Sony TC-FX6c - issues

vegas79

Active Member
Hi everyone,

After bashing my head against the wall I've decided to see if someone out there could help me.

I have 3 Sony TC-FX6c cassette decks that all play wonderfully (why 3, please see below). But they all exhibit the same problem while recording.

If I'm recording anything except for a blank signal, the deck(s) will intermittently peg out one of the channels resulting in an extremely loud "dut-dut-dut-dut-dut-dut-dut" noise. My original one did this so I decided to relegate it to playback only duty and purchased another identical tape deck. The second does did the same thing. After buying a 3rd one that also does the same thing, I decided to give up...

This happens with Dolby off or on, MPX filter off or on, and I've tried using different line sources.

I do have the service manual for this model but I don't know where to start.

Does anyone have any ideas? Thanks in advance.
 
Clean the record switch, typically found on the main PC board inside. The FX6 might have solenoid controls (as I recall), but at least in strictly mechanical decks, problems like this are virtually always (IME) due to a dirty switch.
 
Classical fault ;)

Seconded.

Ever sinde the models TC-K185 and 186, this has been a classical fault on Sony deck's with a record/playback switch (one or two switches, app. 4 inches long, activated by the record button)

Easy to spot - poke it, and you'll know for sure - in my tech day's ive replaced houndred's of those thingie's
 
I'll bet! Usually us DIY'ers can get some more life out them by a good cleaning. It would be nice to have new ones, but the cleaning should at least determine if that is the fault.
 
It worked!!!

You folks just made my day!

It was indeed a dirty record switch. Once I found it, I was able to recreate the problem by tapping on the switch while the deck was recording.

I opened it up, hit it with some cleaner, let it dry and was able to record for 45 min without a hiccup.

This tape deck issue was the last major item to work out for a system restoration I've been working on for the last 15 years. The system is an original Sony component system my dad bought for my mom on her birthday in 1982 when we were stationed at Clark AFB in the Phillippines. As a little kid, it seemed so futuristic with the power level meters, push buttons and leds shining against the brushed aluminum faceplates. I was enamored by it. My mom promised that I could have it when they bought a new stereo (mind you it was only an hour old when I asked for it, lol). 11 years later I finally got my wish but there were things to fix. Now everything works including the clunky remote.

Thanks again for the help everybody! Looks like I have two other TC-FX6c decks to repair!
 
I'll bet! Usually us DIY'ers can get some more life out them by a good cleaning. It would be nice to have new ones, but the cleaning should at least determine if that is the fault.

hehe - tou don't have to clean it to se if it's the fault - the switch itself is the fault ;) Don't know why they are so incredibly bad - all of them ....

If we where outta stock (for new ones) we took them apart, cleaned them, new lube (kind'a faderlube) and re-asse,bled them - they lasted as long as new replacement ones.....

And noone could see or feel the difference - quite easy job ~ apprenticejob ;)
 
You folks just made my day!

It was indeed a dirty record switch. Once I found it, I was able to recreate the problem by tapping on the switch while the deck was recording.

I opened it up, hit it with some cleaner, let it dry and was able to record for 45 min without a hiccup.

This tape deck issue was the last major item to work out for a system restoration I've been working on for the last 15 years. The system is an original Sony component system my dad bought for my mom on her birthday in 1982 when we were stationed at Clark AFB in the Phillippines. As a little kid, it seemed so futuristic with the power level meters, push buttons and leds shining against the brushed aluminum faceplates. I was enamored by it. My mom promised that I could have it when they bought a new stereo (mind you it was only an hour old when I asked for it, lol). 11 years later I finally got my wish but there were things to fix. Now everything works including the clunky remote.

Thanks again for the help everybody! Looks like I have two other TC-FX6c decks to repair!


We'll send you a bill ;-)
 
I came across this older thread and would like some help on a Sony TC-FX5C which is similar to the subject machine except without digital counter.

The machine exihibits the same symptoms of motorboating in playback or record (both channels), and by tapping the circuitboard, I can make it disappear intermittently in one channel.

What isn't clear to me are the switches that need cleaning. The machine has a membrane panel for transport control, relays that do the switching, and tape-select/Dolby(B-C)-on-off. Which do I clean? Or all of them?

I also thought the problem might be in the power supply or grounding, that it starts this low frequency oscillation (motorboating) when higher current draw is callled for. Then again I have to assume that Sony took care of this in development therefore unlikely, or not?

I would greatly appreciate any suggestions!

Michael
 
I managed to fix the machine - Sony TC-FX5C Cassette Deck - and posting a follow-up for archival purposes if anyone should come across this in the future.

Turns out to be 3 defective relays (there are only 3 in the machine). The contacts were corroded and difficult to verify because of its intermittent nature but they were suspect, so I replaced all three.

The originals were Omron 12V Form-C (DPDT) which I replaced with ITT RY-18W which are 18V (that's what I had on-hand), but they do latch to as low as 9V although only guaranteed to 12.6V. I figure it'll do for now and deal with it if latching voltage becomes a problem in the future.

See photos attached - 2 photos of the original defective relay, the other of the boards where new relays (blue rectangle boxes with white tops labelled ITT) were installed.

This machine sat idle for 20 years because of this problem. Now I get to enjoy it again!
 

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I managed to fix the machine - Sony TC-FX5C Cassette Deck - and posting a follow-up for archival purposes if anyone should come across this in the future.

Turns out to be 3 defective relays (there are only 3 in the machine). The contacts were corroded and difficult to verify because of its intermittent nature but they were suspect, so I replaced all three.

The originals were Omron 12V Form-C (DPDT) which I replaced with ITT RY-18W which are 18V (that's what I had on-hand), but they do latch to as low as 9V although only guaranteed to 12.6V. I figure it'll do for now and deal with it if latching voltage becomes a problem in the future.

See photos attached - 2 photos of the original defective relay, the other of the boards where new relays (blue rectangle boxes with white tops labelled ITT) were installed.

This machine sat idle for 20 years because of this problem. Now I get to enjoy it again!


I just serviced one like it. Interestingly these relays are meant to be opened and cleaned/serviced, and whenever I run across this type I will normally not replace them: A good cleaning will do wonders and save you tons of time.

Although I was surprised as to how clean the original relay contacts were for a unit that's been around for almost 30 years, I gave them a quick pass with super fine emery cloth, a touch of wd40 applied with a soaked Q-tip and back to work. Have fun!
 

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Very common failure. What you have to be careful about is sometimes cleaning these relays just doesn't work. Don't know why. You burnish 'em, DeoxIT 'em, everything one would normally do to a dirty relay... Everything seems fine, and a day later, the thing motorboats again.

Sony's replacement part (number is not handy) was a sealed relay. Usually, you just replace the one, not all three.
 
I replaced the relays precisely for that reason.

National Instruments has an interesting article on low current relays that's very informative and talks about this exact problem. What's curious is that the motorboating should by nature clean the contacts but apparently doesn't.
<Article link>
 
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