Motor always on?

lazol

Member (SA)
Oct 24, 2018
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8
Hi everyone, I have a Sanyo 9994k, i was wondering if it's normal that as soon as the power is turned on, the capstan is turning even if the selector is on 'radio' and no deck button is depressed. In other words the motor is always on.
Thanks!
 

dubout

Member (SA)
Nov 19, 2020
205
68
28
Germany
Are the belts OK? Sometimes the tape deck gets stuck in the play position which causes the motor to spin all the time. When the belts snap while playing for example. Open the tape door, try to turn the tape wheel(s) and see if you can push the mechanism into it's stop position.
 
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lazol

Member (SA)
Oct 24, 2018
50
4
8
Thanks for your answers. The deck is working fine, so i think that a leaf switch may be stuck.
I just wanted to make sure that the deck wasn't designed to stay 'on' all the time. While this doesn't really make sense for a portable, i've read that several high-end decks of that time are actually working that way, and this boombox is supposed to be a 'professional' one.
I didn't want to take it apart for no reason, but now i will, and check both belts and switches. I'll post back my finding:)
 

lazol

Member (SA)
Oct 24, 2018
50
4
8
I had a look tonight at the switches and the belts but i couldn't find anything wrong.
The motor of this model is quite weird... It doesn't have the usual +/- cables only. It also have two other cables connecting it to a leaf switch AND 3 more cables connected to a stand alone transistor..Capture+_2021-05-17-22-56-48~2(1).png. Basically there's a total of seven cables going into the motor assembly!! Never saw anything like this before...
Anyway, I found the schematic online, and now i'm wondering about that 'remote' that i circled in red on the picture. Does anybody know what is it?
 

dubout

Member (SA)
Nov 19, 2020
205
68
28
Germany
I have read about another model with this 'problem'. The quick fix was to insert a plug into the remote and / or (?) the microphone sockets. I haven't tested it but it might at least help you finding the error.
 

lazol

Member (SA)
Oct 24, 2018
50
4
8
I have read about another model with this 'problem'. The quick fix was to insert a plug into the remote and / or (?) the microphone sockets. I haven't tested it but it might at least help you finding the error.
Thanks for your suggestion, unfortunately it didn't work.
I've noticed the resistor marked in red was open, i replaced it with an identical one, and it burned again!!
It's a really weird problem, last time i put the boombox on the shelf it was working fine... What could have happened in the meantime when not in use?Capture+_2021-05-17-22-56-48~2(1).png
 

lazol

Member (SA)
Oct 24, 2018
50
4
8
I spent quite a bit of time on the Sanyo today, but i couldn't find the issue.
Dubout's patch solution actually did work, it was just a matter of finding something that fit snugly in the "remote" hole.
Other than that i had to remove the resistor i mentioned, because it kept smoking off every time I replaced it, no matter if the plug was on or off.
Now the box is working fine, i just have to remove the plug when i play a cassette.
Thanks a lot to dubout for the great suggestion and to everyone who tried to help!!
 
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Radio raheem

Member (SA)
May 13, 2009
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uk
this boombox may have been worked on before and the motor power may have been soldered to a different place to get power

i have had boxes like this before,,,,,there are some high end decks like this, personally i don't like the idea....anyway good luck
 

dubout

Member (SA)
Nov 19, 2020
205
68
28
Germany
That you didn't locate the reason for the error is a bummer but I am happy that you have the box at least running again!
 

docs

Member (SA)
Jun 26, 2010
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Check cap C712, C713, C792 and the switches S761, S771 for continuity across the leads when off and on.
Tested on both AC and DC?
Are the other 1W resistors in spec?
Don't discount the motor itself, try disconnect the motor and see if that resistor burns out again.
My guess would be C792 since you put a jack in the remote which could be providing the route to ground if C792 isn't.
 
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lazol

Member (SA)
Oct 24, 2018
50
4
8
Thanks for all your inputs, i had an extra (deep) look at the schematic today and i ended up with the the belief that the problem must be the main power switch.
I checked all the components involved, they all seems fine, and this is the only logical solution after the exclusion process.
Basically when the switch is in the 'off' position it's working fine, but when it's in the 'on' position it engages both the 'on' and 'off' positions together, for some reason.
This would explain both the motor 'always on' issue and the over-current passing through the resistor.
Also, the power button is not a regular on/off switch, the 'off' position says "off/sleep"...thus confirming my suspects.
I won't try fixing the power button, maybe if i find a part box i will attempt the repair later:)
I'm leaving here the schematics from the service manual for your comments, in case you think i may be wrong, and for future reference.Capture+_2021-05-20-10-27-49~3.pngCapture+_2021-05-20-23-17-22(1).png
 
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zarman11

New Member
Apr 4, 2024
4
0
1
Toronto
Bringing back from the dead. My power switch on the GF 868 isn't working. It's stuck on ON and doesn't shut off. I dont know if its causing the cassette motor to always run but the left side tape capstan motor is always on. And it's causing this clicking noise.
I can pause the tape and it wont do that. It will play as normal. So I wonder if the power switch is causing this? Any idea?