Sony TC-730 capstan motor not turning - I need help

[daveyh]

I have a Sony TC-730 reel to reel and the capstan motor does not turn. I know that the unit has three motors and no belts to drive the motors. One rewind, one fast forward and one for the capstan or direct drive play function. The units pinch roller engages but the units capstan motor will not turn. I also know about the stop/start wire switch that must be in the up position before the unit will play tapes.

I don't know if it could be the motor start cap. 250v 4uf or if it might be something to do with the Sony CX-032 IC on the servo board.

At first it played for about six songs than came to a slow stop. It does not turn at all now.

Anyone have any experience with these units that can shed some light on the matter and give me an idea where to start looking before I start throwing leaves into the wind and start replacing unnecessary parts?

I do have a service manual.

 

[daveyh]

anyone?

 

[stoN_Cold]

Check this out fitst: http://www.hifiengine.com/library/sony/tc-730.shtml

 

[dr*audio]

First clean the speed switch, you might be lucky.

 

[daveyh]

Check this out fitst: http://www.hifiengine.com/library/sony/tc-730.shtml

Have one already.

Thanks

 

[daveyh]

First clean the speed switch, you might be lucky.

Cleaned all the switches. Still nothing.

 

[daveyh]

I removed another motor start cap (250v 4Uf) from another parts unit and tried it but it did not work either. I am thinking it is either a bad motor or a bad IC. I searched the internet and only found a Sony CX-032 IC but they want $13.00 for it. I would like to have an idea if anyone else is acquainted with a Sony CX-032 IC. I think it runs the voltage to the capstan motor. I guess no one has ever had the problem with the capstan motor not turning on the Sony TC-730 Reel to Reel before.

 

[petehall347]

have you checked voltage at the motor ?
and reseated the relevant fuse .

 

[daveyh]

have you checked voltage at the motor ?
and reseated the relevant fuse .

I will try that. The motor turns every now and then and just stops. Seems like voltage or a heat problem.

 

[jan_stevns]

I removed another motor start cap (250v 4Uf) from another parts unit and tried it but it did not work either. I am thinking it is either a bad motor or a bad IC. I searched the internet and only found a Sony CX-032 IC but they want $13.00 for it. I would like to have an idea if anyone else is acquainted with a Sony CX-032 IC. I think it runs the voltage to the capstan motor. I guess no one has ever had the problem with the capstan motor not turning on the Sony TC-730 Reel to Reel before.

Your guess is wrong It is a rather typical FG servo system.

I would check the two double diodes D902 and 903 and the transistor Q901 - they are typically shot.

(If the voltage on pin 9 on the CX-032 are higher than 0.63volts - that indicates the Q901 as being defective)

 

[petehall347]

check out page 17 in the manual ..
might be tight bearings

 

[stoN_Cold]

Cleaned all the switches. Still nothing.

I knew you would waste time.

 

[daveyh]

check out page 17 in the manual ..
might be tight bearings

Tired that already.

 

[daveyh]

Your guess is wrong It is a rather typical FG servo system.

I would check the two double diodes D902 and 903 and the transistor Q901 - they are typically shot.

(If the voltage on pin 9 on the CX-032 are higher than 0.63volts - that indicates the Q901 as being defective)

This looks promising. Never seen a CD-2 or a CDR-2 three leg diode. How other than the voltage check above do you check these with a meter? Should I pull them if the are suspect. Are the still available?

 

[daveyh]

I knew you would waste time.

Hey. I'm gonna as fast as I can. :zoom:

 

[daveyh]

Your guess is wrong It is a rather typical FG servo system.

I would check the two double diodes D902 and 903 and the transistor Q901 - they are typically shot.

(If the voltage on pin 9 on the CX-032 are higher than 0.63volts - that indicates the Q901 as being defective)

OK. Pin 9 on CX-032 reads 0.75volts. I also measured the voltage on pin 8. It should be 13volts according to the manual. Pin 8 reads 6.24volts sometimes and then reset my meter and it reads 10.2volts. Reset 6.24volts?

 

[daveyh]

So the CD-2 and CDR-2 are double diodes. So how do I check them?

 

[stoN_Cold]

So how do

With Ommeter on lowest position or diod test. :thmbsp:

 

[dr*audio]

OK. Pin 9 on CX-032 reads 0.75volts. I also measured the voltage on pin 8. It should be 13volts according to the manual. Pin 8 reads 6.24volts sometimes and then reset my meter and it reads 10.2volts. Reset 6.24volts?

The voltage will vary with how much current the IC is drawing. Check the voltage on the other side of R911. Should be 14V. Also measure R911.

 

[outnfront11]

Your guess is wrong It is a rather typical FG servo system.

I would check the two double diodes D902 and 903 and the transistor Q901 - they are typically shot.

(If the voltage on pin 9 on the CX-032 are higher than 0.63volts - that indicates the Q901 as being defective)

Hi, I'm resurrecting an old but appropriate post here...

I have a Sony TC-510-2 (portable R to R). The PLAYBACK is not doing anything at all, no movement in the motor. The FF and RWD are fine.

I've done immeasurable debugging tests and have arrived at this same chip being suspect (IC701 - CX032b).

I checked all the Voltages on IC 701 which is on the servo amp board... this reading only is valid when the PLAYBACK swtich is on:

1,2,3,4,5 = -7mV
6 = 200mV
7 = 13V
8= 13V
9= -70mV
10= 250mV
11,12,13,14 = 0V




My question is, should I replace that chip or is it possibly something else in the circuit?

The only source I can find for a the CX032b is on ebay, and they cost $52!!

Here is a link to the full Service manual in case anyone has the know-how and can have a look!

https://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Sony-TC-510-2-Service-Manual.pdf

Thanks, Jim