phase linear 400

gene french said:
for those interested....
4 tested bad....all on the right channel....all 909....
i understand you cant mix....
of course they stopped making these in the late 1800s....
i have a headache...
crap....
Click to expand...
And now you still don’t know what is messed up on the control board that got recapped
 
yep, and finding replacements of the same age will leave you in the same position sooner or later. Don't torture yourself, start picking up the parts for a proper WOPL build.
 
If you discharged them by shorting eachcap with a large resistor then no...if you shorted out the rails then yes..
 
if i remember the sequence...
i powered up with dbt...all good
connected inputs and speakers...normal power...
played 4 or 5 seconds...then quit
i checked the work...c8 polarity was wrong...i discharged the caps and fixed c8...c8 checked good on the dvm
then dbt again....this time bright...
at this point fuses were checked...the agx 5 amps were both bad...they were 8 amps in the place of 5s
agc8amp was good...light bar still lit...
i rigged in some agc 5amp fuses and tried this morning...hence 5 901s are bad ..all right channel..
all were out of circuit...
 
Discharging the caps should not have any potential to damage the outputs. Hopefully you used a resistor anyway, or there would be fireworks.
Outputs generally die due to both positive and negative being turned on simultaneously, (driver trans/board failure or improper biasing) or shorted speaker leads (less likely). Driving to major distortion also.

Guess we were typing at the same time. There were fireworks.
 
Vynuladikt said:
Discharging the caps should not have any potential to damage the outputs. Hopefully you used a resistor anyway, or there would be fireworks.
Outputs generally die due to both positive and negative being turned on simultaneously, (driver trans/board failure or improper biasing) or shorted speaker leads (less likely). Driving to major distortion also.

Guess we were typing at the same time. There were fireworks.
Click to expand...
the top cap was very minor...the bottom cap was a different story...took us 4 hours to get the cat out of that tree....
dont know how the resistor thing works...repairing crts back in the day we just dealt with the noise...
i discharged the sx1080 also before plunging in...
was noisy at times...but never created a problem
before...
 
quit being in a hurry, the caps will bleed down in a few minutes, your process needs work, thats not how to discharge caps
 
Maybe you need a tech to build you an amp

A SCREWDRIVER???? Put the top back on the amp, yer gonna hurt somebody OR BURN YOUR HOUSE DOWN.
 
Buy an amp already done. Being dangerous is a bad excuse. you don't think you can afford one, but the parts you are going to replace (again and again because of age) will add up and you will still be stuck with a bad, ready to blow up, amp.
 
add up what you have already spent on this "Project", and it's still in a smoldering pile.
 
The old CRTs were high voltage, but much lower joules/capacitance. Read as a mild pop. The PL 400 amps with 80 volts and 5900 uF on each rail can be used as welders. Upgraded power supply caps with 10,000 to 15000 will disintegrate a screwdriver. But I guess you know that now.
 
You must log in or register to reply here.
Back
Top