Yikes! Track 8 just died on 8 track!

[fred s.]

I don't know much bout fixing or diagnosing problems on tape decks...


Unit is a Fostex Model 80 8-tracks on 1/4" tape.

I was recording some demos and everything was fine with the recorder, but around day 3 of recording, track 8 simply stopped recording all of a sudden (no warning signs).

It plays back tapes which were previously recorded, and receives signal, but will no longer record anything.

Is it the heads? Any thoughts?

 

[The Ghost of FM]

It's unlikely to be the heads as it's only a 2 head machine and you said it will play stuff previously recorded.

There's a remote chance that the head is very dirty to the point of not being able to print a signal if it hasn't been vigorously cleaned...has it been cleaned thoroughly since you experienced this problem?

Beyond that, it might be an internal wire harness that needs to be reseated or some other contact point that needs to be cleaned. After that it might be at the component level like a bad cap or open transistor but...before any of that, also ensure that your signal path to the recorder is correct and not the fault of a bad patch cord that is feeding the 8th track or a buss routing issue with the mixer that's feeding it.

Start with the simple things first and only after all of those have been exhausted, suspect actual internal problems with the recorder.

Cheers!

 

[fred s.]

yes the heads have always been cleaned and demaged regularly since ive owned it (about a year or so).

definitely not a mixer issue either, tried a few different things there...

im worried that something needs fixing in the actual recorder...is there anything in specific i should look at? or any good shops in the nyc area to take it to??

 

[sweetbeats]

ferd s.

Sheesh. Sorry about the trouble you are having with your Model 80. Not that there is a good time for technical difficulties but it is especially bad to have it happen during tracking...that can really wreck the mood. Hang in there.

Okay. As long as you are sure it is not an output issue on the mixer or a cabling issue (which I assume you have checked by swapping connections and the problem stays on track 8), the next thing I think I would check would be to see if it is a problem on the amp card for track 8. Maybe a sticking relay preventing it from kicking into record mode on that track.

When you attempt recording on track 8 now does it record silence over previous material, or does previously recorded material remain?

I'll have to check and see if I have a service manual for the Model 80...I know I have the owner's manual but that probably isn't going to go over removing and installing amp cards...I have the manual set for the R8 which is likely similar in construction as far as amp card access goes...hopefully a Fostex user can weigh in on that...

SO...let us know what does happen when you try to record, let us know if you have a service manual and/or any experience removing and installing amp cards. In the meantime (next day or so) I'll look and see if I've got documents here that might help.

The idea is to swap amp cards with another track (like switch cards for tracks 7 and 8) and see if the record problem follows the card. If it does then we can be pretty sure we have isolated the problem to something on the amp card for track 8 and then we can go from there.

 

[The Ghost of FM]

yes the heads have always been cleaned and demaged regularly since ive owned it (about a year or so).

definitely not a mixer issue either, tried a few different things there...

im worried that something needs fixing in the actual recorder...is there anything in specific i should look at? or any good shops in the nyc area to take it to??

This is puzzling if the heads are clean and the connections are verified sound.

I used to have a Fostex R-8 and I seem to remember it having a dedicated input to track 8 for midi/SMPTE time code which was apart from the normal input. Does your unit have this feature with any associated switches on the rear of the unit to switch and choose inputs? If so, has it been inadvertently switched?

And a last quick fix; the track 8 arming button, have you tried repeatedly pushing it on and off to see if it's just a dirty switch...perhaps try dripping in a few drops of de-oxit contact cleaner into there as final external fix.

The remainder of the options sound internal. I'm not sure of a decent Fostex tech in NYC but its a big city so there must be several that could get to the bottom of it.

Good luck and sorry I couldn't be of more help.

Cheers!

 

[fred s.]

i will have to try switching cards. never have done anything like that, is it difficult?

right now i'm just very frustrated and trying to find a fast fix, i don't want to record anything digitally and my only other tape machine is a tascam 22-2 (2 track).

here is the model 80 service manual:

http://rapidshare.com/files/251634913/Fostex_Model_80_-_Service_Manual.pdf.html

 

[dodgeaspen]

Hey Fred, I have had something similar happen with my 38. The difference was that I could not hear track (I think it was 5) in Repro, but I got all kinds of sound out of it in sync mode. Strange but true. Good luck.

 

[sweetbeats]

fred s.,

I have the service manual...and if I didn't I would now thanks to you!

Not really too extensive to swap cards and it would tell us a lot.

First, first, first turn off the deck, disconnect it from mains power, then switch it on (while unplugged) for a few minutes to drain the power from the guts.

Now, look on page 18 of the service manual pdf...There it shows 4 screws 'A' on the back of the deck as shown on figure 6-1. Remove those. Then remove the 6 screws from each side labeled 'B' in figure 6-1...12 total. As far as I can tell that should allow you to remove the back cover and the housing that goes around the top, bottom and sides. Then you gently lay the deck on its back and the amp cards are accessible from the bottom. Look on page 30 at figure 6-12. That's what you should see looking at the bottom of the deck now with those covers removed. Cards 7 and 8 are labeled there. Remove the PCB locking bracket there that straps across the amp cards. The cards pull straight out once that bracket is off. They'll probably be a little snug but just firmly grasp the edge with both hands, gently rock as you pull straight out and it should come. They are meant to come out. Pull 7 and 8 and reinstall them in each other's spots. Now go ahead and fire it up and see if your record problem is now on track 7.

 

[The Ghost of FM]

The channel cards appear to be in groups of two, with channels 1 & 8 on the top slot and 2 & 7 on the slot below it. This means when you pull out channel 8, you are also pulling out channel 1 as these channels are both on the same physical card.

If the swap migrates the issue to track 7, it will mean that there is a faulty component on the PCB. If it doesn't, then problem lays elsewhere.

Fred, do you know how to trouble-shoot faulty parts on a PCB? If you don't have this knowledge, you might as well save the effort of taking your machine apart and just seek out a qualified technician, as you were asking about earlier in this thread. That is, if you don't feel comfortable doing all this stuff. That's up to you to decide.

Cheers!

 

[fred s.]

ok i swapped the cards. it only gets more confusing now...


7 and 8 were swapped (which means 1 and 2 were as well, since they are connected to 2 & 7 , 1 & 8).

I recorded some tones from my synthesizer, and it was all recording, both 7 and 8 were recording...but channel 8 was very faint/weak in playback...however this sort of resolved itself after a few tries.

Now both have a strong signal, and things are working again.

But there is the confusion...why did that fix things?? I can't understand. It sort of worked itself out. I dont see this as a fix really, and still dont trust the recorder until I figure out what the problem really was.

 

[The Ghost of FM]

ok i swapped the cards. it only gets more confusing now...


7 and 8 were swapped (which means 1 and 2 were as well, since they are connected to 2 & 7 , 1 & 8).

I recorded some tones from my synthesizer, and it was all recording, both 7 and 8 were recording...but channel 8 was very faint/weak in playback...however this sort of resolved itself after a few tries.

Now both have a strong signal, and things are working again.

But there is the confusion...why did that fix things?? I can't understand. It sort of worked itself out. I dont see this as a fix really, and still dont trust the recorder until I figure out what the problem really was.

It might be that there was just some oxidization on the edge connector and pulling the card and putting it back in partially cleaned the connection. If that's all it was, then it's not that serious and maybe pulling the card and cleaning the connections could work out to a more lasting fix. Iffy connections can be sort of jump started by plowing some signal through it but the real fix is cleaning the connection points that are compromised.

Cheers!

 

[sweetbeats]

Two thoughts, and these are based on direct experience:

1. it is not uncommon that connections can oxidize over time and reseating the connections can sometimes resolve this. It is better/more effective to apply contact cleaner like Caig Laboratories' DeoxIT to the contacts when doing this.
2. aged relays can cause all kinds of weird behavior...the relays on the amp cards are responsible for doing the actual switching to the source you are wanting to monitor, or what you are wanting the record/reproduce head to do (i.e. record or play back). Assuming they are mechanical relays the contacts also oxidize or become carbonized. This can be resolved by opening them up and cleaning them with contact cleaner, or they can just be replaced. The behavior you are experiencing seems very much like aging relay issues to me.

Let us know what you need advisement on at this point.

 

[fred s.]

cool, i have some deoxit, i will clean the contact points.

if i were tp replace the relays, where would i go about getting parts?

is it a good idea to maybe invest in another model 80 for just parts?

they are relatively inexpensive-under $200 usually.

 

[sweetbeats]

Parts deck?

One man's opinion but I always think its a good idea with older electro-mechanical audio gear. That's me. You need to decide for yourself but I do quite a bit of DIY repairs so I always like to have spares on-hand. I think I would feel particularly so if I had a Fostex deck as parts are considerably harder to come by as compared to the Teac equipment that makes up the majority of my stable.

I have always been impressed with the sound quality of the Model 80 and R8. So, if you like your deck and plan on keeping it for a long long time a parts deck is certainly not a bad idea, especially if you can find one with a good set of heads. That's really the kicker with any deck. It lives and dies by those heads.

Relays...I see on page 55 of the pdf service manual that the amp cards utilize a relay part reference G2E-187P-H. I would have to look that up, but I'd start at Mouser Electronics or Digikey...Looking at the schematic on page 67 the relay, K101, does indeed switch from record to reproduce and if they are getting flakey, like I said earlier, that could indeed cause your problem...could be other things too but in my limited experience that would be my top suspect. Looks like the amp cards, including the relay, run on an 18 volt power rail so that relay will be at least an 18 volt flavor, maybe even 24 volt.

Now, heed what Ghost is saying. He's a smart cookie. Are you handy with a soldering iron? Ever do work on PCB's before? If you are limited in your experience, then this is a relatively advanced project and there is risk involved. There are shields covering the relays so you have to get those off first and then you can get to the relays. If you haven't the right tools or experience it may not be a good idea getting into this by yourself. If you ARE comfortable doing this degree of work I'd seriously consider getting the covers desoldered from the relays and just cleaning them up before replacing them. If they are indeed mechanical relays usually when you get the shield cover off you will see the mechanical reed contacts through the little clear plastic covers on the relays...gently pop the covers off, spray a little DeoxIT on there and GENTLY massage with a soft toothbrush...spray a little more DeoxIT to rinse and lay the card on a towel so that the excess cleaner can drain overnight. Once dry use some canned air to GENTLY blow any fuzz or dust out if any remains, put the covers back on and give it a whirl.

I did this very thing on my Tascam 58 which was giving me levels ALL OVER THE PLACE from unity to nothing and anything in between...flakey switching from sync to repro...it was very odd and frustrating...like chasing a ghost. I did the relay cleaning thing and it ran like a champ. It was like a new deck. So that's where I'm coming from and that may or may not be your problem .

If you aren't comfortable doing that job then ask around for recommendations to an electronics repair shop. I'm sure you can find one that can do the job.

I sincerely hope this helps you get out of the woods you're in right now and quickly.

 

[fred s.]

I have some experience with soldering, etc...

I think I might pick up a "parts deck". Something that has good heads, rubber parts etc.

Thanks for all your help and info. The Model 80 has been working since I swapped out the cards, and cleaned the connections!

 

[sweetbeats]

Hey that's really great!

Maybe that's all it was.

Keep us posted on how it is working!

 

[fred s.]

arghh!! the problem is back on tack 8-but in a new form now! after using it yesterday (and things were working just fine in record and playback modes), but today all of a sudden everything that i try to record on track 8 will play back a bit faint and "breathy"...the same sound you would get if a compressor is on very extreme settings, volume fluctuates in and out.

(i will post an audio sample later this evening)

again the problem is only on track 8, and this is after i switched the amp cards already from the last problem a couple days ago...when track 8 wouldn't record at all. it worked fine for a day or so after that but now has this new problem.

any ideas?

sigh.

 

[fred s.]

-previously recorded material plays back with no problems though, on the same track...its just a problem as of everything recorded today.

 

[The Ghost of FM]

The Model 80 has been working since I swapped out the cards, and cleaned the connections!

In light of the problem reappearing/mutating, I have to ask which contacts did you clean?

It would seem to me that the contacts on the main board that the channel cards connect to is the one which required the contacts being cleaned and not specifically the ones on the channel card as you mentioned that track 7 continued to work well after the swap. This would indicate that the main board's contacts need to be addressed more closely.

Caig's Deoxit contact cleaner is usually a pretty good solution for theses types of issues but in extreme cases, the contacts may have eroded to the point where you need something more then that to actually put some fresh metal on those contact points and if that's the case here with your machine, you might need to use their Pro Gold paste product which gets brushed onto the contact directly and adds a layer of actual gold to the connection, fattening it back up and improving the connectivity of the metal transfer point from one card to the other.

When you originally mentioned that your first attempt didn't work right away, that was a strong clue that the contacts, possibly all or many of them on that part of the main board have degraded with age.

On my 16 track deck, I had similar issues and many of my connectors needed to be treated with the Pro Gold product from Caig and have since remained reliable.

http://store.caig.com/s.nl/it.A/id.1560/.f?sc=2&category=292

This is still a relatively cheap and cheerful fix and less of a pain then trying to source out a parts machine that may be in no better shape then your current unit.

Cheers!

 

[fred s.]

I tired cleaning both connections today again, but it made very little difference.

I guess I can try the "gold" product but I also am wondering if some things need to be replaced.