Thornblade
New Member
Hy guys,
I got hold of a Sanyo M9998 LU recently, from my country's ebay knock-off site. It is the European version with long wave and fine tuning extra knob, made in Japan (some of them were made in Spain also).
I cannot figure out for the life of me the motor speed adjustment. It is running just a biiit slower than my deck, and also when listening to the same music on commercial tapes compared to youtube it's a bit slower.
There is no goddamn potentiometer for speed adjustment in the diagram or on the physical board.
I have dismantled the motor, there is no speed adjustment pot inside its case.
The motor is fed straight from a speed stabilizer transistor (i guess). There is a 1000 uf cap in parallel with the motor and from the emitter of the transistor to the motor there is also a coil.
The motor spins a huge flywheel via a belt which in turn is connected to 2 other belts.
But that's about it.
Does anyone have any experience with such a playback scheme? some other systems of the kind maybe?
Any help would be appreciated.
Thanks a lot in advance!
Some other stuff which might help others trying to service it:
While the radio is working just fine (i was surprised by the AM audio quality in particular), the cassette player part was a mess.
There was a problem with mains hum, I've replaced the two 3300 uf capacitors that it had with two 4700 caps, no big difference... then I added another two 10 000 uf caps in parallel, again nothing.... then I put on the mains line in a filter (the coil capacitor combo stuff), nothing. I replaced the rectifying diodes, no difference.
Then I added one 6800 uf cap next to the diodes (this unit has a really long path from the diodes board to the main board where the filter caps are), that made a huge difference. Then connected the 2 10 000 caps previously installed to the diodes output, hum was greatly reduced, almost zero.
But when I assembled the case some low volume hum (never changing intensity) was still present in the right speaker. After much trial and error I managed to find out that it was due to the speaker out wires being right next to the transformer in ac wires... and that was not my mistake, they were routed like that from factory... jesus... In the end I put the right speaker wires some 10 cm away and now that buzz is almost down to zero, you can hear it only with your ears next to the speaker (left speaker has zero hum/buzz)
Now for the mechanical part:
First, all three belts were melted down to goo. I managed to replace those with some improvised stuff, and to my surprise they work nice... it's been a few weeks of listening now and they still hold. Then after a few days the plastic bits that actually spin the cassette cracked and just fell off. They were made of some plastic that just turned all soft, didn't make it all those decades. Okay, i managed to improvise something for those too, and it was a huge headache but now the tape is spinning normally again.
I don't see any noticeable wow/flutter, the AMSS function is working like it's supposed to. Dolby circuit still okay, the head also is fine.
I got hold of a Sanyo M9998 LU recently, from my country's ebay knock-off site. It is the European version with long wave and fine tuning extra knob, made in Japan (some of them were made in Spain also).
I cannot figure out for the life of me the motor speed adjustment. It is running just a biiit slower than my deck, and also when listening to the same music on commercial tapes compared to youtube it's a bit slower.
There is no goddamn potentiometer for speed adjustment in the diagram or on the physical board.
I have dismantled the motor, there is no speed adjustment pot inside its case.
The motor is fed straight from a speed stabilizer transistor (i guess). There is a 1000 uf cap in parallel with the motor and from the emitter of the transistor to the motor there is also a coil.
The motor spins a huge flywheel via a belt which in turn is connected to 2 other belts.
But that's about it.
Does anyone have any experience with such a playback scheme? some other systems of the kind maybe?
Any help would be appreciated.
Thanks a lot in advance!
Some other stuff which might help others trying to service it:
While the radio is working just fine (i was surprised by the AM audio quality in particular), the cassette player part was a mess.
There was a problem with mains hum, I've replaced the two 3300 uf capacitors that it had with two 4700 caps, no big difference... then I added another two 10 000 uf caps in parallel, again nothing.... then I put on the mains line in a filter (the coil capacitor combo stuff), nothing. I replaced the rectifying diodes, no difference.
Then I added one 6800 uf cap next to the diodes (this unit has a really long path from the diodes board to the main board where the filter caps are), that made a huge difference. Then connected the 2 10 000 caps previously installed to the diodes output, hum was greatly reduced, almost zero.
But when I assembled the case some low volume hum (never changing intensity) was still present in the right speaker. After much trial and error I managed to find out that it was due to the speaker out wires being right next to the transformer in ac wires... and that was not my mistake, they were routed like that from factory... jesus... In the end I put the right speaker wires some 10 cm away and now that buzz is almost down to zero, you can hear it only with your ears next to the speaker (left speaker has zero hum/buzz)
Now for the mechanical part:
First, all three belts were melted down to goo. I managed to replace those with some improvised stuff, and to my surprise they work nice... it's been a few weeks of listening now and they still hold. Then after a few days the plastic bits that actually spin the cassette cracked and just fell off. They were made of some plastic that just turned all soft, didn't make it all those decades. Okay, i managed to improvise something for those too, and it was a huge headache but now the tape is spinning normally again.
I don't see any noticeable wow/flutter, the AMSS function is working like it's supposed to. Dolby circuit still okay, the head also is fine.
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