Hi everybody, first post on here -happy to join the party!
I have an issue with my Fostex XR-7 multitrack cassette recorder that is driving me nuts and I was hoping the collective knowledge on here might be able to help. I would be incredibly grateful!
In the middle of recording yesterday it suddenly stopped recording/writing to the tape without any physical indication that it had stopped. The record indicator still lights up, and all meters show as if it is recording, but when I listen back to the tape nothing has been recorded. This happens for all tracks, and across different cassette tapes I've tried.
I opened the unit up and did not see anything immediately obvious:
-no snapped off/unconnected wires
-no obviously loose solder joints
-no burnt or exploded resistors or caps
I'd be happy to post detailed pictures, take voltage measurements, etc if that will help. Any advice is appreciated!
I have an issue with my Fostex XR-7 multitrack cassette recorder that is driving me nuts and I was hoping the collective knowledge on here might be able to help. I would be incredibly grateful!
In the middle of recording yesterday it suddenly stopped recording/writing to the tape without any physical indication that it had stopped. The record indicator still lights up, and all meters show as if it is recording, but when I listen back to the tape nothing has been recorded. This happens for all tracks, and across different cassette tapes I've tried.
I opened the unit up and did not see anything immediately obvious:
-no snapped off/unconnected wires
-no obviously loose solder joints
-no burnt or exploded resistors or caps
I'd be happy to post detailed pictures, take voltage measurements, etc if that will help. Any advice is appreciated!
I would start by looking to see if the bias oscillator is running. In fact does it still erase previous material?
Also check the record amp output. Scope and probably service manual needed to locate that.
Sounds a bit of an odd one tbh, particularly as it failed part way through a record session.
Also check the record amp output. Scope and probably service manual needed to locate that.
Sounds a bit of an odd one tbh, particularly as it failed part way through a record session.
At least on larger tape, lack of bias won't give silence, it gives distortion.
Yes, trying to erase that Rick Astley tape you found behind the couch would verify oscillator operation. (I *never* used any of "my" music to test a deck.)
Record amp output can be quickly verified at the record head terminals, if they are easy to find.
Power supplies everywhere?
Dirt in switch, loose switch rod/cable? (Less likely since it quit while working.)
USER manual is at bottom of this factory page:
Manuals : Fostex Support
How-to-use, not how-it-works. Block diagram is mixer PoV; recorder is a blank box.
HiFiEngine and others have the same file.
It appears that the machine is available for $300 on the used-gear sites, so it is worth fixing, not worth major excavation.
Yes, trying to erase that Rick Astley tape you found behind the couch would verify oscillator operation. (I *never* used any of "my" music to test a deck.)
Record amp output can be quickly verified at the record head terminals, if they are easy to find.
Power supplies everywhere?
Dirt in switch, loose switch rod/cable? (Less likely since it quit while working.)
USER manual is at bottom of this factory page:
Manuals : Fostex Support
How-to-use, not how-it-works. Block diagram is mixer PoV; recorder is a blank box.
HiFiEngine and others have the same file.
It appears that the machine is available for $300 on the used-gear sites, so it is worth fixing, not worth major excavation.
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I apologize for the ignorance, not sure what the bias oscillator is or how I would check if it's running. However, I did verify it will not erase previous material on a tape.
Lmao! I tried recording over a cassette I had recorded to before (junk recording), but it did not record silence, noise, or anything else over the previous recording.
The recording/playback head? This is easily accessible. Again, apologize for the ignorance but how would I verify the record amp output?
Is this a matter of testing different parts of the circuit are getting power?
I checked once and everything seemed ok, will check again.
Thanks again for all the suggestions everyone.
The bias oscillator is a high frequency (usually 60kHz to 100kHz+ region) oscillator that generates a fairly high amplitude (tens of volts) pure sine wave. This is applied to the erase head for erasing and also applied watered down to the record head where the audio to be recorded is superimposed onto the bias signal. Doing this ensures the head operates in the most linear region of its transfer curve.
So if it is is not erasing the bias generator and its supply need looking at.
If the previous recording remains on the tape, the conclusion is the erase/bias oscillator does not work. It is usually a 2-transistor circuit operating with a ferrite core transformer, and gets supply power from the REC switch. This might gave some hint on the potential issue.
The XR-5 service manual might be similar (page 31 lower left part):
FOSTEX XR-5 MULTITRACKER SM Service Manual download, schematics, eeprom, repair info for electronics experts
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