It does work but the volume is stuck at about 30. when I turn the volume up or down  the lamps light up or dim out as they should but the volume stays the same. Treble and Bass work just fine. All other controls function as they should.

Peeking down inside it looks like at lot of the sound control are routed in and out of IC 6 and IC 4 as well then over to the STK463.

I looked up the chips numbers and all are still available.

Hi there = As a start for the moment, check the capacitor between IC4 and chassis, the MUTE transistor (TR200) and the A/F output hybrid chip IC1, perhaps by replacement.  See what happens - let us know. = Brian (Northumberland) 

Also check 2R50 - it appears to be a pre-set which sets the volume o/p.

Hi again = You need to check out 2IC4 - it's a Dual DC Controlled Stereo Potentiometer.  When you operate the volume control, you should see the DC volts varying at pins 9  and 10.  Check the 16v and 33v supplies and the circuitry round the IC, particularly the electrolytic caps - note the two non-polarised ones C33 and C34.  If you can get hold of a ESR meter, check all the electrolytics  round about and change any suspects - they are notorious! I don't know what your tech. ability is or what gear you have, so I'm shooting in the dark a bit, but lets know how you get on - it's all interesting stuff! = Brian (Northumberland) 

Just a thought - I presume you have the User Manual and you've checked the volume pre-set level/volume store?

Also does the MUTE work - you  did say the volume level was stuck at 30 (I wonder if this is a default setting)  - might be worth a fiddle about before diving into the electronics, but perhaps you've already done this.  Hope I'm not confusing things - let's know when you can.

No the mute does not work at all. When I increase the volume the panel lights up like it should but the volume goes nowhere and when I decrease the volume  it stays the same. Fiddling with the preset for volume was the first thing I did. I even swapped out board 5 hoping for a quick diagnosis from my working 3000, but that wasnt it.

This is my $26 Beomaster - so tearing into it doesnt bother me one bit. Perfect opportunity to learn the way I see it.

What I have either on order or on hand from my local electronics supplier are the caps c7 c18 c30, finding suitable replacements for c33 and c34 are a bit hung up right now but I will get it resolved. I also ordered 2 new OC1&2 caps plus a new STK465. Plus I figure on just going ahead and replacing 2D28. My supplier sells them in packs and usually has them in stock.

I guess I should invest a little money and get some more sophisticated measuring equipment. Right now all I am using a multimeter to test values. Which only goes so far.

Yes its a journey all right, one that I am just beginning. The first part learning how all of it works and the second and maybe more important part is where to find all parts I need locally.

Ok I see where you're at.  Can you read the circuit diagram? If so, print off Diagram B. In order to eliminate a real nasty (a faulty 2IC6), you need to see if the DC volts vary on pins 9 and 10 of 2IC4, and you need to resolve the MUTE circuit.  If these are ok, then 2IC6 would appear to be ok because the Volume Display board does what it is supposed to do! 

Next you need to verify all the PSU (Power Supply Unit) voltages - that they are present and correct. 

If these voltages are ok and you can verify varying DC volts (when you operate the Volume Up/Down) at pins 9 and 10 of 2IC4, then the fault is either with 2IC4 or further on. 

Note:  All the PSU voltages are only low ones, but beware of mains AC (Board 6) on the primary side.  Good luck and give us some feedback when you can. = Brian (Northumberland)

More: If you're replacing OC1and2 - is this because the -30v and +30v are not correct?  If so, you are onto something.  Like I said, check all PSU voltages!  A cheap little A/F sig gen and signal tracer would work wonders when trouble-shooting stuff like this.

A bit more!  As an example, consider this:  Look at 2IC4 - if the 16v at pin 11 was low or very low, you could disconnect the 16v at pin 11.  If then the 16v comes back to normal, you would consider the chip as very suspect or some of its associated components, particularly C30. 

However, if the 16v was still down, C29 would be the likely culprit or the PSU itself, or some other section associated with the 16v supply.  Also, routinely, check any ground connection e.g. 2IC4 pin 18.  A dry joint here could stop the chip functioning correctly.  Much to think about!! = Brian (Northumberland)

The problem will not be in the STK chip since it has no influence on the volume.

I seem to remember that there are some small ceramic capacitors
near the processor that often cause much headache.
Worth checking, I think.

Martin

OC1 & 2 Chips are being replaced as part of a general upgrade. I read it here all the time to recap these things after 20 years so why not.

Plus what sound I was getting was be clear at times and then sound scratchy then clear up maybe fade up a bit then down a bit.

If you are replacing D28, I would follow Martin's advice and replace C55 and C56. = Brian

Ok- not a problem with replacing caps where necessary. If you think of other as a matter of mainteance in general list them and I will go ahead and get them ordered. 

Are those Red/Brown ROE caps that I see in a lot of B&O equipment all due for replacement after 20 years or so. Seems like I read that here and there.

Also, the output TR4 was pasted to the heatsinks as well as the IC! chip. While the paste on the IC Chip was still gooey the paste on the TR4 chip was dry. That stuff look almost like teflon paste of sorts  should all of that be recoated.

Ok = The paste you refer to is Heat Sink Compound.  Clean the old stuff off and re-apply the new compound liberally - it is essential for heat transfer from the semi-conductor to the air via the heat sink.  The caps you refer to do not have to be replaced by ones from the same manufacturer - as long as you replace with the same values (same types) and voltage ratings.  Why are you replacing 2TR4?  Is that because the 5v supply is wrong - or are you doing it anyway?  It is best to verify ALL supply voltages, as this will save a lot of confusion!  Press on - all interesting stuff! = Brian (Northumberland)

I was not planning to replace it.  While I was taking the unit apart a I noticed that the paste had dried up. 

Most of the caps I get from my local supplier are NTE, the ones I order online from Newark are from various companies. Just depends on what I want to pay. I dont usually go for the cheapest nor do I but the most expensive I will pick up an ESR meter this week and I thinks I should invest in a desoldering tool instead of using a wick and some low heat silver solder. 

I have ordered a few in duplicates, might as well replace some of the caps on my working 3000 as well. Not real hard work to solder caps and such. 

I hope to have everything I ordered in by mid week or so.

Ok = Sounds like you are getting to grips with it.  Have you checked  all the PSU voltages yet? 

Before you actually start changing components, can you do the voltage checks and note them all down for me, please? I am particularly interested in the 16v supply at pin 11 of 2IC4 and even more so the volts on pin 8!  If we go about it logically, we will have a better chance of a fix.

Equipment:  Yes you need decent gear - you do right to get a desoldering tool - a good solder is CEL 60/40 2mm.  Have you a high impedance digital multi-meter?  Can you get hold of a Logic Probe?  I think we are going to need these at least - and you have said you will get an ESR meter. 

Now, can you tell me if the low level sound that you have is output from both channels? If not, what is the position in this respect? Also, can you hear any noise in the speakers at switch on/off?

Let me have all the above info when you can.  All interesting stuff! = Brian (Northumberland)

Ok finally got around to changing a few of those caps. I have volume and balance conntrols restored but now I have a nasty hum out of the left channel on my headphones, pretty much all hum in fact, plus after awhile it starts to ccok up the ressistor at the back of the headphone jack.

If I try to power it up off a set of speakers it will only hold for a second or two and then out she goes. 

Solved one problem but now I have another.

A number of possible causes.

1. Could be the bias trimpots in the output amp stage (Replace with long-lasting Cermet types).

2. Check the resistance of the low-ohm resistors at the speaker outputs. 

A regular Multimeter will not be able to do that - its internal resistance is too high.... BUT either the Peak ESR or the EVB ESR meter can do it - they both have a Low-ohm function built-in.

What probably happened was that after replacing the caps, you got good, unimpeded electricity flowing again - too much of it! And now you've got to readjust.

3. You could have put in a cap with backwards polarity - go back and check again. Be careful of the Non-Polarized capacitors - if you didn't notice them, and replaced one with a Polarized, there is the source of your problem.

Menahem

This is all that I replaced

What I have either on order or on hand from my local electronics supplier are the caps c7 c18 c30, finding suitable replacements for c33 and c34 are a bit hung up right now but I will get it resolved. I also ordered 2 new OC1&2 caps plus a new STK465. 

I looked everything over again and again using the pics I took before I pulled everything out as reference and dont see anything installed backwards.

Looking at the wiring diagrams and at the unit the there are only 4 trimpots on the main board R23 R50 R242 and R442.

The function of R23 I cant find anywhere. R50 is pretty simple in what it does. I see that radio AF trimmers are tied to IC4 via IC2. My question is does it also regulate output volume or do they just regulate the final radio output signal from PCB