ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi!I recently got hold of a BG 7000, which has replaced my BG 4500, to complete my Beosystem 7000 (still missing the BL7000, but that's low priority right now). Yay! :-)I gave it a good clean and lube and it runs beautifully. The only problem is that the lamp inside is on constantly. It turns on when I plug the mains and stays on.Anyone have a clue as to what's causing this nuisance?Thanks!
/ Johan
Johan: Hi!I recently got hold of a BG 7000, which has replaced my BG 4500, to complete my Beosystem 7000 (still missing the BL7000, but that's low priority right now). Yay! :-)I gave it a good clean and lube and it runs beautifully. The only problem is that the lamp inside is on constantly. It turns on when I plug the mains and stays on.Anyone have a clue as to what's causing this nuisance?Thanks! / Johan
In my BG 5000, the lid lamp is operated by micro switch 10S1, check that one maybe its "hanging" or not working
Collecting Vintage B&O is not a hobby, its a lifestyle.
In the tangential Beograms of this family, the lamp control is unfortunately electronic, so it is probably not going to be that simple unless the lamp holder or the wiring is somehow short circuiting to ground..
There's one transistor that controls the low side of the lamp (BC337, TR3 in the service manual) and it could be shorted as well.
--mika
Yeah, I had trouble finding that switch in the manual.. :-)I guess I'll have to get my hands dirty. Just figured I'd ask first.Thanks, both of you!/ Johan
tournedos:There's one transistor that controls the low side of the lamp (BC337, TR3 in the service manual) and it could be shorted as well.
After attaching my reading glasses I see that too, in BG 5000 TR1, but will muting work if TR3 is shorted ??
Søren Mexico: After attaching my reading glasses I see that too, in BG 5000 TR1, but will muting work if TR3 is shorted ??
In the schematics for the BG 7000 there is one TR3 (BC337) just below the lamp, which I suppose is the one I'm interested in. I can't see how that is involved in muting? Or were you talking about the BG 5000?/ Johan
Johan: Søren Mexico: After attaching my reading glasses I see that too, in BG 5000 TR1, but will muting work if TR3 is shorted ?? In the schematics for the BG 7000 there is one TR3 (BC337) just below the lamp, which I suppose is the one I'm interested in. I can't see how that is involved in muting? Or were you talking about the BG 5000?/ Johan
BG 5000, The TR1 collector is connected to the mute circuit.
tournedos: In the tangential Beograms of this family, the lamp control is unfortunately electronic, so it is probably not going to be that simple unless the lamp holder or the wiring is somehow short circuiting to ground.. There's one transistor that controls the low side of the lamp (BC337, TR3 in the service manual) and it could be shorted as well.
I finally got around to replacing that transistor, and indeed that fixed it! It seems kind of obvious now in hindsight, but it wasn't obvious for me before you pointed me there.You da man, Mika. Thanks a lot!/ Johan
That's good to hear!
I guess the transistor is a bit lightweight type for that duty.
tournedos: That's good to hear! I guess the transistor is a bit lightweight type for that duty.
You think? How much current flows through there? I never measued..
OK, maybe not after all I just checked and Ic for BC337 is given as 800 mA max. The lamp doesn't seem to be speficified in the service manual (other than "12V") but I don't think it can be more than 100 mA or so.
The transistor should have no problems as long as it is driven into saturation, and it should be with that 1k8 base resistor. Perhaps it was just an unlucky individual
Yeah, that's why I asked. :-)Anyway, thanks for helping out!/ Johan