Philips GA 212: Suddenly Starts Playing too Fast

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Extra Fox

Philips GA 212: Suddenly Starts Playing too Fast

Post by Extra Fox » 24 Nov 2019 04:55

Short Version
I need help diagnosing why my Philips GA 212 starts playing really fast after playing normally for a while.

Long Version
My father recently gave me his old GA 212 and a bunch of records he had acquired in his younger years. He told me that he quit using the player because the speed control quit working and it played too fast.

Apart from the original belt having turned to goo nothing seemed terribly wrong with it. All the lights worked and after cleaning off the old belt and replacing it with a new one it seemed to work. It functioned well enough, I could even adjust the speed, and it sounded decent.

Then after sampling a few of the albums, seemingly out of nowhere it started playing really fast. Stopping and restarting did nothing. I could even power it down and resume and it didn't make a difference.

So I disconnected it and brought it back to my work bench to have a look at the circuit board. I know just a small bit about circuitry so I was really just looking for anything obviously blown or bulging menacingly. Nothing looked bad so I put it back together and tried it again.

I did catch a piece of advice here that suggested the 45 RPM had to be adjusted before the 33 RPM. So I tinkered a bit there despite not having a 45 to test with and, unexpectedly, it worked great. I played two sides of the Allman Brother's Eat a Peach album, but upon changing to the third side it started speeding out of control again.

I looked at the wiring schematic around the speed control area, but I'm fairly well out of my depth there. So right now my theory is that something is happening over time while it's powered on that's causing it to lose the ability to regulate the speed. Perhaps a trimmer or another resistor is shorting out at a certain temperature?

Any advice would be very much appreciated. I'm dying to hear some more of these albums.

Ramjet
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Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by Ramjet » 25 Nov 2019 19:37

Always suspect electrolytic capacitor failure in electronics this old. Many times it is easier just to replace them all than spending time troubleshooting. I have a GA 312 of the same vintage and use it everyday, great machines.

lenjack
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Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by lenjack » 25 Nov 2019 20:24

Does it have an external speed adjustment speed adjust? Manual shows knob G, as speed adjust. If that is correct, I would clean the control with a contact cleaner, while rotating it quickly back and forth about 10 times.

Extra Fox

Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by Extra Fox » 27 Nov 2019 02:17

lenjack wrote:
25 Nov 2019 20:24
Does it have an external speed adjustment speed adjust? Manual shows knob G, as speed adjust. If that is correct, I would clean the control with a contact cleaner, while rotating it quickly back and forth about 10 times.
I can do that and test. When I was peeking at the underside of the board I noted that both the speed adjustment resistors had tracks on them. So I'll give that a shot.
Ramjet wrote:
25 Nov 2019 19:37
Always suspect electrolytic capacitor failure in electronics this old. Many times it is easier just to replace them all than spending time troubleshooting. I have a GA 312 of the same vintage and use it everyday, great machines.
This makes a lot of sense too and it's worth a shot. I reckon I can source those on any of the normal electronic supply sites.

Extra Fox

Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by Extra Fox » 14 Dec 2019 22:39

Closing the loop here, it apparently was the electrolytic capacitors. I'm guessing it was the one in the speed control circuit, but I replace both for good measure.

For future reference I replaced the following Capacitors on the main board (I'm using their number in the schematic as a guide);
  1. (C730, Tacho Control) - Vishay, MAL211838479E3, 47uF, 63v
  2. (C734, Power Input) - Nichicon, UFG1V471MHM, 470uF, 35v
In both cases I opted for higher voltage capacitors as I read that was generally okay. I also used a high-temperature capacitor for the speed control on a hunch, but that may not be necessary.

Again, I'm a pretty rank amateur here with electronics, but pieced together what I needed from the schematic and other advice I found around the web.

Extra Fox

Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by Extra Fox » 26 Dec 2019 23:20

Merde. :x

So the new capacitors went in and it worked brilliantly... for a while, but it still randomly speeds up again after a time. It has improved significantly and I've been able to listen to quite a few albums, but clearly something is still wrong.

I can power it off, wait a bit, and then it will work again for some time, but this is hardly the listening experience I'm looking for.

Any other ideas would be really appreciated.

Ramjet
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Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by Ramjet » 27 Dec 2019 22:31

Have you downloaded a read the service manual yet? I would suggest doing so and performing the "Electrical Adjustments" on page 4 and confirm the "Voltages" from the same page.
C734 is the power supply filter capacitor and C730 with R569 "serve to start the motor quickly". Intermittent problems are the most difficult to fix so Good Luck!

Extra Fox

Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by Extra Fox » 28 Dec 2019 05:15

I have downloaded that and that's getting into some areas I'm not 100 % sure how to accomplish, but I reckon it's always a good time to learn. I've had another suggestion to check the sense voltage going to the motor to see if that's changing, so that's where I'm going to start.

Ramjet
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Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by Ramjet » 28 Dec 2019 18:08

Everything in the GA 212 is referenced to the -9VDC from the power supply. That is why I strongly suggest you start with the "Electrical Adjustments" from the Service Manual. If the required -9VDC isn't exactly -9VDC no other voltages will be correct.

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Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by JTM690 » 08 Jan 2020 22:11

Sort of on topic in reference to the -9vDC. I pulled mine off the shelf after about 25 years. I just replaced the belt, light bulbs and power switch to get it going. When turning it on, the stop light and the auto shut off lights were very bright and the unit would immediately go to Stop after touching the 33 or 45 sensors. I cleaned the sensors w/ alcohol and played with the variable resistor R472 (per the service manual this is what adjusts the -9 vDC which I'm still not sure I'm measuring it at the right spot) which sits near where the red transformer wires connect to the circuit board. After several cycles of rotating R472 and cleaning it a bit. After doing this the Stop and Auto-Stop lights dimmed and the platter spins and speed adjust is working as well as the auto-stop function.

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Re: Philips GA 212: Suddenly Starts Playing too Fast

Post by xraypro » 16 Jan 2020 03:30

From the service manual and the picture of the circuit board, it looks like the ground or 0V is found at A20, and the -9V is at A8 or A12. There may be other places to find it, but this looks pretty easy to get to. The Rule of Almada states "Check the power supplies first."

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