BeoGram

Re: BG4004 Arm lowers even with no record!

Dillen — Mon, 24 Nov 2008 02:45:11 GMT

I have new lamps and sensors but check the lamp position first. The sensor is not easy to replace (and not cheap), but fortunately rarely faulty unless broken (it's a tiny glass piece) or leads pulled off.

Check the signal with an oscilloscope, you should be able to see the pulses from the radial streaks on the platter very clearly.

Martin

Re: BG4004 Arm lowers even with no record!

Ben — Fri, 21 Nov 2008 16:11:54 GMT

Hi Martin

Thanks for the belt kit for this turntable, they fit perfectly!

With regards to the capacitors, yes, I checked and double checked the polarity and values before soldering them into place.

The problem I had before changing the capacitors was the arm not dropping, moving to the end, and back to rest.

I'll check the solders and leads again, but i'm pretty sure they are ok.

Where can I obtain a new lamp and sensor?

Thanks,

Ben

Re: BG4004 Arm lowers even with no record!

Dillen — Fri, 21 Nov 2008 16:03:16 GMT

Obviously, it believes a record is on the platter, my guess would be one or more of the following :

- Dust on lens system

- Lamp output too low

- Lamp misadjusted - filament should sit exactly over the lens and as close as possible

- Sensor bad

- Sensor leads broken

- Cracked solders at the board edge connector

- Electronic fault leading to poor detection

Are you sure you got all those tantals value and polarity right ?

Martin

BG4004 Arm lowers even with no record!

Ben — Fri, 21 Nov 2008 15:38:33 GMT

Quite the opposite of the usual arm not lowering problem.... I replaced all of the old small tantalum beads and electrolytics this evening in a bid to get this turntable going properly, but now i'm faced with the next problem:

The arm will always drop at the LP position, even if there is a single or no record at all on the platter. Could this be caused by a poor light output from the lamp in the detector arm? Can this be replaced by an LED? I noticed that if I disconnect the lamp, the arm wont drop at all and just return back to the rest position.

Any ideas?

Ben