PL700 Rebuild
- Thread starter Overundr1
- Start date
Power switch and arc suppression?
Is there a forum approved switch that both looks period correct and can handle the current, also could use a ac snubber cap or perhaps a cl-80 style to tame the input jolt to the mains?
Hopefully get the bias resistors for the back plane today
While cleaning up wiring noted the ac line to the original switch had extremely dodgy soldering (weak connection) so add that to the list of things that need to be checked for safety when working on one with unknown history. Have found more poor/cold solder joints on this amp than any of the tube gear I have been through btw.
Is there a forum approved switch that both looks period correct and can handle the current, also could use a ac snubber cap or perhaps a cl-80 style to tame the input jolt to the mains?
Hopefully get the bias resistors for the back plane today
While cleaning up wiring noted the ac line to the original switch had extremely dodgy soldering (weak connection) so add that to the list of things that need to be checked for safety when working on one with unknown history. Have found more poor/cold solder joints on this amp than any of the tube gear I have been through btw.
Quite pleased with the led's 
Three rows in, two more to go, give the inventor of the silipad a beer, cannot imagine trying to get those outputs all installed with the old mica and thermal paste. Might mention that offset on the new WOPL board is 1mv or less in both channels without any input with only minor fluctuations, one of the most stable offsets I have ever measured.
Three rows in, two more to go, give the inventor of the silipad a beer, cannot imagine trying to get those outputs all installed with the old mica and thermal paste. Might mention that offset on the new WOPL board is 1mv or less in both channels without any input with only minor fluctuations, one of the most stable offsets I have ever measured.
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Intend to put a trimmer on them, use the trimmer to determine best resistor value then adjust yes sir.
Happiness is - - - on full mains power - - -
Bias easily adjusts, thermal compensation works as designed as things warm up.
Draw at idle no input
Hard work is done, still have ocd tasks to complete (turret replacement/led adjust/triac mod) then hook her up to the rebuilt PL-4000 for some serious listening time.
Happiness is - - - on full mains power - - -
Bias easily adjusts, thermal compensation works as designed as things warm up.
Draw at idle no input
Hard work is done, still have ocd tasks to complete (turret replacement/led adjust/triac mod) then hook her up to the rebuilt PL-4000 for some serious listening time.
Ok time to call in the troops - - -
Amplifier on mains, bias at 350mv after warm up, offset both channels remains at 1mv or less.
At no to low volume amplifier sounds awful, increase the gain and the amplifier clears up
Nothing gets hot, only the regulator transistors warm slightly.
Bypassed power switch no change
Removed meter drive leads no change
Removed lighting circuit no change
Changed speakers no change
Verified no collector to ground on outputs
Verified RCA predrivers in position two and four right to left from transformer
Before I start adding idle bias (thinking crossover distortion) I thought I would ask.
Amplifier on mains, bias at 350mv after warm up, offset both channels remains at 1mv or less.
At no to low volume amplifier sounds awful, increase the gain and the amplifier clears up
Nothing gets hot, only the regulator transistors warm slightly.
Bypassed power switch no change
Removed meter drive leads no change
Removed lighting circuit no change
Changed speakers no change
Verified no collector to ground on outputs
Verified RCA predrivers in position two and four right to left from transformer
Before I start adding idle bias (thinking crossover distortion) I thought I would ask.
