Accuphase E-203

[kjbrell]

I have an Accuphase E-203 amplifier from the early 80s which I bought new. It has worked fine all the time but now my left channel has started to make heavy noise and it shut off itself after a while. It seems start when it got a bit warm. I still love it sounds and must repair it.

Do anyone have some guidelines or typical tips for this problem on an Accuphase?

I have not opened it yet.

Thanks.

 

[chicks]

Welcome to AK! There's a schematic for it on Hi-FI Engine: http://www.hifiengine.com/library/accuphase/e-203.shtml Looks like it uses possibly unobtanium MOSFET outputs.

EchoWars refurbished a beautiful E-202, IIRC, and he would be your man to PM regarding repairing this one.

 

[sheltie dave]

I second Echowars. :thmbsp:

 

[kjbrell]

I will look at the schematics, thanks for the quick response.

 

[EchoWars]

Use the rear panel switch to separate the amp from the preamp and see what happens to the 'heavy noise'.

 

[kjbrell]

Hello,
Du you mean the switch on the rear signed "normal" and "separate" for the Pre Out and Main In?

 

[kjbrell]

OK, I understand, there is no difference.

 

[ryuuoh]

Just to check, you don't also have jumpers installed in the in/out jacks? If not, then the pre amp and power amp will be separated by the switch. Since the problem is still there, the power amp has a problem. I wouldn't use it until the problem is fixed.

 

[kjbrell]

No jumpers, it sometimes work OK a very short time and then when the noise starts on the left channel it shuts off!?

 

[ryuuoh]

The protection circuit is activating because there is a serious fault.

 

[kjbrell]

OK, i have open the box and going through with contact cleaner, however I think there is a tricky problem with some component. Trying to review the boards and caps but it looks good, can´t find any leaking cap. Probably needs to be measured up step by step by someone who knows what he´s doing.

 

[sheltie dave]

I thought we already established this in the second and third posts.

 

[EchoWars]

OK, I understand, there is no difference.

This means the issue is in the power amplifier. Being limited to the left channel means the power supply is probably fine, and we're probably looking at a bad opamp (NJM4559) or bad STK3082 module.

 

[kjbrell]

Thanks for the help, I´m working with the amp now.