It seems that their might be a vinyl revival happening, at least that is one of the topics on Australia Wide, ABC on Friday.
A friend brought over a Technics SL-Q3 automatic quartz direct drive turntable that she recently acquired. It seems that after getting it home, only the left channel was producing sound. After the customary swapping of RCA cables, it was still only the left channel. I suggested removing the head shell, and putting back in, but somehow the communications got crossed and she removed the screws holding the cartridge to the head shell – no matter, just fasten it again – but apparently it was not possible – which was part of the reason the turntable was brought to me.
On inspection, it was quite obvious – the cartridge is a moving magnet type of phono cartridge so the nuts that the screws connect to, basically moved in towards the magnet. I used tweezers to pull the nuts back out, then fastened the cartridge. I showed her how to remove the head shell, and put it back on – ok. Next I connected up my phono pre-amp and then connected the output to a pair of amplified computer speakers. Sure enough, there was no sound coming from the right channel.
After a bit of troubleshooting, measuring the cartridge outputs, and getting 400 ohms on the left channel, and 386 ohms on the right channel, I conclude that the RCA cable was at fault. I turned the turntable upside down on its lid, after locking the tonearm. The base was easily removed by unscrewing the four spring loaded feet.
The view of the insides of the turntable was quite interesting, there was a loose wire loop sitting on the circuit board – obviously, that isn’t right. It seems to be connected to the repeat or memo slide button – but where should it go. After a brief search of the internet I located a photo of this turntable with the wire loop intact. From this I was able to loop the wire first around a drum, then the other end also around the drum in the opposite direction and finally around two little pulleys.
That looks more like it. Then remove a metal shield and so the RCA output cable connections were accessible. I was able to measure continuity from the RCA cables – left inner, left outer and right outer. Right inner – the red wire was not connecting at all – so it seems that the red RCA cable had failed. At the same time, I decided to check continuity from the cartridge to this connection board – the red wire wasn’t connecting – strange, anyway – sort this out after replacing the RCA cables.
The next morning, I located a new RCA cable in my assorted cables box, then cut and arranged the ends so that i could solder them onto the board after removing the old cables. The above photo is a shot of the connections after the new cable was soldered. The little piece of sticky tape is just to provide a little insulation before the metal shield is screwed back on. I checked the cartridge at that point and I was seeing both channels ok – weird. So it looks like I have “repaired.it“. I played a few LP’s to check that it was working and it was.
Today I thought I might check it again as my friend still hasn’t come over to pick it up. When I powered up, I was getting a loud hum from one speaker – it would reduce if I connected the ground wire to the pre-amp output ground, but would not disappear. I switched left and right inputs and the hum swapped speakers – ok. Unplug the input cables and measure the resistance – right channel ok, left channel not ok – what gives. I unscrewed the head shell and plugged it back in a couple of times, now I get no hum. It seems that the spring loaded contacts in the socket of the tonearm may be the problem. This can happen if the spring in one contact is particularly weak or some debris is in the sliding surface that might cause it to jam. This was probably what happened with the red wire previously except now it was the white wire. Anyway the fix is to unscrew the head shell, then push it in and out of the socket a few times to give the springs a bit of push, then release, etc. Now all is well and I played my favourite LP – Solitude Standing by Suzanne Vega.
P.S. The dust cover or lid of this turntable has broken off at the hinges. Also it was very cloudy, i.e. not transparent. It would require replacement so the hinges were removed.
I thought I would give it a try of using Maguiar’s Plastx plastic polish to see if I could brighten it up, and after working on one corner, I could definitely see the difference. Anyway, I can’t do all the work, she should do some in her spare time – it will need a lot of time to polish up but the fine scratches will still be there unless we do a thorough sanding down and then polishing.
Can you see which corner I worked on and see the difference now?