ms16 tachometer not working properly

  • Thread starter Thread starter hertzcontrol
  • Start date Start date
H

hertzcontrol

New member
hello there, i just scored an ms16 from a radio station here in portugal....it was left in storage, filthy for years. I can see the heads are misaligned because of the wear pattern...
the main issue is:
tachometer is not working on play/rec/rew/fwd only on EDIT mode...am I doing something wrong? already cleaned the machine, unplugged and replugged all the switches inside... IMAG1047.webpIMAG1047.webp
 
When you say tachometer, are you referring to the tape counter? Or something in the function of the capstan?

Second: Its hard to tell from pictures of heads but the playback head (the far right one) looks crusted with tape oxide? Or is it just a reflection?
 
If the tach roller registers results in the edit mode, that at least rules out any photo/mechanical issues with the roller assembly, which only leaves logic/transistor switching issues, most likely. If you're not equipped, skill wise, to track that down, seek out an experienced technician to trouble-shoot it.

About your saying that you cleaned the tape path, I'd strongly suggest doing that again with methanol as you've got some seriously caked on oxide there still!

Cheers! :)
 
its the tape counter, doesn't show up the tape position neither on the screen of the machine or on the autolocator, and that rules out the board on top as well...i was ready to order sensors but then it worked on edit mode. It was all stuck! rewind was slow, head protector wasn't popping out, tape lifters didn't move...
this picture was prior to cleaning.
ill be taking it to a hifi repair guy nearby(a good one), nobody does maintenance of r2r's in miles and miles...and this beast weights a ton.
they were using it back in the day with a tascam m520 mixer, using the unbalanced rca connectors on the machine. will there be an audible improvement using the balanced ones? ill be using it with a soundcraft 6000 board( mostly because of the 16 buss outs).
cheers
 
The balanced in and outs are an additional circuit in terms of signal flow, so it's doubtful the sound quality would be improved by using them.

Your hi-fi repair guy should be fine so long as he has the service manual for the machine which contains all the schematics and signal flow logic switching.

By the sounds of it, the machine was seriously rusted by the long term storage and non-use. Hopefully its just a corroded contact somewhere that they can trace down in short order. But if that's the case, there may well be several of the same connectivity issues on other parts of the machine which might get mighty tedious and expensive to find and fix.

Good luck.

Cheers! :)
 
everything else on the machine is working fine, records and reproduces correctly, and every other function works. After a closer look on the psi board, some of the larger capacitors could be replaced. I traced up to the logic board the cables that go to the sensor. well, on the board itself says 5 volt but it only reads 2 something volts on my multimeter. so, hopefully, its a psu problem and that would be easily fixed....
what about the head life? do they look too bad? seller told me they replaced them a year or so before storage, but it looks to me he didn't align it by judging the triangular pattern..."easy" to do?
 
Re: head life and fixes. It's impossible to give any sort of accurate diagnosis based on a couple of photos other then to confirm that yes, the wear pattern is uneven. So a relapping is probably required combined with a total mechanical and electronic calibration after the re-lap job. Easy to do? No, it requires experienced skills and specialized equipment and a calibration tape. The operation/maintenance manual, if you have it, is designed to step a trained technician through the process of calibration. Perhaps also inquire with your hi-fi guy if he is up to that task. We also have a number of threads on this forum on the topic of calibration if you wish to attempt this on your own.

Myself, I hired a local technician to calibrate my MS-16 when I owned one as it was way cheaper to pay him then to invest in all the gear and the MRL calibration tape.

Cheers! :)
 
The Ms-16 uses photo interrupters set 90 degrees apart,-look at the theory of operation if you have the manual. Make sure there isn't gunk partially blocking either the led or the photo sensor.This would explain counting in the EDIT mode,but not in any other mode.
 
local repair guy tested the sensors and they are working...he says it might be the logic board
 
mm, does the technician has significant experience with RTRs ? this is like opening a computer and saying...mmm It's the motherboard. Which means the whole computer is shot in most cases. Fortunately that is not how RTRs work. Due to their age a high percentage of the logic board can be fixed by replacing parts. Any other issue with the machine ? or this is the only one ? transport control ? recording, playback etc ? how is the power supply, need to measure all the power rails +15, -15, +5, etc.

This machine has microprocessor control, if there is a power supply issue, the CPU may behave erratically producing unpredictable issues that may not have obvious links but in this case the EDIT mode what it does is that it invalidates the tension sensor reading as well, there is a condition with that, meaning that if there is no tape installed on the machine, the counter will not move.

So in this case you may have a problem that the machine "thinks" there is no tape installed, so the counter will not move. When you go into EDIT mode the tape tension sensor is "ignored" so the counter can run again and you can spool tape out. I think that is your problem, somehow that condition is not met and then the counter is disabled. Let me look at schematics tonight and give you more specifics.

If the technician that you have has no experience on these machines then he may do more harm than good, so don't let him mess with the machine to try to hack it as it will likely do more damage. I'll reply tonight after looking at the schematics when i get home.
 
MS16.webp

Take the control PCB and measure the three points highlighted in blue, red and green. That is the path for the end sensor. This is the optical sensor located at the RIGHT side of the recorder on the right side tension roller. Push the roller all the way (outwards) and you should see the value changing on those three points. a bad reading will invalidate the counter. That should be your problem. If it is it will be about following the signal and change the ICs in question easily found today and cheap. If you are not comfortable doing electronic repairs, find someone that can follow the schematics and check this for you, it is not hard.

Good luck, let us know if any questions.
 
he is not a r2r expert...he his an high end hifi amp and speaker builder, and the best electronics guy i know...theres no one to service r2r in miles in a row. damn portugal.
 
well guys, I guess I'm not a lucky guy. Repair guy came back to me today, he says he replaced the ICs and the readings are ok when they come into the microprocessor, but nothing comes out, is it possible to have de micro controller busted? just on that? thanks
 
i don't think so. did you check the sensor and output as mentioned on my earlier post ? it may be the tape tension sensor, or a contact. not necessarily an IC. This failure is actually something that doesn't necessarily requires an experienced tape machine technician, an experienced electronics technician maybe able to do the job if you explain the problem well enough, use the schematics and explanation above. I mean based on the limited resources that you have there i would try that.
 
You must log in or register to reply here.
Back
Top