Fostex E-16 reel to reel recorder woes

[Matthehat]

My Fostex E-16 as it's not working properly. I can only get about 5 channels to record and when I try more, one track seems to record over a previously recorded track (15 records over 10 for example). Not sure it it needs realigning? Any help much appreciated as I've cleaned it all to the Nth degree. Really do not want to give up on such a beautiful thing.

Cheers
Mat

[jamesperrett]

This sounds a little more involved than just realignment. Can you post a picture of the heads and also one of the heads with the tape in place? What do the record lights and meters do when it is recording on the wrong track?

[Ted Kendall]

I've a nasty feeling this may be deteriorating electrolytics in the audio electronics. This is more common in the G series, but the signs are familiar. For once, blanket recapping is advisable, but rushing in without experience is not - space is tight and the print can be damaged by electrolyte leakage or heat.

[Matthehat]

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?!)

[Ted Kendall]

Those electrolytics won't necessarily show obvious signs of distress. The matter can be put beyond doubt by measuring the ESR (equivalent series resistance) of a representative sample of the capacitors. There are meters available for this purpose which can perform the measurement without removing the capacitors.

What is a logic board issue, you ask. It's a problem in the circuitry which does the housekeeping in the machine - regulating tape tension, translating control movement into action, switching channel modes, and so on. This tends to be kept on a separate board, but some may be embedded in the channel cards. If several channels are refusing to behave, there may be a common cause in the logic controlling them. I still, however, incline towards failure of the electrolytics and feel you should check this first.

[knobtwiddler]

Ditto to what Ted said. And it might not just be electrolytics, as once things get over a certain age some types of ceramic caps can do very odd things. I doubt it has tants in it, but if it does, I'd replace all of them on sight.

And as per Ted's advice re: delicate tracks. If you intend to recap it yourself, a machine like this one is the very least you'll need to invest for the task: https://cpc.farnell.com/duratool/d00...lug/dp/SD01384

Don't go near the pads with a solder sucker - be warned!

NB - I've seen polycarbonate caps go massively out of value after a few decades. Nakamichi decks are famed for their orange caps going off (not sure what dielectric they are, polyester?).

[Ted Kendall]

These particular caps are a right pain. They are wire ended cans in square plastic jackets which are tacked to the board. Best way to deal with them is to clip each lead, remove the body of the cap and deal with the lead stubs individually. Conventional mini electrolytics with their leads dressed to fit will go in quite neatly as replacements.

[DMcMahon]

I have no experience or real knowledge of this lovely looking machine or its siblings but a quick look at the E16 Service manual shows it to be a pretty complex machine.

In light of the new fault symptoms at Post # 4 I would first start by checking the 5 fuses on the power supply board, then measure the 5 DC output supplies from this board, I do not know how easy or difficult this may be to access.

A lot of the digital logic is controlled by the Control Board (which may be the large board at the rear that can be hinged down) this is microprocessor controlled, depending upon your experience in fault finding on digital electronics circuitry you may struggle even with Forum help.

The manual has some good technical descriptions of the various circuitry but the copy I downloaded does not include the Control board electrical schematic, this seems to be a separate document.

David

[DMcMahon]

Looks like the power supply board is mounted at one end of the power transformer.

David

[jamesperrett]

Originally Posted by Ted Kendall

These particular caps are a right pain. They are wire ended cans in square plastic jackets which are tacked to the board. Best way to deal with them is to clip each lead, remove the body of the cap and deal with the lead stubs individually. Conventional mini electrolytics with their leads dressed to fit will go in quite neatly as replacements.

Ted - you're describing the caps in the G16/G24. The caps in the E16 are conventional through hole components and much much more reliable (i.e. I've never had to replace one in either of my machines).

Matt - to be honest - if you aren't experienced with these things I would get it looked at by someone who is. The tape transport is usually very reliable but the logic is complex and it takes a fair bit of effort to work out what is going on when you go through the circuit. While you can check supply voltages and logic states with a multimeter, you probably need an oscilloscope to check it out properly. However, the one thing that I would check is that you haven't dislodged a connector to the big board at the back of the machine. The reel motors are controlled by transistors that use the top of the machine as a heatsink so it sounds like the transistor controlling the take up reel may have become disconnected.

[Ted Kendall]

Originally Posted by jamesperrett

Matt - to be honest - if you aren't experienced with these things I would get it looked at by someone who is.

Damping but wise words. This is not a machine on which to learn servicing.

[DMcMahon]

Originally Posted by DMcMahon

The manual has some good technical descriptions of the various circuitry but the copy I downloaded does not include the Control board electrical schematic, this seems to be a separate document.

David

Struggling to find a copy of the Control Board schematic.

David

[Matthehat]

Guys thank you so much for your advice so far. The only reason I am trying to do this alone is that I love this machine so much and no one locally or even further afield that I can find is interested in looking at it. ("will cost more than the machine is worth" etc.) So I'm stuffed - with a beautiful, once perfectly working piece of analog gear that I cannot get going again. I want to cry.

Before I do though, I will check if I've dislodged a connector from the big board that @JamesPerrett mentioned (the one that hinges down?).

FYI I'm in Dartford, Kent if anyone knows anyone down here willing to look at it.

[Matthehat]

I've checked the five fuses and they are all good and intact.

Can't see anything immediate untoward - can anyone?

[DMcMahon]

Matt post a request to this part of the Forum.

https://www.vintage-radio.net/forum/...play.php?f=145

David

[DMcMahon]

From your photo carefully make sure that all the connectors (IDC ?) are pushed fully home.

David

[Matthehat]

Thanks David, I've posted on there - hopefully someone will come to my rescue.

[Matthehat]

Yes I checked them all and pushed them all fully down - none were not connected though and it hasn't changed the situation unfortunately.

[knobtwiddler]

If you really are struggling to find a tech who can take it on, one last shot might be to spray (sparingly) the connector pins with Deoxit D5. I regularly see mystery connectors spring to life via its careful application. Make sure not to get it everywhere, and just treat the pins. You can also get droppers for it. It's got me out of trouble in many live sound situations (not with my own equipment, you understand -)

[jamesperrett]

Originally Posted by Matthehat

I've checked the five fuses and they are all good and intact.

Can't see anything immediate untoward - can anyone?

The only thing that jumps out at me is that extra little greenish board that appears to have been added afterwards. I'm fairly sure that neither of my machines have that. However, it looks like it has a Fostex logo on it so it could well be original.