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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 20th Aug 2022, 11:09 am   #21
jahmadeus
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Join Date: Aug 2022
Location: California, USA
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Default Re: Fostex E-16 reel to reel recorder woes

Quote:
Originally Posted by Matthehat View Post
Sorry for huge delay. I've had the whole thing opened up and closely inspected the caps. They look brand new with no bulging or leaking or anything. I've also taken out the channel boards and re-seated them. I've given the heads another deep clean and went to give another go, however now the machine is doing something even weirder!:

The issue it has is when it is powered on, the capstan / pinch roller engages immediately, as if the unit is in PLAY. Pressing STOP (or any other button) won't make the pinch roller disengage. I also tried loading a tape and when I turned the unit on the "take-up" reel didn't advance so the pinch roller just spit the tape out the right side of the deck. My capstan is spinning clockwise though at least.

What on earth is going on here? please use full words and not abbreviations or jargon as I'm an idiot and learning but not particularly familiar with the lingo. Someone mentioned a logic board issue (what even is that?!)
I have just experienced this same strange symptom.

First off, thanks for your description of events. It is because of your post that I was able to re-think my approach in finding this problem (I too was convinced it was a defect on the system control board).

Since this issue started when you had done some re-assembly of the unit. I decided to do the opposite, take all my cards out. Aha! This fixed the issue. One thing I noticed was, due to the way the connector board is mounted, it undergoes a lot of stress when the cards are removed/inserted.

Upon inspection of the connector board. I noticed that there were small fractures all around the board near the mounting points. In the two back corners the damage was particularly bad. Many broken traces.

I have yet to patch them all, and simply flexing the board stopped the symptom so I do not have an exact smoking gun yet but can confidently say it is most likely a connection problem on the connector board, NOT a logic issue on the system control board (thankfully...).

The only thing I have not ruled out is it being a fault on one of the cards dragging something down (I have not re-installed them yet), but I find that unlikely.

I've seen this symptom reported in a few threads but with no solution, so clearly it is somewhat common in these units based on the design of the chassis. If you are still battling with this thing, hopefully this update is helpful.
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Old 7th Sep 2022, 5:27 am   #22
jahmadeus
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Default Re: Fostex E-16 reel to reel recorder woes

Sorry for the back to back posts. Just wanted to leave a follow up to my previous post.

So I ended up getting the better of this unit.

1. The connector board was indeed fractured in MANY different places. I had to break out some 30awg buss wire and patch approx. 20 traces. There were several that did not look broken but upon ohm'ing the trace it showed some resistance.

2. A finding that might not relate to this specific symptom. My 18V rail that powers the channel cards was down (read 1v). Replacing the 7818 regulator at the top of the unit cured this.

3. So this is where things get a bit interesting. I inserted one channel card at a time, turning on the unit after installing each one. I noticed that after a few cards were installed (about 3), any additional card in any available slot would cause the pinch roller to engage. However, I noticed that if I then took that card out and slowly reinserted it, making sure that it made good connection with the pins, the issue would stop. I was able to get all 16 cards back in, stopping to re-seat ones that caused this issue. My guess is that this problem is caused when certain cards do not have all their pins making good contact.

4. The cards with the NR switches should be (if I am interpreting the schematic correctly) cards 1 and 16. The unit I am working on had its cards taken out and put back in out of order so this was not the case. Worth checking for on your unit, probably not related to this main symptom.

Pinch roller no longer engages on power up. All channels record. All controls work properly.

I wish my diagnosis was more specific and conclusive as far as the exact cause. Without any documentation on system control logic (a separate document from the service manual...) I am kind of flying blind here. But hopefully following my footsteps will get someone who reads this in the future out of a jam.

Best of luck to all!
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Old 7th Nov 2022, 10:39 pm   #23
Matthehat
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Default Re: Fostex E-16 reel to reel recorder woes

Thanks so much for your detailed instructions! I can't wait to give it another go tomorrow (I've shelved this since my last post). The pinch roller problem only arose after I took out a few of the channel boards to inspect them. So I'll poser it up and remove and slowly replace each one to see if it fixes it.
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Old 9th Nov 2022, 1:44 pm   #24
Matthehat
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Join Date: Apr 2022
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Default Re: Fostex E-16 reel to reel recorder woes

Frustrating ly your point 3 above didn't work for me. I took each channel card out and re seated but the whole time the roller was engaged . Any other ideas?
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