Looking for a tape tech in reno nv

[blungo2]

I need someone to work on my Otari MTR-12. There's a good tech in Sacramento, Rainbow Electronics, but it's such a pain to haul my MTR there.

Anyone?

[Mo-Tech]

I overhauled most of my MTR-12 recently. What're the problems you have?

[blungo2]

Last time i calibrated it for a different type of tape, all seemed to go well, but after that it had an incredibly low output of the recorded signal. I expect i screwed somehting up, but it's also possible that there's something else wrong.

Are you in Reno? I definitely need someone more capable than me to look at it.

[Mo-Tech]

Sorry, I'm in Europe.

Did you also try both bias I and bias II position adjustments on Audio Control board to confirm both don't work?

If yes then, some possible causes:

Have you opened any of the rear doors recently? I've had it twice giving me a huge scare, it was one of the cable connectors (to XLRs inputs/outputs) coming loose and they can come loose very easy, maybe even if you move the machine around too much and giving it smaller "bumps".

Sometimes Ref Flux button can become stuck between positions, ditto IEC-NAB button. I have those a good contact clean and lube, now they work again for years to come.

Also check the bias, possibly also from Audio Cards (2.5 mm hex key while observing oscilloscope connected to record head and turn the slug to max bias output so that the noise component riding the sine wave is symmetrical with the max position as well) if it's radically out of bias it can lose most of signal strenght. You need extender board to do this adjustment - very hard to find so I built one myself.

Also on rare cases the bias adjustment screw itself can be blocked, worn out or damaged. If you turn bias screws over or under you should hear "clicks" when it hits the max or min, but should be loads of turns between them.

I've also had one of the caps coming loose of contact on front panel near "SRL" buttons (probably from pushing them with too much force too often), giving similar weak channel. But this should be only one channel affected, not both.

When you have confirmed it's not the bias and both channels are still weak I'm suspecting something to do with Audio Control board or power feed to audio cards from bottom power board (a faulty relay or a damaged cap or burnt resistor somewhere?)

PS: I re-capped my machine completely, all audio path I used audiophile capacitors (Elna Silmic II and Nichicon Muse series mostly) - the sonic performance improved considerably on my MTR-12, loads of more "depth" and "3D", thicker bass, silkier mids, smoother highs, it's definitely more "snappy" and "musical" now vs aged stock Nichicon caps put into it back in the '80s. Even VU-meters now follow dynamics spot-on, before it was with a slight delay which I first thought to be normal on MTRs, LOL. Actually first it wasn't big improvement, just little over stock, but then figured the components are brand new, so now after I've "run-in" the caps (needs easily over 10-20 hours of work both record and playback side), got better every single day I used it and I can tell I'm glad I did the re-cap (took me many days of work though!) to release the full potential of the beast - when done right, sonically amazing and very underrated machines, they really are.

[blungo2]

Thanks. Most of the work you described is over my head though.
I may give it a shot if i get braver/smarter.