Tascam MS-16 EQ caps on Rec Board

M

man-bot

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I've been following the other MS-16 thread and see there is a lot of knowledge on these machines here so I'm hoping I can find some help for my issues.

My MS-16 works great... for the most part. I however have 4 channels with limited range on playback it appears. One has no low frequency response (nothing under 300hz) - If i record on the channel its fine, but repro and sync modes are very thin on playback. If I swap card the recorded material sounds fine.

Then I have 3 more cards that are out of spec on the high end in repro and sync (maybe 5db out... so not pleasant... rolled off).

Any idea where to start replacing caps to try and remedy the situation? I'm good with an iron and I have a Hakko 808 so desoldering is no issue... just need some guidance as to what to replace.

All ideas welcome!
 
Do you have the schematics?

Also, I would suspect relays as opposed to caps as the culprit.

---------- Update ----------

And just to confirm: the problem follows the card, right?
 
I do have the schematics - but I've never been great at tracing signals via schematic (life would be so much easier with vintage gear if I had rudimentary EE education!). Also I don't have an extender card so it makes it difficult to trace on the actual card itself.

I had changed out all the relays - but I am realizing that I do have 4 cards in that I bought off eBay that have the original relays. Would they affect signal though? I assumed the signal wouldn't pass through the relay itself, it would just switch the path (i.e. repro or sync) that the signal followed. I can swap and try though.

The problem follows the card for sure.

Mike
 
Absolutely the signal goes through the relays. That there is your electromechanical routing switch.
 
Ok - I'll try a relay swap first. Once I'm done I'll report back - I have a bunch of good ones on hand.

Thanks!!
 
I concur with Cory about the relays being a top suspect. They caused some ghosts on mine. That's great that you have fresh ones on hand.
FWIW last year I went through the tedious process of testing all the electrolytic caps on several cards of my MS16 with an ESR meter and I didn't find any out of spec.
 
Ok great! I have them on hand as I swapped out all relays once I got the machine and have some extras here. It would explain why I am seeing the same behavior across a few cards.

BTW - I have been listening to the Freelove Fenner recordings and admiring the tones! Do you use the Otari or MS-16? Really interested on how you get your drum tone.
 
That's great. Hope that fixes it. Do you have an extender card? If not, I'd be happy to send you a scan of mine and its measurements (it'd be pretty easy to fabricate if you're the diy type).

Thanks for the kind words. We mostly use the MX70 ourselves. But I'm never unhappy to use the MS16. If anything, it sweeps a little flatter. I just find the lower freq head bump on the Otari a little 'tastier'.

We mix it up a bit with drum recording but we we usually use a homebrew tube mic (peluso ck-12 capsule) as a mono overhead. Probably our most often used snare top mic is a beyer m260. We also like an md441 as a snare strainer mic. The room is pretty dead and the ceilings are pretty low. We like a little 1176 on the snare and Kepex expander on the toms. We usually do a mono bounce of the drums too.

For comparison's sake (and to factor in the sound different drummer's attack) we tracked the rhythm section for this band (they did a lot of their own overdubs at home) a very similarly manner to our own stuff and also used the mx70. And we also mixed it here to the same 2-track:
https://soundcloud.com/topsss/hollow-sounds-of-the-morning-chimes
Incidentally, for another song with that band we had to switch from the MX70 to the MS16 because of SMTPE gremlins. The whole band preferred the Tascam over the Otari. All other things were equal (except for tape stock 499 on the ms16 and GP9 on the MX70 but both machines were freshly aligned/with azimuth checked).
 
Ok - swapped relays and no love. Still significant roll off in the lower frequencies. Any other ideas? I'm going to assume it has to be some of the caps in the signal path.

I don't have an extender card - a scan would be brilliant… I can etch up my own.

Thanks for the drum recording breakdown - still working on getting good sounds. I typically go Oktava MC-012 for overheads, SM57 on snare top and D12 on the kick (the old one - amazing bottom end). Maybe I need a bottom snare mic... Not happy with my drum sound overall - hats and cymbals are way to trashy. I usually use a recorder man setup but thinking I need something new to get some shimmer.

Any thoughts on caps in the signal path?
 
So I'm assuming you already tried putting those 4 cards through a full calibration procedure, yes? Record EQ, sync and reproduce frequency response, etc?
 
Hey Sweetbeats - Yup, that is how I noticed the frequency rolloff. When recording 100hz tone there is no signal... which wasn't typical for the rest of the cards.

The same thing goes with the other 3 card being a problem - not as significant as the first one, but they're out of spec (i.e. more than 3 db off when aligned at 1 khz). As the MS-16 only has a single eq pot for adjustment (not hi and low) these cards are out of the acceptable range per the manual. Most noticeably the high end is rolled off on those. Other cards align well in their slots so its not the heads.
 
Looks like C14 is directly tied to the Lo EQ pot. So I'll try there to start as well as replacing the 50k trimpot that is the Lo EQ adjustment.

The other cards out of spec have the original relays... they switch fine but I'll swap them out to check frequency as the sync and repro EQ is fed directly from the relays as far as I can see.

I'll report back once the changes have been made.
 
So you did a FULL calibration procedure on these cards? Repro eq? Bias tuning and checked the bias traps, etc?
 
I did a full calibration minus bias tuning (not sure what that entails - I did check and set proper overbias). I also didn't touch the bias traps - if memory serves me correct the manual states it's set at the factory and rarely needs to be touched. I'll have to review the manual again and go through those procedures.
 
Bias tuning really should have to be touched unless a bias amp or oscillator was changed, but adjusting the bias traps is pretty simple and I like to do it on a machine that's new to me...who knows what has happened over the years.

I'm sorry to brow-beat, but I want to be sure...you checked/adjusted the repro eq and record eq? And if so the low frequency adjust on repro just maxed out and you still have that steep roll-off around 300Hz?
 
No brow beating at all!

I went through the manual and bias tuning and bias trap adjustment isn't difficult so I can certainly set up and check out those portions.

As far as alignment - yup it was a full alignment all the way from checking input levels against meters (and adjusting) all the way through bias adjustments, repro and sync levels as well as all EQ adjustments. With the Low EQ maxed out I still have a steep rolloff.
 
No extender card - I could fab one I'm sure.

No pink noise generator - but I'm sure I could run one off a computer and feed it into the MS-16 so no issue there.

I do have a scope meter - Fluke 123.
 
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