No, don't start swapping parts over as you could potentially introduce new faults to your refurbished beomaster. These hifis are rather delicate with age and require a great deal of care when working...

You would need to check the power supply and look for dry joints. More than likely the fact you have disturbed a marginal wire or board header plug with a bad joint. The board to board connectors also go bad, requiring bridging wires.

You would normally need a scope to check for life in the micro, although the 5v power supply / reset line and the possibility of dry joints is where I would start!

I actually have one on the bench today that I am refurbishing, I estimate there will be 12+ hours of work, but that does include replacing the led chips... I will take pics as I go along :-) (I really will this time!!!)

Olly, we are holding our breath then!

I agree with you about connections and solder joints. Those should always be looked into first!

Allright, at the moment I got both machines opened up and I was about to swap the pcb's but decided to check this post first. The "new" beomaster which has a great looking exterior actually doesn't look very good on the inside, everything is dusty, the main caps look dirty and there is a lot of rust on the cover under the input panel.

It would be sweet if I can get my original unit going again and put the front panels of the "new" beomaster on it along with the tone control pcb (which was hardly working at all)

Problem is that I don't have a scope and checked all solder joints I can reach without removing the metal cpu cover. I'm just at loss on what to do next, so this seemed like a feasible option.

Where do I find the 5v supply?

It's great news for you Jacques cos I will finally be able to fully test the other cpu board recap and send it to you :-) Postponed today as I was underground until 3am this morning and I need to do some wall papering now :-(

Beomaster4 if you are not experienced with a soldering iron I would not recommend removing the screen of the processor, the board is very delicate and will more than likely get damaged in the process. The 5v regulator is on the heat sink under the display panel on the right wall of the machine. It is a 7805 I would replace that and its associated capacitor. The processor reset circuit is on the display panel you will need the service manual though to adjust that. Maybe send the boards off to someone (Martin?) to have them looked at? Then you can work on the rest of the machine yourself?

Where do you live?

I live in The Netherlands.

I'm pretty handy with the soldering iron, so I don't think that should be a problem. I do have some basic knowledge about (dc) electronics, but not nearly enough to troubleshoot a machine like this. I do have a copy of the service manual.

Since the display is displaying 8's (volume: 8.8, channel: 8, freq: 8 8, balance: 8) doesn't this imply that the 5v supply is working? The display board only gets power from the CPU board, so that must be energised.

Is it really such a sin to swap the CPU board from the "new" beomaster in my original one? I already swapped the display boards just to rule that out, doesn't make a difference, also displays the 8's. I'm just very much tempted to swap the boards since I have 2 non-working machines here, so as far as I'm concerned it can't get much worse :P.

Just because you have got a 5v supply, does not mean it is clean enough for the micro! and Again, if the reset circuit is not working on both the display boards how has swapping helped determine where the fault is?

Not being funny but this is quite possibly the worst piece of B&O you can pick up and try to fix without previously having experience with B&O gear, it really is a very delicate machine!

By all means if you would rather try swapping the processor boards over and risk loosing a piece of hardware that can fetch £100 on its own on ebay, and you feel you have nothing to lose then do so, just make sure you at least do so in an anti static environment and be absolutely methodical in your approach, and you are happy nothing else external to the processor board has created the problem in the first place!

Also check for dry joints and the connectors while you are at it!

Let us know how you get on :-)

Hi Olly,

Thanks for your advice. I know repairing this machine is way over my head, but it's an old unit from my parents. I don't have the means to buy a new one or get it professionally rebuilt. Since I'm pretty handy with 12v car electronics and soldering, I decided to give this a go.

Since I'm only down by 25 euros so far, I decided not much would be lost by swapping the boards. I do understand that this may not be a wise choice, but I did it anyway. So, I tried the "easy shortcut" and it didn't work. The other cpu gives me the exact same behaviour.

The original cpu board I took out looks pretty good, the solder joints all seem to be in good condition. I can't really check the traces without removing the pcb cover. However, the fact that both cpu boards give me the same behaviour may point to a problem elsewhere, like you suggested.

So how exactly do I go about checking the 5v and reset circuit? I found it in some of the diagrams, but don't know where exactly to measure.

Check the reset line on both the display and processor board.