Beogram 8002 stops short

[Die_Bogener]

deleted

[antlestxp]

I have made some progress. This table didn’t turn on at all when I got it. I replaced all the caps and clean al the mechanicals to get to this point. It spins and locks on speed. I tested with a rpm tool. The carriage moves pretty freely in both directs. The part I’m stuck at is the arm stops short. It makes it to the same spot every time I press play and will just sit there spinning. It won’t respond to stop from this state. It will only respond to stop if play was never started. I did replace the led on the encoder and get pulses from the diode readers. I’m not sure what else to check.

Beogram 8002 touble

 

[Die_Bogener]

You start a Beogram to play without a record?

Nice, you will destroy the MMC if it continues.

That’s a safety feature.

[chartz]

Hi,

This should be in the Workbench, where it’s really at as regards repairs.

Check your connections, and the bulbs, especially the one in the control panel, and if good, check adjustment as per service manual (5-3).

[antlestxp]

Die_Bogener wrote:

You start a Beogram to play without a record? Nice, you will destroy the MMC if it continues. That’s a safety feature.

As you can see there is no cart attached. If a 45 is placed on the platter it does the same as well as a 12. It is clearly stopping short of the record detection process.

[antlestxp]

Everything in the control panel has been replaced and adjusted to spec. New bulb and photo sensors went in. It seems like an issue with the rotary encoder. The arm moves for a couple seconds before it stop. I’m going to check the connections between the encoder and cpu again when I have free time.

[chartz]

I remember I had to replace the IR diode in one of my decks. An easy task, if it comes to that!

[sonavor]

Have you performed the service manual adjustment for the forward and reverse scanning control buttons?
Both should measure around 620 mV at their steady-state (not pressed) position.
If those are adjusted correctly then perhaps you do have a problem with one of the position sensors.
Those can be replaced if necessary.  I believe Martin has a replacement part at the Beoparts store.

The source of the problem could still be elsewhere though.
To see what is going on for sure you would need to attach some probe wires to measure what the various sensors are actually doing.

-sonavor

[sonavor]

Sorry, I didn’t read the previous threads closely.
It sounds like you have set the steady-state levels on the scanning buttons where the LDRs measure 620 mV.

I would connect an oscilloscope to the sensor signals and see if any are showing any signs of problems.

Here are the sensor measurements I captured on a Beogram 8002 a little more than a year ago.  The oscilloscope measurements are towards the end of the post.  There are also photos of where the test probe wires are soldered to.

-sonavor

[antlestxp]

I have replaced the emitter diode on the encoder. I can’t find the correct part for the 2 receivers.

[antlestxp]

sonavor wrote:

Sorry, I didn’t read the previous threads closely. It sounds like you have set the steady-state levels on the scanning buttons where the LDRs measure 620 mV. I would connect an oscilloscope to the sensor signals and see if any are showing any signs of problems. Here are the sensor measurements I captured on a Beogram 8002 a little more than a year ago. The oscilloscope measurements are towards the end of the post. There are also photos of where the test probe wires are soldered to. -sonavor

Thanks for pointing me in the right direction. Looks like you probe at r11 and r8 for the 2 receiver diodes. Do you know what part number the receiver diodes are if they are the problem.

[sonavor]

If you used something like an OP240 or OP245 IR Emitter then their corresponding phototransistors are OP550 or OP 560 for the OP240 and OP555 or OP565 for the OP245.

The IR Emitters have been hard to get for a while but fortunately you already have that component.

Before changing any of these components I would measure the existing signals and make sure the part is where the fault is.

-sonavor

[antlestxp]

Very helpful. Your posts got me through a 4002 restoration! I used a camera to determine the emitter was faulty.

[sonavor]

Great. You meant to write that you got through your BG8002 restoration, right?

Congratulations and good work.

-sonavor

 

[antlestxp]

No I’m still working on this one. I meant I got a 4002 running from your blog a while ago.

[sonavor]

Oh, that’s fantastic.  We’re always glad to hear that it provided some help.

-sonavor

[antlestxp]

Got it up and running. Circled back to the basics. Checked my solder work. Pulled as much as the old solder my vacuum could. All new solder. Cleaned and checked all mechanicals. Then checked my work and calibration of the control panel. It was the control panel. My adjustment was close but not close enough. Had the relocate the new receivers into a better position then readjust with the screws. Soldered a connector to the panel I could leave measuring equipment to made quick work of it. Now I just need to finish up the rest of the adjustments to the tone arm.

 

Thanks again. This is my 4th and probably final beo. RX2 TX2 4002 and now this 8002. Every table I have wanted over the years.

 

8002 up and running

[chartz]

Good job. Little things, always ☺️

[beogram8002]

well done, that is great news, another 8002 playing vinyl again 🙂

[Author]

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