Nakamichi TA-2A with no sound...

Hello all,

Today I went to an estate sale and found a pristine Nakamichi TA-2A. No scratches or other visible wear on the outside, just covered with dust. I brought it home and hooked it up...all the lights and switches seem to be working and I can hear the "click" a few seconds after powering up but I can't get any sound out of it. I tried both A/B channels and nothing. What I do hear after turning it on is a slight buzzing noise from the transformer...or at least it sounds like that's where it's coming from. I thought that may be the problem but I'm a novice at best when it comes to the internal workings of an amp. Any suggestions on how to better diagnose the problem would be greatly appreciated. Thanks!

Are the jumpers in place from pre out to main in?

Happy trails,
Larry B.

Yep, jumpers and then check fuse.

I'll bust it open and check. Just to be sure, is there any way you can help me identify where the jumpers are?

Back panel, more or less dead center, just to the left of the speaker connections. No need to open anything.

Happy trails,
Larry B.

reible82nd said:

I'll bust it open and check. Just to be sure, is there any way you can help me identify where the jumpers are?

Click to expand...

Like these

Pre Output to Main Input:

There are no jumpers! Man it was right in front of me and I never even thought to look. Could I use a short set of RCAs or do I actually need jumpers?

Yes, RCA works the same way.

Let us know what happens once you connect the cables. I also have a TA-2A, with a strange problem.

Sunny, is that pic yours or off the net?

Happy trails,
Larry B.

1tumbleweed said:

Let us know what happens once you connect the cables. I also have a TA-2A, with a strange problem.

Sunny, is that pic yours or off the net?

Happy trails,
Larry B.

Click to expand...

From the web.

I had the same missing jumper issue with Rotel RX-855 though.

What kinda problem are you having?
I have 4A if you think of upgrading.

Mystery said:

What kinda problem are you having?
I have 4A if you think of upgrading.

Click to expand...

It randomly turns itself off. Not protection mode, I mean OFF.

http://www.audiokarma.org/forums/showthread.php?t=615148

I bought the TA-2A to use with my computer and cassette deck. A 4A would be lovely, but a waste in this setup.

Happy trails
Larry B.

I hooked the jumpers up and it works flawlessly!!! Oh man, I miss the Nak sound for sure! I have it hooked up to a set of Snell E/IIIs and it sounds superb! I was able to get the TA-2A, a Definitive Technology C-1 center (already posted it on Craigslist) and a mint pair of Snell J/IIIs with foam rot for $90!!! I already ordered the foams for the J/IIIs and will get those done next week.

Thanks again everyone for your help! I feel like an idiot, but a very happy idiot!

Should I be concerned about the buzzing sound coming from the power supply? It's not loud by any means, but I can hear it when I first turn the unit on.

As long as it's not coming through the speakers it's nothing to worry about. That receiver has one monster transformer, and all that current can cause buzzing in an older unit where the glue has dried, and the laminations buzz. Just something you might have to live with...unless someone has a cure I'm not aware of.

Happy trails,
Larry B.

The hum also might be coming from the power supply board. It has a smaller transformer mounted to the PC board.

Ok, that makes me feel better. Thanks for all the input. I plan to give it a deoxit bath so I'll check both transformers when I have it open. This really is a great little receiver. I really like the sound and it has considerable volume for its size.

Okay - I know this is an old thread, but I just took a Nak TA-2a in trade for a surround sound receiver I was selling. When powered on, the green light by the power switch flashes, and there is no sound output. I hear the power relay click on when I power it up, but not the expected speaker relays clicking on a second or two later. Is this possibly the protection circuit? Any suggestions for how I should deal with this? I'm pretty comfortable with rooting around inside a receiver, but would like some direction.

Ptras said:

Okay - I know this is an old thread, but I just took a Nak TA-2a in trade for a surround sound receiver I was selling. When powered on, the green light by the power switch flashes, and there is no sound output. I hear the power relay click on when I power it up, but not the expected speaker relays clicking on a second or two later. Is this possibly the protection circuit? Any suggestions for how I should deal with this? I'm pretty comfortable with rooting around inside a receiver, but would like some direction.

Click to expand...

Before you blame the protection circuit you need to find out whether it is simply doing its job. You might have a fault in the amp itself. The amp output before it reaches the protection relay would need to be checked for the presence of DC voltage, there should be none.

^^ what glen says.

There are a few known issues with this receiver that you should check as well, some of which could relate to your issue:
-- the original resistors R309L and R309R on the main PCB were a bit under rated and can fail. They are 22KΩ, half watt; replace with metal oxide resistors, 1W or better
-- Q525 on the logic board was also under rated and can fail (see addendum in the SM). I used a PN2907A-AP (suggestion of Mannegizen) but note you have to fold the leads to get the right ECB pin order
-- check solders of the speaker relay on the PCB. Its been common experience reported here that they develop a poor connection to the PCB, and can be remedied by reflowing (see posts by Freddymac).
-- check around Q207 and Q208 (main board, for bad solders as well, as they run hot. They are in the +/-18V regulator circuit, and you can check those voltages at CN-24, Pins 1 and 2 (Pin 3 is ground).
-- once you get it running, be sure to check the amp bias, and set to factory specs.

Welcome to AK, BTW.

If you search here, and at diyaudio, you will find a number of threads on TA-2s, and they contain a lot of good info. Most of the little I know about fixing the Nakamichi receivers I learned from member Mannegizen, and hopefully he will show up soon. They are great sounding units, definitely worth fixing.

Also, if you don't already have a copy of the SM, you can download it from hifiengine (need to register, but its free, and safe).