TEAC 80-8 Reel Motor Grinding and Pinch Roller Problem

Greetings, I have been learning how to repair this TEAC 80-8. Referencing other threads on this site and many more, I've been able to install new microswitches, 3D print and install a new tension limiter, replace the capstan belt, free up the frozen pinch roller assembly and clean it. There's a few more minor things I'd like to do, but I'm at a standstill now with the reel motors grinding when trying to turn the reels. Also, I may have reassembled the pinch roller assembly incorrectly, as it does not make contact with the capstan now. Here is a video showing these issues, I also included some pictures just to show the general state of the machine. With my limited knowledge, I would assume the reel motors need oil, but I'm not sure how to do this as I do not see the oil tubes like the capstan motor has. I plan to be very active in this thread and will provide more info as needed. Thanks for any help!

(I cannot post links to the video/photos yet as this is one of the first posts I have made. When I can, I will)
 
So, first of all, you’ve got some serious corrosion going on all over that machine. It looks like it may have been submerged at some point and not properly dried out? I’m surprised it’s working as well as it is.

The noise from the reels is just the brake bands rubbing on the drums. Are you saying it makes that noise in FFWD and REW also? The brake bands may be missing the felt pads. But the bottom line is when the machine is in STOP, the brakes are engaged, they’re going to rub if you move the reels by hand.

The pinch roller: nothing I can think of would cause that problem just from removing and reinstalling the roller. Either the solenoid or solenoid linkage is binding, OR the solenoid is not getting the correct voltage. I’d start by ensuring the linkage and solenoid can move freely. If they can move freely, check the voltage.
 
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Yeah I have no idea how it got in this shape. A friend recently acquired the unit and asked me to look at it.

The felt pads are there, I suppose the noise is just from me turning it by hand. I have a Tascam 38 and 48 and they do not squeal like that when turned by hand in STOP mode, which is the only reason I thought something may be wrong.

There does seem to be some issues with reels turning though. The right reel struggles to turn in FF mode, and will move some if coaxed by hand but eventually stops. And pressing PLAY makes the left reel spin for a few seconds and then stop. REW seems to be fine. Also, it seems to all work better with no reels on. I uploaded some more videos demonstrating all this. Videos

For the pinch roller, I just had to shift the solenoid over a bit. You can see in those videos that it's much closer to the capstan now.
 
Let’s be real here...with the machine showing that kind of corrosion, it is going to have to be disassembled and gone through. I mean, like, open up the reel motors, etc. if it *was* submerged, bearings will be shot, corrosion could be impeding the normal mechanical operation of the motors, electrical connections could be corroded...you’ve got you’re work cut out for you.

The left motor spinning clockwise when you hit PLAY is normal...that’s to provide holdback tension in PLAY to ensure positive tape-to-head contact. But the right side should be spinning counter-clockwise to provide take up tension. It appears the right reel motor doesn’t spin at all regardless of the transport mode unless encouraged and then it gives up shortly thereafter. So you’re going to have to figure that out. Start by verifying the motor is getting power when you hit PLAY or FFWD. If there’s no power you have to start tracing backwards from the motor to find out where the fault is. If it IS getting power then we’re back to disassembly and overhaul. I’m assuming you have the service manual, yes? If you’re going to do this you MUST have the service manual. And yes the motors will perform better with reels off if there are problems. They are not performing to spec, there are likely multiple problems contributing to this, and if you add a bunch of mass for the motor to manipulate it’s going to make things worse.

On the pinch roller, don’t just shift the solenoid and call it good. The pinch roller is supposed to engage the capstan shaft with a certain degree of pressure. You have to get a spring gauge to calibrate the pinch roller pressure. But before that consider that you indicated it was contacting the capstan shaft before you removed the pinch roller, and then it wasn’t after. The solenoid didn’t move in that time. You need to find out what cause the change and address that. Don’t just band-aid with a blind adjustment of the solenoid.
 
Does the fact that the right reel motor spins some when encouraged and then gives up not imply it is getting power? Yes, I do have the service manual.

In freeing up the pinch roller assembly, I removed the solenoid. I didn't make that very clear initially. I'll get myself a spring gauge then and follow the procedure in the service manual.

Thanks for all the help.
 
Ahhh okay. Got it (regarding the pinch roller adjustment). Okay. Yeah if you have trouble finding the right spring gauge(s) (usually there are a couple ranges to get in order to be able to adjust the pinch roller pressure and brake tensions) let us know...the ones I have work well and are made by Ohaus, so Google that.

And, yes, the fact the right motor moves with encouragement indicates it is getting power, but that power needs to be a certain voltage, and capable of delivering a specified degree of current. If it’s supposed to be 24V, but there’s a bad connection anywhere between the motor and the power supply, logic and tension circuitry restricting the current flow, that voltage may draw down to near nothing under load. Or the power supply could be roached...not as likely here since the left motor spins, but we don’t know how the left side would do with loaded reels. Can you load tape and get it REW okay?
 
Will do, thanks.

The left reel rewinds just fine with a full tape reel on it. I have a multimeter, where exactly can I check the voltage going to the right reel motor?
 
No...follow them the *other* direction. From where the come from. Look in the service manual. The schematic will tell you where they go.
 
Welcome on in, [MENTION=204906]thedudleys[/MENTION]

You've probably got your wings by now but I completed the link for you in your earlier post.
Good luck. :)
 
Ok, I have found the point on the PCB assembly designated for the take up reel. Is this what you meant? I don't have much experience working with schematics, and to be honest I'm not really sure how to go about testing the voltage in this scenario. I'm sure this should be a simple task

This is the schematic you're talking about, right? And would that Supply Voltage Check procedure outlined in the service manual have to do at all with what I'm trying to accomplish here?
 
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“I’m sure this should be a simple task.”

No.

Opening up a complex electromechanical device and probing around and troubleshooting is not simple or elementary. I’m not sure what your friend is expecting of you, but it may end up being best to take it to a local repair shop.

I’m purposely being a bit non-specific in my advice because I have no direct experience working on or operating an 80-8.

I don’t even know if the reel motors are AC or DC powered.

The schematic you linked us just what it says. The Power Supply. The image you posted is too grainy to read. If I have time I’ll look at my copy, but I’m not making any promises because what you are dealing with will likely consume many hours, and I apologize but I just can’t invest that kind of time. It would be different if it was a machine that was clean and appeared well cared for, but because it has been so neglected it is likely the problems are complex and require a lot of cleaning/inspection/testing/troubleshooting, and without being at the machine everything takes 4-5 times the amount of time.

Maybe someone with direct experience working in an 80-8 will chime in, but for me to get involved to the degree you are asking I’d have to first learn the machine, and then start chipping away at what the issues might be.

The power for the reel motors does come from the power supply PCB, but that’s not likely the best place to measure power supplying the take up reel motor. We want to see if the power at the motor is below spec, and since the wires going into the motor aren’t accessible, you follow those wires upstream from the motor to where they connect to next upstream from the motor. You can do this yourself at the machine. Just follow the wires. I assume you have a voltmeter?
 
It looks like the reel motors are AC powered. They get varying degrees of voltage depending on the transport mode. The transport control switches activate different relays on the power supply assembly that control the voltage powering the motors.

I’m not positive but I think the wires go from the reel motors to respective terminal blocks. That’s where you want to start with your voltage measurements. But, again, I’m not positive. The capstan motor, supply motor and take up motor each interface with components designated as TB201, TB202 and TB203 respectively. I cannot find these parts in the parts lists anywhere, so I’m not positive that’s what they are. You’re my eyes and hands and you’ve indicated you do not have much experience with this kind of stuff, and this is relatively advanced work, so this is where it becomes immediately difficult. But see if the take up motor wires go next to a terminal block. If they do, the same should be true of the supply motor wires. Set your voltmeter to AC volts, put the machine into FFWD and measure AC volts across the red and orange wires. Then put the transport into REW mode and do the same but at the supply motor terminal block. For the supply motor there should be two red wires. Again, difficulty level high because I can’t see the machine...I can’t tell you which red wire to reference. If I was at the machine I could tell you, so measure between the first red wire and the orange wire, and then measure between the second red wire and the orange wire. Post the results. That’s the best I can do.

Those tests in the service manual for the power supply PCB don’t apply here because those are for the regulated DC power rails that power the audio electronics and logic, not the relays and motors.
 
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I don’t even know if the reel motors are AC or DC powered." Fork! I see Sweets has established that the motors ARE AC fed now so be very careful. You are obviously an intelligent chap but lack experience of poking about in electronic gear. Many AC tape motors here were fed from RAW MAINS via dropper resistors and so there is a very real risk of shock from a chassis/ground referenced supply. 115V might not be AS lethal as our 230 but it still CAN kill yer and in any case, shorting mains to ground will be quite a damaging exercise!

Tip: I used to file my meter probes to a fine, sharp point so they can 'stab' through cables.

Dave.
 
What he said ^^^^^^

Please be careful.

I meant to mention earlier I’m not responsible in the event you zorch yourself or the gear. Proceed on your own accord and at your own risk.

Dave, it looks like the various AC voltages are furnished via multiple windings off the main transformer. So that’s good...no resistors. I don’t think there is any full line voltage coursing throughout the machine, but I did see 80V. Yes...great care should be taken. Sparks. Fire. Meter probe welded to innards.

I’m not speaking from experience.

No.

Of course not.
 
What he said ^^^^^^

Please be careful.

I meant to mention earlier I’m not responsible in the event you zorch yourself or the gear. Proceed on your own accord and at your own risk.

Dave, it looks like the various AC voltages are furnished via multiple windings off the main transformer. So that’s good...no resistors. I don’t think there is any full line voltage coursing throughout the machine, but I did see 80V. Yes...great care should be taken. Sparks. Fire. Meter probe welded to innards.

I’m not speaking from experience.

No.

Of course not.

Heh! No, none of us have EVER done such a thing! Even with LV DC supplies, a short will certainly bugger any regulator circuits since I doubt they are "78" regulators and therefore 'fairly' S/C proof.

General tip. If any of this old gear, tape, mixers. di-da, have borked voltage reg' circuits, unless you are cork sniffy about 'originality' replace them with 78 or 317 chip regulators. You probably would not be able to source the exact same transistors anyway.

Dave.
 
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