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

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

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    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.

    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

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    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?

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    Quote Originally Posted by sweetbeats View Post
    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?

    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

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    The Channel 6 Card has hardly any power when swapped
    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:
    Attached Thumbnails Attached Thumbnails img_6695_11_1-jpg  

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    Quote Originally Posted by sweetbeats View Post

    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.


    THANK YOU SO MUCH!
    You are the best
    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

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    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.

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    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.

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    Quote Originally Posted by sweetbeats View Post
    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.




    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

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    Quote Originally Posted by RandyRhoads1981 View Post
    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
    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.

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