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Author Topic: Studer A800/ No record trk 7  (Read 4370 times)

Robomatic

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Studer A800/ No record trk 7
« on: January 02, 2011, 03:31:10 PM »

Hi Guys,

   I'm having a problem getting getting track 7 to record while monitoring repro. I have input (1 khz @ +4db) Track 7 plays back the from the test tape in both repro & sync but when I load a blank roll of tape, apply 1khz and go into record the vu meter is not coming up in repro. It comes up in sync however. I have a rms volt meter on the output of trk 7 and there is nothing there so it is not recording? I swapped out all the cards from a working channel and its the same thing. What am I missing here? Is there another area I should be checking? All the other tracks are functioning correctly in record and repro/ sync.

Thanks,

Rob
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Mike Cleaver

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Re: Studer A800/ No record trk 7
« Reply #1 on: January 02, 2011, 09:34:09 PM »

Wiring to the tape head or contacts to the head.
If it's plug-in, clean the contacts and socket.
Check the wiring on the plug.
By swapping cards and having the problem continue, it has to be the head or the wiring.
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Robomatic

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Re: Studer A800/ No record trk 7
« Reply #2 on: January 03, 2011, 02:28:13 PM »

Hi Mike,

    I pulled the head and checked track 7 for continuity on record/ repro. All good with no shorts to case--Thank God! I'll clean the connectors and re-install. Hopefully that will be the problem.I'll let you know.

Thanks,

Rob
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radardoug

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Re: Studer A800/ No record trk 7
« Reply #3 on: January 03, 2011, 03:03:38 PM »

If you have repro and sync playback then the problem is not on the reproduce side. Somewhere in the record logic? Do the lights do what they should?
To check if it is recording turn the tape over and see if track 18 plays back. But this is superfluous if you have repro.
If you have changed the channel card, check that that channel card works somewhere else.
Then you are down to a logic problem or a motherboard problem.
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Robomatic

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Re: Studer A800/ No record trk 7
« Reply #4 on: January 03, 2011, 03:27:50 PM »

Hi,

    If the head connections are good, then a mother board/ logic problem must be it. All 24 tracks playback in repro & sync from the test tape. The record lights on track 7 on the meter bridge are on when in record (normal), but there is no output from track 7? while monitoring in repro. Sync has output. I did notice that the on the HF Driver card the top led is not light(trk 7 only)No Bias??. This problem does not follow the card because I have swapped in a working channel. I have also checked/ cleaned the molex connectors on the back of the card cage (tracks 7 & Cool. If it's not the head connection what card do you think I should start with to trouble shooting the record logic? It will have to be track specific because all the other channels are working. What about this "Rehearse" function? From what I've read, many engineers recommend disabling this circuit not by simply pushing the button. How do I go about taking the rehearsal function out completely?  

Thanks,

Rob
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Robomatic

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Re: Studer A800/ No record trk 7
« Reply #5 on: January 04, 2011, 12:47:10 PM »

Hey folks,

     The head connections/ head stack appear to be good. I'm thinking bias right now. I dont think track 7 has bias and therefore cannot record. Could the master bias oscillator be bad on just that one track? EG. Not supplying a bias current?
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sodderboy

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Re: Studer A800/ No record trk 7
« Reply #6 on: January 08, 2011, 08:26:52 AM »

Robomatic wrote on Sun, 02 January 2011 15:31

Hi Guys,

   I'm having a problem getting getting track 7 to record while monitoring repro. I have input (1 khz @ +4db) Track 7 plays back the from the test tape in both repro & sync but when I load a blank roll of tape, apply 1khz and go into record the vu meter is not coming up in repro. It comes up in sync however.


What do you mean "it comes up in sync"?  Is this after you make a record pass and play it back in sync, or just that when you switch to sync during the pass it actually displays input?

You did not check continuity to the head with the VOM did you?  Better demag before any further testing!

If indeed there is no signal recording on to track 7, even after a full card swap, look again to the molex connectors behind the card cage.  The problem is most likely there, where signal is not making it from the I/O section to the record card.  The card swap eliminates any problem with bias or otherwise on the cards.  You need to get to the input of the record card to measure if you are getting signal from the I/O.
Mike
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Robomatic

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Re: Studer A800/ No record trk 7
« Reply #7 on: January 10, 2011, 06:26:14 PM »

While in Record flipping between repro & sync the meter comes up in sync and does not in repro. (1khz @ +4). Machine is in auto input. Press stop to show input (relay) and play/record to monitor the record signal. I'll check the molex connectors again but if the problem is there it is not an easy one. I have had the cage down many times trying to find a loose connection there. I've cleaned and re seated all the molex connectors with no luck as of yet.

Thanks..
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