Akai AA-1135 Revival / On the bench

[Smitho]

First Post! 

 

Have used SNA as a great resource over the years and thought I'd start participating a little more. 

 

Lucky enough to find this immaculate non-working aa-1135 example locally in Adelaide.  I've read how they are a little underrated and were one of the big rivals to Sansui etc. 

 

 

 

Symptoms were - no sound. Was hoping for something simple however it wasn't quite the case. 

 

Got it home on the bench. The protection relay had kicked in. I popped the cover and was a little concerned that someone had been there before me. There was an LED kit fitted, and a large cross next to the left channel "Batwing" output transistors. There was also a large ceramic 5w resistor blown apart on the board with one half completely missing. 

 

 

I proceeded to check the output transistors, even though I still suspected them, they tested ok. Given the large resistor had blown, there had been a large current draw. I tested the driver transistors next and they disappointingly tested ok. Power supply and relay tested ok. Fairly stumped, I thought I would take a stab in the dark and rebuilt the amp board starting with the transistors.  

 

 

 

Upon starting the rebuild of the amp board, I found that a driver transistor (2sd438 I beleive) had infact gone short. Which I was a bit of a moment for me. Being a little bit of a novice, checking transistors I must have overlooked the fact that it had gone short between Collector and Emitter. I replaced the NPN and PNP pair with KSA2690 and KSA1220 replacement pairs on both channels. 5W resistor was replaced. 

 

 

After some hesitation and checking with the Dim Bulb tester. It worked. I adjusted the DC offset and I gave the whole thing a once over with deoxit and a clean.

 

I used it as my main amp for a few weeks however I was slightly underwhelmed with its sound. Not deterred I decided to give it a recap. I utilised decent Elna Silmics and Nichicon Fine Golds/Muse. 

 

I must say, giving a 41 yo amp a recap did it wonders. Really cleaned up the high frequency to my ears and brought some clarity to the soundstage. It brought a smile to my face, and was really worth the effort.  Hopefully it'll go for another 40 years! 

 

 

 

 

[curuxz]

This post is great, it is the same issue I have. I hope you don't mind I have sent you a PM asking about exact parts, I think this is the key to getting my AA-1135 alive again!