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Discussion Starter #1 (Edited)
So the 8 track doesn't work that I got with the 69 I bought. The belt was gone so I cheaply put on a o'ring. Finally bought a few 8 track tapes (Fleetwood Mac and some Willy), put it in, nothing...

I open the 8 track back up and find that the motor (with the belt/o'ring removed) will turn a revolution up to about 3 when it's first turned on, but that's it. It spins freely by fingertip and you feel a bit of a vibration with the power on when holding the belt pulley. Any suggestion as to why this is happening? The motor? The capacitor?

I know about starting and running capacitors so maybe this one needs that as well and that's the problem? With my volt meter across the motor feeds I get a surge when the power is first turned on (not long enough to get a reading), then back to just millivolts.

I posted a picture of the circuit board with the capacitor, diodes, resistors and transistors...

As a side note, I can turn the big pulley and get sound so the motor issue is the last thing that needs fixed.

Allen
 

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Have you tried connecting the motor directly to a power source bypassing that circuit board? I'm not sure what voltage finally gets to it so be careful, I have an adjustable supply for checking that stuff. If the motor is bad or needs brushes find a local hobby store that still deals with model trains, (I know, not too many places like that left), I'll bet they have a few guys they know of that restore those things, they are the ones to talk to about redoing a small motor like that or finding pieces like brushes that will fit.
 

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Discussion Starter #5
Have you tried connecting the motor directly to a power source bypassing that circuit board? I'm not sure what voltage finally gets to it so be careful, I have an adjustable supply for checking that stuff. If the motor is bad or needs brushes find a local hobby store that still deals with model trains, (I know, not too many places like that left), I'll bet they have a few guys they know of that restore those things, they are the ones to talk to about redoing a small motor like that or finding pieces like brushes that will fit.
I haven't but that's a good idea. I'll get a small battery or even a 9v and give it a try.

Thanks,

Allen
 

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The caps need to be replaced anyway regardless so start there. Try to find a schematic for it. There should be a Sams Photo Fact for it somewhere.
 

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Discussion Starter #8

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Electrolytics like the blue one in your pic are famous for drying out. Once the electrolyte is low or gone, failure is imminent. Digikey and Mouser have these parts all day long. I used to R&R old tube amps. The majority of the failures were caps, followed by tubes, then carbon comp resistors.
 

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Discussion Starter #12
Electrolytics like the blue one in your pic are famous for drying out. Once the electrolyte is low or gone, failure is imminent. Digikey and Mouser have these parts all day long. I used to R&R old tube amps. The majority of the failures were caps, followed by tubes, then carbon comp resistors.
Is that the same as a run capacitor?

I've used Digikey numerous times so I will look there.

Allen
 

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Discussion Starter #15
1st, when I drove up to the house, there were 4 does in the side yard. I know, no picture, didn't happen, I tried to get them before they went past the tree line but to no avail...

Now to preface my findings. Someone may come along and call what I have found hogwash (and it may be). I'm going to put this in layman's terms because a layman is writing it. I know a little about electronics and the components but I am also always willing to learn so feel free to teach me anywhere that I you see I'm wrong. Hopefully this will help anyone trying to figure out the same problem.

To recap, When an 8 track tape is put into the player, the motor will spin, 1-3 revolutions, usually 1-2. The first thing I did was replace the diode in the circuit because the diode would ohm both ways (still in the circuit). This did not fix the problem (same results). Upon @gregb's excellent suggestion, I bought a 9vdc battery (thinking it wouldn't be a full 12vdc but would be enough to spin the motor) and it worked. Going from the yellow leg to the blue leg of the motor, it would spin as long as it was hooked to the battery. Thinking the capacitor, as @ylexot suggested (and already thinking it myself), was bad, I found one that I had on circuit board and replaced the (what I thought was a running) capacitor. Again this did not solve the problem. We are now up to where I started this evening on testing.

I again tested from ground (on the radio chassis which was hooked directly to the battery) to the blue wire. It would get a burst of voltage and then fall to millivolts. I decided to check the incoming voltage into what I am calling the "speed control board" (spc) as learned from Barry Fone as suggested by @JeffTepper (Barry's 8 Track Repair Center...We do FM Conversions). I found the power supply feeding the board via an orange wire had 9.8vdc leaving the power supply (this could be low because the battery in the vehicle is not fully charged). It also arrives at the spc (same voltage). This is where I discover that the incoming voltage from the orange wire is feeding both the capacitor that I replaced and the tan/black/yellow/black/red capacitor in post #1 (polyester capacitor). So in essence, it is feeding two circuits on the spc.

I then find that the polyester capacitor via a resistor feeds the yellow wire.

WAIT!!!

The yellow wire (I thought) was the ground wire to the motor?!?!?

I check the voltage to the yellow wire and zero (0). I decided to take the yellow wire loose, as I had some suspicions at this point, and check voltage coming through the resistor or to see if maybe the resistor was the culprit. I got a little over 11 volts with the yellow wire not hooked up. HMMMM...

I dig further and find that there are actually three wires going to the motor, how did I miss that (stuff is tight to say the least)?

So now I know there are three wires going to the motor, Blue, Yellow and Black. Black is for sure ground, it is soldered to the radio chassis.

So before I give my conclusion, I'll let you all give your conclusion to see if I am thinking correctly.

Thanks!!! I will give my conclusion in the morning, or simply say, yeah, that's it!!

Allen
 

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Discussion Starter #16 (Edited)
In conclusion, since the motor would run using the blue wire and yellow wire and the fact that with the yellow wire loose from the circuit I have voltage there (but not when it is soldered in place), it is obvious that the yellow wire is shorted to ground in the motor.

To further explain how I think the setup works, the blue wire, hooked up to the capacitor that I replace is to "kick" off the motor since there is a load on it when first starting up. That is working as is should. The circuit also sends voltage to the yellow wire to run the motor, this part is not working because of the short.

I need a new motor. Little did I know, the answer was in the thread title all along...now to find a source (Barry doesn't sell the motors).

Allen

P.S. I don't know what would happen if I use the blue wire to both kick start and run the motor. I'm guessing it wouldn't last long.
 

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Discussion Starter #18

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Discussion Starter #19 (Edited)

To a fault I can't give up on getting something to work. State of the art, 1969.

The 8 track will be sent off now that I'm satisfied I could at least make it play...

Enjoy Stevie Nicks and Fleetwood Mac...

Allen

P.S. The vibrato at the end is a bonus!!! :pirate::pirate: :grin2:
 
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