70s Cassette Deck Repair. AKAI GXC-730D

Thread Starter

Othello7

Joined Sep 18, 2018
24
I don't know if this is the wrong forum to post this on so if it is please tell me.

This cassette deck had been sitting around in a garage for a long time when I picked it up.
It's main initial problem was that it would continuously reverse when it wasn't supposed to.
This was due to the belt connected to the counter being old. I replaced that and
everything worked fine, for a while.

1st problem:
Recently it has the problem where it doesn't play any sound in the left channel when
you press play. but at a certain level you can hear it, clipping kind of? a noise that sounds
like its trying to get through. and after a certain duration provided that it is doing
this clipping out thing it will come on and be fine until you press pause or stop. This is
one of those older 70s equipment with hardly any chips in it and tons of resistors and
capacitors all over the board with wires going everywhere.
It seems like a circuitry problem so I thought it might be ok here.

2nd problem:
A lot of the lights are dead. They all seem to be incandescent. On some of them the
leads going to them are rusted and broken so I don't even know if those are burned out.
But I cant find any kind of replacement on the internet.

Light 1:
Power to pins: 5V ~ AC
DSC00625 - Copy.JPG
Mounted like a resistor with wires coming from each end.

Light 2:
Power to pins: approx 20V DC
DSC00627.JPG
The size of an LED.

Here's some images:
DSC00620.JPG
DSC00621.JPG
DSC00622 - Copy.JPG
Sorry about it being blurry on this one:
DSC00623.JPG
Hope this helps.
 

SLK001

Joined Nov 29, 2011
1,548
Akai's of that era were notorious for cold solder joints. If you're really interested, I might still have some of the lights. Just remember that this is a cassette player, both obsolete and outmoded.
 

Thread Starter

Othello7

Joined Sep 18, 2018
24
I like cassette tapes and I want a high-end cassette deck.

Dodgydave thanks for the service manual. I hadn't thought of that.

I forgot to mention that about a third of the time I press play it works fine from the start.
But the hissing noise is louder and even with no tape in it makes it. Which I discovered
before it started cutting out but at the time I also discovered that the elevated hissing noise (left channel)
would swap to the right channel if I played it in reverse mode. Just thought that was interesting.

SLK001 does that mean I would have to check all the solder points on all of the boards?
 

Thread Starter

Othello7

Joined Sep 18, 2018
24
Also, when I measured the voltage to the lamp, it read 5v AC.
Here, in the service manual, it says 8v... eh just a thought.
Screenshot (175).png
The other lamp is writen as 24v too.
 

Dodgydave

Joined Jun 22, 2012
10,139
Your best bet is Voltage test points, in play,ff, rew, and check them at the psu. As for Audio faults, ideally you need an amplifier to follow the tape head signal or an Oscilloscope.
 

Thread Starter

Othello7

Joined Sep 18, 2018
24
It does appear that there are leaf switches that control the buttons but I don't know where there would be one that affects only one of the channels. then again this is complicated, maybe its hidden?

I did find though that when I touched the board depicted in my first picture at the top (not touching any contacts just moving the board a little) then it would immediately snap into working. I detached the board from the frame and discovered that it was bent:
DSC00628.JPG
I also looked at the bottom to see if there where any obvious cracks in the solder or something and it looks fine.
DSC00633.JPG
 

Thread Starter

Othello7

Joined Sep 18, 2018
24
I have narrowed it down to it has to be that board. I can use it in my system now but it has to be on the top because whenever it has the problem I need to take off the top and do one of two things:
-Wiggle the wire clump going to that board (which also wiggles the board)
-Tap on the corresponding side of one of the two little black boxes (top and bottom)
 

Thread Starter

Othello7

Joined Sep 18, 2018
24
Darn and on top of all of that I just learned it is running two fast as well. This is starting to seem like a lot.

I went do do my first recording on it and the record button mechanism was stuck which I had to break free. And then afterwards when I tried that recording on a different cassette player it was slow. I tried it on 3 other players.

It is hard to inspect the board where the fault is because there is a lot of wires going to it and they aren't exactly on connectors or very long.
 
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