Help with Oktava ML-52 II please

[daydreamer]

Hi,

Andy here, new to forum...


I've spent a fair amount of time over the past year researching and building a a humble recording setup. Lots of research, and some impulse buys. This ML-52 II was one of the latter...unfortunately.

Basically, I saw it on ebay advertised as being modded with the Lundahl transformer and like the look of it and threw down 300 bucks US. I got it, plugged it in and it sounded bad, scratchy and bad. But it did work to an extent; there was a signal.

I openned it up, as you do, and found that one of the two ribbons was real slack. Damn. USPS can't really be blamed, 2.5 microns wasn't going to like international post I guess. So to cut to the chase, I get more 2.5 micron foil, shape it and install it. Not a bad job if I do say so, looks nearly indistinguishable from the other untouched ribbon. Doesn't touch anywhere, roughly same tension. All good, I thought.

I go to plug it in, (I'm using a Triton Audio Fethead Filter to get the extra gain needed) and..nothing. Absolutely nothing. change leads, remove filter, change to another lead, volume cranked, nothing.

I really don't know enough about these to troubleshoot any further, I'm getting into electronics, but I'm a complete noob in reality.

any ideas on what could have gone wrong, and what I can do?

thanks
Andy
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[crazydoc]

I'm not familiar with the specific mic, but first I would use an ohmmeter to check the continuity from the ribbons to the transformer, through the primary and secondary of the transformer (and that there is no short between the transformer windings), and through the connector. Look at any solder connections to see if they are broken or look cold (dull), as whoever modded it may not have been up to snuff with his soldering skills.

 

[daydreamer]

Thanks for the reply Crazydoc, that what I needed; just some a pointing in the right direction!

I just spotted a thread about this mic on the forum, I'll have a read of that as well.

thanks again

Andy

 

[daydreamer]

Well, lesson learnt i suppose; don't buy ribbon mics off ebay.
finally got it producing a VERY weak signal with a lot of hiss and quite frankly don't want to see the insides of that messed up russian piece-o-sh*t again!!!

I ended up pulling everything apart (not the transformer though) re-ribboning both sides after cleaning everything to a gleaming shine, (apart from the insulation wax) and resoldered a dodgy ground wire.

Mic is not useful as is, I would not recommend this mic to anyone as the internal workmanship is poorly designed and insanely hard to work on. The only thing it has got going for it are good looks.

thanks again crazydoc.

andy

 

[crazydoc]

Don't give up on it yet. What is the part# of the transformer? Are you sure it has the correct specs and that it's hooked up correctly? If all the connections are good in the mic, I'd suspect the transformer - there's no other electronic component that would be bad. (edit: unless the magnet is weak)

 

[daydreamer]

sorry for the late reply, got caught up on other things.

Almost did give up, got a bit of advice over at gearslutz which also helped, but I think the main one was checking the soldering like you suggested. Finding the ground wire just holding on was probably the biggest issue. I think I may have to recheck one of the ribbons as well. It didn't clamp at all before I snapped the clamp screw, it is being held with solder..) I think I need to recheck/ replace the insulation between the ribbon holders, magnet and frame. It is some sort of orange wax paper which could be too old.

I'm going to try putting 2 preamps and the triton fethead in the chain to see if I an get a reasonable signal out of it though, I may just be judging it too harshly in my impatience.

as far as transformer numbers etc it doesn't have anything that's visible, I would have to remove it somehow, I think it is glued in though. Magnet is really strong, it's a PITA working with metal pliers around it!!

I'll try to get a decent signal going first, then make a judgement about the rest.

thanks for the encouragement,

Andy