Sony M-100B Microcassette Voice Recorder HELP

Hi!

Few days ago I got from eBay a nice Sony M-100B microcassette voice recorder ultra thin which I guess is pretty rare. It came with original leather cover and the additional battery pack for AA batteries.

Item turns on, but I can't hear anything from speakers and headphones. It plays, engine works, Rewind and FF seems fine, but no audio at all. I tried to press REC and record my voice, but then if I put same cassette in other voice recorder, I see that nothing was actually recorded. I also tried with an external Mic, and, nothing ...

Seller said was working fine, so I opened it to clean a little bit the contacts and I've found one cable from the mic and 1 cable from tape head disconnected.

Could be this the reason of the issue?

I soldered back the cable to the tape head (there are two), and now trying to put back 1 cable (out of 3) to the Mic but it's really small and so difficult.

I tried already the device after I put back the tape head cable but, it's still quiet, no sound.

Do you think if I put back also that Mic cable it will be fine? Maybe without that Mic cable, the signal circuit is not entirely closed? No idea.

Thanks for your help and advises


Dani

 

Okay thanks, I will try soon a second attempt before giving up.

Meanwhile I ordered on eBay a same one but with battery pack AAA broken, so it's sold as un-tested because of this issue.

I really hope all is fine with this one if I put on the battery pack of the one I already got. Looking forward to receive it, restore it and let it works, because I think this is a fantastic piece really!

 

Yes, when I opened it up first time I was amazed!

 

Just an update about this case. Eventually I was able to make one fully working, out of 2. It still needs some details to be fixed, but it works very well and I'm so happy for it.

Now, the second one is not in the same conditions of course, and it doesn't seem an easy fix. I found out that maybe there is a faulty component, thanks to the multimeter. I'm not so experienced but I'm comparing the circuit of this faulty one with the one fully working and one component doesn't make any ''Beep'' with multimeter, so I guess circuit is interrupted because of that. Anybody knows what kind of component is this one chrome and with blue feet? Is that a sort of capacitor?

There are five in the upper side of the mother board and they are all connected each others except one. I tried to refresh the soldering but still no contact or signs of life. What kind of component it is? Basically there is no sound coming out from the recorder, at all. For the record, in the working one, all of the five components make their ''Beeps'' with the multimeter.

However, I'm documenting this repairing and I will post it soon on my brand new YouTube channel:

https://www.youtube.com/channel/UCWc9QIAuJCbnmDEJKsFkSAw

Feel free to follow me so you will get notified when I will post this Sony M-100B repairing adventure video I will also make soon another video about repairing of 5 faulty microcassette dictaphones SONY I bought on eBay.

Cheers


Dani

 

Hello .. first of all congratulations for the work you do ..
but in this case I would start to redo a couple of welds ... the point you indicate looks like two poorly made welds touching and the component is on the other side of the circuit ....
If you look at the same circuit as the one that works I think that is not so like this

 

Hi, thanks a lot!

Yes I'm aware of the bad welds and were made by me very quickly actually, but this is after I found out the issue. I will make them better soon. Regarding the 2 components touching each others, I checked the working one and they are exactly in the same position and touching each others. So are they capacitors?

Thanks

 

Hi ... if they are capacitors ... I've never seen them like this ... if you touch the two pads with the test leads of the tester ... and they conduct cannot be capacitors

 

Right, I see. In the working one they all conduct each others, but in the faulty one just one of those components is kind of isolated so I guess that's the issue.

I will get soon the service manual from eBay to understand what is that and try to find a solution. In the meantime I completed the working one and I will soon edit and release my restoring video into my channel. Looking forward

 

Here is the video I just released about my repair challenge of 2 SONY M-100B:




Enjoy, and Subscribe if you like, as I will soon release other videos like that. I got a bunch of broken dictaphones still to be repaired.

Cheers!


Dani

 

Hi any update in this investigation ? I have an M-110B in excellent condition but with no sound at all. It records, but no playback. I can only hear a faint output through the earphone at max volume, though if i adjust the volume I can hear some scratching from the speaker. I have measured those blue components and they appears to be capacitors: in continuity mode. none of mine beep, but I measure capacitance across each one of them (in the range of uF). Service manual is not available so I am a bit stumped ...

 

Hi! I also replied to you from my YT channel. Well, if none of your capacitors beep, then must be a different problem. In the working one they all beep even when the unity is totally off, and they are interconnected each others. Can also be the Pause button? The main signal pass through the Pause button before reaching all the rest, if I'm right. I'm not an expert, but just learnt something while working on my pieces. Take multimeter and track the signal starting from the Tapehead cables/connections, and you will maybe see if there is a block somewhere before the capacitors.

 

Thanks for both your replies, I was actually able to fix mine, the issue was far more simpler than expected: someone has smashed on the volume pot and both of its older joints were broken. Traces underneath the pads were broken so I had to scratch a bit of solder mask and reach for a working piece of trace. After that, audio is back. I am also adding a bit of vinyl glue to strengthen the volume pot. The belt is shot, way too loose; I am temporarily using a (terrible) chinese belt which is good enough for playback; next order with Marian (FixYourAudio) I will add the proper belt for this recorder.

 

What a great news! Thanks, as I'm planning to buy other broken ones most probably with the same issue. So it could also be the volume wheel, right! For the belt, I also ordered initially a 30mm belt to Fixyouraudio, but then I realised that a 29mm fits better.

 

Yes, I took notes from your video for the size of the belt you ordered. I would think the thinner the better: for 0.5mm Marian has 26 or 30 mm, while 29 is only 0.75 mm. You said 30 mm is too loose, but 29 is stretched or 26 could be possible as well ?

As a further possible root cause for missing audio: the PCB has two layers of traces, I would not be surprised if there are one or more cracked via's.

 

26 definitely not. The 30mm 0,5 seems perfect but I had some problem with one unit so I ordered also the 29 which fits also well but yes, it's 0,75mm. I would order both, just in case. You know, I have already 5x Sony M100B and it can be that for some reasons the 30mm doesn't fit very well or is too loose. I'm not a collector, just buying them for my music project, and I really love this model, it's incredible inside!

Are you just a collector/amateur?

 

I am not a collector specifically on micro-cassette recorder, I like portable audio (walkman, discman, MD recorder,...) and voice recorder. I have a few voice recorders I bought off flea markets, but nowhere near a collection, it's just a random set of recorders, basically what I could find at decent prices. This M-100B was to good to pass, excellent cosmetic conditions, almost complete in its box with all accessories. I like to fix stuff if I can, that is why I would like to have it run properly.

So far the only problem I'm having is that the tape transport is noisy, but I guess I will have to live with that, plastic gears after 30+ years slightly shrink and do not match perfectly with some play between them. I am actually surprised that a couple of gears with iron core and plastic teeth are still intact with no crack. An MC recorder I personally bought in the 80's (Sony M-5) now have a cracked gear and ticks.

Regarding the design of this M-100B, yes it is incredible inside and very good looking on the outside. But I disagree with Sony philosophy back then to make everything as small as possible; that comes with a price and in the case of M-100B is the removal of a tape counter, something I find essential on a voice recorder. To me the M-100B is too thin, buttons are too small for my fingers and they appear very fragile.
The M-100B is a great exercise in engineering - when I first saw it I could not believe they could have made it so small, but something I would have not bought myself back in the 80's: I would have gone for something sturdier and slightly bigger with a better hand grip

 

Here are some pictures of the unit ..

 

Fantastic! Not sure how much you paid for it, but you can re-sell it for 150 Eur if fully working.