sansui g8000

[maclvrbr]

I see the speaker relays cannot work with out RL 03 correctly operating. I assume now what I have is a signal problem. After c;leaning the switches I now do not have either right or left signals from headphones , thanks for the guidance

 

[maclvrbr]

I have confirmed all relays are working correctly . Also the right channel does work but left channel is missing thanks.

 

[LBPete]

It sounds like it's in protection. The output signal passes through the MY4 relay before going to the two LY2 relays. These are the three relays grouped together on the power supply board. Next to these relays, there are two coils each with a big resistor in parallel. The amplifier output circuit passes through them before going to the relays. Measure the voltage between chassis ground and each of these resistors. That will give you a close approximation the DC offset voltage. If its higher than 100mV or so it will kick into protection. If it's not too high, you can adjust it down with the trimmers on the driver boards.

- Pete

 

[LBPete]

You posted while I was writhing my last post. If you have normal sound from either channel, it's not in protection and the relay coil circuits are working. Do you have another amplifier or receiver that has pre-outs? Connect the pre-amp of the other amplifier to the amp of the G-8000. This will tell you if the channel drop is in the pre-amp or amp of your G-8000.

- Pete

 

[maclvrbr]

Yes the receiver is not in protection red light blinks for a few seconds then green light appears solid, also Dim bulb is barely illuminated,, From preouts to auxillary of another receiver I still only have left channel with sound.

 

[LBPete]

No, not pre outs to aux. Move the connected/separated switch to separated and connect the pre out of the other amp to the Main in of the big G. This will bypass the pre-amp in the G. If that gives you sound from both channel, you know the amp section is good and the channel drop is in the preamp section of the G.

Before you do that, have you jumpered across the pre-out/main-in of the G? This will bypass the connected/separated switch. Use the shortest RCA cables you have. This will test the connected/separated switch. If you get sound from both channels when you do this, the switch is the problem.

- Pete

 

[maclvrbr]

I jumper ed the preout- main in connections still one channel operational. Connected a cd player to main in connectors of the G and still only one channel operational

 

[LBPete]

That brings us back to the relays. Do you have a small speaker a piece of speaker wire and a couple of alligator clips you can use for testing? If so, and you can carefully connect that test speaker to a point on a circuit board, go back and look at post #23. Connect one lead of the speaker to chassis ground and touch the other lead to each of the resistors mentioned in post #23. This will test the amp circuit up to the speaker relays. Be very careful when you do this, not to touch anything else.

- Pete

 

[maclvrbr]

Thanks for the help, I did get sound from one set of resistors but did not from the other set.

 

[kevzep]

Have you tried some headphones? This will narrow down whether its the speaker relays or not.
If you have not got audio in both channels then it is very likely in the power amp for that channel.

 

[maclvrbr]

I have used the headphones only one channel audible

 

[kevzep]

I think the problem is back in the amplifier. The relays are not the issue I'm thinking.

Okay so we know the issue is in the power-amp, that narrows it down a lot.
Have you measured the bias to see if theres current flowing though the circuit?

 

[maclvrbr]

I will check it, the manual states checking bias using TP+ and TP- for 16mv, I cannot find these test points, pg 12 of service manual, thanks

 

[dr*audio]

TP + and - are on small terminal strips in the 2 rear corners.

 

[Hipocrates]

I cannot find these test points, pg 12 of service manual, thanks

 

[maclvrbr]

Thanks

 

[maclvrbr]

left rear bias .9 mv, right rear bias 0mv. Ideas? I also connected a cd player into aux input on G and did not get sound from either channel.

 

[LBPete]

left rear bias .9 mv, right rear bias 0mv. Ideas?

The bias test point terminal strips get oxidized. It's sometimes hard to make a good connection. Scrape a shiny surface on them and test again. 0.9 mV is essentially zero so you probably are not getting a true reading.

I also connected a cd player into aux input on G and did not get sound from either channel.

Did you have the connected/separated switch in the correct position? When you connect to the aux or any of the other normal inputs the connected/separated switch has to be in the connected position. If you connect to the main in that switch should be moved from "connected" to the middle position.

In the various tests, when you get sound from one channel, is it always the same channel with sound?

Thanks for the help, I did get sound from one set of resistors but did not from the other set.

Here's a picture of the speaker relays on a G-9000DB. It's very similar to a G-8000. You see the gray covered coils with the big gray resistors with two red stripes on either side of them. The audio output from each channel of the amplifier passes through these coil/resistor combinations. Did you touch your speaker wire to the conductor of each of these resistors? When you say you got sound from one side, was it fairly normal sound?



- Pete

 

[maclvrbr]

yes Pete the sound was normal , as mentioned I only got sound from the resistor on the left sie closest to relay. No sound from the resistor on the right ( between the 2 relays), thanks for the help again. I did think the values were low and will recheck bias.

 

[LBPete]

If you didn't get sound at one of these resistors and you are feeding a signal into the "Main In" terminals, than the dropout is definitely in the amplifier for that channel. Get a good bias current reading and we'll go from there.

- Pete