700/1 “Tim” WOPL driver board

[AngrySailor]

I would need a dummy 8 ohm load to test Tim’s output right?

 

[laatsch55]

Test it for what?

 

[laatsch55]

I’ll have to check the 5 ohm jobs again. Measured them in circuit for 2.5 so I’d assume they’re both 5ohm... no odds Lee, not many 700/1’s pop up easy thing to miss. Bias seemed to steady out after a minute. I’ll check again, left the top off. I’m doing a voltage in/out check at 1khz on the carver rn. Seems to be lacking output. I think I’m clipping the carver before I can drive tim to clipping. Somethings quiffy...

Yeah, don't sound right. Unplug the Carver and let it sit for a few minutes and try again.....

 

[laatsch55]

That Carver tested at 838 into 8 ohms....

 

[AngrySailor]

That Carver tested at 838 into 8 ohms....

Sorry lee I’m talking about the carver pre amp. Was wondering about testing Tim’s output voltage at say 1khz with required input signal. My scope isn’t working to watch for distortion but would give me an idea if it’s putting out near rated power at 1.4?v input?

the carver pre amp is giving me wonky readings. Gotta step out for a little bit glen is helping by phone and there’s 60hz AC at near all the rca jacks... she’s not right... Tim’s dead silent no input though.

 

[laatsch55]

1.75 volts input on Tim to get to 350 per...I think that's 53 volts??

 

[AngrySailor]

1.75 volts input on Tim to get to 350 per...I think that's 53 volts??

Just going through checks with glen and testing signal strength through the path. Tim’s getting the voltage out of the pre, the pre can drive nearly 3v. If I put a 70hz tone from the pre into Tim and turn up the volume it clips as 18vac on the speaker outs. 4 ohm woofer section. Seems low.

 

[AngrySailor]

Right channel clips at 18v left no clipping at 24v and I need to reset the generator for any more input... ok left channel clips at 27vac @70hz, right channel clips at 18vac@70hz. Seems there’s a right channel problem and that’s the speaker side I though needed to be re-coned but it’s clipping. I even swapped the drivers between left and right cabinets...

 

[AngrySailor]

Somethings wrong on the right channel. Bias was 350 now it’s 565 and not really adjustable... I’ve had problems bringing up the right channel especially with the second row of outputs... I think something wonky there like a bad transistor socket...

 

[laatsch55]

Could very well be. Check the test points on the driver board, make sure you are getting +,- 15 in the middle and rail voltage on the top test points...all 4 rail fuses good?

 

[AngrySailor]

Rail fuses good, +\-15v checks good both channels. Bias 565mV right channel pot at minimum. Gotta put it back on the bench and pull that second row I bet it drop to 180mV...

 

[laatsch55]

With a shorted output, you can have a wounded bias resistor and/or wounded emitter resistors..

 

[laatsch55]

Clean them sockets and put a little squeeze on the socket tubes...

 

[AngrySailor]

Same intermittent issue with this right channel. Back to 13v bias with no outputs installed. This went away last time I cleaned the backplane thought I had it licked. The amount of thermal
Paste through last guys used on this amp is obscene... I really need to remove all the guts down to the bare chassis to Clean it all... temped to power wash this fucker or put it through the dishwasher!!!

 

[AngrySailor]

Right channel bias resistors just let the smoke out on the right channel negative rail... think I’ve got to walk away for the day!

 

[AngrySailor]

Fug...

 

[laatsch55]

Time to check the bias trannie, andf the rest of those emitter resistors..

 

[J!m]

Same intermittent issue with this right channel. Back to 13v bias with no outputs installed. This went away last time I cleaned the backplane thought I had it licked. The amount of thermal
Paste through last guys used on this amp is obscene... I really need to remove all the guts down to the bare chassis to Clean it all... temped to power wash this fucker or put it through the dishwasher!!!

Remember- top rack only.

 

[laatsch55]

Same intermittent issue with this right channel. Back to 13v bias with no outputs installed. This went away last time I cleaned the backplane thought I had it licked. The amount of thermal
Paste through last guys used on this amp is obscene... I really need to remove all the guts down to the bare chassis to Clean it all... temped to power wash this fucker or put it through the dishwasher!!!

Doubt the dishwasher would do it...

 

[Floyd Loonie]

Very nice job! How did the unit work after the effort and time? I asked around about WOPL for my PL700/1 that is stuck in protection circuit mode, and the replies I received were overwhelming for the "don't waste your time & money/not worth doing" side of the opinion poll! Ican understand the OG 700/1 is kind of a red-ish tinted dred lock lookin' step child, but I had that amp for many years & it was reliable and was 50 years old when it finally quit working... Lots of HiFi amps stop working long before that age!! I don't have the training,skill, or any of the necessary test equipmet needed to fix the unit. But I have not given up on finding a way to put it back in service playing music for someone else to enjoy. I enjoyed reading your comments that were posted as you put that board together. THANK YOU!!