Sharp VZ-3000 upright both sides play linear tracking system

OK so here's a thread revival. After selling this unit on for a LOT less than I paid for it, it may be coming back to me in the same state it was sold in !

The new owner emailed me, said he never got to finishing the rebuild and would I like to buy it back from him. I said OK, for the original sale price. He had traced the fault to the EQ board so I may be in with a shot at finally getting the thing going again !
 
Well after a further email, it looks like I'm getting it back next week.

Now I'm more comfortable with soldering etc, I'm planning on fully rebuilding most of the boards, especially the power, EQ and amp sections. Probably at least recap the turntable board too.

Gonna take my time with it, medium term project.....
 
Good stuff! I will stay tuned.
I have fixed my original issues however as part of that I damaged something on the EQ board myself. Had to put mine into storage for a few weeks while moving house.
 
Ok so here I am with another update on this saga.

First up, do not EVER assume an IC is bad without checking all other components ! I recapped the power amp board and replaced the STK463 because I thought it was bad. The results were, well, not what I hoped for. The recap had made an obvious improvement because the DC was way down on the outputs BUT - the right channel was very quiet and distorted badly with increasing volume. After checking all the components of the power amp again, I decided to try dropping in the old STK463 again. As soon as I did that, both channels were back and going great !

Next up, I checked all functions of the EQ board, cassette deck and level meters and they all looked and sounded good. One thing that had been bugging me, however, was the odd sized capacitors on the power supply board. Reluctantly, I pulled the power supply out again and replaced the main power caps and filter caps. I also re-soldered the power switch was had cracking solder joints and was arcing quite badly !

I then moved on to the record player and tried to work out why the cartridge / door motor was running constantly. During this exploration, I switched on the unit only to be greeted by a big flash and a plume of smoke from somewhere near the main power switch. I turned out not to be as bad as I thought - what happened was the power switch was still not fully soldered down to the board and had arced again - this time burning a little bit of the PCB coating away, hence the smoke. I was relieved that I hadn't fried any components.

So right now, I have two things to do. One is to properly address the power switch issue and the other is to repair or replace the faulty 'player door open' microswitch. This switch is telling the player CPU that the door is open all the time (it never sends a low signal to the relevant CPU pin) hence why the motor is running all the time trying to close the door........

I'll be back with more updates soon.
 
Man, the more I dig into this thing, the more problems I find ! I resoldered (again) the power switch but I did it a bit better this time. Rather than reflowing the existing solder, I removed it completely. When I did this, I found the pad had lifted away from the PCB so I scraped away some coating to reveal more PCB surface and then resoldered onto the newly exposed area. This seemed to work well and the switch is solid again.

As it turned out, the door open switch is not the only problem with the record player - the 'rest position detection' switch is also broken. This means that the CPU thinks the door is open as well as closed and it also thinks the tone arms are never at rest. I'm not surprised the player doesn't work !

I've ordered a replacement belt kit from a seller in Australia and a pack of compatible micro leaf switches from a seller in Hong Kong. Hopefully once these parts arrive I will have had time to recap the player PCB too :)

I'm going to work on the speakers soon - they need new foam for the woofers and I may take a look at the crossovers to see if they need new caps.
 
The pack of switches arrived yesterday, as did the belt kit. Pretty impressive that parts from Australia and Hong Kong took a mere 5 working days to get to NZ.

Got the belts fitted, switches later today.
 
Broken switches now replaced and we have record playback, albeit on side B only at the moment. Watching the player door swing open under its own steam for the first time was a rewarding experience ! I think I have a problem with voltages from the photointerrupter on the side A tonearm now - from what I can see, the voltage is always 'low', so the drive motor never advances the arm. I need to track that down now - hopefully the interrupter is OK an it's a problem with a resistor or diode somewhere.....
 
Seems the issue is - when the unit is powered, the side B tone arm solenoid circuit is switched on which (I think) knocks out the side A tone arm angle sensor. This kind of makes sense, because the tone arms are linked - so when one is moving, you wouldn't want angle sensing for both of them going on. I now need to wortk out why the side B solenoid is energised as soon as the unit is powered up.....
 
I think I've found the source of the problem - the transistor used to switch side B (Q524) seems to be shorted so, as soon as power is applied to the unit, it switches on and attracts the side B solenoid. This also then knocks out the side A tonearm angle sensing and therefore no drive for side A playback.

I've found a replacement transistor so I'll be back with an update once that is installed.....
 
Replacing that transistor has resolved all the weird problems ! The side B solenoid is no longer energised when the unit powers up (which, coincidentally, I found was putting a big strain on the main power switch) and the side A tonearm motion is not being cut off. I found another issue with playback though - a Fujitsu 221D012 relay which switches A/ B channels had gone bad and was giving very muted audio. I was lucky to be able to find one in the US, so I got it sent over and fitted it yesterday - playback now sounds great.
 
My next job is to reassemble the unit and finish the speakers. The woofers in the Sharp speakers we too far gone to re-foam so I opted to transfer the drivers and crossovers from a spare set of Infinity Reference 10's I had lying around. The cabinets are similar in size, although the Sharp is ported and the Infinity is not. I need to mod the Sharp cabinets to take the Polycell tweeters but the woofers are a straight swap. I also need to cut holes in the back to accommodate the crossover / binding post units.
 
Due to having infrared sensors for disk loading, I have discovered this machine does not play coloured or transparent records. No biggie though.
 
I discovered a further problem after partially reassembling this unit - as you can see in the pictures above, the tape level meters are partly active even though no tape is playing. I found this very annoying. Also, I found there was a problem with random noise coming through the speakers when no source was playing - it sounded like someone blowing into a microphone or rubbing their finger across a stylus. I figured that this phantom noise must be the reason why the tape level meters were active. Through a process of elimination (otherwise known as unplugging lots of stuff), I found that the level meters settled down when the erase head was unplugged from the tape deck control board. This also seemed to remove the scratching / blowing sound I was getting so I can only assume that the erase head was somehow introducing feedback into the audio path somewhere.

I have assembled the unit again now and I'm working on finishing the speaker modifications next.
 
I will post a lengthier reply tomorrow but basically, I sold the Sharp as 90% complete with just the speakers to finish. Once I ironed out all the gremlins, I realised it was the faults that I enjoyed fixing but the unit itself was just surplus to my needs right now. It went to a good home for a decent amount of coin :)
 
Is this thread now closed as i'm doing one up and A side light isn't working is it a diode as i don't know the correct name?
 
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