Playback volume from old Sony voice micro cassette recorder is very low?

Thread Starter

Rahulk70

Joined Dec 16, 2016
521
Hello folks,

I have an old Sony V.O.R M-529V microcassette recorder. Was found in a box packed away years ago and put in some fresh batteries and tried to play some old micro cassettes I had. But the play back volume from the recorder even at full volume from the speaker was almost in audible. I tried plugging in a earphone and now the audio was a bit more audible but still quite low for full volume.

I tried a few different tapes but did not make any difference. Tried changing the recording speed modes, but no change. Tried different batteries, again same thing. As a last resort I cleaned with some q-tip and head cleaning solution. And no change. I opened up the recorder and see that the belt of the pulley is fine, the board also looks perfectly fine. No corrosion or damage of any kind inside.

Do, you guys think the magnetic head is damaged or maybe the Audio IC on the board is dead? Any suggestions on what I should look into?

Thanks in advance
 

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Yaakov

Joined Jan 27, 2019
3,464
Old electronics often malfunction because electrolytic capacitors dry out. You might give replacing any on the PCB a go. If it's old enough, it will use through-hole components so it's not as difficult as SMD.
 

MisterBill2

Joined Jan 23, 2018
9,235
My suggestion is to try cleaning the tape head. Any coating of anything that moves the tape away at all will reduce the volume a whole lot. The second thing would be to operate the record/play switch back and forth quite a few times. You may need to use some safe contact cleaner on the switch. I had to do that to fix a cassette deck just 2 weeks ago. I also needed to use the cleaner on the volume control. Probably the fastest fix I ever did. And certainly it was very effective.
 

Yaakov

Joined Jan 27, 2019
3,464
My suggestion is to try cleaning the tape head. Any coating of anything that moves the tape away at all will reduce the volume a whole lot. The second thing would be to operate the record/play switch back and forth quite a few times. You may need to use some safe contact cleaner on the switch. I had to do that to fix a cassette deck just 2 weeks ago. I also needed to use the cleaner on the volume control. Probably the fastest fix I ever did. And certainly it was very effective.
The contact cleaner is a good idea, particular if the control is noisy at all. The TS mentioned "a tip and head cleaner" in his post, though.
 

MisterBill2

Joined Jan 23, 2018
9,235
If the IC were bad there would be no sound at all. Very low sound was exactly the symptom of the recorder cured with contact cleaner on the record/play witch and in the volume control. I could not even see the opening in the volume control. For the switch, I squirted the cleaner in both ends.
Do NOT get any of the cleaner on the belts, that may cause problems. I have scrapped a few tape machines in which the belts had been partly dissolved by something. It might have been the plasticizer in the case, or ???
 

Yaakov

Joined Jan 27, 2019
3,464
If the IC were bad there would be no sound at all. Very low sound was exactly the symptom of the recorder cured with contact cleaner on the record/play witch and in the volume control. I could not even see the opening in the volume control. For the switch, I squirted the cleaner in both ends.
Do NOT get any of the cleaner on the belts, that may cause problems. I have scrapped a few tape machines in which the belts had been partly dissolved by something. It might have been the plasticizer in the case, or ???
Back in the 80s I repaired audio and video equipment. I did a lot of open reel recorders that were from the 70s. The belts and pinch rollers were usually trash. We used to get all of our belts from MCM, who is still around I think. And, there was a rubber rejuvenator that could improve a pinch roller or belt if it wasn't cracked.
 

Audioguru again

Joined Oct 21, 2019
3,505
My old clock radios have intermittent volume controls because the terminals are loosely fastened to the resistive track with simple pressure. A squeeze with pliers fixes some of them for a few more years.
 

Thread Starter

Rahulk70

Joined Dec 16, 2016
521
First of all thank you so much for the replies and suggestions. After looking at the feedback from you guys I decided to open up the recorder and inspect the head connections, the belt and the board components thoroughly. Head and belt seems to be fine. But I did notice that after recording if I try to plug in a headphone or computer speaker via the 3.5mm jack the audio does play but had a lot of noise and distortion. But pressing down the JRC 2128 IC made the sound louder and distortion sometimes reduced but was still present. I took a closer look and found the soldering connections had a slightly white crusty coating all over the connections on most components and some residual brown stuff mostly flux I guess. Which can be a a bit corrosive at time. Any way I put flux all over the board and reheated all the connections & reapplied solder and then cleaned it with ethyl alcohol. Then sprayed the volume pot and jacks with CRC co-cleaner contact.

Now I tried playing back and the volume from the main speaker was a lot louder but there was lot of distortion. I'm confused if this is a blown speaker or some issue with a component like a short SMD capacitor or something. But playback through the 3.5mm audio jack is perfectly fine now! :) The cassette on the right is okay but audio recorded on the left one seems to be the better. I tried recording a song and then playing back via the 3.5mm jack and its fine.

Also as @Yaakov mentioned I need to change the electrolytics as they may have dried up. But the issue is some of the newer replacements of those values are much taller and will not allow the board to be seated.
 

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Thread Starter

Rahulk70

Joined Dec 16, 2016
521
That seems unusual, most of the newer components are smaller. Are the replacements the same voltage rating?
Actually the issue is they are a bit more thinner in diameter and a bit taller. Well in most modern circuits it's not an issue. Only in certain low profile situations a shorter cap of wider diameter is required I guess.

The caps are
1. 16v 10uF x 4pcs
2. 6.3V 47uF x 3 pcs
3. 6.3v 22uF x 2pcs
4. 50v 1uF x 1pc
5. 4v 220uF x 1pc

I was able to find the items 1, 2 & 4 in low profile. For the 5th item I don't think they sell in 4V a lot but 6.3v should be fine assuming I can get a wider but shorter one.
 

MisterBill2

Joined Jan 23, 2018
9,235
Using a cap with a higher voltage rating is always OK , but if it is a LOT higher size may be an issue. 6.3 instead of 4 is fine, if it fits. And still, contact cleaner in the R/P switch is still a good idea.
 
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