Hi everyone 

I have just acquired a BM8000, in reasonable condition and providing some acceptable sound at the moment.  However, it is going to need some TLC to get it back into good condition.  Since this is my first BM8000, and knowing how powerful this unit is, I expected to feel the heat sinks doing their work.  However, I didn't expect to find them running so hot.  So my question to all BM8000 owners is, how hot is hot?  My first tests were carried out at very modest volumes and a setting of 2.8.  After ten minutes of running time, the air temperature directly above the heat sink was 58°C and I couldn't put my hand on the metal for very long.  According to my power meter, the unit was only pulling 80W at that time and yet, the spec sheet states that it can consume up to 700W!!!.  I am sure that in Europe, the BM8000 would make a useful additional heater but here in Australia, I will be a bit concerned to switch this unit on, especially in summer time.  Any feed back on how hot I can realistically expect this unit to get and how hot it can go without incurring damage will be appreciated.

Geoff

Hi Geoff,

I have the same generation 6000 which is said to 'run hot' compared to the 8000 and even after higher volumes running for hours it never gets hot enough that you cannot touch the metal fins.... So I would say it sounds as though something is not performing as it should causing yours to run hotter.

Now, If you are technically minded you could try looking at the following thread which describes opening up and fixing a BM8000 that ran hot in one of its channels... not sure if this is the same issue... But anyway here it is...

http://forum.beoworld.org/forums/thread/84163.aspx

Well I'm sure it will be worth fixing what ever the issue is..... I can't say how much I enjoy the rich , smooth sound of my system....

BTW... this isn't the 8000 system that was sold on ebay in OZ  this week is it? If it is.... well done! 

I had a BM 6000 that ran very hot - in addition to the heat sinks there was an area on the underside that was extremely hot (the transformer/power supply?).   Some of this vintage equipment runs hot - I also have a BM 5000 that even in standby mode could serve as a space heater.  

Hello

I have a BM8000 & a BM6000 and they both ran very hot even at zero volume before a capacitor change and a setup in accordance with the service manual.  The no-load current and output offset amplifer settings on the main amplifer boards are the important ones to get right and you will need a DVM because they need to be set to 18mV and +-5mV respectively.  Since the cap change and setup they hardly generate any heat at all, even when left on for hours.  The main amplifier boards are quite awkward to remove from the BM8000 so unless you feel comfortable doing a job like this then leave if to a technician who a) has the service manual and b) has preferrably done one of these before...

Kindest regards

Richard

They really should not run hat hot. Mine was fully serviced and since then has run cool unless pressed into serious service and even then it is not that hot!

I own both 6000 and 8000. They are being used on a daily basis and are recently serviced by Dillen.

The BM6000 runs hotter than the BM8000 but you can put your hand on it without the risk of getting burned.

The BM8000 will stay about the half of a BM6000 even after playing for a few hours.

My Beomaster 8000 blew fuses and took 240 watts! It should take 30-40 watts only!

It sounds like it needs a service before it gets worse. Dillen here can supply special made cap kits with clear install instructions but you need to be able to use a soldering iron or know somebody who can do it for you.

 

Thanks everyone for all of your contributions. 

It seems that there is an overwhelming vote in favour of a relatively cool heat sink under normal operating conditions so there is certainly something wrong with this unit.  Now that I know, it will be fixed in due course.  I also have a BM6000 and while it does run warm, it never feels as if it is going to be able to fry eggs for breakfast.  I will use that one as a reference and aim to get the 8000 to operate even cooler.

I will be tackling this job myself as I get a great deal of satisfaction from taking non working B&O models and getting them back into useful condition.  This will be my tenth Beomaster and while there is very little room left on my shelves, I will have to find somewhere to display this monster unit.  After all, I have waited nearly 25 years to get one.  I remember seeing it in the shop when it first appeared, being captivated by its beautiful appearance and totally disappointed when I found that the price tag represented a half a years salary.

To soundchoice70, your detective work was correct and I did get this collection off Ebay last week.  It seemed impossible to think that one could pick up one of the B&O flagship collections for so little.  With the Beomaster not far from working properly, the BC9000 now basically working again after a fuse and belt replacement and the BG8002 sitting there just waiting for a good clean up and service, I have plenty to keep me busy for a while and the results I know will be brilliant.  What is perhaps more important is that here on BeoWorld, there are many people who regularly donate their time and knowledge and with this resource, my project is sure to be a success.  I had already read Rick Jansen's brilliant set of opening up details before the unit had arrived home and that was a very good start. 

Thanks again for your help everyone

Geoff 

Ha!

Great deal... last I saw it it was only AUD127.50 or something like that.. including CDX and M150, CX100 speakers.... was so tempted... but the thought of shipping it all here to Singapore and not knowing what (if anything) was working stopped me..... oh and who could forget of course the huge shipping bill! But looks like it could have been worth it tho...

Well I hope that you can get it all back in tip top condition... after waiting so long you are sure to enjoy it!

Just an update

Did two things today, first tested the BM6000 and found that the heat sink temperature only went up about 15°C.  I could put my hand on it quite comfortably.

Second, dismantled the BM8000 to get access to the amplifier boards to set the no load currents.  These were way off mark, the worst being around 250mV, so I reset them as close as I could get to 18mV.  Next time round, I'll take the amp boards out and replace the pots because they are now very unstable.  The end result is that the heat sinks are now running with barely a 5 to 10°C increase and the power draw has gone down from 80W to 42W.  It cetainly does feel cooler than the BM6000 so your advice was correct.

Took out a lot of dust in the process and she's looking much better all ready.  The dismantling and reassembly wasn't anywhere near as complex as I expected so my confidence is high to do a proper job after I source some spare parts.  By the way, it looks as if someone has had a good go at the caps already.

Thanks again for putting me on the right track, it looks as if another Beomaster has been saved from the scrap yard.  I'll definitely be keeping this one.

Regards

Geoff 

 

Yes, those idle current trimmers are often past their exp. date. and will easily affect your electric bill.

They don't go out of adjustment, they go bad. Sometimes you can adjust back and forth, eventually breaking through oxidation, duse etc. to find a spot where it looks fine but that's just until the Beomaster has been moved around or gets warm. The trimmers oxidize and develop intermittent faults, sometimes even fall apart physically.

They are cheap components, replace them and readjust. Do one channel at a time and do the DC offset ones too while you are at it. You will be surprised at the difference, the adjustments will be very smooth.

The Beomaster 6000 has exactly the same problems, actually all 1970's and 80's Beomasters with discretely built output stages have.

The Beomaster 6000 will have a very warm spot on the bottom plate, that's normal. It's cooling fins will also feel slightly hotter than the BM8000 but that's mainly because of the power supply regulators heat sink at the right side. Similarly, the BM8000 will feel warm at the top of the glass panel where heat escapes through a grill. The BM8000 will keep it's cooling fins at room temperature even if playing at "normal levels" and definitely if idle. The Beomaster 6000 likewise, apart from the right side as mentioned, where it will become "pleasantly handwarm".

Martin

Thanks Martin, I always appreciate your advice.  I will be replacing the trimmers as soon as I can source some horizontal, 100ohm items which are pretty hard to get over here.  Can you use a higher rating such as 200 or 250 ohm if the 100's prove too hard to get.  They will be less sensitive but should work??

One item that has cropped up since the 8000 has cooled down is a faulty mains capacitor on board 7, rated 330nF and 275Volts.  This has been slowly burning in the background but wasn't apparent when everything else was smelling hot.  From local information, this item is going to be hard to get.  Can you recommend some alternative values or combinations that I can try if such a capacitor is no longer available.

Thanks

Geoff

Hi Geoff,

The trimmer should be 100 Ohms. I have some in stock if you need.

That capacitor should be a Class X component. I don't know where to buy a new cap of this value but I may have a good used component in stock, I will have to check.

Martin

Thanks Martin.  This morning I managed to find a supplier of a suitable mains capacitor, class x2 and have fitted it.  The BM8000 now seems to be working well but no doubt something else will crop up soon - such is the nature of these old amps.  As for the trimmers, I should be able to source some locally but they might look a bit different to the existing ones.  At the moment, I can only source 200ohm items in the original style so I might have to wait.  Anyway, I am in no hurry to take the Beomaster apart again right now.

Thanks for the offers and the help

Geoff

I am new to the BM world and was lucky enough to have been able to acquire a BM8000 in pretty good condition.  It has similar issues to many that have posted here, hot heat sinks, burned out LEDs.  I want to thank everyone for their posts, because if it had not been for you, I would have never known the "quick" fix to the hot heatsinks.

I am starting to replace the LEDs on the displays, as they are all bad.  I will keep you posted.

Thanks!

Welcome to Beoworld and thanks for signing up as a silver member, your support is greatly appreciated !

I've developed my own techniques for repairing the original displays and it's not an easy task but please keep us informed as you progress.

Martin

Martin,

I removed the display for volume (two seven segment displays).  I used a high power magnifying glass to see the existing "LEDS" on the board.  These belong in a museum!  I can't believe they even used these, but now it makes sense why they are so vulnerable to vibration etc.  I am going to replace with smd LEDs that fit into the display's case.  I am not sure about the Vf on the LEDs but I am going to try a couple different ones.  I will also mount a socket header strip to the pc board, with a matching male header on the display.  This will make for much easier future removal/replacement.

 

Gerhard

Gerhard:

I successfully redid the entire display on my BM 8000 2 weeks ago replacing all segments with surface mount LEDs.

You really need to replace all of them because there the voltage between the old and new leds don't match and more importantly because the display is strobed. The new ones are much more efficient and are too bright.

I replaced all the current dropping resistors with 820 R in order to match the brightness of the original display. I prefered mine to be a bit brighter than original, but if you are picky you can go with a slightly higher value dim it a bit.

As you dim the LED the color gets closer to the original, but it isn't exactly the same.

I've taken pictures of the entire process which I'd like to share with the group but haven't figured out how to attach them.

Regards,

 

Derek

GDSammet:

I removed the display for volume (two seven segment displays).  I used a high power magnifying glass to see the existing "LEDS" on the board.  These belong in a museum!

So what are they actually? Chips bonded in place like in 70's pocket calculators?

@auric, I'd love to see those photos. When composing a post, click on the "Options" tab and you'll see an add/update option. Only one attachment per post, though...

 

Here is a close up image of one of the segments with 1.7v power  applied.  I used a 105mm macro lens with a 36mm extension tube.  The "silicone chip" is less than .5mm in diameter.  The difference between the Beo LEDs and traditional LEDs is the LEDs we use now are encapsulated to prevent damage from vibration etc.  The filament wire you see is a gold strand and is very delicate.  This is the piece that breaks from vibration.

I am wondering what value and physical size SMD LEDs you used.  I have ordered two sizes with a 2.1Vf.  I would like to see your picture too.  To attach a pic to a message, just reply, not quick reply, and click the "Insert Media" button.

Gerhard

GDSammet:

Here is a close up image of one of the segments with 1.7v power  applied.  I used a 105mm macro lens with a 36mm extension tube.  The "silicone chip" is less than .5mm in diameter.

Yes, this is indeed the LED type I was referring to. Although it was still smaller in the early calculators, and the displays actually had a plastic "magnifying lens" over each digit to make them readable. I think I have one in my junk box somewhere... as well as some larger early LED 7-segment displays, which internally had LEDs pretty much like in your picture and a "light box" above to diffuse the light.

Well done with the picture BTW

 

Derek

auric:

Gerhard:

I successfully redid the entire display on my BM 8000 2 weeks ago replacing all segments with surface mount LEDs.

You really need to replace all of them because there the voltage between the old and new leds don't match and more importantly because the display is strobed. The new ones are much more efficient and are too bright.

I replaced all the current dropping resistors with 820 R in order to match the brightness of the original display. I prefered mine to be a bit brighter than original, but if you are picky you can go with a slightly higher value dim it a bit.

As you dim the LED the color gets closer to the original, but it isn't exactly the same.

I've taken pictures of the entire process which I'd like to share with the group but haven't figured out how to attach them.

Regards,

 

Derek

I am curious which LEDs you replaced, for which display, and what value.  I have ordered several which might work, but I have not received them yet.  Which resistors did you replace?  My volume display and balance displays are completely dead.  Only one or two segments work.  The tuning display has 3-4 segments which are dead or dying.  In looking at the Service Manual diagram, the volume and balance "share" resistors which might be good in my case, however, the tuning display might have to be completely rebuilt also since all of the segments are related to the same set of resistors.

I just finished replacing the R226 Trim Pots on the Amplifier boards.  I found 100ohm Trim Pots with the same footprint as the stock ones.  I used Digi-Key (DigiKey.com) part number 3352E-101LF-ND ($1.24 USD each).  The legs fit perfectly in the factory holes without bending them or making any modifications.  Once I replaced them and reset the milivolts to 18mv everything worked perfectly.  It was easy to get exactly 18mv also, since the new Trim Pots were clean.