Tascam 38 bomb

A

Abominable ID

New member
I'm gonna just drop a massive message with a lot of dumb newbie questions right now, but first I would like to thank everyone for all of the extremely valuable information on this forum. I have learned so much, that I know I would NEVER have been able to embark on the tape journey without it!:guitar:

I have recently acquired a 38 which has a host of problems. It seems to PLAY/REW/FF and all that, but how do I know if either of my REEL motors is not up to par? Is there a test?

Also, all of the VU meter lights are out. None of my fuses are blown. IS there a fuse for all the lights, and is it possible that they are all blown? Are there any replacement bulbs available today? (Like in the threads I've read from 10yrs ago-Including LED mods...)

Next, when I have the deck sitting flat on its feet, it starts to make this weird mechanical sound. I panic and return it to its functional position of tilted back about 20 degrees or so...anyone know what that could be?

I am not using the noise reduction unit with the 38, don't even know what that sounds like, probably never will. Should I be recording differently (like really hot), or change my machines record levels on the channels cards? ( I'm using a Tascam m-216 board)

And my final grandaddy question is: What is the function/purpose of the REPRO/SYNC head? If I can play and record both on SYNC, what is the purpose of REPRO? I discovered that tracks 3 and 6 recorded with SYNC, are not being played back by REPRO. So I thought, "oh, well I will just use SYNC." My 38 had other plans. I was very bummed to discover that now track 7 will not play back through SYNC, and even more tracks will not play back through REPRO. I'm very frustrated because I just got the whole system set up and was laying tracks and now this.:cursing: Am I to remove all the channels cards (which I have no idea how to do), find the relays, and spray De-Oxit in them and attempt to clean them and make sure my cards are seated properly? Also, I've read about "bad soldier joints on the 30's series"...does anyone know where those are? Is there a procedure for this sort of problem? I desperately want to get back to tracking and taking this machine to a pro is not an option.

Everything seemed to be okay at first, but the more I've used the machine the track problems began to manifest. I am extremely grateful for any suggestions or leads anyone might have. Cheers!

-Ash
 
On a professional deck, the heads are usually optimised for a specific purpose, e.g. the record head is great at recording but bad at playing back. The repro head is tuned for best playback and isn't great at recording.
On the 38 the heads are kind of middle-of-the-road and can do either task, I think they have some kind of compensation circuitry in the deck to help with that. Hence the TSR-8 which replaced it gets away with a single head for both record and playback.

Disadvantages with just using the sync head are that the repro head is actually playing back what you've recorded, rather than just mirroring the input. If you're doing a live band recording that's useful because you can hear that it's actually recorded properly. If you're overdubbing you don't usually monitor from repro because you're hearing things 1/15th of a second after you've actually done them.
The other disadvantage of just having a single audio head is that calibrating the deck becomes nasty. With a separate playback head, you calibrate that first, and then you can use that to adjust the recording head in realtime. Otherwise you have to record a bit, rewind a bit, play it back, adjust, repeat ad infinitum.

As you may be aware from what you've written, with the 30-series the typical culprit for the sync/repro switching failing (and dead outputs) is the relays going bad. However, I never really got that far with my '32, so I've not had any practical experience of replacing them. I have a feeling most of the relays are sealed so I'm not sure it's practical to repair them.
 
The repro and sync heads on all TASCAM 8-tracks have the same playback specs. The repro head is there for alignment purposes. Once alignment is done, all production is usually done in sync mode. The advantage is that the same head that records the signal, plays it back, yielding more accurate performance.
 
Abominable ID said:
Next, when I have the deck sitting flat on its feet, it starts to make this weird mechanical sound. I panic and return it to its functional position of tilted back about 20 degrees or so...anyone know what that could be?-Ash
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See my post, (post number 4) on this thread:

https://homerecording.com/bbs/general-discussions/analog-recording-and-mixing-tape-and-gear/tascam-38-restoration-almost-complete-capstan-wheel-sliding-grinding-383022/?highlight=#post4347325

This should help you cure the mechanical noise, which is caused by the flywheel rubbing on the underside of the head mounting plate. Make sure to clean away all the melted rubber goo from the underside of the capstan bearing, shaft and inside the flywheel.
 
Grr! cannot find a specification for sync replay response. Best I can find it this..* Tascam 38 *

I think it unlikely however that Tascam would use a replay optimized head for record/sync? Record heads have bigger gaps to allow higher flux levels before 'pole tip saturation' this leads to a loss of extreme HF compared to a dedicated replay head with a finer gap.

Dave.
 
Thanks everyone for links and feedback. I have apparently solved my track output problem for now! I am getting record/playback on all 8 tracks with both SYNC/REPRO heads! I don't know if it was the card swapping and De-Oxit on the terminals, or the loving words I spoke to the machine...probably neither. Maybe a little jostle un-stuck my relays. I discovered that laying my machine on it's side (with all covers removed), and removing the back silver lower panel, provides much more access to the cards, and allows for more delicacy in handling.

Now that everything is normal, I guess I will be tracking with SYNC head and using the REPRO only for tape alignment like Rick said right? I probably won't be recording any bands, just myself a couple tracks at a time.

Does anyone know which relay (k101, k102, k103) on the cards is usually the problem child? Is it possible to replace? Substitute? I feel like this problem will be coming back!!!

Thanks quiberon for the flywheel tip, I will have to wait until the next time I take the machine apart. That sounds like the problem for sure.

Lastly, I made no progress with the VU meter bulbs so I'm assuming they are all blown. I'm just looking for a replacement, or attempting an LED mod like from the 10 year old threads. If anybody has a good link, I would love to have it.

Appreciate everyone's time,

-Ash
 
See how it goes, first. You might be lucky and the cards just needed re-seating. K101 is the repro/sync output switch, K102 mutes/unmutes the output, and K103 switches the sync head between record and playback mode. (This from the '32 schematics, I believe the cards are mostly the same).

The G2V2 relay seems to be out of production, I can't find a datasheet for it and the '32 schematics are doing a terrible job of saying which pin is doing what so that a compatible equivalent can be found. I might have to get my spare channel card down from the loft and study it in detail. There is a 24v G5-V2 but whether it is pin-compatible I have absolutely no clue.
 
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ecc83 said:
Grr! cannot find a specification for sync replay response. Best I can find it this..* Tascam 38 *

I think it unlikely however that Tascam would use a replay optimized head for record/sync? Record heads have bigger gaps to allow higher flux levels before 'pole tip saturation' this leads to a loss of extreme HF compared to a dedicated replay head with a finer gap.

Dave.
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I ran the TASCAM studio in the late 70's/early 80's. The only 8-track that didn't have the same repro specs in play and sync was the 70 series machine.
 
ecc83 said:
How and why was that then?

Dave.
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I had been loosely affiliated with TASCAM via Dick Rosmini, who was at various times a consultant to TASCAM, JBL, Yamaha, among others. (The very 1st TASCAM 1/2" 8-track, the 70-H8 prototype, was used on one of my sessions.) The music from that date was used to demo the machine at trade shows. A few years later, TEAC USA decided they needed a place to test early production and prototype TASCAM gear under real world conditions. My house fit that bill. They installed the prototype Model 15 console, the #3 90-16, a pair of JBL 4333's, a 35-2 mastering deck, a bunch of mics, and all the necessary wiring to make it all work. My friend, John Horton, former engineer for Ike Turner, measured and treated the control room afterward.
 
RRuskin said:
I had been loosely affiliated with TASCAM via Dick Rosmini, who was at various times a consultant to TASCAM, JBL, Yamaha, among others. (The very 1st TASCAM 1/2" 8-track, the 70-H8 prototype, was used on one of my sessions.) The music from that date was used to demo the machine at trade shows. A few years later, TEAC USA decided they needed a place to test early production and prototype TASCAM gear under real world conditions. My house fit that bill. They installed the prototype Model 15 console, the #3 90-16, a pair of JBL 4333's, a 35-2 mastering deck, a bunch of mics, and all the necessary wiring to make it all work. My friend, John Horton, former engineer for Ike Turner, measured and treated the control room afterward.
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Oh! I was not questioning your bona fides Rick! I am just a nosey, tekky bugger and wondered why Tascam would not fit the best replay head they could? Even in the cassette world it was recognised that a combined rec/play head was a compromise and 3 head machines developed even though it took some pretty drastic and clever engineering!

Dave.
 
ecc83 said:
Oh! I was not questioning your bona fides Rick! I am just a nosey, tekky bugger and wondered why Tascam would not fit the best replay head they could? Even in the cassette world it was recognised that a combined rec/play head was a compromise and 3 head machines developed even though it took some pretty drastic and clever engineering!

Dave.
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The designers never discussed the how and why aspects with me. FYI - TASCAM was not the 1st to use an r/p head on a multitrack machine. Scully was. Their machines had no repro head at all, bringing the cost way down. Audio performance was excellent but alignment was a royal pain.
 
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I've had a couple 38's over the years. I used them as my main recording decks in the 90's, before switching to other machines/more tracks. I liked the sound and the ease of use, never did have or use dbx with them. The one I have left, I started experiencing problems where track 8 would record, but not play back. After a lot of searching around, I uncovered a common problem with channels dropping because of solder joints going bad. Apparently, low temp solder was used in the construction, and tended to un-solder with a lot of use, or when moving the machines.
I bought myself a magnifying lamp and spent hours re-flowing all the joints on the motherboard, and the machine worked without problems for a couple more years, at which point, I gave it to my brother to use, and a year or two later, it started giving him the same problem.

As to the repro/sync question, the sync head, as you may guess, is used for playback during tracking, so that you're hearing recorded sounds in sync with the new ones you're recording. When playing back to mix down for mastering, it was recommended both by the manual and others to use the repro head, which I was told is a better quality head. I don't have any scientific info to back that up, but that's what the manual said.

If you record a track, and it plays back on one head, but not the other, that to me would suggest a head problem, but that's just my gut. Make sure both heads are thoroughly clean. The tape formulations I was using in the early 90's were notorious even then for gunking up the heads pretty regularly. Any time too that you have a problem with an edge track - 1 or 8, it's possible too that it's a physical alignment problem. The fact that you see the needle moving when you record does not mean anything is actually being recorded; only that there is a signal going in. I have a TSR-8 that, despite fairly low hours, would not record on any track. Turned out that the record head was just that dirty. After a lot of cleaning, it worked fine. But those are just some common things to check.
 
seankerns said:
...As to the repro/sync question, the sync head, as you may guess, is used for playback during tracking, so that you're hearing recorded sounds in sync with the new ones you're recording. When playing back to mix down for mastering, it was recommended both by the manual and others to use the repro head, which I was told is a better quality head. I don't have any scientific info to back that up, but that's what the manual said.
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Incorrect. Take a look at Entering Record - Tascam 38 Operation And Maintenance [Page 8] under the subheading "Sync."
 
Regarding the VU meter lamps, do you have a multimeter? If so you can check to see if power is getting to the lamps. I can’t get to my 30 series documents at the moment...anybody know if the lamps in the 30 series are AC or DC powered? If somebody can answer that, once known, set your multimeter to
AC or DC volts as indicated, find where power enters the string of meter PCBs, and measure to verify power is present. Each meter and its lamp are mounted to their own little PC board...or sometimes in pairs...the lamp power is usually connected at one end and then propagates in a daisy-chain from board to board. They are often a bit of a pain to access. I put my money on the lamps all being burnt out. You can still get lamps, but I’d need to see which ones they are. Typically you have to unsolder what’s in there and solder in new lamps. How are your soldering skills?

Regarding your tracks now functioning, it is quite possible re-seating the cards and/or jetting the relays with DeoxIT improved things. If the relays are getting dodgey the fix will be temporary and start acting up again, at least that’s my experience. Replacing them is the only cure. And I’ve not been able to determine current replacement parts for two of the three relays. I’ve never had a 30 series machine, so have never had one in front of me to lay eyes on the actual pin configuration of all the relays.

Regarding sync vs repro head response, as head manufacturing tech improved (thinner laminations in coil construction), manufacturers were able to use a compromise head coil gap length with response specs that still exceeded earlier generation repro head performance on machines with distinct gaps between the record and repro heads. Being able to have one part assembly to manufacture for both the record and repro heads lowered costs...the heads are a high cost part on a tape machine...and meant the talent had better sound in the cans when overdubbing. So, as already stated, on a machine like the 38, the repro head is often only used for calibration/alignment (and this IS a nice time-saving feature) or if there is need for real-time playback monitoring during tracking to verify the quality of your print and make tweaks while recording...also a handy feature.
 
sweetbeats said:
Regarding the VU meter lamps, do you have a multimeter? If so you can check to see if power is getting to the lamps. I can’t get to my 30 series documents at the moment...anybody know if the lamps in the 30 series are AC or DC powered? If somebody can answer that, once known, set your multimeter to
AC or DC volts as indicated, find where power enters the string of meter PCBs, and measure to verify power is present.
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Everything in the 30-series is rectified so it's all DC. Helpfully the schematics don't give voltage levels for the lamps, or expected voltage for that line of the power supply. If I'm reading it right there's a 16v capacitor in the power line driving the lamps so my guess would be 12v for the lighting circuit.
 
Very grateful for all the replies! I ordered bulbs from a guy on Ebay that were pictured in a 38 VU meter, and I had somehow (with my multi-meter, or online?) got the idea that they were in the neighborhood of 6v 100ma? So the ones I bought are 6v 150ma, and I put one in and nothing...then later I was sort of moving those wires a little and the bulb started working! I got super excited and replaced all of them and everything seemed fine...until about 2 min later when the counter and VU meter lights began to flicker continuously-like something charging and then discharging. And of course there is a fuse for that whole circuit . But I am wondering if that 50ma difference is screwing up the circuit and possibly doing damage. There are points where the lights and counter get so dark as to be unreadable. Did the guy sell me the wrong rated bulbs just to make a measly $10? Or is there another problem with the circuit? I scoured the schematics and manual, and I could not find ratings for the bulbs, and all the threads pertaining to this issue seem to be almost 8 years old regarding bulbs from Parts Express which are no longer sold. I measured with multi-meter and I think it was around 7v. I would totally do the LED mod, but I feel like I don't know enough about the circuit ratings. Does anyone know the exact rating for those bulbs?

-Ash
 
I am very jetlagged and have some big holes in my foundational knowledge of electronics at the best of times, but my first inclination would be to suspect an intermittent connection. That said, it might be worth videoing the lights going strange and posting it here.
 
JP,
Since my last post, I solved my lamp/meter problem by buying another machine in better condition than the first. However, my MAJOR issue now is of course still the relays on the PCB cards. I have reflowed the soldier on the motherboard to no avail, and I am positive the relays are the culprit. I am about to try the cleaning method detailed by Sweetbeats in his Tascam 58 thread, which will only work for two of the relays on my 38, the third is fully closed in plastic. I read in one of your old posts about the relays in your 32 and wondered if you had a)ever replaced them b) any idea if such a thing was possible? Or any information on getting and keeping those guys working! Cheers!
 
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