Vintage Products

Re: Just bought BM1900

VW411 — Tue, 02 Aug 2011 01:24:36 GMT

Great to hear! Thanks!

Re: Just bought BM1900

Dillen — Mon, 01 Aug 2011 03:10:35 GMT

There's no bracket.
The Beomaster 1900 (and 2400) is already prepared for wallmounting so
you just need two screws in the wall.

Martin

Re: Just bought BM1900

VW411 — Mon, 01 Aug 2011 02:22:46 GMT

I've found out what was causing the problems in the left/right channels. It was the balance potentiometer i had repaired earlier. I hadn't had pinched the potentiometer assembly back together tight enough, so there was some loose movement in it.

Does anyone have a picture of a wall mounting bracket for a BM 1900? I'd like to place the BM to my livingroom wall, but i'm not sure how to do it yet... I was thinkg i'd hang the BM directly to the wall so it would hang exactly vertical. But i've understood the brackets (atleast for a BM 4500) will position the BM slightly canted. If i hang the BM vertical will the lid stay slightly open all the time?

Re: Just bought BM1900

VW411 — Wed, 20 Apr 2011 09:28:52 GMT

Thanks for the replies guys! I'll check the areas you pointed out and tell how the BM reacted.

Re: Just bought BM1900

Dillen — Tue, 19 Apr 2011 16:28:31 GMT

You could check the potentiometers again but when you repaired the potentiometers, you probably
had the whole tonecontrol board disconnected from the rest of the Beomaster.
Depending on the exact version of the Beomaster, the tonecontrol board has either two or three
connectors underneath and they are of different types.
If yours are the type with connectors in the form of piggyback boards with leads going to them,
the leads are often found to have too long un-insulated lengths and they will easily short to other
connections under the board when mounted. Especially the large connector near the center of the board.
Some Beomasters have a piece of thick tape fitted underneath the board to address this issue but it
may have fallen off, dislocated or never been there.

Martin

Re: Just bought BM1900

tournedos — Tue, 19 Apr 2011 16:03:33 GMT

If that "fix" requires only the slightest touch, it might be a grounding problem... but if you need to apply any pressure for the sound to change, I would start looking for a conventional intermittent solder joint or bad connection. In the latter case, try poking around the circuit boards while it's playing to see if you can isolate the sensitive area.

If the problem disappears when you open the receiver, consider stuff like a too long screw in some place!

The "furry feeling" (an excellent choice of wording in some recent thread) is pretty much normal in all B&O kit that has exposed aluminum surfaces, so that shouldn't have any effect on this issue.

Re: Just bought BM1900

VW411 — Tue, 19 Apr 2011 06:48:47 GMT

Well, this is strange. I just noticed that when i push the aluminium panel down with my finger, just above the green fine tuning lights, the right channel comes alive again. Maybe some grounding issue? I've also noticed that sometimes you can feel some slight vibration on the aluminum surfaces of the facia -like electricity was leaking somewhere. Oh, and now i remembered that when i was repairing this BM i noticed that if you accidently touched the opposite ends of the facia with metallic tools you could siwtch the BM on and off

Re: Just bought BM1900

VW411 — Tue, 19 Apr 2011 04:24:34 GMT

I've only recently noticed that the right channel of the BM1900 sounds somewhat muffled. Left channel has noticeably clearer and more crisp sound. I live in an apartement building so haven't really had the chance to test the speakers earlier. The living room is also quite small, so it's been difficult to notice the differences between the speakers. This problem occurs in both speaker connections (1 and 2), with every speaker i've tried and with headphones too. Could a bad bass potentiometer cause this? I'm asking this as that's the only potentiometer i haven't checked/repaired yet. The bass potentiometer doesn't crackle but i think it doesn't adjust the bass quite as fluently as it should -it sounds like it only starts to work at the end of the scale.

-Pirkka-

Re: Just bought BM1900

VW411 — Thu, 10 Feb 2011 03:37:32 GMT

Thanks!

Good to hear, the thump is normal. I noticed that it's much louder if i switch the amplifier to standby and then immediately back on. Whent the BM's been on standby for a while, the thump is hardly noticeable.

Anyway, this BM 1900 is in full working order now. Now i'm already looking for a next project...

Thanks especially to Martin for all the help!

Re: Just bought BM1900

Dillen — Tue, 08 Feb 2011 09:53:40 GMT

Good job !
Yes, it's fairly normal to hear a thump sound when switching on.
Not a loud bang, just a pleasant greeting.

Martin

Re: Just bought BM1900

VW411 — Tue, 08 Feb 2011 09:27:22 GMT

I just finished the repair works for this Beomaster by glueing the broken treble potentiometer back together. Man i hate flimsy 70's plastics...

Here it's glued already. Sorry about the poor pic -just bought a new camera and don't know how to use it yet...

Martin sent me a better rectifier which i aslo solderd in position. Now all i have to do is install the wooden trim back in place and it's all done for this one.

I wonder where i could get small enough din adapters that fit into the small slot underneath the amp. And i'll have to find some new rubber feet also, as the originals were dry and cracked.

Re: Just bought BM1900

VW411 — Sun, 06 Feb 2011 06:00:39 GMT

Here's some project pics:

New caps

All the soldering was done when the BM was positioned like this. This way i could reach both sides at the same time.

Here's the burnt rectifier

All the capasitors removed. Removing these was quite straght forward. Only few palces were hard to reach. Soldering the new capasitors in position was much easier as the caps were smaller than the originals.

And here it is! After replacing three marking lamps for the sliders, everything works fine.

Re: Just bought BM1900

VW411 — Sat, 05 Feb 2011 15:13:05 GMT

Changing the lamps solved the problem. Thanks Dillen!

By the way, is it typical for these amplifiers to make a thump when switched on? I have a pair of BeoVox 2702 speakers connected to this and the thump is noticeable. It doesn't sound anything different than my fathers old philips music center from the 70's. But for an equipment this sophisticated, i was surprised to hear the thump so clearly.

Re: Just bought BM1900

Dillen — Sat, 05 Feb 2011 02:45:10 GMT

The tone control lamps forms part of the 15V discharge circuit.
If the lamps are bad, it may take a longer press of the standby pad to
bring the Beomaster in to standby.
Occasionally, it won't at all.
Check the two leads that goes to the underside of the tonecontrol lamp board.

Martin

Re: Just bought BM1900

VW411 — Sat, 05 Feb 2011 02:32:38 GMT

I finally ordered the capasitor kit from Dillen and it arrived on friday. So i spent the whole evening replacing the caps. I also bought a new rectifier as Dillen said it's propably shot. When i opened the BM i noticed that the rectifier was indeed in poor condition -burn marks were clearly visible on the circuit board.

After all the soldering work it was time to test the BM 1900. Everything worked well and the humming was gone. The treble slider isn't still working but i havent done much to it yet.

But then i noticed some new problems. The marking lamps for the slide buttons aren't working anymore. And when i switch the BM to standyby mode it goes to a state where it's on standby but the volume marking lamps are also lit. This happens if i push the stanby button only gently. With a stronger push the BM switches to a standby as it should. I have to check the forks underneath the buttons, if there is a bad connection again. I'll have to check the slide button's marking lamps too. I had to solder the caps in somewhat awkward poistions as i didn't dismantle the BM completely , so i hope i haven't cracked or broke anything.

But all in all i'm happy with the result. I'm going to check the problems i mentioned and then all i have to do is clean the slide buttons and propably repair atleast the treble's connecion. Afther this the BM 1900 is back in business!