TRC 975 decks not functioning!

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Fatdog

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JVC Floyd said:
You should start by checking if the motor spins, if it does then you probably need new belts.
^^ This. :yes:
 

FWSnake

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Hisrudeness said:
Then you need to fix the motor too. When you switch the box on and press play does the motor do anything?
Just got back to it. Upon observation, nothing is spinning when I activate the deck(s). You're likely right about fixing the motor, but I don't have the foggiest notion on how I should start with that.
 

jimmyjimmy19702010

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May 5, 2012
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Try turning the motor over by hand with the drive belt removed. Dry/sticky bearings can cause a motor to seize. Drop a couple drops of machine oil into the top bearing and turn the brass pulley whilst pulling it in and out slightly.

On the other hand, sticky belts or a stuck deck mechanism can cause similar issues. It's a basic deck with one motor doing the duty of two motors in better decks. So you've probably got two main drive belts running from the one motor so either deck can be causing issues.
 

FWSnake

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jimmyjimmy19702010 said:
Try turning the motor over by hand with the drive belt removed. Dry/sticky bearings can cause a motor to seize. Drop a couple drops of machine oil into the top bearing and turn the brass pulley whilst pulling it in and out slightly.
On the other hand, sticky belts or a stuck deck mechanism can cause similar issues. It's a basic deck with one motor doing the duty of two motors in better decks. So you've probably got two main drive belts running from the one motor so either deck can be causing issues.
I'll try what you suggested. Is this solution supposed to fix the problem entirely or will there be an extra step or two afterwards?
 

Fatdog

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FWSnake said:
I'll try what you suggested. Is this solution supposed to fix the problem entirely or will there be an extra step or two afterwards?
I guess we'll find out. :-D ;-)
 

FWSnake

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jimmyjimmy19702010 said:
Try turning the motor over by hand with the drive belt removed. Dry/sticky bearings can cause a motor to seize. Drop a couple drops of machine oil into the top bearing and turn the brass pulley whilst pulling it in and out slightly.

On the other hand, sticky belts or a stuck deck mechanism can cause similar issues. It's a basic deck with one motor doing the duty of two motors in better decks. So you've probably got two main drive belts running from the one motor so either deck can be causing issues.
It seems like you have to take apart the whole deck mechanism to actually be able to remove the motor. And after some searching, I wasn't able to find any brass pulley. How would I go about accessing it?

Really wish there was a service manual for this :drool:
 

Helmar

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Dec 21, 2015
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You do not need a service manual once you have the tape mechanism in front of you like on the pictures you showed.
However you need a structured way of checking and fixing the error.
Did you check by using a multimeter if there is any voltage on the motor after pressing play?
Are you able to rotate the motor manually be hand?
At this point you do not need to take the unit apart. Maybe only some cleaning and sanding of the microswitches is required.

Best regards
Helmar
 

Superduper

Member (SA)
I'll bet all you need to do is replace the belts. The humming of the motor is almost certainly due to it spinning. The belts are probably just slipping on the pulley. Service manuals typically don't give you a step by set on how to rebelt anyhow because in general, it is presumed that the technician possesses the mechanical aptitude to perform this simple task. You're going to need further disassembly beyond that if you really want to replace the belts though. If you can't overcome that hurdle, then we probably can't help you. You can't fix something by looking at it.
 

Helmar

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The tape mechanism looks very similar to Hitachi 3d80/88. There, one can change the belts without taking the unit apart or removing the motor.
 

FWSnake

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Helmar said:
You do not need a service manual once you have the tape mechanism in front of you like on the pictures you showed.
However you need a structured way of checking and fixing the error.
Did you check by using a multimeter if there is any voltage on the motor after pressing play?
Are you able to rotate the motor manually be hand?
At this point you do not need to take the unit apart. Maybe only some cleaning and sanding of the microswitches is required.

Best regards
Helmar
Haven't used a multimeter to check for a voltage output, but shouldn't the humming imply that there IS voltage coming from the motor anyways?
The motor cannot be rotated manually by hand. I figured I would have to take apart the drive mechanism to actually remove the motor and try jimmyjimmy's suggestion.
As for cleaning microswitches, I'll try that out as well.

Superduper said:
I'll bet all you need to do is replace the belts. The humming of the motor is almost certainly due to it spinning. The belts are probably just slipping on the pulley. Service manuals typically don't give you a step by set on how to rebelt anyhow because in general, it is presumed that the technician possesses the mechanical aptitude to perform this simple task. You're going to need further disassembly beyond that if you really want to replace the belts though. If you can't overcome that hurdle, then we probably can't help you. You can't fix something by looking at it.
Guess I'll get a set of belts and try that out. Replacing belts won't be a problem, especially if Helmar is correct with the deck's similarity with the Hitachi model.
 

Helmar

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Dec 21, 2015
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You are right, I overlooked that the motor is humming.
So voltage and mircoswitches are probably OK.
Is the motor rotating or is it somehow blocked?
After removing 2 of the belts you can find out if the motor is blocked or the gears it is driving-
 

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hopey

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Dec 28, 2014
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I have seen this mech before and was rackin my brain. It's the same as sharp xbass left deck auto stop right deck auto reverse. It's the belts alright and there is also a stupid flywheel brake that gets in the way. Also the tape speed was different between the decks as you can see one motor and two different mechanical loads. sharp gx-cd60ht

I sucsessfully got this one working. It may be just the fly wheel brakes but I replaced the belts any way. There is also a plastic guide which you have to navigate the belt through. You can do all this without dissembling the mech. I actually cut the head off the brake stop with a snap blade which also releases the spring. The stop is made redundant but is only to stop the fly wheel turning in transit. After doing this both decks started working but you should replace the belts as well. I made up custom belts to suit.
 

FWSnake

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Helmar said:
You are right, I overlooked that the motor is humming.
So voltage and mircoswitches are probably OK.
Is the motor rotating or is it somehow blocked?
After removing 2 of the belts you can find out if the motor is blocked or the gears it is driving-
It ceases to rotate, meaning it is being blocked or obstructed by something.
 
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