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JVC TT-101 Won't Stop

The Stop button on my recently purchased QL-10 doesn't work. It worked at first after the TT warmed up, but then quit completely. I since have replaced all 37 electrolytic caps on 3 boards, but it made no difference. The power voltages are correct. The button itself is fine and shorts pins 6 and 9 of the P8 connector on the main board, but the motor doesn't stop. What could be wrong? Any particular transistor or adjustment? Please help! -Alex
safesphere
65 responses Add your response
best-groove's avatar
best-groove
842 posts
 
@gary7 what is SM? You have also replaced cables?  I notice that some seem new or fairly recent.


I would like to delete all the wiew wrap contacts and connect pins with contacts to detach; this would facilitate further maintenance by excluding all the tangle of cables.
gary7's avatar
gary7
73 posts
 
Sorry, SM stands for service manual, as OM is for owners manual. I did not replace any cables. vinylengine.com is a great resource for turntable info and manuals.
gary7's avatar
gary7
73 posts
 
Been a month and still runs & stops as it should. Yea.
best-groove's avatar
best-groove
842 posts
 

yippee ki yay
gibsonian
71 posts
 
Wouldn't it be a great thing to use the TT-101 schematic and build new PCB's that we could transfer the hard to find IC's to and then populate the rest with all new components, then place this new circuit in it's own box and connect with an umbilical cord to the motor, like the big Technics?


lewm
12,868 posts
 
It'd be great but you'd want to shoot yourself before you finished.  There would be many pitfalls.  Some of these circuits are affected by lead length, just to begin with. Also, it is a trick to get a multiple pin IC off a PCB and then successfully transplant it to a second PCB and have it work.  Plus, you'd have to have the new PCBs made in advance, of course.  It would be a heroic effort, either way.
gibsonian
71 posts
 
Yes you would need someone with enough knowledge to design PCB properly but the making of them is easy once designcompleted, and not so expensive. 

R&R of the IC's I agree is not easy and not without risk.  Acquiring a supply of these would make this a go for me.  Calibration, service would be much simplified and these beasts would survive much longer this way.
best-groove's avatar
best-groove
842 posts
 
Some of these circuits are affected by lead length, just to begin with.


are you sure of 100% of what you say?
best-groove's avatar
best-groove
842 posts
 
It would be a heroic effort, either way.


surely; but once the master is done the road is all downhill
lewm
12,868 posts
 
bestie, I have no idea whether or not the particular circuit and ICs of the TT101 would be affected by lead length, but I am certain that some such circuits, using very wide bandwidth SS devices operating at high speed, are so affected. JP probably can answer your question specifically.
gibsonian
71 posts
 
I'm game if there would be enough interest in such an endeavor.    We'd need a guru however. 
gibsonian
71 posts
 
Obviously circuit design and conductor geometry would have to be considered. 
best-groove's avatar
best-groove
842 posts
 
conductor geometry
it would be sufficient to replicate the awg of the internal cables, I see no difficulty because they do not have shielding.

As regards the pcb I see that lately an ebayer sells the originals for Technics sp 10MK2 at prices between 350/450 €
Those who could replicate these or those of the TT-101 could do a good business by selling them at less cost.
gibsonian
71 posts
 
With a group buy I am sure we could get them for less than $50 each.  We would need someone to create the Gerber files for quote.
best-groove's avatar
best-groove
842 posts
 
 @gibsoniana

great who knows how to do it, unfortunately it's not my job.
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