AudioThrift
New Member
I have a Sony PS FL-7 linear tracking turntable and the platter doesn't seem to want to spin. I don't know a lot about schematics, as I'm still a total novice at this but I'm hoping someone can give me an idea of what might be preventing it from working.
I've had it apart a few times so far. I already changed the belt on the tonearm so that moves correctly now. I thought maybe it just didn't spin when the tonearm position sensor switch was down or it didn't read movement. But no dice there because that thing moves now and it didn't solve it... plus I saw a couple YT repair vids where the tonearm didn't move but the platter did. I thought possibly the ambient light was screwing with the sensors because I've seen that happen before so I put it all back together and tested it and I noticed something: When everything is back together, sometimes I can coax it to turn very slowly and weakly if I give it a little push and it will go until the slots pass the light sensors and it stops (so I know that part's working correctly, at least).
So, of course, I pulled at apart AGAIN and I pulled the whole board and motor assembly, covered the light sensors with my PG&E gas bill, and again was able to get it to spin really slowly but continuously (maybe 8-10 RPM at best)... after many many attempts to push it with my finger. There's also no dried grease; it's oiled and spins with very little resistance... just hardly any power.
I don't have an oscilloscope or benchtop power supply because I just can't afford them. The only tools I have are a multimeter, a component tester and a soldering setup... and of course, all the basics like screwdrivers and that crap. I'm beginning to suspect that it's the TA7256P chip but I don't base that on much. I desoldered a few of the caps and tested them on the component tester and they seem to be within tolerances. The tiny little delicate wire leads that attach to the coils also seem to have continuity and appear intact.
I did notice that when it's trying to run, I can measure only .0001v to .0005v fluctuating on one of the pairs of wire coils with my multimeter. I would think it should be more than that.
I don't want to just buy the TA7256P chip unless I'm confidant that's the problem just because I don't want to spend extra money I don't need to. That belt was ten bucks.
I'm sorry if I'm asking something really obvious but, again I don't have ANY idea what I'm doing. I appreciate your patience in advance and any help or pointers you guys can provide.
I've had it apart a few times so far. I already changed the belt on the tonearm so that moves correctly now. I thought maybe it just didn't spin when the tonearm position sensor switch was down or it didn't read movement. But no dice there because that thing moves now and it didn't solve it... plus I saw a couple YT repair vids where the tonearm didn't move but the platter did. I thought possibly the ambient light was screwing with the sensors because I've seen that happen before so I put it all back together and tested it and I noticed something: When everything is back together, sometimes I can coax it to turn very slowly and weakly if I give it a little push and it will go until the slots pass the light sensors and it stops (so I know that part's working correctly, at least).
So, of course, I pulled at apart AGAIN and I pulled the whole board and motor assembly, covered the light sensors with my PG&E gas bill, and again was able to get it to spin really slowly but continuously (maybe 8-10 RPM at best)... after many many attempts to push it with my finger. There's also no dried grease; it's oiled and spins with very little resistance... just hardly any power.
I don't have an oscilloscope or benchtop power supply because I just can't afford them. The only tools I have are a multimeter, a component tester and a soldering setup... and of course, all the basics like screwdrivers and that crap. I'm beginning to suspect that it's the TA7256P chip but I don't base that on much. I desoldered a few of the caps and tested them on the component tester and they seem to be within tolerances. The tiny little delicate wire leads that attach to the coils also seem to have continuity and appear intact.
I did notice that when it's trying to run, I can measure only .0001v to .0005v fluctuating on one of the pairs of wire coils with my multimeter. I would think it should be more than that.
I don't want to just buy the TA7256P chip unless I'm confidant that's the problem just because I don't want to spend extra money I don't need to. That belt was ten bucks.
I'm sorry if I'm asking something really obvious but, again I don't have ANY idea what I'm doing. I appreciate your patience in advance and any help or pointers you guys can provide.