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Re: Lost left channel on Beomaster 1900

BryanCannings — Mon, 23 Jan 2012 07:53:10 GMT

After reading this thread I just fixed the bass potentiomoter on my 1900 and thought I would post a few photos and notes in case it helps anyone else about to do the same.

Firstly I wasn't sure how I was going to solder out the potentiometer because the circuitboard it is attached to has a bunch of wires conneted to it which don't have much slack, making it hard to work on. Then I noticed a groove in the plastic below where the board sits so that once you unscrew it, you can stand it on its edge to access both sides without disconnecting any of the attached wires - makes it much easier.

Once you have the pot out of the board, you have to take it appart by bending straight the 4 metal hooks on the underside which hold the metal slide rail in place at each end. I just loosened these and I was able to slide out the metal rail, which gives you access to the loose contacts pictured below:

The tiny bits of plastic holding the brass contacts had both broken, so I removed them.

These are the brass contacts removed. I used tweezers.

After I had cleaned the lubricant off the black plastic where the brass contacts mount using contact cleaner on a cotton bud, I superglued them back in place as per Dillen's instructions.

24 hours later I put it all back together and the bass adjustment is working again. Many thanks to Dillen for the instructions.

Re: Lost left channel on Beomaster 1900

Dillen — Tue, 06 Jul 2010 00:46:36 GMT

Welcome to Beoworld !

You have an answer to your PM regarding the lamp kit.
The kit comes with detailed (dis-)assembly instructions which will also help you gain access to the tonecontrol board.

Martin

Re: Lost left channel on Beomaster 1900

tmblack — Mon, 05 Jul 2010 21:55:19 GMT

I just bought a 1900-2 and found the balance control to be broken as well.

How do I open the unit and gain access to the slider PC connectors?

Re: Lost left channel on Beomaster 1900

Dillen — Mon, 25 Jun 2007 12:09:54 GMT

Good job !

Martin

Re: Lost left channel on Beomaster 1900

bartdubelaar — Sun, 24 Jun 2007 05:12:34 GMT

A picture of the broken slider:

The left one is broken the right one is still OK. As you can see I had to remove a lot of grease before I could start with the superglue. The plastic tab that has broken is really small, it's about 3.5 mm long and 0.5 mm wide.

I've forgot to take a picture after the fix.

Re: Lost left channel on Beomaster 1900

bartdubelaar — Sun, 24 Jun 2007 04:59:39 GMT

My Beomaster works again! I'm really amazed by the strength of the superglue. When closing the pots the metal sliders are pressed down quite a lot, which takes so much force that I really thought the glue wouldn't hold. But it's been playing songs now for two days without breaking (knock on wood), so I suppose the fix worked out allright! Thanks for all your help! I'm enjoying my Beomaster again.

PS. I also checked out all the caps that I could see with the top part removed and they all looked fine.

Re: Lost left channel on Beomaster 1900

bartdubelaar — Mon, 18 Jun 2007 10:35:45 GMT

Martin, thanks for your extensive reply! I will try to fix them according to your suggestions. Good tip on checking the capacitors. I will post my results later this week.

Re: Lost left channel on Beomaster 1900

Dillen — Sun, 17 Jun 2007 06:47:24 GMT

Solder out the pot and take it apart.
Be careful, especially with the bronze parts and their tiny coal tips (avoid touching the tips or they will most likely fall out and become lost).
Clean the black plastic "sliding bridge" using isopropanol (tapehead cleaner) and glue the bronze slider back into place using superglue.
Give it an extra tiny drop and leave it to settle completely (overnight). No glue up the bronze arms and none on the tips either, only around, under and on the base of the bronze part.

Now would be a good time to clean the tracks in the bottom of the potentiometer. Give it a bit of contact cleaner, leave it to soak for a couple of minutes and then wipe it dry using cotton buds.
Clean and dry is good.
Don't just spray contact cleaner in and leave it there.
It will losen the oxidation and shift it around alright but it takes human action to take it out.

Put the pot back together and solder it in.
If one pot is bad, then the other two are probably going too, check them all (don't mix them up, they are of different values!).
Finally, while in there, take a look at the radial type capacitors at the main board, check if they look cracked or like they have started to leak something.
If so, grab a cap kit and replace the lot. There are
about 60 of them in there and you'd be amazed at
the difference. A lamp kit is also available.

Martin

Re: Lost left channel on Beomaster 1900

Jandyt — Fri, 15 Jun 2007 16:47:59 GMT

Hi Bart. I think it might be a good idea to send a PM to Martin (known as Dillen on here) If he hasn't got one, I'm sure he will point you in the right direction.
Also try Frede (Known as Classic) he has the patience of Job when it comes to repairing small parts of B&O equipment.
Good luck!

Andy T.

Re: Lost left channel on Beomaster 1900

bartdubelaar — Fri, 15 Jun 2007 15:58:35 GMT

The problem is indeed the balance slider. The plastic tab holding the slider for the left channel has broken. It seems impossible to fix, it's so small and it should be able to withstand some pressure. Has anyone of you got any idea how to fix this. Or maybe where I can get a replacement for this 'ruwido' brand variable resistor?

Thanks,

Bart Dubelaar

Re: Lost left channel on Beomaster 1900

bartdubelaar — Wed, 23 May 2007 04:21:27 GMT

Playing with the balance slider does not reveal any working spots. Only when I push the balance slider all the way up (balanced to the right) then there is some cracking noise coming from both speakers. Good tip on using the headphones to check the output, I will do that when I get home.

The bass control also stopped working a few years ago, it never bothered me much as the way the sound is right now is ok for me. The broken bass slider also has no working spots at all, I can move it freely without any sound difference from the speakers. So maybe the balance control has a similar problem.

Re: Lost left channel on Beomaster 1900

dave1900 — Wed, 23 May 2007 03:54:47 GMT

I agree the most likely cause is a faulty balance slider, they do age and go faulty. Either the carbon track deteriorates or the plastic carrage mechanism fractures. Typical probs are when sound comes and goes, scratchy with blank spots, steps in volume. In my case the actual slider/wiper mechanism had broken leading to major surgery. I did a web search for a replacement slider, alas non found so I very carefully rebuilt the existing one which thankfully is still working fine. I did wonder if to contact a B&O dealer for spares but the thought of the encounter put me off.

To get access the slider you need to remove the rear vented cover and then the two screws near the lid hinges. Half open the lid and gently wiggle the whole cover loose. It is held by plastic tabs that mesh with the sloping front.

This may seem like a silly suggestion but make sure the 1900 is the prob and not the leads/sockts to and from the speakers, it may be worth doing a quick check with headphones to make sure the fault is in the 1900.

Re: Lost left channel on Beomaster 1900

joeyboygolf — Tue, 22 May 2007 16:14:05 GMT

Could be the balance potentiometer itself. They are inclined to get worn or dirty or both. Does the sound come back if you wiggle the balance control?

Lost left channel on Beomaster 1900

bartdubelaar — Tue, 22 May 2007 16:05:12 GMT

Hello all,

Yesterday the left channel of my Beomaster 1900 kept disappearing and appearing again, now it is completely lost. It doesn't matter which input I choose. Also when I turn the balance slider all the way to the right I hear some cracking coming from the left speaker. Any ideas on where to look for the problem?

Any help is greatly appreciated.

Bart