Tacam 122mklll Calibration Question

[Brad Naylor]

Hello, new poster here, thank you for the forum.

I'm having a difficult time reconciling the Meter Level setting in the downloaded manual on a Tascam 122mk3 (page: 15 item: 3). It's asking for 400Hz input at -10dbV on the RCA's, then the input pots to be brought to the same output level on the RCA's, then asks for the meters to be adjusted to 0db.

This procedure puts my meters on +3db and I'm questioning this. I have several new, and near new reputable level tapes that when played, following playback level calibration with a Teac MTT-150, show the following:

MTT-150: about +.5db
Sony P-4 L300: -2db
RCA 1-101 Standard Reference Level: -2db
Abex TCC-121: -2db
Sony P-4-L81: 0db

Can someone help me understand why the procedure in the manual is so much different that what I believe I should see? Sam? Thank you.

 

[Garnok]

Yeah, and me too. I see a similar critical discrepancy, plus some murkiness of what I'm supposed to see and how to set "nominal" levels. In fact, I find no certain and reliable definition of how to choose a "nominal level", since the output is governed by a front panel knob.

And to be frank, the entire alignment routine in the Mkiii manual leaves a lot to be desired, and yes I'm working from an OEM paper copy.

But I did find one bit of potential help. Try reading the MkII alignment description. Although there are differences, I found that the MkII alignment - as a PROCESS DESCRIPTION - seemed more logical and similar to many ORAT processes. It also offered several helpful "nominal level" clues that were totally absent from Mkiii. Mostly, I found it helpful that it is a process description, not the near gibberish that I find in my MkIII manual.

And finally, did you find the correct levels at the claimed test points in step one in your 122 Mkiii? My manual claims them to be at test points 5/6. But I find them at tp 3/4, so my manual appears to have them backwards! (112 and 122 appear to be mistakely backwards)

Any insights you have about this alignment process are welcome. I'm not a newbie and I have a full and complete bench of everything necessary to do this job by factory standards, plus 45 years of working on ORAT. Glad I only have four of these to fix.

 

[Brad Naylor]

The mk3 and it's service manual both are a nightmare, I'm glad Boeing didn't choose to blend three 737 iterations together into one desperately footnoted document the way Tascam did. I didn't have a problem with the test points no, they are marked on the PCB and I typically measure Dolby levels on that chip anyway.

Following quite a bit of online research, I seemed to find some consensus that the MTT-150 should place the meters at -1db and that also causes the deck to behave the way I think it should. Later on, I picked up another that had service tags on the back, and that one agreed with the -1db from the Dolby tape so I'm comfortable with that number for now.

I'm curious if your paper manual is a dedicated one? I've searched the usual suspects for quite a while but have yet to see one. I do have a hard copy of the disastrous, 3 in 1, poorly written amalgamation, they so disingenuously call a "service manual".

 

[Garnok]

Hi Brad,

Yeah, the MkII manual is dedicated to the 122Mkii. It is fairly decent, not GREAT, but decent. It even has fold-out schematics and everything. Not roadmapped, but at least not cut across two pages.

The amalgam 3:1 "document" for the 112/122mkIII is not worthy of the name "service manual", IMO.

I guess I'm spoiled, as I'm used to working with Tektronix and HP manuals. These Tascam manuals leave a lot to be desired. I have a Model 32 manual and an earlier Teac manual as well. They too leave a lot to be desired.

Thanks for the tip on the -1db / MTT-150. I have three units untouched and one that I've twisted on a little. My gut was trending in that direction, but again absent a real measurement, and because of the dearth of reliable test tapes and manual instructions, it is a bit hit-or-miss. I remember the good old days when one could still acquire real analog test tapes of reliable characteristics. (I cut my teeth on analog tape, starting in the 70's.)

Oh well...at least I have two of the four units working.

Now I'm going back to troubleshoot the dragging and again noisy capstan motor in #3 unit. This, AFTER recapping the driver board and re-lubing the capstan bearings. It ran fine for a couple hours, but is now chittering and running a few percent slow. Something evil this way comes, I fear.

Cheers to you!
Keith
coolblueglow

 

[Brad Naylor]

Keith,

Thanks. I have the OEM mk2 manual, I was asking about the mk3, if you found one dedicated to just it, or only the combination one we both despise?

 

[Garnok]

Hi Brad,

Nope, I have what you have - the "amalgam". That is the only thing I've ever seen. I've never ever seen a Tascam 122MkIII manual solo. Personally, I don't think they exist. I have always wondered if Tascam sort of started out with the MarkIII as a "variant" - some sort of semi-disorganized approach to upgrading or combining manufacturing of their Cassette deck line away from the one-off design of the 122MkII or something? Maybe that explains the half-assed documentation? I dunno. It is bad.

FWIW, I'm an old retired geezer now. But I was buying Tascam decks back in the 1980's and 1990's, during the heyday of my recording industry career, and I've sourced a lot of them. Back then Tascam always felt to me like they were a little stuck between "real" studio equipment and consumer stuff. Ditto for Otari. Of course I was used to actually working with Sculley, and Ampex, MCI, Studer, and high end Sony (video) gear, and the like. In comparison, the Tascam stuff seemed a bit toylike.

So I chuckle these days when I hear people wax poetic about how "amazing" their vintage analog Tascam and Otari stuff sounds. Back in the day, based on A/B comparisons, everybody I worked around thought a Tascam 32 RTR was pretty sub-par compared to a well set up Sculley 280B or an A80 Studer or whatever. But cassettes were the bottom of the sonic barrel. In fact, we only barely accepted cassettes and only because our customers wanted to drive around in their cars and listen to mixes of their songs on cassettes...in a car. As you can imagine, that's about the worst possible way to judge a mix. Naturally, they would sometimes come back and say "I dunno...but that mix doesn't sound as good to me now as when we heard it yesterday!" That's when they were sitting in a million dollar control room with the best monitors money could buy and a noise floor of less than NC20 listening to the first generation master playing back.) Gee I wonder why? Ya think maybe it is because you were listening to a 30IPS half-inch master yesterday, and now you're using a stripe of tape that is effectively about 3/32 of an inch wide and running at 1/15th the speed of the master, and playing back through a pair of $79 pioneer 6x9 bouncing off your rear window.

So, you think that might have SOMETHING to do with it? hehe

We literally despised and even HATED cassettes...but we had to make cassette dubs for reference because the customer said so.

 

[Brad Naylor]

I have seen a dedicated 112Rmk3 manual so hope for the dedicated mk3 may be futile, but I never bow to futility.

The mk3 was the bean counter version when they saw the digital writing on the wall, it cannot be made to sound good in my opinion. They have bias trims for Type 1 only, then a single one each for Type 2 and 4. No separate levels or EQ. To save money they relied on the cheap exterior trims but still no EQ, anywhere to be found. Lots of other cost cutting also in every corner, the whole deck was a gratuitous compromise.

The mk2 was the pinnacle for Tascam, well built, ample controls, and can be made to sound excellent. I think Tascam's purpose was to corner the radio station and home studio market which they did in spades. They were well built until the 112mk2/122mk3/112rmk3 iterations but even those were wildly successful.

None of these are at the level of your A80 or Sculley's of course, even Willy Studer wouldn't build a cassette deck early on, but as tape formulations and deck technology got much more sophisticated, I think they were certainly worth their salt, and created many music lovers that may have been lost to the complexity and cost of studio gear.

I own cassettes and open reels also, cassettes are fun, reels are serious.

 

[Garnok]

Well, good to hear about the 112MkIII manual...and hope springs eternal.

Yes, I think your analysis of the situation with the MkIII is spot on. Fortunately I have a single MkII. So I'm going to move out these three MkIII if I can get them working right and hang on to the MkII.
And yeah...I know you are right about cassettes bringing tape to the masses. It certainly did make things available that wouldn't otherwise have been that way. Lot of people got to taste a smidgen of the faery dust via cassettes.

Personally I only think of cassettes as one-way devices now. I just make them the best playback they can possibly be to recover archival material that has survived ONLY in cassette format. (I have some). But once I get those historic recordings into something better, I'm beyond done with cassettes. Personally, I cannot ever imagine actively recording ANYTHING onto cassette for any practical reason. That's just me, though.

Cheers to you,
k

 

[Garnok]

Oh, and any ideas on the chittering capstan, post control-board rebuild? I replaced just the SMD caps with good stuff. The caps had not leaked...just had a couple which were defective here and there. (most were actually still working fine - but I replaced them all for obvious reasons) So one of the three decks ran fine for a couple hours and then started getting noisy and running slow. Yeah, I lubed the thing, but I did them all the same way and only one is making the weird chittering noise, so I assume it is not running stable somehow. I guess I will change those other two or three non-SMD caps and hope for the best.

Anyway, if you have other ideas - I'm all ears.

 

[Brad Naylor]

I haven't experienced the chittering problem, I've seen them dead, running too fast, and intermittent, but no chittering. I imagine you've already scoped it, other than that, since you have others, I would swap boards to narrow it down. Did you by chance check the end play? Sometimes previous owners will mess with that brass screw thinking it repairs the bad SMD capacitor problem. I think the spec. is 1,5mm but I can doublecheck.