Fostex G16S speed problem

C

clemkeyz

New member
Hi everyone one!

I've been a stalker for a long time but now I need your help. I have fostex G16S that I am restoring and it seems that the unit had a hard in time in the fedex truck. Nevermind I repaired everything to make it work again. But now that the transport works and the reels are rolling, it appears to be rolling really fast in play mode. As fast as FFWD actually. I've tried to change the maximum speed in the 2nd menu and set it to the lowest level but it only affect the rewind and ffwd. I've checked the brakes, pinch roller etc.. Its seems that the capstain is rolling really fast and and the reels motors too.

Is there anyone here who know something about it?

Thank you!

I have the URLs for the manual and service manual but since its my first post I guess you know how to google it!
 
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I don't know that machine, but does it have a tach roller like the TSR-8? A lot of the microprocessor transports use one as part of the feedback loop for tape speed etc, and if the tach signal isn't present for some reason they can go very strange. The TASCAMs for example, tend to hit maximum speed and ignore all inputs from the command panel.

Simple things to first check include - is the tape counter working? Is the tape laced up correctly? I once managed to loop it the wrong way around the tach roller and having the MSR-24 lose control with the master tape for an album I'd nearly completed was not a fun experience, believe me.

More advanced things - at the bottom of the roller there should be some kind of pattern on it, e.g.
plateguide.jpg Photo by tapewolf | Photobucket

Make sure the pattern is there, make sure it's properly glued to the roller, and is reasonably clean. Make sure the photointerruptor circuit is working (and the photodiodes etc aren't caked with dust). It might use red LEDs, it might use infra-red ones. Phone cameras can often see into IR so that might be a way to make sure they're glowing (obviously the machine will have to be powered for that to work).
If you've had the machine apart, make sure that the photointerruptor board is actually plugged in!
 
Thank you for the reply! Actually, I solved the problem with some great help from an old tech from LE STUDIO in Quebec and an tech from Fostex in London. The problem was the distance between the FG pick up coil and its inductor wheel in the capstan motor itself. The speed is back to normal but now the machine make a little mechanical noise. I will do further test and let you know if it was worth the pain. I will run this as a mobile rig for analog recording!
 
Ah, right. Useful to know - it did sound a lot like a servo loop gone wrong, and that would do it. Glad you got it working.
 
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