Now..Tascam MSR-16 wacky!

ron-e-g

ron-e-g

Member
Hello, I previously posted about a Tascam MSR-16 I purchased. It seemed in pretty good shape. I had no tape so I could not completely check the transport and Play/Rec functions. While checking the input's (from my M-520's Oscillator). I noticed track 16 had a different reaction to the signal than the other tracks. I interchanged track Rec/Play cards 16 for 15. The symptom moved to track 15. At this point I removed every card marked them w/permanent marker sprayed with DeoxIT, and re- installed them. The problem seemed to only appear as the DBX 9-16 button was engaged. Not during the actual depressing of button ,but rather while the DBX system was engaged. I removed the cards, marked them, sprayed them , and reinstalled them. No change. I then removed the two panels on the back to gain access to the 8 DBX cards. I disconnected them, sprayed them and reconnected. I also sprayed the Control PCB, and other various targets! No change. I decided to post here "Tascam MSR-16 wacky card" I didn't know what to do at this point. I had no tape to check the Transport, or Rec/Play functions. I decided to send it to a local Tech for a free estimate on repair. At this time, I noticed the counter roller was the consistency of clay. So I sent it to terry's Rubber rollers. I dropped the machine at the Techs.

Three weeks later he called to ask if I had an empty reel. He also said this machine is indeed messed up. He said he couldn't get the control panel or the transport button to respond, but that he checked and it was getting power. I was confused. I had never seen those symptoms. It always had gone through a "self check cycle" (my description)where all the lights would flash then it settled down to a "ready for user mode" (again my description) I even have a Pic. of it. (See next post). Now, when power is applied the VARI "fixed", and Vari "vari" lights, light, along with the LED tape counter light. Then a couple of seconds later the Tape speed "low" light, lights. This is where it stays the four lights on..nothing responds to the touch. I did notice the edit button seemed to be sticking so I attempted to remove the control panel PCB to gain access to it. After removing several screws I got scared of springs and tiny things flying so I stopped and tried to fix by spraying DexoIT and even WD40 from the front side It helped , but did not fix completely. I reconnected the two ribbon connecting cables after. I know, because later I double checked. After six weeks I called the tech who still hadn't looked at the machine other than power it on once. I told him I wanted to pick it up. I mean after all it could sit around here as well as his place. I did not say that to Him! ;) Too..I could have access to it to screw it up even more :) I've checked the connections I accessed previously and smelled I don't smell "burnt"

OK finally my question; Any one have any idea what I should do to get this back to where it was? I mean I could of course send it to somewhere to a Tascam Tech but given the value of these today that's probably not cost effective. I guess I could sell it as "for parts or repair" I would take a bath on that. I just keep thinking it's something very simple.

I'm actually hoping someone here that has technical knowledge of these models will read this, and recognize the symptoms I stated and be able to help me zero in on the probable problem area.

Anyone ...help please?
 
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So, the processor is failing to boot properly? That might be as simple as a power supply issue or a faulty connection. Otherwise it is likely to be difficult to debug. The MSR-24 has an EPROM, though I'm not sure what it does. The contents look similar to the ATS500 so it might be used only for interfacing with other hardware. On the TSR-8 there doesn't appear to be an EPROM at all and the software is AFAIK burned into the microcontroller's ROM area in the factory. I'm not sure which route the MSR-16 took, or whether the MSR-24 ROM would make a workable substitute if the problem is a loss of program code.
 
Is that what it sounds like to you jp? I would say "failing to boot properly" would describe it. Not sure about the Vari speed control (duel lights). I'm quite sure it is something very simple. As I never saw this, until I poked around inside, and started spraying things!! I looked at the connections I tampered with. However, In getting access to the DBX cards. The main control PCB (in rear) must be unscrewed and moved aside. There could be a connector dislodged from that. I was even thinking that the DeoxIT might have shorted something out.
 
Hmmm, a difficult one. I think you might have been a little too eager in the beginning. The original fault sounds like something and nothing....a slight problem with card 16? The manual I'm sure states that all setup is done without DBX engaged, otherwise I would have thought you would get funny readings. Where to go from here? How much have you got in the machine? If a few hundred bucks, then it might be worth sourcing another machine and using this one for spares........even at that price it's not cost you much. With another machine you could always swop things over to try and find the problem. I would ahve thought even for spares you would achieve around the $150-200 mark for the whole machine....more if you parted it out. Just my tuppence worth. Al
 
My first thought was power supply. IC logic based equipment does some strange-ass stuff if the logic power supply isn't right.

Is the power supply on a plug in card as well? I would check the logic power input (should be +5V DC) at the Control PCB with a good meter set to DC volts (should read close to +5V and be *stable*), and also measure with the meter set to AC volts (should be really close to 0...nothing more than a millivolt or two).
 
Thanks Al. I agree, It's a shame though. I'm still convinced it is something simple. Thanks for your thoughts on the subject. I got the machine in a bundle deal.


Sweetbeats, You may be on to something. The power supply is on a card. Matter of fact, it is next to the eight DBX cards. It is entirely possible I dislodged the connection there. I will check. Thanks for the specs.
 
ron-e-g said:
Is that what it sounds like to you jp? I would say "failing to boot properly" would describe it. Not sure about the Vari speed control (duel lights). I'm quite sure it is something very simple. As I never saw this, until I poked around inside, and started spraying things!! I looked at the connections I tampered with. However, In getting access to the DBX cards. The main control PCB (in rear) must be unscrewed and moved aside. There could be a connector dislodged from that. I was even thinking that the DeoxIT might have shorted something out.
Click to expand...

I'm not sure what the boot code is going to do, but if it's going to take a while to initialise I'd definitely make it flash the lights on until it was finished, which is what the TSR-8 does. If I were designing it I'd be tempted to make it display something on the counter too, that way if the boot sequence didn't complete it could at least give you an indication of what - kind of like how the A807 shows the ROM build date and the Otari displays error codes if something went amiss.

I'm no expert on microprocessor systems, but as an educated guess I'd say it was one of two basic scenarios:
1. The microprocessor is halting or going into an infinite loop
2. The boot code is doing a presence check on the hardware and has decided something is missing

Case 2 would point to some kind of connection problem or similar failure. It's likely that the pattern of lights still left on could tell the programmer or service tech exactly what has gone wrong, i.e at what point the boot sequence has stopped at and what it was trying to do. It's possible this is in the service manual, but I could also see TASCAM wanting to keep this kind of stuff close to their chest.

Case 1 might mean an electrical problem, such as noisy power, insufficient voltage levels or anything along those lines where the power is garbled in such a way as to scramble the logic levels and crash the processor.
As Sweetbeats said, check the power supply.
It might also indicate some kind of hardware failure, e.g. the RAM chip has gone bad, the EPROM has lost its program or failed checksum, or possibly even the CPU itself has been zapped. But the power supply is usually the first place to start looking.
 
Thanks jp.

Maybe someone with a fully functional unit, will chime in here and confirm the proper power on cycle of a MSR-16.
 
The MSR-16 uses a Hitachi HD63701Y0P. I can't find an exact datasheet for this chip. I'm hoping that the P means it's preprogrammed with a masked ROM - there are other variations which have an EPROM area (and possibly some which use an EEPROM instead?). The UV version can apparently be reprogrammed in the same way as a 27C256 EPROM, but this also means that it would lose its programming over time. A chip using a masked ROM (or a fuse-based PROM) chip wouldn't have this problem.

Studying the control PCB schematics and TASCAM's block diagram of the Hitachi chip's innards, it does seem to be a single-chip design, i.e there is no external RAM and EPROM chips to fail so that at least rules that out. Again, I'd look at the power supply first.

After that, my best guess would be that the boot process has stopped because the processor has tried to communicate with one of the peripherals and hasn't got a valid response.
What we can at least be reasonably sure of is that the CPU is able to communicate with the front panel PCB otherwise it wouldn't have been able to turn the lights on and off.
 
Getting deep! After reading my initial post I realize I left a couple of things out that may be important. In it's present condition. When the power button is pressed. both vari fixed (green), and vari (red) lights light at the same time, and stay light. along with the Tape counter display. A few seconds later the Tape speed low (red) light will light, and stay light.. All the while if no tape is threaded, the supply reel spins clockwise, and the take-up reel also spins counterclockwise. The capstan is also spinning. If tape is threaded (Both reels), there is no reel movement. I can however manually force the pinch roller to the capstan and get tape movement.
 
ron-e-g said:
Getting deep! After reading my initial post I realize I left a couple of things out that may be important. In it's present condition. When the power button is pressed. both vari fixed (green), and vari (red) lights light at the same time, and stay light. along with the Tape counter display. A few seconds later the Tape speed low (red) light will light, and stay light.. All the while if no tape is threaded, the supply reel spins clockwise, and the take-up reel also spins counterclockwise. The capstan is also spinning. If tape is threaded (Both reels), there is no reel movement. I can however manually force the pinch roller to the capstan and get tape movement.
Click to expand...

I don't like the sound of that at all. There shouldn't be any movement at that point. The capstan in particular is only supposed to start when the right tension arm is engaged. It might be worth checking the sensor on that, thinking about it, though it wouldn't explain everything you've just described.

This shows the boot process for a healthy TSR-8, and also for the MSR-24:
 
That Video is exactly how mine use to start. Thanks for that jp. So my guess is, the guy I got this from took me. It's probably only worth what time I want to spend answering questions on ebay boxing, shipping....ect to part it out :cursing: You know one thing..even when It seemed to function properly (excluding the TRK16 issue). After tying up the tension rollers,when I hit play the supply reel turned backwards! I don't know if this is a normal function given the fact I had no tape! Seems clockwise rotation on a supply reel is not right!
 
No, sweetbeats you didn't miss that..you don't miss much!:D I haven't yet. I actually don't have the machine here at home right now.
 
Okay. Fair enough. You should check that out when able. It's the first thing I think of (power supply issues) when logic is acting like that. It will do the strangest things.

And on a tape machine, servo transport or not, the supply reel when no tape is loaded *should* rotate clockwise in PLAY. This is to provide back-tension and is normal.
 
Sweetbeats,

OK, I will check Power supply. I do remember it being the ninth card. Positioned next to the DBX cards. I don't remember checking it's connection though. As for the supply reel thanks for clearing that up for me. Maybe "all's" not lost after all! :)
 
Yep..Among the other things. I can't believe anything I have done could cause this. All I have done is disconnect, and connect the DBX card connectors, remove, and reinstall the Amp cards and spray around some DeoxIT! Oh and disconnect, and re connect the control panel connectors. I did BTW figure out what was wrong with the edit button. It seemed to be sticky. When I would depress it it would stay down when pressed again. I would have to press the spool button next to it to get it back up. It was rubbing on the plastic around itself. The escutcheon. I folded some sandpaper very thin, so as to fit the button opening (with the PCB removed) and sanded it slightly. Smooth as butter now! Now... if only the rest would work properly!
 
Might be worth checking continuity on the PLAY button if possible, though I would not expect the machine to actually respond to PLAY properly until boot is completed.
Come to that, I'd be a little surprised if the keypad scanner was running while the during boot, but I suppose there might be some kind of diagnostics mode, e.g. 'Hold down FF, RWD AND STOP during power on to make it do X'.

Actually, it might be interesting to power up the machine with the control panel disconnected and see if that makes any difference.
 
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