Pioneer SX-434 Power Board issue

[Walterramjet]

Yesterday, I received my new-to-me Pioneer SX-434.
The ad on ebay said it was recently serviced and in good working order. The trouble is, I discover after plugging in that the only thing working are the dashboard lights. That makes sense because the transformer secondary that feeds the lamp circuit goes to the power board, then through a mini-fuse and leaves the board and onward to the lamps.

What I dont know for sure; What are the engineered voltages of the power transformer secondary taps supposed to be? None of this info appears in the service manual or on the drawing. I do see what the DC volts should be around each transistor and power board output (B+ etc...). It would be nice to know what the power transformer's secondary AC volts should be for terminals 9,7, and 8 on board AWR-062. The scratch-pad has the measured values with 120vac supplied to the primary. Thanks

 

[ivandezande]

I don’t think the voltages in matter…..Why do you need to know them?
Also why did you measure AC on the DC outputs?
What are the DC voltages on pins 2, 3, 4, and 5?

Did you check the speaker protection fuses?


Next time I’d post in the Pioneer subforum. More eyes.

 

[Walterramjet]

I wrote down the AC volts first and then realized they should be DC.
The voltages on pins 2, 3, 4, and 5 are clearly written on the scratch pad.
The fuses are good.
will post on Pioneer subforum. Thankyou.

 

[ivandezande]

I wrote down the AC volts first and then realized they should be DC.
The voltages on pins 2, 3, 4, and 5 are clearly written on the scratch pad.
The fuses are good.
will post on Pioneer subforum. Thankyou.

Gotcha, sorry, the writing confused me.
The AC in values look right.
So where does the voltage stop? Does the AC get through each fuse? Do the diodes turn it into DC?
Find that, and you’ll find your issue. Seems like you’re missing a ground or something weird.

 

[Walterramjet]

thank you Ivan. yes, the AC volts gets through the fuses, but you are right, I haven't looked at the diodes and capacitors. I'm worn out so hitting the hay. will have to pick this up in the morning. carry on bravely!