Looking for someone who can restorate a Sony C-48 in Europe

[thewotan]

Hello there! I hope this is not the wrong part of the forum to ask this.

I inherited a Sony C48 which is faulty. It cuts sound intermitently, and it also has cracks and pops sometimes. After opening it it seems like a general mess inside, and one of the diaphragms is busted (which I suppose is the origin of the fault). Seriously, it looks like the mic did something bad to the "tech" who worked on it. I hate it.

I would like to know if there is anybody in Europe who has experience working on this mic. It is my understanding that reskinning the diaphragm would not get it to original condition... If that's the case, and the only possible way to restorate it would be with a new C48 diaphragm (which would be impossible hard to get), could the bad diaphragm be disconnected and configure the mic as only cardioid?. Right now, setting it in cardioid with the polarity pattern switch doesn't make the problems go away.

It's incredible, but sometimes it works. And it sounds wonderfull. But it doesn't take long before it starts going bad. I would really like to get this working, but I know it is out of my repair skills.

Some pictures of the crime:

 

[kingkorg]

It is my understanding that reskinning the diaphragm would not get it to original condition...

Who ever told you that stop listening to them! I am sorry for the tone. Of course it is possible, it is just important to find the right person to do it. I have worked on these mics successfully, however i am busy at the time and don't have the time to offer you help. I have measured fully operating originals, and i can say they are unique and marvelous mics. From what i can tell the capsule is the same as c800G. So good luck finding original replacement.

They are nothing like u87 (k64, k87) capsules so whatever you do, don't use anything but original capsules in this mic. The magic of c800G and your mic comes from unique backplates, not the diaphragm itself!

This mic is a u87 with c800g capsule in a nutshell. I would use it over u87 all day long!

 

[mihi_fuchs]

Have you checked the tantals and electrolyts in the circuit. As it sometimes works shortly, the capsule seems to work actually at least sometimes properly.

Maybe worth looking in the caps first. They are easy and cheap to replace … but of course it’s a vintage - so you alter it.

Maybe measurements could help. Check the voltages and if they drop around the jfet obce it goes bad.

Hope it’s not the capsule, that would be a pity ;-)

 

[ElSmurf]

Looking at the pictures I'm amazed at the awful soldering job. I'm assuming this isn't how it left the factory. I think a reflow of some suspicious looking joints couldn't hurt. Would be in line with the symptoms you describe.

 

[thewotan]

Who ever told you that stop listening to them! I am sorry for the tone. Of course it is possible, it is just important to find the right person to do it. I have worked on these mics successfully, however i am busy at the time and don't have the time to offer you help. I have measured fully operating originals, and i can say they are unique and marvelous mics. From what i can tell the capsule is the same as c800G. So good luck finding original replacement.

They are nothing like u87 (k64, k87) capsules so whatever you do, don't use anything but original capsules in this mic. The magic of c800G and your mic comes from unique backplates, not the diaphragm itself!

This mic is a u87 with c800g capsule in a nutshell. I would use it over u87 all day long!

That's good to hear! I don't remember where I read about reskinning not being able to restore the capsule to original condition. Glad to know that's not the case!

It is a wonderful mic indeed. Sounds better than a u87 to me. I've managed to use it to record some acoustic guitars and it sounded like a record with no processing whatsoever.

I'm not really in a hurry to get the diaphragm restored. Would you be up to it whenever you have more free time?

 

[thewotan]

Looking at the pictures I'm amazed at the awful soldering job. I'm assuming this isn't how it left the factory. I think a reflow of some suspicious looking joints couldn't hurt. Would be in line with the symptoms you describe.

Really awful. No way this is how it left the factory. You are right, reflowing it wouldn't hurt. And I don't think I could do it worst

 

[thewotan]

Have you checked the tantals and electrolyts in the circuit. As it sometimes works shortly, the capsule seems to work actually at least sometimes properly.

Maybe worth looking in the caps first. They are easy and cheap to replace … but of course it’s a vintage - so you alter it.

Maybe measurements could help. Check the voltages and if they drop around the jfet obce it goes bad.

Hope it’s not the capsule, that would be a pity ;-)

No, I haven't! It wouldn't hurt to check the caps, as well as reflowing the PCB. To be fair, I assumed it was the diaphragm because the issue reminds me of another mic I had ages ago with a bad diaphragm. But I suppose a bad cap could also describe the symptoms.

Many thanks to everyone for your assistance!

 

[mihi_fuchs]

No, I haven't! It wouldn't hurt to check the caps, as well as reflowing the PCB. To be fair, I assumed it was the diaphragm because the issue reminds me of another mic I had ages ago with a bad diaphragm. But I suppose a bad cap could also describe the symptoms.

Many thanks to everyone for your assistance!

hope your capsule is still working on the „untreated“ diaphragm. if it‘s just a cap or connection you may still have a really nice mic for cardioid only.

fingers crossed ;-)

 

[jeremynothman]

I'm fairly sure that I saw Andreas Stenzel sending off a C800G capsule to Rico Vetterlein. Maybe Andreas would also be happy to work on your C48 (and presumably Rico would be happy to do this capsule as well).

 

[Whoops]

That's good to hear! I don't remember where I read about reskinning not being able to restore the capsule to original condition. Glad to know that's not the case!

Rekinning is actually what people do to be able to restore the capsule to original condition.
But it needs to be a quality reskin job made by a person with a lot of experience in reskin jobs

Check here:
http://www.drefahlaudio.com/

 

[thewotan]

I'm fairly sure that I saw Andreas Stenzel sending off a C800G capsule to Rico Vetterlein. Maybe Andreas would also be happy to work on your C48 (and presumably Rico would be happy to do this capsule as well).

Many thanks for the info! I'll try to contact them and see if they would take it.

 

[thewotan]

Rekinning is actually what people do to be able to restore the capsule to original condition.
But it needs to be a quality reskin job made by a person with a lot of experience in reskin jobs

Check here:
http://www.drefahlaudio.com/

Hey Whoops, thanks for chiming in.

It was my understanding that reskinning can take the capsule to working condition, but it was very difficult to restore it to original condition. I'm glad to learn I was wrong.

I'll check that site you linked, thanks!

Rekinning is actually what people do to be able to restore the capsule to original condition.
But it needs to be a quality reskin job made by a person with a lot of experience in reskin jobs

Check here:
http://www.drefahlaudio.com

 

[Whoops]

It was my understanding that reskinning can take the capsule to working condition, but it was very difficult to restore it to original condition. I'm glad to learn I was wrong.

Like Kingkorg said you need the right person to do it, and also using the same material.
But Kingkorg, Soliloqueen and Tim Campbell know much more than me in this regard...

 

[kingkorg]

Like Kingkorg said you need the right person to do it, and also using the same material.
But Kingkorg, Soliloqueen and Tim Campbell know much more than me in this regard...

At least the person reskinning it would have to be aware this is not the same as Neumann's k67. For whatever reason people, at least publicly, perpetuate the nonsense Sony's capsule is a Neumann's clone.

The good thing is that this capsule has one side that seems to be fine, so the tension, thickness, capacitance, and FR can be checked before the job. This would be my tip to whoever lays their hands on it, but isn't sure how to attack the problem.

Another great thing would be to confirm if this is 100% same capsule as the one in c800g. To me, it certainly seems so.

Sony's capsules are not some kind of miracle either. One side of the capsule i worked on had wrinkled diaphragm at the screw. Nonetheless, the capsule worked just as it should. Just to say Sony isn't flawless.

 

[jp8]

Looking at the pictures I'm amazed at the awful soldering job. I'm assuming this isn't how it left the factory. I think a reflow of some suspicious looking joints couldn't hurt. Would be in line with the symptoms you describe.

That solder job really hurts my eyes. What a mess! If you decide to solder on these boards yourself, do not use modern lead free solder but 60/40 or 63/37 tin-lead solder. Use a temperature controlled soldering iron set to 260 -350C. Use the lowest temperature that works for you. The solder joint should look shiny and bright once solidified. A good joint has just enough solder to cover pad and wire, but the wire end should still be visible through the joint so you can visually check the joint quality. Remove excess solder using a solderpump or solderwick. Avoid the cheap chinese solderwick. Chemtronics solderwick is what we use at work and works perfectly. For fastest removal of solder, use the rosin based wick.

And now comes what is perhaps the most important thing: cleaning of the boards, most notably the head amp board that connects to the capsule. The PCBAs are probably soldered using rosin flux based solder. The solder wick, if used, also leaves flux residues. The ionic content and somewhat hygroscopic properties are detrimental in the high-impedance area of the head amp circuit and could have caused some of the noises described. Use a brush and lots of IPA to remove the flux. Or better, use a specific flux remover suitable for rosin based fluxes. I use Chemtronics Flux-Off, ES835BE, which should be safe to plastics. If the circuit has polystyrene caps, do not use IPA. Flush away all debris and flux residues using the flux cleaner.

Good luck repairing the C-48!

Jan

 

[doorunrun]

The soldering looks about the same as a lot of Japanese transistor radios from the '60x and '70s.

 

[Latie]

I would have the mic checked out first, it has definitely been tampered with, that soldering and the little cables are inexplicable. Maybe the problems come from the state of the circuit. Touch the capsule only if you are sure that the problem is isolated there. I should take mine apart to show you some pictures, but can tell you: that's not what the inside of the mic looks like - the hose system connecting the body to the stand is annoying, and when I do these things I sometimes lose something. My c48 had a broken PCB, I had to re-solder it, but it doesn't look like that at all. It does not have the brightness (that subtle happy distortion) of some neumanns, but it's magnificent. Its low mids have something definitely beautiful. The capsule is not the one of the c800g, some say is related to the one of the original c800. greetings

 

[kingkorg]

The capsule is not the one of the c800g, some say is related to the one of the original c800.

How did you come to this conclusion, and are you aware that original c800 uses totally different type of capsule? Not k67 related at all.

 

[Whoops]

I would have the mic checked out first, it has definitely been tampered with, that soldering and the little cables are inexplicable. Maybe the problems come from the state of the circuit.

Peter Drefahl the person I recommended, does both things, he reskins capsules and also repairs mic circuits and electronics

 

[thewotan]

I would have the mic checked out first, it has definitely been tampered with, that soldering and the little cables are inexplicable. Maybe the problems come from the state of the circuit. Touch the capsule only if you are sure that the problem is isolated there. I should take mine apart to show you some pictures, but can tell you: that's not what the inside of the mic looks like - the hose system connecting the body to the stand is annoying, and when I do these things I sometimes lose something. My c48 had a broken PCB, I had to re-solder it, but it doesn't look like that at all. It does not have the brightness (that subtle happy distortion) of some neumanns, but it's magnificent. Its low mids have something definitely beautiful. The capsule is not the one of the c800g, some say is related to the one of the original c800. greetings

Yeah, I was strongly suspecting that... I'm not that good with DIY, but my soldering is WAY better than that. It was hard to believe that such a good sounding mic would have that awful work from factory...

Thanks for the tips! I'm not going to touch the capsule, as I've never worked on one before, and don't want the C48 to be my "training" capsule.

If you have the time and don't mind doing it, I would appreciate pictures of the innards of a good C48