TEAC Cassette Deck - Malfunctioning Electronic Controls

[bob p]

I've got a mid 1980s Teac V4RX cassette deck that I've had in mothballs for a number of years (maybe 15 or more). It got put away because of a problem with the control interface, and because I just couldn't bring myself to part with it. Now I'm starting to entertain the idea of fixing it.

The deck has electronic pushbuttion controls, that seem to send a signal that operates a solenoid or a relay. Under normal operation when you push the PLAY button, the electronic contact would cause a relay/solenoid type of click as the playback heads pop up into position.

The deck began malfunctioning, so that if you pressed the PLAY button the clicking sound would take place and the head assembly would pop up into position, but it would immediately fall back down to the idle position.

The remainder of the electronic controls (FF, RW, STOP) all function normally. The only control that causes problems is the PLAY feature.

As it turns out, I have a wired remote control for this deck. IIRC the deck behaves exactly the same way when the external wired remote is used.

If anyone has insights on how to repair these sorts of cassette decks, or whether parts are even available, I'd appreciate any tips that you might be able to provide. Thanks.

[Steve Conner]

Hi Bob,

The head loading solenoid probably draws a lot of current. My guess would be that the power supply has a bad filter cap or something, and the solenoid drags the voltage down and makes the microprocessor reset itself.

FWIW I have a similar Sony model that I kept, though it's totally irrelevant in this day and age, because I think the logic controls are cool It's also the best sounding cassette deck I've come across, though that's not saying a lot...

[Brad1]

That's a possibility. Another may be that something in the transport is causing the deck to think it's at the end of the tape, and kicking it out. Something that is maybe adjusted improperly that senses the tension.

Does it do it when there is no tape in it also? That would seem to preclude any tape-tension tab causing it by the tape itself dragging, but it could also be misaligned or something? Perhaps you have a bad belt, or a dirty or sticky other part that affects Play?
If it's not running everything together properly, perhaps it simply won't let it play. FWD and REV don't require the heads to be engaged, which is why they work. It's possible the Play button is actually working, but that a mechanical malfunction is kicking it out.

Tear it apart and check all the belts, and clean whatever you can get at. Make sure there's not a big dust bunny trapped in there dragging the transport. Look at all the moving parts and see if you don't have some grease hard-caked in there dragging things. If there is, try cleaning them, and then applying a bit of fresh grease. If someone had previously used something like WD-40 in there, it could be that those parts are gummy. A 30-year old tape deck is likely to have some lubrication problems, especially if it has just sat idle for 15 years.

Just some possibilities.

Brad1

[Enzo]

My vote is the gears that turn to move the head assembly up and apply the punch roller are drifting past their stop point instead of stopping crisply. I have had to correct this on numerous decks.

This might be due to aging lube, slop in the gears, dirt, etc.

Also on some models there is a pot conected to the mech linkage. The setting of the pot tells the logic what position the transport is in. This as opposed to actual switches and contacts. Just exactly as some effects selector"switches" in guitar amps are really just pots that the DSP decodes as switch settings. If that pot gets dirty, it won't read position right.

I hate tape decks.