Fostex A4 trouble

W

WarmJetGuitar

New member
Been working with a Fostex A4 since April and it's been working perfectly fine until today. Out of nothing it started dropping in speed at both 7.5 and 15 ips. The tape path is nice and clean, the pinch roller looks alright and I tried with two different tapes.
A friend of mine who's an analog head told me to open the thing and clean it from dust.
It's definitely worth a try, but where to go if it doesn't solve my problem? I don't wanna call him all the time asking stupid questions.

Could it be the capstan belt? Or the pinch roller?
When the dropouts occur the rolling thing above the pinch roller (related to the capstain motor? What is its name?) goes down in tempo.

I have yet to clean the pinch roller as it is partially hidden by some plastic and I'm worried about the risk of dropping liquid inside the machine itself.

Please help an analog noob.
 
Things has started getting weird: came back to the studio today to fix some things and today the machine worked perfectly fine.
I suppose there is something just about to be worn down but what? The belt? Too much dust? Any help would be greatly appreciated as I'd like to prevent any major breakdowns.
 
Do you have a SM? I have and found from the internet easily enough, the SM for the A-8 which I'd assume has the same transport. I don't have it handy at the moment. And I'm pretty sure I have the SM and OM for the A-4 somewhere although I don't own one of those machines.

These are all belt driven, so it sounds likely that it is a loose or stretched belt? There is a seller on Ebay, (mars something or other) who sells Fostex belt kits. I can't vouch for the seller, but likely will need to buy belts myself here soon enough.

You said the tape path was clean, but just to be certain are you using fresh or known good tape? If you're using, e.g. Ampex 456 or 457 and it is from the 80s or early 90s, it is farily certain that the tape is sticky, and gunking up the tape path, which will slow the deck down.
 
I have an A8. the plastic cover over the pinch roller easily unscrews and allows you to take off the pinch roller to clean it. Just turn it anticlockwise and it should unscrew.
 
What is a SM?
The belt sounds like a reasonable bet, I'll take a look as soon as I can.

"I have an A8. the plastic cover over the pinch roller easily unscrews and allows you to take off the pinch roller to clean it. Just turn it anticlockwise and it should unscrew."

Thanks a million man! :)

I use old Scotch and AGFA tape (I'm always broke and spent much tape as we improvise a lot) as well as one roll of fresh RMG-tape. The problem occurs on all types of tape.
 
Oh - yes I do, found it on the net :-)
The problem seems to be solved; all it took was a gas duster and cleaning the pinch roller. Let's hope it keeps running. Now I just need to fix my "new" Tascam 38 so I must warn that lots of stupid questions might be asked soon.
 
"Only stupid question is the one that isn't asked" What issues with the 38? I have one of these too, but it is in good working order. I think you will find it somewhat easier to work on then the smaller Fostex
 
Picked it up very cheap (£90) including four Ampex 456 knowing that it needed a new pinch roller, a NAB and maybe a belt. Maybe I'll need help changing the belt later on. The heads look great from what I can tell.

I chose it because we needed an 8-track for our band and Tascam is known for good sound, easy access to spares and gooey pinch roller - or maybe despite the pinch rollers :D
Anything particular I should be aware of regarding this unit?
How do you like yours?
Which mixer should I choose? I'm out look for something with at least 12 channels as it will work together with the Fostex for different purposes and financial situations.
At it looks now it will be fed by a nice 70's Yamaha EM 300, a Behringer Euroline, an old Boss desk and a Behringer tube preamp. However this is a weird way to make it to seven tracks at the time, so I'm looking for something easier - an old MCI would be great but so would a Studer A80 but I'm on a budget.
 
Search the forums here for mixer recommendations, there are quite a few Teac/Tascams that will go nicely with this unit, I used a Teac 5 for a while, and now use a Tascam M-520, but lots of variety in between. The pinch rollers do get gooey, but they are still available, or can be rebuilt by Terrysrubberrollers.com. I've had him redo a MSR-16 roller.

The Ampex 456 unless it was mfg after 1995 is no good. If the Ampex logo on the box is in the middle of the box or if the boxes are an overall grey colour, the tape suffers from a chemical breakdown. It will leave a sticky gooey mess on your tape path. There should be a sticker on the side of the box indicating a date code. It will be either a two digit or four digit year and a julian date. E.g., if it says something like 89045, it is no good.
 
Yeah I'm aware of the 456 (and mine is very old with grey boxes) problems from reading on HR but I have to live with it for the time being and buy some RMG tape when there's enough cash.
There's at least three different 1/2" tapes from RMG; SM468, SM900 and SM911. Which one is most similar with the Ampex 456 tapes?
I got a new pinch roller and NAB on its way from Tascam :-)

For something completely different: the Fostex can't completely delete what was on the tapes before we started using them. Is this a tape wear issue, a callibration issue or a worn out deleting head?

I'll try to catch a Tascam desk then. Thanks for all your help.
 
911 is the closest to 456. However, strongly recommend don't use the old 456. It is going to be bad if it isn't already, and it will gum up your tape path. I had it so bad, my 38 actually slowed down and stopped. You can however. unscrew the flanges, throw out the tape, and get new tape on "pancakes" and save some money that way. (That will save you approximate US$20 or so give or take.)

As for erase, could just be an electrical adjustment, or perhaps a height misalignment. See the manual for the adjustments. It is probably an electrical adjustment, as erase heads typically don't wear as fast as record/playback heads, if the record/playback head is in good condition the erase should be as well.
 
Thanks, I'll try to figure out how to adjust the eraserhead. The heads on the A4 looks mint, the machine was hardly used before April this year.

And thanks a million for the advice about RMG 911. I'll get some of those ASAP. When cleaning the 38 I could really see what you're talking about - it was dirty as fuck.
 
Hi! I am new to this forum. I have a Fostex A Series 4 track rtr with some problems, rewind is slow to a stop when half spool and also the take-up spool spins fast as if on FF when tape is not loaded to it. I don't a service manual, finding it hard to get on the net. Can any of you guys help?
 
LTC said:
Hi! I am new to this forum. I have a Fostex A Series 4 track rtr with some problems, rewind is slow to a stop when half spool and also the take-up spool spins fast as if on FF when tape is not loaded to it. I don't a service manual, finding it hard to get on the net. Can any of you guys help?
Click to expand...

The slow stopping RW could be a break going bad but I don't know about the FF with any tape. Sounds really weird. I would take it to a tech if I was you.
The A4 sounds great and has double the trackwidth of the other Fostex machines.
 
When i turn on the machine the takeup is spinning fast, this is without tape and the tention arms are down!!
 
You must log in or register to reply here.
Back
Top