Servicing a SONY DAT machine (Pictorial)

[SaSi]

Something looks to be blocking the travel of the arms while they "try" to fully extend. The video is a bit shaky and quick but if I'm not mistaken, both the left and right loading arms appear to fully extend and their "edges" are inside the "stops" at the end of the travel. Is that so?
If not, the S and T posts may be loose and not able to fully insert into the stops.
If yes, then something else could be mangled under the surface.

The mechanism that extends the loading arms also takes the pinch roller with it on a "branch" of that right hand side arm. Nothing looks like broken there. I noticed that the plastic arm with the foam "cleaning cushion" / "brake" for the head drum is missing. Did you remove it or did someone else? It could be a hint for someone else messing with the deck and perhaps removing or incorrectly assembling things back.

It looks like you will need to open up the transport into three pieces (top part, undercarriage, drive PCB) and see if some safety clip is missing and something is loose or out of place.

 

[DogsPart2]

I purchased my PCM-R500 new in 1999.
It continues to work flawlessly.
Great machine.

 

[squatski]

hi, ok Xmas is out the way now so i can carry on with this.
Yes sorry the video is shaky.
This is the 2nd time I've opened this unit up.
With your question,

If not, the S and T posts may be loose and not able to fully insert into the stops.
If yes, then something else could be mangled under the surface.

the answer is yes, they go right to the end.
I've split the whole transport into 3 sections like you said. Same thing happens but if you get it a nudge with your finger (the whole '0' shape shiny metal bit holding the pinchroller and that extra white roller) it goes up towards the capstan. You don't even need to nudge it with your finger - I can just tilt the whole thing and it will fall into place which makes me think there's nothing there (no spring) to even push it (PR) against the capstan.

So maybe it's the tape it self that pulls the pinchroller back when it's tugging back that white roller. ???

 

[squatski]

Anyway I dont think the problem is the pinchroller/capstan

My problem is to do with the take-up reel stopping during playback. Now looking at it all, it could be something to do with the black solenoid not pulling back the brakes enough?

It's impossible to tell without the machine being on but I'm not sure if it's a good idea to wire it all up again and power on while it's in pieces ??

 

[squatski]

here's another video. 1st half showing you that loose bit which I'm sure it meant to be loose (at least on this model)
and 2nd half if me looking around for problems causing this takeup reel stop. It could just be the motor stalling. It looks like a cheapo motor. The belt on it looks fine

http://www.youtube.com/watch?v=lQslUAHExBA&feature=youtu.be

 

[SaSi]

The gear between the two reel tables is meant to transfer motion to either reel, depending on direction. It's supposed to swivel between the two reels. It looks to be working ok but as you point out, the break doesn't seem to disengage.

There are two solenoids controlling break and back tension. IIRC, a yellow and a black. One of them is for back tension and the other for breaks. The back tension solenoid has a screw accesible from the left edge of the transport that adjusts back tension. Break tension is not adjustable.

I had a similar issue with a couple of transports and in the end I "accepted" it was the break pads. They felt sticky to the touch and looks like the adhesive bled through the pad making the break pad stick to the take up reel plate.

Try to stick a piece of scotch tape over the brake pad causing the take up reel not to rotate. It may fix the problem but I doubt it will give adequate braking function. I'm still in the search for appropriate brake pad meterial. It so happens that I used the offending transports as organ donors so I didn't actually need to solve that problem - yet.

I'm still puzzled that the pinch roller doesn't engage the capstan. There is a wobble built into the pinch roller lever but it should have pressed against the capstan when fully extended. The "real" action is happening under the face of the transport, where the levers extend. Can you share a video of this view? I never had this issue so don't really remember how the pinch roller lever is mounted. I need to examine a transport to remember.

 

[squatski]

thanks sasi.
I will do video tomorow morning of the underneith bit.

With the brake pads.. I too think that it could be the brakes and not to do with the motor, if the black solenoid isn't pulling back (or back enough) then it's breaking the takeup reel at random points in time. The break it self doesn't feel sticky, it's not like those rectangle white pads like on the backtensions, it's like a little see-through plastic ring on a thing.
I'll try putting scotch tape on it though.

About the black solenoid though - are you sure you can't adjest it? if you took it out, I'm sure it would have the same screw adjestment on the back like theh yellow one. You can see to top of something that looks like an adjestment screw.

 

[squatski]

I dont quite understand that black solenoid brake. for me I think it needs to be on all the time during playback? is that right? because the black solenoid being on means pulling back that sea-saw (if I can get away with calling it that) and take the brake off.

 

[hdrobien]

From my understanding of Sony DAT the black solenoid is only to prevent the wheels to turn in stop mode. In all other modes (play, ff, rewind) it is released so it only works as on "on/off".

The yellow solenoid controls back tension during play (very sensitive) and ff, and braking during rewind (less important).

In your case, if the take up wheel stops turning, you should check if the wheel turns freely when the brake and the tension control are both released (black and yellow solenoids). Maybe there is something stuck in here.

On the video I also noticed that the white pad of the supply wheel on the tension control has slipped away a little bit, even if I believe that it should not be related with the take up reel problem.

Concerning the capstan problem it is normal that both guides reach their end position before the pinchroller hits the capstan. You have to turn the loading cogs a little bit more for that. If it is too hard, there must be a problem with the white "carriage" underneath. This carriage is in fact in 2 pieces with springs allowing the pinchroller to continue its way even with the guides at ends.

I would be intested by a picture of the all carriage

 

[squatski]

http://youtu.be/wkwiWkyGYOQ

it does move smoothly, it's just my it was differcult with 1 hand holding that and 1 hand on camcorder

 

[hdrobien]

No offense but your videos are not very clear.

Could you put yout camcorder on a stand and operate (slowly and steadily) the mecanism with both hands ?

Did you check that the take up reel spins freely when you release the black solenoid ? I believe that tension control (ie yellow solenoid) is "off" when the unit is not powered.

 

[squatski]

No offense but your videos are not very clear.

Could you put yout camcorder on a stand and operate (slowly and steadily) the mecanism with both hands ?

Yeah sorry about that, I think next video or stand it and zoom out abit more because I was moving it around to try and show you it all at once. I'll make it HD too because zooming out, my cam goes a bit blury. anyway

Did you check that the take up reel spins freely when you release the black solenoid ? I believe that tension control (ie yellow solenoid) is "off" when the unit is not powered.

If you mean spins freely by means of using my thumb & index finger to move the motor wheel (the one holding the belt) then yes. That's with the brakes free from my other hand pushing back the black solenoid.

Is there no why I can test the whole thing powering it on and tricking it to think there's a tape loaded? or is that simply not possible?

 

[squatski]

I've tried to draw a picture because it's hard to get the camara in there. I noticed the brake on the tape up reel, it's half and half on both the cog wheels, is that normal?

 

[hdrobien]

If you mean spins freely by means of using my thumb & index finger to move the motor wheel (the one holding the belt) then yes. That's with the brakes free from my other hand pushing back the black solenoid.

OK but did you try to turn directly the take up wheel ? (when the swivel gear is not engaged on the take up wheel).

Did you try to put the felt pad of the supply wheel back in place ? You should also check if both felt pads are sticky?

Did you try to increase the motor torque ?

 

[squatski]

OK but did you try to turn directly the take up wheel ? (when the swivel gear is not engaged on the take up wheel).

Did you try to put the felt pad of the supply wheel back in place ? You should also check if both felt pads are sticky?

Did you try to increase the motor torque ?

Hi, yes I can spin the wheel even without the swivel gear not engaged, it's all very loose and good. BUT i do have to press down on the black solenoid.

No haven't done anything to the supply wheel pad but I will soon, I did take out the takeup reel pad, the black plastic with the pad on it - I felt it but it didn't feel sticky or anything. When I put it back though I notice it's quite close (well, very very VERY close) to the takeup reel wheel. only a tiny tiny push of that yellow solenoid and it will stop it.

I don't know how to increase the motor torque, I can't see the yellow thing on the main PCB that's supposed to adjest it. I saw on one youtube video where some one added their own.

 

[squatski]

ok hopefully a better video

http://youtu.be/-085Y6_NJ5w

 

[squatski]

I think what I'll do is try that scotch tape idea sasi mentioned. I know it's not a long term fix but at least it will tell me if the problem is these brakes and not the motor.

Put it all back together again and see if I still see the takeup reel stop. Will do this tomorow don't have time now.

 

[hdrobien]

Much better video. I can't see anything wrong except the felt pad on the supply wheel.

If you put scotch tape on the pad be aware that it will modify the back tension control (increase) as it will make the pad thicker. This will also modify the back tension in rewind as both pads won't have the same thickness anymore.

Concerning torque, I don't know wich model you own but there must be a potentiometer somewhere on the printed circuit board.

 

[SaSi]

I can't remember off the top of my head but I think the black solenoid is mounted on slots at the edge. It might be that if you loosen the screws and push it all the way back, it will pull the levers just a bit more.

I've had the same issue with take up reel not running smoothly and the only solution I could find was to remove the break pad. It felt sticky to the touch. I still haven't been able to find a suitable material to stick in it's place though.

 

[squatski]

Concerning torque, I don't know wich model you own but there must be a potentiometer somewhere on the printed circuit board.

60ES. There is what looks like a potential meter philips screw adjest at the bottom of the PCB.

But even if I were to adjest that, that won't fix the problem will it?

I can't remember off the top of my head but I think the black solenoid is mounted on slots at the edge. It might be that if you loosen the screws and push it all the way back, it will pull the levers just a bit more.

but if the black solenoid is futher back, it's taking the break off when the black solenoid is doing nothing, and when the black solenoid is pulling back it's just taking the break off even more off, if that makes sense. so there wouldn't be any breaking action. at least - that's what it looks like to me.

It looks to me like the yellow solenoid break is too close to the takeup reel but there's no way to pull it back. I could just take that pad off all together but all hell would break loose if I were to rewind :sigh: