ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi There
I've a Question about the Output Amplifier Board's of the BM 8000.
Member Mohawk (Fredrik from Sweden) made some PCB's new back in 2010.
I know, it's a long Time ago, and I tried to reach Fredrik over P.M and Email, but didn't got an Answer so far.
Is there anyone out there who knows about Fredrik or has somebody 2 or more Poweramp PCB's lying around?
A CAD File from the Board would be very helpful too.
He has made some other PCB's of the BM8000 like the Display PCB.
You can read it in the archived Forum under folowing Link:
https://archivedarchivedforum2.beoworld.org/forums/p/33481/274371.aspx#274371
I hope someone could help, we're comming to the Age of the BM 8000 where more and more Board's are burned seriously and a new Board would be fine.
Best Regards
Christian
Hi dear Members
Seems that there is no soloultion for that Problem?...very sad.
Have a nice Sunday
Hi Christian
I will help you out and produce a new batch of those PCBs.
If others are in the need of new PCBs for module 5 and 8, feel free to contact me.
Best regards
Fredrik
Hi Fredrik,
I would be interested in the output amplifier boards.
If you are ambitious to take on the task a new pcb for the microcomputer board would really be welcomed :-).
-sonavor
Hi I would be very interested on the 5 and 8 PCB modules!
Regards Egon.
Hi Fredrik.
I am interested in pcb module 5 and 8.
Kind regards
Henrik
Hi
I have noted your interest!
I will list the prices of the PCB:s here soon when I got an indication of how many boards there are demanded in total as it affects the price/each.
Regarding the CPU module I have no PCB drawing completed yet. I started to make that layout back in 2010 for my restoration project of the BM-8000 at that time. However my CPU board was in good order and still works fine so I never finished that drawing. I might continue that work in the future to help you save your BM:s but it is a very time consuming job since it is dual layer PCB. It would help me a lot if someone had a scrap module 9 for me I could take apart to reverse engineer it and make the drawing complete.
/Fredrik
Yes, the CPU module would be the most difficult. I will check my spares but I think all of my spares are working boards. Plus a decision will need to be made as to which of the two Beomaster 8000 Microcomputer board layouts to reproduce. I would vote for the later model as it has the easy to open shielding box. The earlier BM8000 units have a box that is soldered shut and a little bit of a pain to open. Do you already have some ideas on a replacement shield box?
Also, Martin (Dillen) might have a non-working, faulty BM8000 Microcomputer board in his archive.
-John
Hi John
Hmm I have not seen the older version of the CPU unit. Do you know if it differs much between versions except for the shielding box? Would be interesting if you have pics of both the versions to show me.
I emailed you a few photos of the two Beomaster 8000 Microcomputer boards.I will also post one of each here.
You can see that on the early Microcomputer PCB the shield box completely removes. However, you can also see that the mounting points have places where the solder pads for the box mounts tore away from the board.
On the later serial numbers the top and bottom lids removed easily from the board but there is a frame for the box that is soldered to the pcb in a way that makes removing it a difficult chore.The later serial number boards with the improved shield box resulted in components moving around a bit on the board and rerouting of some traces. Overall I think the later model boards are better but both work well when restored. I think a replacement board would be best to be modeled after the later board but with possibly a new (third) shield box design that mounts easier.
Troublesome issues with both legacy Microcomputer pcbs are the grounding plane and thin traces. It is common to find boards with solder pads coming loose along with part of the traces. B&O also released some service bulletins that called for running wires to and from points where the connections were a problem. I think a fresh new pcb would solve a lot of nuisance problems that show up in these aged boards. New board connectors will also help.
Jacques
Hi Chartz
Hehe well there is a certain demand now for it. I think thats fun since it gives a longer service life for these BM:s. I am glad if I can help those with PCB:s that had gone too far to rescue.
I am glad to hear that my old thread was appreciated, it was a lot of work since my BM was over repaired and finally the guy had given up and sold it as is. However it was a fun job to get it into service again and it still works fine.
I dont know why I have only 5 posts, maybe all my old posts got into the archive. I have not been here for some years due to other priorities in life but finally Spassmaker found me somehow and I tried to log in and my account still existed, so here I am haha.
Hi everybody in the need of new boards!
I have managed to calculate some prices for you. It has got much cheaper nowadays compared to when I first made these boards back in 2010. At that time I think the boards set me back about 60 Eur or something per each if I remeber right. There was some interest in my PCBs back then but the price was too high. I agree with that.
Today (10 years later ) I can offer the PCB boards for these prices:
Power Amp (Module 5) - 16 Eur / each
Display (Module 8) - 22 Eur / each
I hope you find the prices acceptable. It includes the board cut out to fit the BM and it also gives me a small compensation for all the hours spent reverse engineering those boards to be able to make the PCBs.
If you plan to buy larger quantities (for example 10 PCBs) then I can probably make another price for you, just send me a PM.
Thank you very much for the pictures and explanation of the two versions of the CPU boards.
Hope we can find someone who have a scrap CPU board that I could take apart and use as a template to make a new CPU PCB.
I can definately recommend anyone to replace the board connectors, esp the female ones on the display board and wire harnesses if you have intermittent problems. The old connectors are probably worn out and lost their spring tension. I replaced my connectors in the old restoration thread.
The new board prices are acceptable I would say.
A Beoworld member just had a Beomaster 8000 restored for him in the USA and possibly has a spare Microcomputer board as he ended up creating a working Beomaster from two. I sent him a request to see if the extra board is something he will part with and a picture of what version it is. I am still thinking a new PCB should be based off the latter serial number boards. -John
Excellent prices.
I'll have two amp boards and a display board please!
John,
Probably my bad memory but wasn't it you who found a third version of the CPU board two or three years ago or so?I remember discussing it (perhaps not with you) and we ended up deciding this must likely be B&Os latest (aftermarket) replacement board, seeing as the previous boards had problems.I can't find any photos of it in my notes, but I seem to remember it being a very light green'ish color.
Martin
Please keep in mind to NOT fit metal-film resistors in the output stage board in places where B&O didn't.Fit like for like.
Dillen: John, Probably my bad memory but wasn't it you who found a third version of the CPU board two or three years ago or so?I remember discussing it (perhaps not with you) and we ended up deciding this must likely be B&Os latest (aftermarket) replacement board, seeing as the previous boards had problems.I can't find any photos of it in my notes, but I seem to remember it being a very light green'ish color. Martin
Hi Martin,
You are probably right :-)
I will go through my collection and check them again.
John
Dillen: Please keep in mind to NOT fit metal-film resistors in the output stage board in places where B&O didn't.Fit like for like. Martin
Same as 10 years ago. Good advice.
sonavor: Dillen: John, Probably my bad memory but wasn't it you who found a third version of the CPU board two or three years ago or so?I remember discussing it (perhaps not with you) and we ended up deciding this must likely be B&Os latest (aftermarket) replacement board, seeing as the previous boards had problems.I can't find any photos of it in my notes, but I seem to remember it being a very light green'ish color. Martin Hi Martin, You are probably right :-) I will go through my collection and check them again. John
I went through my Beomaster 8000 Microcomputer boards that I have on hand. I have two of the early type boards (the one with the soldered shut shield box) and I have four of the later serial number boards (with the easy, pop off shield box lids).
Of the latter boards, one has a PCB number of A802493 while the other three are C802493 PCBs. The early board that I have as a spare is marked F802401.
Here are some photos.
Here is an early PCB 9 with a later PCB 9. Note the difference in the ground terminal posts on the rear of the board.
So we'll see what is available when Fredrik is ready to work on the new board layout. If I have to I can probably sacrifice one of these later serial number working boards (Of course I will remove all of the components first :-) ).
Hi all
Manufacturing process is now running. I will post a link here to my ebay when the boards are ready for purchase and you will be able to buy them from there.
We have to settle with the best layout board and I agree with you that the later ones are better to work with. No need to remove the components if you send the unit to me, I would like to see which components that are fitted in some places if I would need that information.
Thanx 👍
I have not been thinking about the shield box at this stage. I will see what is possible to do with it when I am working with the layout of the pcb. Imagine if we have new pcb:s for this and use a similar solution of the shield box as in the later versions, would we really need to remove more than the top cover of the shield for examination?
I would recommend to use the shield box. The CPU can be quite noisy and sometimes be heard at higher volume settings. The routing of cables from the CPU is very important too and it should not be mixed with signal cables if possible. It is also the opposite to not let the CPU module get disturbed by external interference.
I think b&o had to cut costs here and there although this was a flagship back in the days. There are a lot of compromises in the BM 8000 for example the PCBs and usage of cheap components (capacitors, trimmers, potentiometers, switches, connectors etc.) that could be of better quality.
Hello everybody!
Finally the PCBs are manufactured and I sell them from my ebay account, please check the links below:
Power amplifier module 5 - https://www.ebay.de/itm/184366234176?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
Display module 8 - https://www.ebay.de/itm/184366237060?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
Superb!
I’ll order a set in a few days.
👍🏻👍🏻👍🏻
Seems ridiculously cheap to me! Thank you for doing this as will keep a number of these behemoths going!
Peter
Hi Guys
Thank you all for your orders!
Shipping is now in progress, so you will hopefully receive your PCBs soon. Happy soldering :)
I want to point out a misprinting on two diodes D201 and D202 on the power amplifier boards. This misprint originates from B&O original PCBs. I will correct this in future versions of this PCB. The diodes shall be mounted in the opposite direction showed on the printing, see picture below. There is also a reminder of this in your parcels.
Noted...Thanks
The boards arrived safely today. I won't be able to get to them for about three weeks but looking at them makes we want to get started. I keep an opened up, working Beomaster 8000 in my workshop so that is the unit I will use to test them. I'll let you know when I am ready to try them out.
Thanks!
I received the spare Beomaster 8000 Microcomputer board. Here it is stripped down pretty far and almost ready to ship to you.I did test it before stripping it down and it did function. However, as you can see in these photos there are a couple of jumpers for some of the original traces as well as a few missing solder pads. I left the add-on board B&O added during production so you have that as a reference. This should keep you busy :-)I will try to get these off to you on Monday November 30th.
Regards,John
I just love how much solder they used on these boards
Yes. I had to take apart, empty and clean my desoldering gun after that exercise.