Resurrected a Customized WOPL 400

[laatsch55]

The little , green, resistor lookin things....

 

[scottonnob]

The little , green, resistor lookin things....

Okay, I'll be right back.

 

[laatsch55]

With no outputs in, no fuses blowing, the bulb should be dark. The cycling you are talking about is the recharging of the main caps. If the +/- 15 voltage is good, and the backplane fuses are good , I don't think there is anything wrong...

 

[scottonnob]

Yeah, dah, of course. Now I understand. There are two fuses on each board. On both boards, the top fuse has continuity, but not the bottom. The bottom has no continuity.

 

[scottonnob]

With no outputs in, no fuses blowing, the bulb should be dark. The cycling you are talking about is the recharging of the main caps. If the +/- 15 voltage is good, and the backplane fuses are good , I don't think there is anything wrong...

My other problem, however, is that the relay isn't working.

 

[laatsch55]

A blown backplane fuse could cause the relay not to work. Check DC offset next time it's turned on...

 

[scottonnob]

A blown backplane fuse could cause the relay not to work. Check DC offset next time it's turned on...

So how and why would those backplane fuses blow?

 

[scottonnob]

So how and why would those backplane fuses blow?

So I guess I'm dead in the water until I can get more backplane fuses, correct?

 

[laatsch55]

You had problems with a bias tranny right?? Check offset on both channels...

 

[scottonnob]

You had problems with a bias tranny right?? Check offset on both channels...

I didn't check the bias. I'll do it right now. I thought the fuses would make everything moot. But I'll put the meter on it now.

 

[laatsch55]

Not bias, offset. CHECK offset.

 

[scottonnob]

From the bias test points on the board, to the respective + speaker posts I get open circuit. Nothing. On the top +15v point, I get +15v. On the bottom -15v point, I get 1.4v. Also, I'm not getting any voltage to the leads that provide power to the meter light-fuses.

 

[scottonnob]

From the bias test points on the board, to the respective + speaker posts I get open circuit. Nothing. On the top +15v point, I get +15v. On the bottom -15v point, I get 1.4v. Also, I'm not getting any voltage to the leads that provide power to the meter light-fuses.

Sorry, 0 offset, both channels.

 

[laatsch55]

With the relay out, youre not going to get anything from the speaker posts, you'll have to test from the "out" test point on the backplane. Check rail voltage on the top of the backplanes also...

 

[scottonnob]

With the relay out, youre not going to get anything from the speaker posts, you'll have to test from the "out" test point on the backplane. Check rail voltage on the top of the backplanes also...

Okay, one more time. Be right back.

 

[scottonnob]

From GND, TP3 to OUT on the backplane boards, I'm getting, believe it or not, left 66.8vdc, right 12.94vdc.

 

[laatsch55]

Try ground to TP3...

 

[laatsch55]

Rail voltage?? TP1, TP5.....

 

[laatsch55]

Scott TP3 is OUT, I see Ground to TP3...

 

[scottonnob]

Try ground to TP3...

Yeah, I did use TP3 for a ground on both boards.