Phillips GA 312 very weird speed/stop sensors behaviour that fixed by itself

[JohnnyBoy743]

Hello guys, so recently i bought a Philips ga 312 from a very responsible seller here where i live. (He even made a vídeo showing that turntable was in proper shape and everything was working)

Today it arrived in Mail, i took it of the package and adjusted voltage selector under plate, and straight mounted it into system, but first times i turned it on it was stuck on 33rpm and The 'touch' buttons doesn't answer properly or right (even The green lights seemed a little dimmed, as can be observed in video below. Also, it was only switching directly from 33 to 45, The stop button/sensor would flash and light up very dimmed, but unable to do anything.

After some minutes plugged and turned on and messing around clicking the buttons , i made it slowly start to work properly by itself, now it seems to be working fine, all buttons and auto stop mechanism seems functional.

Someone has a clue of what happened to this funny contact buttons? Does the shipping transportation messed up with it someway? Should i be worried?

Link to before and after videos: https://imgur.com/a/yeKra88

Thanks in advance!

 

[sregor]

My theory would be there was something conductive across the touch sensors. We used to see problems like that when cleaning with windex, and it wasn't completely dry.

 

[Fritz411]

I owned a 312 for a long time and found that I sometimes needed to moisten my finger before touching the buttons, especially in the dry winters. Science, or something...

 

[JohnnyBoy743]

Update: Today, after 4 days the little problem reapeared again, it was with stop bulb (or led, since it has a slightly different color that the rotations ones) activated, but the platter was moving, and it refused to stop, even after turning on and off. After like, 3 minutes, it started working good again by itself. I noticed a weird sound "like a hd starting to rotate" when this happened, it showed a tendency to light up the 33 rpm bulb during this event, and stop light refused to light up during this, unless i stay with my finger on it. Poltergeist activity maybe? Someone has a clue where to start if needed to service it? Here are the video of the problem and the magic solution by itself

https://imgur.com/a/bTetZr8

 

[gslikker]

No idea, but it looks the stop button light is extremely bright on the video. The lamp current in this unit influences the tough control (does not work if lamps are not in).
The auto stop seems to use 6V (6.3) 100mA lamps, the 33 and 45 button use 50 mA lamps.

So make sure the lamps are the right ones and make good contact.

I am not into turntables but I know there is enough info to guide you on the internet, if you look for the 212 instead of 312.

 

[ramjet]

The service manual can be downloaded from here https://www.vinylengine.com/library/philips/ga-312.shtml, you must be a member (free sign up). Two things come to mind, first, as gslikker has pointed out, there are two types of lamps used in the early GA 312, later units used LED's. The difference in illumination of the switches on your turntable is interesting, to say the least. Second, all electronic functions are dependent on the power supply voltage of -10vdc being correct.