Foreplay 3 amp no output (Paramount)

[Paul Birkeland]

If tapping things changes voltage dramatically, you should go through and reflow all of the solder joints in the amp and look for broken wires.  If you'd like to send these in for repair, I do handle legacy repairs and I can get this amp fixed up for you.

-PB

 

[Mr. Self-destruct]

Cool thanks, gonna reflow first.

 

[Mr. Self-destruct]

223 vdc on the green board Transistor

 

[Mr. Self-destruct]

250vdc on one Transistor
500 on the other.
Little green board w 4 leds,the Transistor has 223vdc

 

[Mr. Self-destruct]

Still getting same issue. I'll check voltages again. Tomorrow with the manual.

 

[Mr. Self-destruct]

Voltages.
It's been on for over an hour. If it does fault, as soon as I goto take voltages, it comes on.

 

[Paul Birkeland]

If you look at the white printing Q2 on the A side of that PC board, then look at the large blue resistor next to it, you can see a typical solder joint that hasn't flowed out all the way.  You can see the brown flux built up in the middle of the joint around the lead of the resistor, and that kind of joint can cause intermittent issues that seem to resolve themselves as soon as you touch them. 

Having said that, it's also really important not to resolder any of the LED solder joints, as that can damage the LEDs since they have been sitting around absorbing moisture over the last decade or so, and heating them up will boil that moisture right out and blow the LED.

 

[Mr. Self-destruct]

Thank you! I do see that.  Just reflowed.
It was playing a few hours today before it went out. When I took it to the bench, even when I went to test voltage on the main board Transistor, it came on. Hope that reflow did it. Cheers!

 

[Mr. Self-destruct]

Turned it on today nothing out of one block. When I unplugged it and looked underneath one LED was lit for quite a while after it was unplugged then it went out slowly put it on the bench, came on right away and then was intermittent.  I will attach a video. https://youtu.be/n2ojGXXEJZI
Tested all 20 terminal strips. Voltage is properVariation 10 to 15%

 

[Mr. Self-destruct]

I'm also getting 123 to a 124 V out of the wall I don't know if that makes a difference but I when I tested the terminal strips I was using my variac at 1:19 like it says in the manual.

 

[Paul Birkeland]

If poking the power supply board is having those effects, there may be a loose part or a bad solder joint on the power supply board (which is a total PITA to remove).

 

[Mr. Self-destruct]

Really pretty much poking anywhere on here brings it back to life but yeah it does look like a pain in the ass to remove

 

[Paul Birkeland]

A broken wire would create these kids of issues. If you just barely touch the bad wire with your meter, it should easily set that off.

 

[Mr. Self-destruct]

If I barely touch ANYWHERE it will set it off. 1st board, 2nd board, transistors, tabs,.....anything high voltage. Meter touches, brings it back to life.

 

[Paul Birkeland]

If I had that amp on my bench, I would poke around to see what was most sensitive or what I could do to make the problem permanent, then take measurements to see what's missing.

 

[Mr. Self-destruct]

When I poke around with a wooden paintbrush on everything nothing changes as soon as I use any piece of metal whether it's needle nose or a screwdriver that's when it comes back to life

 

[Mr. Self-destruct]

I reflowed the 2n2907 .  one LED's does not light anymore  but I'm not getting the speaker ticking like I was before using the probe. Audio but no treble

 

[Mr. Self-destruct]

1. 445dc
5. 64dc
6. 64dc
7. 200dc
9.  270dc
11. 200dc
12 128dc
14. 57dc
15 1.2dc
16. 465dc
19. 275

 

[Mr. Self-destruct]

One LED out, no treble,  290vdc to b1 on 9 pin socket. Should be 195ish. Other 8 pins read fine.  Touched terminal 11 all leds lit and treble came back, touched another terminal went dark again.

 

[Paul Birkeland]

You have a loose or broken wire.  I wouldn't bother reflowing a transistor on the C4S board when you can poke the power supply board and cause things to drop out.