National Panasonic RQ-4050FD austostop and motor MMT-5ST9RA issues

Status
Not open for further replies.

toshik

Member (SA)
Mar 1, 2015
500
2
18
56
St. Augustine, FL
I've got my childhood radio National Panasonic RQ-4050FD and need some advise on the mechanism repair.
Both white and silver grease went rock-hard.
Everything was taken apart cleaned-lubricated, put back together and rebelted, however I can't figure out the autostop - this is the one with stick-out plastic pusher.
It does not work - if I push the pusher up I still need to assist it by pushing at the small spring-loaded wheel to the right (on the picture between the left reel and capstain). The long spring is still pretty hard.
Maybe this autostop thing is due to motor weakness?
Original motor MMT-5ST9RA had very hard rotating shaft and did not start by itself.
I put a drop of synthetic oil into the exposed bearing under the pulley and it moved freely, however still had some dead spots. I blew compressed air inside and it's better.
It still catches a dead spot and won't start rotating but at least stays on. Plus if I listen closely to it it sounds like a mini-tractor maybe it's normal for this motor? It would be a bitch to take it apart since the motor is inside the swaged outer case.

.
 

Attachments

toshik

Member (SA)
Mar 1, 2015
500
2
18
56
St. Augustine, FL
Ok I took everything apart, tons of brush dust inside and pretty much nothing left to armature contacts.
It's just a large groove! Taking it apart turned out to be not that big of a deal.
At this point I'm opened to suggestions on what can be used as a replacement. I think Pioneer had a very similar motor.
 

Attachments

Michiel

Member (SA)
Dec 29, 2012
209
41
28
Netherlands
Best is to find out if it turns clock wise or counter clockwise and order a 9v motor with the same specs. Most modern motors have a speed regulator pot in the back. It's a bit trail and error, replacing a motor.
 

toshik

Member (SA)
Mar 1, 2015
500
2
18
56
St. Augustine, FL
It's CW if looking at the pulley side. Rotation direction can be easily changed so it's a matter of correct RPM.
Was there certain logic behind RPM and rotation direction in trems whether the motor was used as drive-it-all motor, separate capstain or Rew/FF motors?
 

Michiel

Member (SA)
Dec 29, 2012
209
41
28
Netherlands
With modern motors with speed control it's not easy to change the rotation direction. If you change polarity it doesn't change direction. There is no logic between rotation direction and speed I'm aware of. Separate motors for capstan and rew/ff are very rare for boomboxes. The only ones I know of are the JVC 2 motor decks in boxes like M90 and PC5.

Best is to try a normal 9v CW motor and hope the mounting holes line up.
 

toshik

Member (SA)
Mar 1, 2015
500
2
18
56
St. Augustine, FL
Got a replacement motor - everything is fine, got the autostop separate issue fixed is well. Idler tire in this model is 22x17x2.5mm I could not find any recently available replacement for it.

If I remember physics correctly reversing one of 3 coils inside would make the motor spin in the opposite direction :-)
 

caution

Member (SA)
Mar 25, 2014
2,498
334
83
Boomboxery
Great work toshik, I don't know why, but I cringe at having to deal with a bum motor, but you softened the blow. Thanks.
 
Status
Not open for further replies.