Philips 312: Table starts when I press start, but stops when I take finger off

Raccoon1400

Super Member
I have a Philips 312 table here. It starts as it should when I press the 33 or 45 rpm start buttons, but it stops again as soon as I take my finger off the button. What could cause this? It uses those touch sensors, as opposed to actual buttons.
 
Yeah, 212's and 312's have that happening. I think it has to do with bulbs (which are funny values), but I will let those better versed in these give an actual answer.
In the meantime, I know a guy that has one with the same affliction and he solves it by laying a dime on top of the the 33 or 45 button. I can't say if it would kill it the rest of the way or not...but he didn't mention flames...
 
+1 on the bulbs. We used to see a lot with generic (#47?? maybe) bulbs and that causes the circuit to malfunction. Need to get the correct bulbs. Search the forums - some people have posted second sources for good bulbs.
 
+1 on the bulbs. We used to see a lot with generic (#47?? maybe) bulbs and that causes the circuit to malfunction. Need to get the correct bulbs. Search the forums - some people have posted second sources for good bulbs.
The bulbs do light up though? At least when my finger is on the button.
 
The bulbs do light up though? At least when my finger is on the button.
The bulb is part of the transistor flip flop that holds it on. The bulbs are 50 mA (33, 45) or 100 mA (stop) 6 Volts. If they are higher current like normal bulbs, they don't work right. There also is problems if the shut off bulb is dead.
 
racoon
If interested in a set of proper lamps PM me. At one time I ordered the correct ones from England, and I know I still have some in the shop. I have not found any 212/312 tables to restore in a long time.
jim
 
How could the bulbs be the issue if they aren't burnt out? And they do appear to be original.

What transistors make up the flip flop? Maybe I should look at those. Edit: I see them now. BC558B. Two per speed.
 
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2 more "recollections" if the stop bulb is out or stop circuit problem, then there are similar symptoms. The early 312 used a lamp and photocell (I think)
Also, if you cleaned it, the cleaner residue causes funny problems, but I think that it tends to stick on one speed.
 
2 more "recollections" if the stop bulb is out or stop circuit problem, then there are similar symptoms. The early 312 used a lamp and photocell (I think)
Also, if you cleaned it, the cleaner residue causes funny problems, but I think that it tends to stick on one speed.
Well, the stop bulbs appears to be out.

I have another one of these tables that I never quite got working mechanically, but the electrical part works. The stop bulb doesn't actually seem to turn on though?

I could always use LEDs and use a parallel resistor as well as a series resistor to make the current and voltage the same, right? I've done this in other units where the right bulb was needed for the unit to function.
 
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ok, you forced me to look at the schematic. Check the voltages around the 2 stop transistors - ts428 and ts436. The collectors should be at 5.6 volts. Either one stops the circuit by pulling the voltage low, which turns off the 33 and 45 flip flops.436 is the manual stop and 428 is the auto shut off. If they are ok, go back to checking the flip flops. For reference - the original 33 and 45 lamps were 6.0 volts at 44 Ma. Later were 50 mA. There are higher current rated lamps that fit and use 6.3 volts, but they mess up the logic.
 
ok, you forced me to look at the schematic. Check the voltages around the 2 stop transistors - ts428 and ts436. The collectors should be at 5.6 volts. Either one stops the circuit by pulling the voltage low, which turns off the 33 and 45 flip flops.436 is the manual stop and 428 is the auto shut off. If they are ok, go back to checking the flip flops. For reference - the original 33 and 45 lamps were 6.0 volts at 44 Ma. Later were 50 mA. There are higher current rated lamps that fit and use 6.3 volts, but they mess up the logic.
Correction: It is a Philips 212. My bad.
 
So I pulled TS434 (looking at the correct 212 schematic now!) and tested it with the meter and it tested good I soldered it back in and now it works!
 
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