For years I've known of B&O gear, but never seriously considered it for myself, because it was always SO expensive! But recently I came across a Beogram and Beomaster 8000 for sale locally. So now they are mine, and I am blown away by how well engineered and aesthetically beautiful they are. The Beogram works great (except for having to occasionally tap on the control panel), and is the best sounding TT I've ever heard.

The Beomaster is another story. I bought it (literally) last night, so I have only spent a few minutes with it. But it has some glaring issues that I would like to fix. I am pretty handy with a soldering iron, although the kitchen table hasn't fared so well...another story there. The first and most obvious issue is that one channel is kaput. Through 'phones, the left channel seems fine, but all I get is a low hum out of the right. With the balance all the way to the right, and with the volume up to 6, I get distorted music output from the right channel.

The other issue is that after a short time the microprocessor goes on the fritz: the relay clicks open, and I lose all sound. Radio reception goes dead. And after a couple more minutes, the display starts changing inputs and radio presets on its own, then eventually freezes up.

I've heard enough good things about this receiver that I dearly want to get it working. I have the OM and SM, can anyone point me in the right direction on what to look for regarding these issues?

Thanks very much,

        -jhoyt

P.S. Can a "universal" remote be programmed, in lieu of the original Beolab Terminal?

I too found a Beomaster 8000 a few years ago with the right channel dead.

As soon as I found out that a channel was dead, just like you described it, I turned the Beomaster off. So I never noticed any problems with the processor or had relays clicking, but I assume that burned out power transistors can do all kinds of strange things to any circuit and cause voltage fluctuations in other circuits including the processor and then anything can happen.

So with the help of a servicemanual, downloaded from this site, I exchanged the power transistors and a few other transistors on that particular amplifier circuit. Each channel has got its own printed circuit and the layout of the Beomaster is relatively logical, even though patience is needed disassembling and reassembling. When the damaged transistors have been replaced it is very important to trim the amplifier and it is explained in the servicemanual how you do that. The damage to the amplifier could very well have been caused by being "out of trim". Slightly out of trim and the power transistors will get VERY hot, but as soon as the 'No Load Current' and the 'Offset Output Amplifier' has been adjusted properly the heat output should be a lot lesser. The right side of the beomaster is always warmer because this is where the main power circuits are and you will notice that there are also a few power transistors on the display circuit, which also releases some heat. In my case the beomaster was running as it should after these repairs, but you might consider exchanging worn out capacitors and those trimmers that I mentioned before on the power amplifier circuits. Exchanging components on the power amplifier circuits naturally means checking offset currents and voltages again.

My Beomaster 8000 has played happily ever since I repaired it and I very much enjoy it.

Good luck with the repairs

Welcome to Beoworld !

Grab a capacitor kit and replace the lot.
Replace also the trimmers for the DC offset and idle currents and readjust to
factory specs.
Check for cracked solder joints at all connectors on the processor,
display boards and check the general condition of the low voltages
power supply board.
Not the easiest system to work on but definitely one of the nicest to own and use,
not many modern systems can do what this system can.

The same goes for the Beogram 8000 (capacitor kit and solder joints) though
if it works fine there's really no rush.

Martin

Well, I discovered the souce of the bad right channel--the driver board has some cooked parts. The left channel's board looks like it's gotten "warm", as they are wont to do, but not "cooked". The problem with the flaky input switching is not readily apparent, but I'll look for bad solder joints and bad caps. And, there was a loose ground wire, so that may be partly to blame.

Here are some pictures of the guts:

1. Right side output board, behold the charcoal...


2. Left side output board


3. Power supply board


4. Entire insides


5. Toroidal transformer & supply caps


I am so blown away by this receiver--IMHO it belongs in the pantheon of "monster" receivers. The transformer is 6 1/4" in diameter! This is totally different from anything I've ever worked on in the past, but I think it will be totally rewarding as well.

Well, based on the pics... looks like you indeed have found an issue! I would deal with that first.

jhoyt:

The other issue is that after a short time the microprocessor goes on the fritz: the relay clicks open, and I lose all sound. Radio reception goes dead. And after a couple more minutes, the display starts changing inputs and radio presets on its own, then eventually freezes up.

Regarding this... I had similar wonky issues and this thread fixed mine!

Yes, that one will need all components from the drivers (BF857) and outwards replaced as a minimum.
It can be very tricky to get it all right if you are not very experienced and the power supply
won't hold back if something gets in the way electronically so look out for flying parts of
transistor housings etc.
If you are not very experienced with repairs of this type, I would suggest you look for a
complete and working amplifier section. It may be the easiest and cheapest
solution in the long run.

Martin

I have the predrivers on my list to order. Would the power transistors need to be replaced as well? I have not physically seen them, so I don't know what they look like. But there were no signs of overheating on the heatsink.

Before I go to Digikey and place my order, does anyone have a Module 5 they want to sell?

The power transistors are sitting on the heatsinks. They are darlington transistors, so they are listed as ICs.

You cannot tell if a transistor is OK by just looking at it.
I would replace the whole lot.
Even if they still measure fine, there's a good chance that one or more will suffer
from internal scars that will show up as a drastic failure sooner or later.
Watch out for counterfeit transistors. (No joke!).

Martin

I have my orders placed, and will receive them in a few days. I found the BF859* transistors at MCM, the rest at Digikey. I decided to shotgun all the electrolytics, since I have heard the RDE's are ticking timebombs.

* BF859 shares a datasheet with BF857, and appears to be a higher-voltage version of the original, Vce/Vcb is 300V, vs. 160V.

Well, good news and bad news. I got all the suspect components swapped out, and all the wiring harnesses put back where they go. The receiver powers up, and tests (Monitor + Standby) fine.

However, the power amp section does not power up. There is no voltage across the main filter caps (should be 55V), and there is no delayed relay clicking on. Upon the first turn-on, there was a wisp of smoke from...something. Something around the "Startup" board. However, nothing looks bad. So...

What do I look at now?

If the "startup"-board is the one at the back with the fuses etc. then I suggest you take a good look at the board and the fuses.

If the relay(s) does not click, check that you got all the cables and connectors back on correctly. Eventully, check
for cracked solder joints at the connectors.

Martin

There are two distinct relay "clicks". I'm not sure how many there are onboard, though. I believe the fuses are good, also. One I visibly checked, the other ohmed at a dead short. I'm thinking something happened on that board, but what? Other than the relays, fuses, wires, and two big resistors, there are two small diodes. They "look" OK, but my next move is to test them, and replace if necessary. It's weird that even the big rectifiers have virtually no voltage across them.

And, the computer is acting up now. I left the unit on all night, and this morning it was on the fritz. I was able to run the self-test, and it came back with TE 3...what does that mean?

The Beomaster 8000 is a wonderful machine but not the easiest to repair. Even experienced tech guys
develop grey hairs occasionally.
The service manual is download'able from our main site at a small fee - well worth it for all the info
kept in there and this site will be happy to see some support.
That manual would tell you that TE3 is a defect around 9IC3. Pin 31 in particular may be shorted.

Martin

Thanks, Martin. I already have the SM, but didn't see the error code matrix before. I just found it. I will definitely check 9IC3, especially in the vicinity of pin 31. The unit works for a while, so I imagine the issue is heat related. Possibly a bad solder joint, or debris, or something. Thanks for the direction.

I will check over the startup board (7) tonight, I have replacement diodes if needed. It seems like the startup circuit is not powering the 55V system up at all.

Thanks again,

Jeff

I discovered something: the two diodes on the startup board test OK (out of circuit, of course). However, the two big power resistors, 5.6 ohm, measure at ~200K! That would certainly explain the lack of power to the transformer, as those are the first components the AC sees as it comes in from the mains. Time to look through my junk and see what I've got...

Update: this morning I replaced the bad power resistors on the startup board. But the problem is continuing. I've traced it back to the "delayed relay" section of the power supply board (6). Could the receiver be refusing to come out of a "protect" mode?

No,

If the relays click one after the other with a few tenths of a second between, that part is working.
If they release again soon after, something is wrong in the amplifier(s). Could be a too high
idle current or badly adjusted DC offset (or something else).
Try measuring the +/- 55V and see if it is supplied to the amplifiers at all.
If so, then try putting a voltmeter to the amplifiers center rail (speaker output) and check for DC.
Does the "clipping" light flash on the front panel at startup ?

Martin

Here's what's happening:

At startup, RL2 instantly closes. However, RL1 never does. So I have full preamp/control functionality, but there is NO 55V voltage in the system. RL1 never energizes, there is 0V across its terminals, traceable back to the "delayed start" circuitry on Module 6. I get lost there, though. The capacitor is new, and all else looks visually OK.

Is this circuitry part of the "protection" system? (The "clipping" light never comes on at all.) I did pull and test the output transistors; B-C and B-E were OK, but C-E were shorted. Would this cause the +/-55V rail to shut off?

How much would it cost to get those transistors (TIP141/146 x3) from you?

I read, in another thread, you guessed (correctly) that a trimmer pot shorted, and took out the emitter resistors and output transistors. This appears to be exactly what happened in my unit. I have replaced the trim pots (on both output boards) with 10-turn Bourns type, but I am very frustrated that I can't get the 55V to the board to properly set the bias voltage!

Thanks for sharing your knowledge!

Jeff

Sounds like there still is a problem with the startup resistors or their circuit board.
RL2 closes, that's fine but RL1 is supposed to close shortly after the "soft" voltage is present on
the transformer secondary.
If the secondary shows no voltage at all, RL1 will never close and the amplifiers will not get any power.
Maybe a burned PCB track ?

If you already replaced the output stage transistors, there's no reason to replace them again, unless
proved faulty.

PS: Wonderful avatar !

Martin

The startup resistors have been replaced with 5.6 ohm 5W wirewounds, but the output transistors have not been replaced yet. Now, are you talking about the smaller transformer secondary windings? I didn't check them for proper voltage. I will dig in there. But I do want a quote on those transistors.

Also, the tuner is not remembering my presets...even with the unit powered on! Is there a special memory cap somewhere, or something else?

Thanks for appreciating my avatar. If you're a Muppets fan, there's a whole section of new Muppets videos on YouTube. I highly recommend their "performance" of Bohemian Rhapsody.

No, I'm talking about the +/- 55V secondary voltages.
You can also measure if any mains AC arrives at the (large) transformer primary at all.

The FM presets are stored in a chip on the processor board. The BM8000 should be able
to remember preset stations even if mains was disconnected for a long time (days or more).

Make sure you have everything connected properly and there are no broken solder joints
or PCB tracks, especially at the processor and display boards.
Signals essential to the general functionality of the Beomaster passes through the
display board to- and from the processor board, like f.e. strobe signals for the buttons
on the tonecontrol board (FM store etc.).

Normal is:
Tune in to a station, press "Store" and the "P" will start flashing on the display,
then press the preset button (1-9) you would like to store this station at.

The transistors I will have to look up.

Not a Muppet fan in particular but I do like Stattler, Waldorf, the Swedish Chef
and of course Muppet Lab.

Martin

Probing around, here's what I'm getting:

Power resistors: ~115VAC across each

Large transformer: 0V in, 0V out

Small transformer: 115VAC in, 18.5VAC & 5VAC out

I started a new thread about the Delayed Relay circuit.