Measuring Tascam Ms-16 Output Voltage and Rec/Play Cards

RandyRhoads1981

RandyRhoads1981

New member
Hey there,
I finally got my Multi-Meter working and now
I am going into my Tape Machine to try and
find the culprit of why it isn't working
in Sync Mode and why the Channel 6 Card
is barely responding to any signal.:confused:

So... I have some questions:
1)How do I measure the Output of my MS-16 from the XLR connectors?
2)Do I place the Leads on the Hot and Cold pins?
3)Which Lead goes on which pin?
4)Do I need Alligator clampers?

I also want to check some of the components
on the Rec/Play cards.
Specifically the Opamps/IC's.
5)Are there certain pins I need to measure
on the IC's or can I use any?
6)Can they be measured from the top, or
does it have to be from the solder points?
I ask because I don't have an extender card
and the bottom is a very tight spot.

Any advice/input would be very appreciated.
Thanks,
-Thomas
 
First of all, is your meter a true rms measuring meter? It becomes important of you are using it to measure audio amplitude. You want a true rms meter, and if you're going to be using for calibrating the amplifier electronics then you should consider getting one that is accurate over the audio spectrum.

K.

Now...

  1. See below, and...assuming your meter is unbalanced (its just got two probes right?), you need to compensate your reading to account for the fact that you aren't measuring both legs of the balanced circuit...with a balanced meter it has 3 probes and you are measuring pins 2 and 3 referenced to pin 1...with your meter (assuming it is unbalanced/two probes) you'll be measuring pin 2 OR pin 3 (take yer pick) against pin 1, so you are missing the oomph of one of the signal conductors...What to do? Easy...just know that what you measure with your unbalanced meter is going to read -6dB from actual levels. That means a +4dBu 1kHz test tone reproducing off a test tape, for instance, is 1.23V AC RMS, but your meter will read 0.62V AC RMS. Here's my favorite converter tool: http://www.sengpielaudio.com/calculator-db-volt.htm. Oh...and if you haven't figured it out yet, when you are measuring audio amplitude you want to measure using AC volts, not DC.
  2. Yah.
  3. Connect the lead plugged into the COM jack of the meter to pin 1 of the XLR; connect the lead plugged into the AC volts jack of the meter to pin 2 or pin 3 of the XLR.
  4. Dunno...depends on how you want to do it. The most accurate way to measure output levels with a meter is to have the output "loaded", or connected to an input. That means you need a 'Y' or splitter cable. I have an XLR splitter for this so the output can be connected to the mixer but I can still "sniff" the levels coming off the deck. For now, since you're not calibrating it but just checking relative levels to track down a gremlin I wouldn't worry about this but its something you might want to consider. So anyway I don't need alligator clips because I have a female XLR plug into which I can just stick the probes...handy.
  5. Well, that depends entirely on what you are wanting to measure, and what chip you are testing. Generally, just about every pin on an IC is doing something different with respect to the circuit...some of the functions are duplicative, but for different paths of the circuit. First you gotta figure out what it is that you are wanting to test; what you are trying to determine. Then you need to understand how the IC may (or may not) play into that investigation. Unless I KNOW an IC is the culprit I don't automatically assume they are the trouble. More often than not in my experience they are NOT the problem. Study the schematics...download the spec sheets for the IC's and study them. Gettin' all probey with yer probes without knowing what you are looking for or what you are doing...not thinking things through and being calculated and methodical...is a fine way to make sparks.
  6. Doesn't matter...the legs or pins go to the solder joints...leg bone conecca to the hip bone...

What experience do you have doing this sort of thing? You can really hone in without even turning on your meter by studying the block diagram and then when you narrow down the zone you can then get into the schematic and hone in and test. Have you determined that channel six is or is not the amp card by swapping them around? Is the problem intermittent? Is your tape shedding? Are the heads spotless?
 
sweetbeats said:
What experience do you have doing this sort of thing? You can really hone in without even turning on your meter by studying the block diagram and then when you narrow down the zone you can then get into the schematic and hone in and test. Have you determined that channel six is or is not the amp card by swapping them around? Is the problem intermittent? Is your tape shedding? Are the heads spotless?
Click to expand...


Not much experience.
Not much money either, so I wanted
to try and find the problem myself.

WOW. That was a LOT of really great info.
All my questions were answered and more.
I felt that maybe the IC's were the problem w/ Ch-6
because they handle power/amplification(right?).
Well, thanks for telling me all of this.
I am way outta my league beyond testing
the XLR Output.


The Channel 6 Card has hardly any power when swapped.
My Machine nor Tape causes shedding.
The Heads are magnificent.
All Tracks in Sync Mode are Intermittent
but Channel 6 is never working.
Also, Channel 5(in Sync and Repro) dropped about
-3db a while back and it never recovered from it.
Don't know what that means.

Thank you so much:D
 
The Channel 6 Card has hardly any power when swapped
Click to expand...

Can you clarify this? Do you mean the problem followed the card when you tried it in another slot?

  • Have you reseated all the cards? By reseating I mean pulled the card from its socket, applied some DeoxIT D5 or DeoxIT Gold to the card socket, plugged it in and unplugged it a time or two to "exercise" the connection?
  • Have you reseated the cable connections between the meter/amp unit and the transport? Does there appear to be any oxidation on these connections?

Once you have addressed the above questions/procedures, and if the problem remains then answer me this:

Is the global issue (all tracks intermittent in sync) kind of like an "I'm going nuts...this is driving me freaking crazy" problem that you can't seem to nail down, like its changing all the time and some channels work sometimes and not others and you just want to cry?

If so, and others may disagree and if there is something else to consider before jumping to this possibility I hope they chime in, but it may be time to replace the relays on the amp cards.

I had this same hair-tearing experience on my 58, which uses the same amp cards BTW...at the time I was able to rectify the issue by opening up the relays and cleaning them, but if they are exhibiting problems then cleaning them is a temporary measure at best. The real solution is to replace them. On the 58 and MS-16 amp cards there are two relays per card. I put a picture below and outlined the two relays. Notice one has a chrome cover over it, the other doesn't...they both should have the covers. For some reason the covers were missing on one set of relays on my 58. Anyway, those are them...you've got 32 of them and its what I'd be looking at as the problem.

Also, yes SOME of the IC's on those amp cards provide for signal amplification, but understand that they don't function on an island. Many components play into that amplification...setting the internal gain, filtering, etc. And some of those IC's do other things like serving as a comparator to tell the peak LED when to light, or driving the VU meter needle...remember, gettin' all probey with yer probes, yada-yada...

Also, in my experience, the failure mode for an amplifier IC is "I quit", not "I'm not workin' so good". In my experience they have problems if they've been overdriven and then they cook and are done. Just another bit to add to the brain there on why I wouldn't personally jump to the assumption that an opamp is bad...if you are getting *some* sound, then the "amp" is working.

Here's that picture:
 

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sweetbeats said:
Is the global issue (all tracks intermittent in sync) kind of like an "I'm going nuts...this is driving me freaking crazy" problem that you can't seem to nail down, like its changing all the time and some channels work sometimes and not others and you just want to cry?

If so, and others may disagree and if there is something else to consider before jumping to this possibility I hope they chime in, but it may be time to replace the relays on the amp cards.

I had this same hair-tearing experience on my 58, which uses the same amp cards BTW...at the time I was able to rectify the issue by opening up the relays and cleaning them, but if they are exhibiting problems then cleaning them is a temporary measure at best. The real solution is to replace them. On the 58 and MS-16 amp cards there are two relays per card. I put a picture below and outlined the two relays. Notice one has a chrome cover over it, the other doesn't...they both should have the covers. Anyway, those are them...you've got 32 of them and its what I'd be looking at as the problem.
Click to expand...



THANK YOU SO MUCH!
You are the best:D
I don't think I have a hair left on
my head after this fiasco.
Believe me, I have cried over it.
Exactly as you described it.

Yes, The problem follows the Channel 6 Amp Card.
I have cleaned and reseated Cards 1-4, but to no avail.
I have also thoroughly cleaned and reseated all Transport-Amplifier-Meter
Bridge Connectors.
A little bit better, but still persists.
I have been looking into new Relays for about a month now.
I have found the MR62 24v Relay, but I can't really find
the G2V-282P Relay for the life of me.
And that is the Sync/Repro Relay.
I was thinking of the IC's for the Channel 6 Amp Card.
Did you replace all of your relays?
Where did you find them?

It feels so good to have someone finally answer my
questions in whole and has had the same problem.
Thanks SweetBeets:D
 
About the G2V-282P 24v Relay:
I have found it, but it says 47/7 on it.
What does this mean?
I have also found one that is G2V-2-US-24v
It is an 8-Pin as well. It isn't sealed.
 
The cleaning/reseating of the cable connections could make things temporarily better if it is a relay issue...

I didn't replace my relays...I just cleaned them and it took care of the problem...but then I made a careless error and toasted that mint-mint-mint condition 58.

This is the part where you say "wait...I'm listening to this guy because why?"

Anyway, I got in over my head and ended up selling it to a friend on the forum who is local to me and he patched it all up quite nice, and I think he may have replaced them...I'll investigate.

Never replaced relays but believe me its the way to go if they are getting tired/problematic.

Can anybody help Mr. 1981 out on a Mouser or Digikey CAT# reference/link for those relays?

Oh, and with channel 6 it could be that once of the relays is just worse off. At any rate we can be reasonably sure its a problem with the card since the problem follows. Reseat all the cards and apply a good contact cleaner. Always the first step with this sort of thing IMHO and we'll see what we come up with as far as links to replacement relays if you choose to go there.
 
sweetbeats said:
The cleaning/reseating of the cable connections could make things temporarily better if it is a relay issue...

Can anybody help Mr. 1981 out on a Mouser or Digikey CAT# reference/link for those relays?

Oh, and with channel 6 it could be that once of the relays is just worse off. At any rate we can be reasonably sure its a problem with the card since the problem follows. Reseat all the cards and apply a good contact cleaner. Always the first step with this sort of thing IMHO and we'll see what we come up with as far as links to replacement relays if you choose to go there.
Click to expand...





Thanks so much.;)
You have been so helpful.

By the way, if I send a signal to the Input
of Channel 6, it is ok. So that works.
I think I forgot to mention that every Track is perfect
in Repro mode, except Channel 6 of course.
Once I get a Solder remover, I'm going to
try and clean/re-seat the Relays.


About the link you sent, the Relay is G5V, but
the Relay is G2V, do you think it still would work?
Do you think I should try them anyway?

Thanks again for all the help;)
 
RandyRhoads1981 said:
Thanks so much.;)
You have been so helpful.

By the way, if I send a signal to the Input
of Channel 6, it is ok. So that works.
I think I forgot to mention that every Track is perfect
in Repro mode, except Channel 6 of course.
Once I get a Solder remover, I'm going to
try and clean/re-seat the Relays.


About the link you sent, the Relay is G5V, but
the Relay is G2V, do you think it still would work?
Do you think I should try them anyway?

Thanks again for all the help;)
Click to expand...

So when you monitor the input on channel 6 the output level is okay? Its just when you are monitoring in sync mode?

You don't "re-seat" the relays. If you are going to take an iron to them then it better be to replace them, and if you are thinking of replacing them then don't bother cleaning them.

If the problem is only in sync mode globally, have you tried reseating the head connector for the sync head?

Those relays I linked are better than stock and were used by another member on his MS-16.
 
sweetbeats said:
So when you monitor the input on channel 6 the output level is okay? Its just when you are monitoring in sync mode?

You don't "re-seat" the relays. If you are going to take an iron to them then it better be to replace them, and if you are thinking of replacing them then don't bother cleaning them.

If the problem is only in sync mode globally, have you tried reseating the head connector for the sync head?

Those relays I linked are better than stock and were used by another member on his MS-16.
Click to expand...




Awesome!
I'm gonna buy some.
Glad to hear they work.


Yes, the Level is good upon Input mode, but
it is very faint if I monitor in Sync during Record or Playback.
I haven't checked it's Output Voltage on the Multimeter yet.

If you don't remove them, then how do you clean them?
Yes, I have cleaned the Sync Head connector and reseated it.
 
Not to rain on your parade, but just remember that there's no gaurantee that that is the problem or the entire problem. Not a bad idea to put the relays in anyway, but it is curious that repro is fine, but sync is not.

And how'd you get 25 for $13? I thought they were, like, a couple bucks each?
 
sweetbeats said:
Not to rain on your parade, but just remember that there's no gaurantee that that is the problem or the entire problem. Not a bad idea to put the relays in anyway, but it is curious that repro is fine, but sync is not.

And how'd you get 25 for $13? I thought they were, like, a couple bucks each?
Click to expand...




That's what I thought.
They're usually expensive.
I am somewhat prepared for the problem
to still be there.
But if it doesn't help, at least I have new relays
for a very cheap price.

It seems logical though, that Repro is
fine but not Sync playback.
Which is what that Relay is for.
The Schematics say it is for Sync.
And the other is for Record.
Would that mean Repro is included in that Relay too?
If Sync and Repro are combined in that Relay,
then I am really stumped.
I was more excited about getting the Relay I
couldn't find for a really cheap price
and all of them that I need plus more.

I've kinda learned with my MS-16 to
expect the unexpected.
Which is good and bad.
I do think that it is the Relays.
If not, i'll keep on searching.

I don't know if this piece of info helps,
My Machine came from Georgia, which
is extremely high Heat/Humidity.
Perhaps the Humidity has caused
for some components to
a)Fail
b)Malfunction Intermittently
Just a thought...
 
Naw. It's really hard to wack out a MS-16 and only a total nut job for a previous owner could do something like that to a beautiful machine that might have cost somewhere between 8 and $15k when new, depending on options, but a zillion of them have been treated that way. :eek:

Try turning the thing on and leave it on for a full day to heat it up before doing anything. BTW, I have a couple dozen spare channel cards if that would be easier, which me thinks for sure it would be. Do you have any idea how long it might have been setting before you bought it and powered it up?

Georgia huh ! Well, I would almost bet that you prolly latched on to another one of those poor machines that either some metalhead OR rapper seeking that "WARM" . . . . "SATURATED" . . . "+9" analog distortion (ha ha) totally jacked up and then sold because he had screwed it up so badly. Most of those idjiots really need their arses :spank: for wacking out such perfectly good machines. :mad:

Danny
 
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pianodano said:
Naw. It's really hard to wack out a MS-16 and only a total nut job for a previous owner could do something like that to a beautiful machine that might have cost somewhere between 8 and $15k when new, depending on options, but a zillion of them have been treated that way. :eek:

Try turning the thing on and leave it on for a full day to heat it up before doing anything. BTW, I have a couple dozen spare channel cards if that would be easier, which me thinks for sure it would be. Do you have any idea how long it might have been setting before you bought it and powered it up?

Georgia huh ! Well, I would almost bet that you prolly latched on to another one of those poor machines that either some metalhead OR rapper seeking that "WARM" . . . . "SATURATED" . . . "+9" analog distortion (ha ha) totally jacked up and then sold because he had screwed it up so badly. Most of those idjiots really need their arses :spank: for wacking out such perfectly good machines. :mad:

Danny
Click to expand...




Haha. Thats funny.
Well, my machine came from a Gospel Studio in Georgia.
I tried finding them, but I didn't know the name of the Studio.
Yesterday, I left her on for quite a while and
she was working great. I switched from Repro to Sync
many times and most of the time all 14 Meters came up.
14 Meter because Channel 5 doesn't play in Sync.
And Channel 6 doesn't play in Sync or Repro.

The reason that is so cool, is because I can get
all of the Meters to stay up constantly in Sync
but as soon as I switch to Repro and back, it's
back to where I started.
Anyways, I'm gonna try keeping her warmed up again.
Maybe the hotness kinda cleans off some oxidation or something?

I sure could use some Channel Cards.
Very useful to have around.
How much would you sell some of them for?
I guess I would want somewhere around 6 of them.
 
Forgot to say this,
My machine has been sitting for a very long time.
Don't know about it's use or how long it sat in Georgia,
but the previous owner here in LA had it for about
10 years(maybe more) and only did a Tape Transfer and nothing else.
And then it sat in a closet until I came and picked it up.
 
RandyRhoads1981 said:
Forgot to say this,
My machine has been sitting for a very long time.
Don't know about it's use or how long it sat in Georgia,
but the previous owner here in LA had it for about
10 years(maybe more) and only did a Tape Transfer and nothing else.
And then it sat in a closet until I came and picked it up.
Click to expand...


Well, I would definitely leave it on daily while you are home, for as long as possible for a while. Equipment does not like to sit for a long time without being powered up. I have often heard in the past that some electronics technicians will very slowly over a period of days, bring equipment that has not been powered up for a long time, up to line voltage using a regulated power supply. But since your machine has already been powered up, that's a moot point now and I wouldn't be too concerned.

Re the spare channel cards, I had bought quite a few from a guy that parted out his machine and another 16 from a guy that broke down a machine into components, ie I bought the entire amplifier with the cards in it. Actually I bought that entire machine except that he had already sold the record enable/track assignment module.

I seem to remember that I paid Evan (the first guy I mentioned), $20 each for his cards so I would like to get at least that amount for them. I haven't tested them at all, but Evan assured me that his machine was working on all tracks when he took it apart. I had planned to send 16 cards to Jim Williams at Audio Upgrades so that he could do his miracle mod to them, but for now that's on the someday . . . to do list. Where are you located ?

Danny
 
Randy,

I have read back through your thread and I can't see anywhere that you have tired swapping another known good channel card with track 6. Have you tired that yet?

Warning !!! MAKE SURE that you number ALL channel cards for their respective channel with a sharpie BEFORE pulling any out so that you can put them back in exactly the channel they came from. You will be sorry if you don't unless you happen to have a spare day or two to spend on alignment from scratch and - a whole truck load of test gear.

Have you already tried recording 1k tones at 1.23v (if you're running it balanced) from the mixer or an oscillator to see what you get back out of it ?
ie; you need to really verify that it's not the meters acting all weird. Defeat the DBX for now when printing tones.

I see that you have your age on your profile. It is very admirable that you have taken on this project, but you have to keep in mind that you ain't messing with software and computers when you are dealing with a precision ATR. These machines were built with amazing attention to detail and craftsmanship and there is nothing about them that was built from the standpoint of todays throwaway mentallity and worse yet, now they are from a generation of lost skills and most likely those lost skills mean that they will never be built again. These things can be somewhat expensive to get set up correctly when wacked out and often times, younger folks just are not willing to bite the bullet and invest in the test equipment and alignment tapes, especially when they can get Reaper for free and run it on a laptop. But with dedication, your machine can be setup and will sound great, so hang in there.

Danny
 
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