JVC direct drive tape deck problem (TD-V541)

[Xenon-Codex]

The tape starts and then immediately slows to less than half speed. If i try more, it slows to a autostop. But the (always on) motor is so strong that I can't stop it by pressing with my finger... What makes it stop if playing any cassette?
I changed these capacitors on the motor board:
http://www.audiokarma.org/forums/ind...oblems.239117/

[R_J]

Re: JVC direct drive tape deck problem (TD-V541)

There are three other motors in this deck, Check the 12 volt supply to the drive ic's IC702 & IC703, also check if it is the capstan motor drive is engaging the pinch rollers.
If I remember the dd motor drives the capstans, if it is not slowing down then you must have slippage between the pinch roller and the capstan or poor takeup torque by the reels.
What makes it stop is that the reel (hall effect) sensors are not seeing the reels turn so the mechanism will stop.
Something else that gives problems could be a oxidized cam switch.

[Xenon-Codex]

Re: JVC direct drive tape deck problem (TD-V541)

Voltage on the IC's does not drop when pressing play. On the cam motor it's 11,1V until I press play, when it drops to 10,98V. Also the reel motor gets 3,5V, which is correct. So I think it's not the power supply. Is there an easy way to get it running without a cassette?
EDIT. Cap-motor voltage stays at 11V even if I stop the motor with my finger...

[R_J]

Re: JVC direct drive tape deck problem (TD-V541)

The capstan motor is the direct drive motor. It's the capstan that regulates the speed, the tape is pressed to the capstan by the pinch roller, and the reel motor drives the reel to take up the tape. so if the speed is slowing down you could have a bad dd motor.
The d.d. motor is a multi phase motor, it is not like the other brush type motors so its 12 volt suppply would not be effected by a speed change.

It should operate without a cassette if not, there is likely a switch or lever somewhere that needs to be pressed to to indicate there is a cassette in the unit, should be faily easy to figure out.

[redwire]

Re: JVC direct drive tape deck problem (TD-V541)

Only one capstan is true direct drive, in typical JVC fashion they always sneak truth in features lol.
First, I would suspect the belt needs replacing, there is one between capstans and connected to the flywheel.

TA8409S is an H-bridge with two-speed control for the take-up reel motor.
Capstan speed control servo is done at the motor, it just gets 11V power switched. There should be a servo and trimpot on the capstan motor PCB, you'd have to take it all apart to troubleshoot - if it's a motor problem.

I'll bet flipping autoreverse gives you no speed problem because the (capstan) belt has load playing on one direction. If the belt is really stretched, the flywheel would not turn so good.

[Xenon-Codex]

Re: JVC direct drive tape deck problem (TD-V541)

I removed the covers, and got it to play without a cassette. Now it runs at normal speed, and requires some force to stop if I press the reel by finger. No cassette can be so stuck that it wouldn't spin. The belt seems to have good traction. It keeps the speed also when I put a tapeless cassette into it.

[Xenon-Codex]

Re: JVC direct drive tape deck problem (TD-V541)

Could it be the second capstan (which the belt drives)? It makes loud resonance type noise at times, sounds like worn out bearing. Funny that the motor works even if the backplate is loose and the speed varies depending its position.

[R_J]

Re: JVC direct drive tape deck problem (TD-V541)

It could be that the capstan motor bushing is worn a bit, make sure it is not rubbing on the coils or anywhere else
You should be able to hear it when in play mode and if you remove the capstan flywheel you may see where it is rubbing, If may not be but worth a check
Is this the motor?
Do both flywheels spin freely without the motor attached?

[redwire]

Re: JVC direct drive tape deck problem (TD-V541)

You gotta lube the motor and capstan bearings, just don't get oil on anything rubber.

Grab each (installed) capstan with a finger and gently wiggle it. There should be no slop or free play.
If there is a lot of capstan bushing wear, the capstan runs crooked and the cassette tape will curl away from the tape head. Usually I see the tape get crinkled and damaged as the tape head guide tries to center the tape but the capstan keeps curling it.

[Xenon-Codex]

Re: JVC direct drive tape deck problem (TD-V541)

The motor has no play, but the second capstan has about one millimeter slack sideways. All bearings are well oiled. I prevented the second pinch roller to rise up to the capstan, and now the deck plays faster but not the correct speed. So the rollers are slowing it down. Maybe the motor is at its last legs after all, or the bearings are so stiff?

[Xenon-Codex]

Re: JVC direct drive tape deck problem (TD-V541)

May be useless to fix this deck as I got it for free, and I also have two TD-R452 and KD-V11 and KD-V100. All of them are working. But still it's a pity to trash this...

[redwire]

Re: JVC direct drive tape deck problem (TD-V541)

The capstan's purpose is to control the tape speed, so pulling back the pinch roller should make it play fast. This is normal. Is your complaint the speed is wrong, with playback on the direct-drive capstan (not the belt-driven one)?
I would look at the belt and see if it is slipping after a few seconds.

If the capstan bearing seems worn, perhaps the deck has a lot of miles on it. But the tape head would also be worn badly. They wear out together. Did you look at that.

You can try ask JVC for the part, if they have them. It never hurts.

[Xenon-Codex]

Re: JVC direct drive tape deck problem (TD-V541)

If I press the pinch roller to capstan, both of them slow down simultaneously. If press the capstan down with my fingernail while lifting the roll up, it plays better and nearly stops when I stop pressing the capstan with my finger. The bearing must be worn out and it gets stiffer when the roller pushes it upwards. The rattling noise comes from it, and gets occasionally louder.
The head does not look very worn, and the belt is not slipping.

[R_J]

Re: JVC direct drive tape deck problem (TD-V541)

If I remember the correctly, the capstan motor runs when it is turned on so it likely has a lot of hours/years of running, you can remove the capstan from the bushing and see if it the capstan shaft is worn, it should look the same (chromed) its entire length but if it is darker where it rides in the bushing, theres not much you can do except clean it and re oil it using a light oil.

[Xenon-Codex]

Re: JVC direct drive tape deck problem (TD-V541)

It was the capstan bearing which was so stiff that the motor couldn't spin when the roller pushed against it.