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
My own TT101 turned out to have a tiny crack in one of the PCBs which was finally diagnosed only after what had been an intermittent problem became a constant problem, enabling JP Jones of Fidelis Analog to sniff it out and repair it.  But the defect in function of my TT101 was not like that reported here.  Mine would come up to speed for a minute or two, then exhibit inaccurate speed for about 30 seconds, then crash.  This problem came and went at first (the definition of "intermittent"), moving the turntable to various parts of my house would either cure or cause the problem, probably because moving the turntable was causing the PCB to flex where it was cracked, causing a short to come and go.  JP tells me that he has since serviced other TT101s, and cracks in the PCB are not uncommon.  

My TT101 and I have been happy together for about 2 years now.  I use it regularly in rotation with 3 other turntables in two systems.

@gary7
 
My TT-101 has started having same issues with the stop button.


Knock on wood, perhaps the resident expert will comment.
I think JP would agree that the most likely story is that the crack was there since it left the factory or that the PCB swells and contracts with changes in humidity, thus rendering it susceptible to cracking at areas were expansion and contraction are constrained by the many fasteners that hold the boards in position.  The latter hypothesis is consistent with my observation that it behaved differently (prior to repair) when it sat in our kitchen or a repair shop vs when it was set up in my basement audio system, where temperature is cool and air is moist.

My own TT101 came to me as part of a QL10 (TT101 chassis + plinth + UA7045 tonearm).  The whole thing was "like new" when I bought it, possibly suggesting that it had had a problem from new.  I purchased it very cheaply, described by the seller as "broken", on faith that I could fix it or find someone else to fix it.
@lewm  I have read a lot in the world of the problems that happen to this turntable and I have to note that all problems are the same and similar; maybe you were unlucky with the break of the pcb and I have not read of other cases equal to yours but never other turntables like this have had a lot of problems like the TT-101.
Turntable that sounds good (when it works) but so delicate too delicate and problematic ... it is easy to understand it by reading the defects that happen.