Akai AM-2800 relay kicking off. Please help!

[Moska77500]

Hello AudioKarma members out there and greetings from Winnipeg, Canada. This is the first time I post a message in the forum, and all help will be much appreciated. I do have a couple of problems with my recently acquired Akai AM-2800 I hope you can help me.

1. The VU meter bulb is not turning on (there is only one bulb for the two meters). I replaced the one that was burnt with a new led 8v, but it is not turning on. Upon inspection I found out the previous one was a 6.3 volt (the manual says 8v). I took a reading from the transformer output and I am reading only 2 volts on it. Not sure what is wrong with it.
2. Assuming I could live with no light on the VU meters for a while, I decided to leave it running and enjoy the sound. After 30 minutes or so, I heard a click from the relay and no sound at all after that. The unit remained on (red LED on), but no sound. Turned the amp off and on again with no luck. Left it off for a few minutes and it worked again, but just for a minute or two. It clicked again. Next day I tried the same thing, with the exact same results.As mentioned, the first click happens after 30 mins (Aprox), left it rest for a few minutes, turn it on again, and next click in a couple of minutes.

Any ideas? Where should I start troubleshooting?
Any help / hint will be much appreciated.
Thanks in advance for your help!

 

[Oldsansui441]

Hi Moska and welcome, beautiful amp you have there, those Akai's are quality units. It will either be your dc offset or a prob in the protection circuit.

I would definitely start by checking your dc offset, best to download the manual and have a read. Be very careful adjusting things in a live unit if you haven't done so before. Also don't trust original trim pots, at the very least (with unit off) use contact cleaner to clean them by turning back and forth many times, then return them to their original position before attempting any adjustment with unit powered on.

If you have a multi meter you can check offset at the speaker terminals whilst the relay is engaged only. Adjust as close to zero volts as possible.

If offset is fluctuating could be the input differential pair transistors failing also.

Cheers.

 

[Okke 70s]

..given that you have only 2V on the meter bulb, I would:
- check input voltage setting
- check all output voltages of the transformer
- replace the mains fuse (if your model has one).

It is indeed a nice amp, I use mine daily. Once you got it running properly I got some refurbishment/tweaking suggestions for ya as well.