AKAI PS200C Pre and PS120M Power Amp

[skippy124]

Hi,

Had these come in for a quick look over and repair of the Pre amp that had started smoking. I thought that it might be of interest to post up some pictures, there is no a lot of info on these. Apologies in advance - some of he photos are not ideal!

The preamp -







output transistors




lots of large Nichicon bi polars




The cause of the smoke



These Rifa class X noise suppression caps are known to fail spectactuarly - smoke and then in some cases flames!

There are a couple on the power switch - one of these is on the way out



All three were replaced







The offset trim pots were also replaced with multiturn versions to make the offset adjustment easier to perform and for better stability over time. All function were checked, and some noisy controls attended to.

I also had the companion power amp in for a quick look over, and to repalce the 4 meter globes. This power amp is the lower output verson - 130W per channel (the PS200M is 220W per channel).

Very well built, dual mono power supplies, large heat sinks, two pair of output transistors per channel, and weighs 30kg!!











heavy duty output leads





output caps





lots of watts in......





I didn't get a chance to have a listen to the combo, possibly I will get a chance if it comes back for a Led conversion for the Power Meter illumination.

Cheers

John

 

[restorer-john]

Maybe a bit of preventative maintenance on the brown goo of death next time in comes in might be also a good idea?

Nice internal shots.

The Hitachi epoxy encapsulated twin reed relay (on the preamp output) is also often an issue- the epoxy reacts with the copper relay coil and corrodes it internally resulting in an open relay coil and a dead output.

 

[skippy124]

Hi John,

I did advise the owner that some remedial work should be considered next time it is in for the LED upgrade. The glue in the power amp is not too bad in terms of collateral damage to surrounding components. In the Pre I replaced a couple of transistors that had lead corrosion due to glue contact.

And thanks for the tip re the double reed relay!

Cheers

John

 

[avionic]

A lot of oxidation on those heavy violet wire fasteners.

 

[restorer-john]

Those little epoxy reed relays are trouble yes. Akai used them in quite a few of their slimline silver 80s preamps and Hitachi used them in quite a few of their tape decks. Marantz used them as headphone output relays on the PM80 (quarter A). So if you ever get a PM80 that the headphone socket doesn't work- you know why- that little Hitachi epoxy bastard.

 

[restorer-john]

What I find interesting is that all the speaker wires are violet, left right, positive and negative. Original however as web shots are all violet.

That's funny.

 

[slimecity]

I knew Akai made some nice gear - these are lovely - were there many hi-end Akais made by the company?

 

[restorer-john]

I knew Akai made some nice gear - these are lovely - were there many hi-end Akais made by the company?

Not in quantity, but yes, Akai made some awesome TOTL stuff.

Take for instance the reference master amplifiers, cd players and cassette decks, tuners etc in the late 1980s.

They also had a reference midi system the likes of nothing I have seen before or since- the M-930 system. I have three pairs of the prototype speakers from that system. The drivers are die cast, pure carbon fibre and vapour deposited titanium.

Their TOTL open reel decks were lovely too.

Have a look at a GXR-99 cassette deck if you want to see high end early 80s from Akai.

 

[slimecity]

Nice. yea I had an AM-2800 at one stage. Totally lovely - great build quality & sound. Inside the amp it was really nice. The knobs were awesome too and they were so shiny the amp was blinding when sunlight hit it, sweet.