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Teac a7300 capstan issues

B

bwayjoes

Active Member
Hello!

I am a complete new guy to reel to reel but have beem looking for one for a long while. I grabbed a teac 7300 today everything works (rewind,ff,pause, lights etc.). When power is off capstan turns freely, when I power on, the capstan freezes. I loosened the screw on the back of the motor, but it's still seized under power. Any thoughts?

Thanks. Jim
 
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One thing I noticed as well, the counter is not turning in ff or rw. As well, after i hit play the arms lift the tape to the heads,but after a second or two they drop down. I'm not sure if the problems could be related or not.
 
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Sound like the capstan motor drive circuit is defective if the motor seizes only when powered up. See if the plug-in connector for the board is cracked. Also try cleaning the connections with Deoxit. Pin 7 should have 24 VDC.

If above is good, test all xistors and diodes on the board. Check the drive coils for continuity. Check electrolytic caps.

Schematic is on hifiengine.com See page 48.
 
Well, no luck on cleaning. After setting powered on for 15 minutes, the motor got fairly warm. The board that is connected to the female end of the connector got VERY warm and ad that toasty electronics smell to it. I can't see anything visibly wrong with it though. Thanks again for the help tapetech, I know these can be a headache. I just don't wanna put a couple hundred into this if it something simple
 
It's not something simple. Likely, the motor drive board needs repair. Possible defect transistor, diode, cap or coil.

This deck is worth repair. A good shop could repair the motor drive board (if that's really the defect).
 
I took the capstan motor out and on the board that attaches directly to the motor there is what I believe to be a rectangular white resistor that has gotten very hot. The board is black underneath it so I can't read the number. There was also a pinched wire under the motor that I can see copper through the insulation. Hopefully not much damage has been done.
 
That large resistor might be R910. Should be 4.7 ohm. If it overheats, then Q904, Q905 or Q906 could be defect. Also a shorted C910 could cause that.
 
Thanks.I should have said 24.9v. So I want to test the components you mentioned earlier, what kind of voltage should I be looking for on the transistors and cap? And should I measure the resistor that got hot? Thanks for your help AND patience.

Jim.
 
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You need to remove the resistors, caps, diodes, transistors and test them individually with a DMM. Test coils for continuity.
 
This is not your problem I'm sure, but when I got my 7300, it had a dime, yes a 10cent dime stuck in the motor housing keeping it from spinning-- a scratched, mangled dime.
 
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