in high Meg Ohms range, so I use my LC75 leakage current test, two of the diode show off scale leakage current at 50V scale (GI854 is rated at 3A, 400V ), seeing 3A rating and the location where these Diodes are which the board turned brown so they have been running hot. So something is not right, I check the ripple frequency, it show 60Hz instead of 120Hz for full wave rectification. The AC output of the transformer is just a little over 6VAC, so I expect the DC to be higher than that and should be close to 6VDC at full load by the tube filaments. Check the AC ripple with my Fluke RMS, it shows >1VAC. I check the DC voltage it shows about 4.5VDC which seems to low for 6V filament. I look on line and see that the some of them has 4700uF 25V some of them has 10,000uF (this one has 10,000uF 35V installed by the repair shop). Open it up and it looks like the filter cap for DC power supply for the filament and the audio source selector relays has been replaced. I turn it on and can hear the relay clicking away for about 1/2 minute and then stop, I can get the sound from the amp through the speakers OK. ![]() ![]() I have this unit in for repair, it was supposedly repair by the High end pro shop due to clicking sound when it is first turned on and was not as loud as it used to be.
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