Kenwood KR-9400 Multiple Issues; Help Wanted

[gort69]

Which outputs did you buy, and from whom? I hope not ebay - high risk of fakes

2sb539 PNP sub mj21193g https://www.mouser.com/ProductDetai...=sGAEpiMZZMshyDBzk1/Wi/PUgtclNldlku4LxBLjaR8=

2sd287 NPN sub mj21194g https://www.mouser.com/ProductDetai...=/ha2pyFadujEihMqaz/hhkq6TQqOjR1kS1vnU717vwU=

 

[Shaun b]

The sb539 I found original new old stock of. The sd287 I did get from eBay but from a seller who had like 100,000 sales with 100% feedback. They tested ok. For as much as u can test with a dmm

 

[Shaun b]

Regarding +/-B at +/-62Vdc.
This is an unregulated supply.
What is the voltage rating on the main filters. SM has 15000uf/50V with a +/-B at +/-46Vdc.
If main filters are 50V then it's a voltage "input/selector" problem
If mains are 63 or ...80V then it's a SM error, move on...

They are 80V. I think its in the amp board although Im not sure. I know when its not hooked up I get sound from the other side. I tried with board seated and outputs removed but it still would not come out of protection

 

[gort69]

It sounds like the left amp board then. I would remove the left amp board and set it aside and move the right amp board to the left card slot and see if you get audio out of the left channel.

 

[Shaun b]

It sounds like the left amp board then. I would remove the left amp board and set it aside and move the right amp board to the left card slot and see if you get audio out of the left channel.

I replaced couple resistors and a transistor that came out of another receiver and now it comes out of protection but the sound is weak and the volume knob doesn’t seem to control it. The right channel sounds so good. I can’t wait to hook it to my
Altecs. I’m gonna look through some parts I have and see if I have any caps of these values. Should I be looking at any specific component based on new info?

 

[gort69]

Which transistor did you replace, why and with what?

I would - starting with the drivers (Qe10, 11) and working back toward the input (Qe1,2) - pull and test the transistors using the 6-way diode test. If you find a bad one(s) (likely) don't buy a replacement from ebay! You're just begging for trouble if you do. Buy the appropriate subs from a reputable source such as Mouser, DigiKey, Newark etc.