Beomaster 2400 Restoration Problem

[jfrancis49]

Hello All,

I recently spent 3 months restoring a Beomaster 2400, lots of capacitors (Thanks Martin for the kit.) I had it all working today (I thought) and was listening to music from my CD player for 6 hours, and I know the radio works. I realized however the front panel for the touch sensitive area was not letting me change the volume up or down (the remote works). All other buttons worked with touch activation. So I took off the front panel to try and get the pins to align for the volume. I was having trouble getting them to either work at all or align for all of them. Then the last time I tried, when I switched on the power to the 2400, it came on without going into standby mode and it defaults to FM4. If I try switching to another input it stays at FM4. When I put on earbuds and turn it on to see if there is radio I hear a station for about a second and then it stops and I hear nothing but hiss up and down on FM4. The stereo lamp indicator flashes at first and then goes off. I have tried it several times with the same result, only FM4. I looked to see if I had bent anything that might be touching, I saw two resistors that were very close together, if not touching. Not sure if that is the cause. I did the no-load and 15 volt current adjustments. I was not able to do the FM voltage adjustment because the trimmers even when turned all the way counter clock-wise did not give me enough voltage.

Any ideas on what might be the issue would be appreciated.

John

[Pindsen]

Hi,

I assume you have changed 2C92 (2200uF).
I had something similar once (but also ripple noise in speakers) where ripple on 2C92 capacitor was too high due to defective rectifier (2D50). I changed to a 6A rectifier and the ripple was lower which made the odd behavior go away.

/Pindsen

Location: Denmark

[jfrancis49]

Hello Pindsen,

Thank you for your reply.  Yes I replaced the large capacitors as well as the rectifier you mention. I am not sure if the rating was a 6A rectifier, it says 3A,6A on the data sheet. Were your symptoms the same as I described? Could the rectifier have been defective although new?

John

[Madskp]

The behaviour of your touch buttons got me thinking about a Beomaster 3000 I worked on some years ago which after my work had both non working touch buttons, and also the volume would just go up by itself.

I got some suggestions in a thread here on Beoworld about the transistors in the touch button circuitry and replaced some of them without any change in behavior.

But then at one point I noticed that the flex cable between the two PCB’s under the touch buttons had some bad connections (broken cable where it was going through the PCB), but also that some of the wire ends from the flex cable was bend and touching each other on the solder side of the board.  solving these issues fixed the problems with the touch buttons.

So I would suggest that you look into those connections s they can easily be bend or damaged when working on the system.

I don’t know if the BM2400 PCB for the touch buttons is also divided in two or if it is using the same flex cables, but I hope this can be helpfull in your troubleshooting anyway

Location: Denmark

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