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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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29th Jun 2021, 11:31 pm | #1 |
Diode
Join Date: Jun 2021
Location: Sheffield, South Yorkshire, UK.
Posts: 4
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Sharp VZ 3000 cartridge motor
Hey everyone. Tbh never joined as always found answers fairly quickly. Have worked on a fair number and variety of equipment, but this has me stumped.
When first tested the cartridge motor spun but barely moved the door. Not sure about the tonearm. Belt was cracked and loose, and main belt had almost dissolved. Cleaned it all off and replaced the belts. Turntable now starts and stops in both directions, but the cartridge motor will not activate, either open or close the door or move the tone arm. Have spent a few evenings on it and just cannot work it out. Pin 2 of the microcomputer will put out high and low signals. The motor does spin - tested with a 3v supply and it's fine. I did blow r701 but replaced and voltages there seem fine. However I'm only getting about 1v on junctions between q501 and q504, and q502 and q506 in the control circuit. I think it may be a switch or sensor issue, but regardless of what I try I just cannot get it to work. Any solutions, or even suggestions of things to take a look at would be greatly appreciated |
1st Jul 2021, 7:52 pm | #2 |
Heptode
Join Date: Nov 2008
Location: North Walsham, Norfolk, UK.
Posts: 899
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Re: Sharp VZ 3000 cartridge motor
Had one that wouldn't switch to low speed after the arm dropped, it was the logic chip between the motor and CPU IC51 (4011 quad nand gate) had 1 gate stuck might be worth a look. Also read the manual carefully and check all the different criteria that make it work it's really good, wish they made manuals like that these days. They are fiendish machines to look at first but approach it logically and they are really easy to fault find on. I have done probably hundreds of these over the years and had them sent to me from all over the country for attention.
Good luck with it
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1st Jul 2021, 10:31 pm | #3 |
Diode
Join Date: Jun 2021
Location: Sheffield, South Yorkshire, UK.
Posts: 4
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Re: Sharp VZ 3000 cartridge motor
First of all, thank you. Any suggestions are very much appreciated.
Have studied the manual and think I checked that IC, but as it wasn't mentioned in the cartridge motor section I guess I just overlooked it. Pins 1, 3 and 8 are all measuring 5.27v, regardless of the position of the various switches. Service manual schematic quotes 10v for pin 1 and 0.5v for 3&8. Re-checked with the adjustment of the door in relation to the switches. Would your guess be a faulty chip? Believe I have one laying around so may try and swap out tomorrow. Thanks again for the advice |
2nd Jul 2021, 11:01 am | #4 |
Nonode
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,814
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Re: Sharp VZ 3000 cartridge motor
Another thing to look at is dry bearings on the motor, I had a VZ3500 that the turntable motor wouldn’t run on when I’d changed the belts, with no belt fitted the motor ran fine, but as soon as it was loaded by the belt it would give up, I put a tiny drop of clock oil on the spindle just where it enters the motor and it’s been running fine ever since.
Regards Lloyd |
2nd Jul 2021, 5:15 pm | #5 |
Diode
Join Date: Jun 2021
Location: Sheffield, South Yorkshire, UK.
Posts: 4
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Thanks for the advice. Though even with the belt removed the motor won't spin. And even 3v applied across the motor connection directly is enough to open and close the door.
On another note I replaced ic51 and pins 1, 3 and 8 all display the same voltage as before. Anyone have any other ideas? Am going over the service manual and at a loss as to what to check Also, with the motor disconnected I'm getting roughly 1v across the supply pins cnp501. This will show -1v when I select side b. Obviously not enough to drive the motor and a lot less than expected when operating correctly |
4th Jul 2021, 11:42 am | #6 |
Diode
Join Date: Jul 2021
Location: Worcester, West Midlands, UK.
Posts: 1
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Re: Sharp VZ 3000 cartridge motor
Hi, Just joined up as I'm in the same (or very similar) boat to you, the door/cartridge motor not moving on my VZ3000.
CNP501 reading around 0.5v - seems constant. Motor tested with 3v and working fine. If i trick it into thinking the door is shut with a record in, the solenoids clunk reassuringly and the deck spins, so everything around it looks alright. Just gotta figure out what's gone wrong. You seem much better at this stuff than me, so would appreciate if you get anywhere dropping it into the forum so I know where to go next. I do have a decent meter and solder station, but am a bit of a newbie so any tips gratefully received! Thanks! Chris |
4th Jul 2021, 11:20 pm | #7 |
Diode
Join Date: Jun 2021
Location: Sheffield, South Yorkshire, UK.
Posts: 4
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Re: Sharp VZ 3000 cartridge motor
Hi Chris.
Yeah, sounds like the same issue. I'm no expert - wish I was! Worked on a fair few players, as well as a couple of reel to reels, but my main experience and knowledge is from building, modding and repairing guitar amps and effects. Relatively simple circuits by comparison, and the number of sensors, switches and solenoids on this thing have thrown me. Are you getting similar voltages? I'm experiencing around ic51, and the 1v on the emitters of q501 and 502? Schematic quotes 11v |