Cassette tape component

It's the cam control solenoid. Works the latch that releases the cam gear to allow it to be driven to its next phase. As to the fault, check any tape presence sense switches that it may have - normally 'leaf' types in a clear plastic protection 'sleeve' mounted at the top edge of the deck, and also check that the belt which drives the take up spool is good. It's very common on Technics decks for that belt to go 'elastic' and slip.

Arfa

Many thanks. These things can look strange if you've not seen them before.

There's about 5 of 'em, 2 for write-protect and 3 for . I ran compressed air thru, but couldn't figger how to get the plastic cover off. The copper leaves *look* OK, but ...

Do you know ... do the plastic covers just slip off, or does one need to unsolder, or ???

I'd better just replace that one. Might take a while to find a replacement.

Thanks, P

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."

"Puddin' Man" wrote in message news: snipped-for-privacy@4ax.com...

Auto tape-type detect, that sort of thing. You might also find another rather smaller and 'open' one on the main body of the deck, that is there to detect when the head plate has reached the end of its travel in the 'heads in' position.

I ran compressed

The contacts get 'sooty' and need cleaning by pulling a piece of paper soaked in isopropyl alcohol or switch cleaner through them.

Can be either. The covers are pretty much always 'clipped' on by a tiny dimple at each side, but the trick is that in order to slide them off, they sometimes need to be clear of the deck metalwork. Sometimes they will come off simply by being 'firm' with them and wiggling, but sometimes, you need to slip a thin scalpel blade or similar between the switch body and its cover. If the switches are causing trouble, the deck usually cuts out very quickly after starting, as the vibration of the heads going in, 'rattles' the switch and makes its contacts momentarily fail, which the system control micro then interprets as there being no tape present, so shuts the deck back down to 'neutral' so that the door interlock will be released. If the heads go in ok, and the deck runs for a few seconds - possibly even actually playing the tape correctly (music-wise) - then this is usually due to failure of the take up spool to rotate. The system control allows a few seconds for this, as cassette tapes can get tight, and the take up run a bit erratically. They try to produce a compromise between allowing a tight tape to be played, and not producing too large a tape loop, if the take up spool is genuinely not going round at all. You can force the deck to run by locating which of the leaf switches is the tape presence detect one, and shorting it, or holding it up with your finger. On a Technics deck, you may need to have the inner door frame closed for the deck to run, but you can have the outer door trim removed to get your finger in. You should then be able to see the take up to check if it is running, and see why not, if not. You can also check that the torque at the spool is sufficient to run the tape.

You should be able to see or 'feel' if the belts are bad. Suspect the take up drive belt particularly if it's one of the Technics grey ones.

Welcome.

Arfa

Yes, found the head-plate sensor.

4 little dimples per switch. I baby-ed 'em, nursed 'em, spread 'em open a tad to ease the cover off, and many dimples broke anyway. Old, brittle plastic. Got the clear covers off, but they won't re-mount, just hang loose and rattle-y.

Ran a jewelers file thru the contacts, then cleaned 'em with the contact cleaner on paper.

The belt is black in color and doesn't appear to be the problem.

I put it back together sans plastic covers and re-tested. Same result. No evidence that the leaf switches are the problem.

Many symptoms seem to point to a faulty motor, but it's curious. The playback motor was working. When I swapped it into the record-deck, I also got the same result (just 3 clicks, then nothing).

If you can think of anything else, I'm all ears, but as of now, the score is as follows:

Matsushita: 2 (assuming I'm forced to pitch both units) Me: zero :-(

In any event, you've been extremely helpful, and it is -very- much appreciated.

Prost, P

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."

It's very unusual for these motors to fail totally, and I would be surprised if you were unlucky enough to have experienced two under the same roof. Time for some more detailed observations, I think. *Exactly* what happens when you attempt to play ? Any motor movement at all ? What about if you try other functions such as wind or rewind ? Have you managed to bypass the tape presence switch ? Have you tried 'working' the deck by hand i.e. press the solenoid plunger in with a small screwdriver tip. You should see the cam gear 'unlock'. Then rotate the forward capstan (left as you look at the back) clockwise (viewing from the back). This should cause the cam gear to rotate to the next phase and relock. Probably "fast forward", but might be "play". You should be able to do that for all four phases, and make sure that the deck is doing what it should be mechanically at least.

Arfa

Exactly 4 clicks. Solenoid plunger pulls in, comes back out, pulls in again, comes back out again.

None perceptible.

Same as 'play' above.

I dunno which it is. There are 3 for which I cannot trace the circuitry. But I confirmed that all switch circuits were closed except for the sensor for plate height (head position). When I short that one, the solenoid actuates.

I can't see the gear without dis-assembling the drive components (again).

I can hear it click.

Not sure I follow that. When I continue to rotate, I get additional clicks. After 2, the cassette won't come out. After another click it will.

Major (weird) news. You'll recall I have 2 RS-TR255's, call 'em A. and B. I've been working on A. Thought to check something on B. to see if it was same as A., pulled the cover, tested playback, and it worked. It failed per A. less than a week ago. Also does reverse play, FF, etc.

There are 4 gold screws on the drive plate on B. that are absent on A. Looks like they just keep the big wheel from coming off (but it's shaft does that). I thought to install the 4 screws on the A. unit, but it wouldn't take 'em: screw holes *look* the same, but they aren't threaded as on B. I double-checked, both A. and B. are RS-TR255's.

Strange, eh? Well, at least I won't be chucking B. in the garbage for a while. I even got readings on the vu, so I guess it's working (for now).

Thanks, P

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."

"Puddin' Man" wrote in message news: snipped-for-privacy@4ax.com...

With no tape in place, the deck should do nothing - no clicks, no motor movement, zip, zilch, nada. Now, if you press each switch up in turn with a finger tip, one of them should get the deck doing something - even if it's just the solenoid clicking behaviour. The switch that you had to press to get that, is the tape presence switch.

You don't need (or want) a tape in place to work the deck by hand. You don't want any power applied either. The cam gear should have four phases. That is "stop" or neutral, "FF", "Play" and "Rew". The periphery of the cam gear has four positions with missing teeth that correspond to each of these phase positions, and four raised latch catches on the surface, which also correspond. The lever worked by the solenoid, catches on these latch positions in turn. The cam has a bias spring to keep it pressed against the latch lever. Suppose the cam has the deck in the "stop" position. The missing teeth in the cam gear periphery which correspond to that position, will be over the drive gear which is at the centre of the forward capstan. So the capstan can freely rotate, without driving the cam gear. When the solenoid is activated to select a transport mode - say "FF" - the latch will disengage, and the bias spring will start to rotate the cam gear, until the tooth-free area has moved around, and the next section which has teeth, has engaged with the gear at the centre of the capstan. By this time, the motor should be running, and driving the capstan. This, in turn, will drive the cam gear round until it reaches the next area where teeth are missing. This will stop the cam in the new position, and the solenoid latch will drop onto the catch at that position on the cam gear surface, and hold the gear at that position, again against the bias spring. At this time, various levers running in grooves under the gear, will have moved their positions to work what ever bits of mech that they have to i.e. moving reel idlers into place and disengaging reel brakes etc.

That is odd. The 255 does not appear to be a model that was valid in the UK, so I can't get data for it off the Pan engineering website. There is a 155 on there, which might be pretty similar. Have you checked for voltage at the "+" terminal of the motor when it should be running ? The motor should have

4 terminals. "-" is common to chassis, "+" should have switched 12v on it, and "A" and "B" are the speed control terminals

Arfa

Just checked. The service manual for the 155 is the same as for the 255

Arfa

There are 6 leaf switches on top of the tape slot. 5 of these look identical and have plastic covers, the other is shorter and is exposed (no plastic cover). This last one senses the head-plate being raised. It fires the solenoid when jumped. None of the other 5 seems to actuate anything with the manual test you described. I tested on both units.

Thanks. That helps a bit. I still can't see it happen, but your description seems to "cover the bases".

I measure ~12v dc from the chassis to one of the contacts when I 'play' a tape.

If it is available and doesn't cost a bundle, would appreciate a link to where I can find it.

Thanks, P

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."

You have to press a function button at the same time. Your finger is 'pretending' to be a tape ...

Have you checked for voltage at the

If the ground to the motor is good, and 12v 'appears' on the "+" terminal of the motor when a function button is pressed, then I'm pretty sure that on those motors, they should run, regardless of what's going on on the "A" and "B" speed control terminals. You could try disconnecting the motor ribbon, and feeding an external 12v from a power supply directly to the motor, and see what happens.

Is the email address that your post was sent from - with the "DOT" changed of course - valid ? If so, I'll send it to you. If you would prefer it to go to a different address, mail me off-group at the address I used to send this.

Arfa

Sorry ... my mind was elsewhere.

I have it now. It looks strange, all 5 switches *appear* to close whenever a tape is inserted.

I looked a bit for a handy-dandy live 12v supply that I could get my big, clumsy alligator clip onto for a jump to the motor, and didn't find anything suitable.

I suppose I could rig an old pc power supply, but ...

Yes, it is valid. Just substitute . for DOT and it should work OK.

Many Thanks, P

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."