Can someone provide theory of operation circuit description for tangential drive?  I see a xfmr coil connected to first stage of IC3 then another coil bridging final stage of IC3 over to the main drive coils plus there is the brake.  I do not understand how all this is supposed to work.  This thing began to work after some new capacitors and reflowing of joints but then went south.  First the platter began laboring and pulsing then it went super fast and stays that way no matter what commands.  Power plug to wall: 100+ rpm.  Lost the +15 coming out of regulator; new one same problem.  Thank you.

Down in corner near D5 maybe are two afterthought mini boards hanging on for dear life via  screw through a transistor.  I cannot correlate them to the only schematic I have for a 8000 from vinylengine.  If anyone can direct me to a schematic update that includes these, maybe it will help fix my loss of +15V and the out of control 100+ rpm platter that cannot be stopped by anything other than unplug from wall.  Thank you.

Since I am not receiving any response or help with this I am going to throw the entire thing in garbage pickup.  My friend wants the platter and nameplate to mount as artwork but the rest of it is fast becoming utterly worthless.  Good bye to bang and olufsen.

Hello Thomas,

Unfortunately I don’t have the technical expertise to advise you on this. But before I would trash it or give away the platter I would see if you could find someone to service it. Outside that non-working Beogram 8000 turntables still are worth abut on eBay. Someone else might be able to buy and fix it or use the parts to resurrect another nonworking one.

The latest:  I paid $50USD for a new strobe wheel.  I can see pulses on pin 12 of IC1 from the pickup I had to also replace.  But there is no regulation; the platter is still going way too fast.  The next chip in line is inside the uProc oven and will be quite difficult to get at.  Still contemplating trashing it.  Not sure what should be visible at pin 14 of IC1 but seems like it should be some version of the pulses.

You have already achieved more than most owners could/would.
These Beograms are wonderful decks, but not easy to service as they are so different from everything else, and it's often seen that several problems and faults are present at the same
time, which can easily confuse matters immensely and make diagnosing difficult.
I suggest you leave servicing to someone with more experience. The results will be great and the Beogram is worth it.

Whenever I have problems with my car, I try to fix as much as possible myself, - and I can
do quite a lot myself, really - but every now and then a repair is necessary for which I simply don't have the knowledge, experience and/or tools and instruments, and in these
cases I bring it in for servicing at a pro car repairshop.
I don't throw my car away just because a problem comes up that I cannot solve myself.

Of course your Beogram can be repaired.
If you are in - or near - Denmark, I'd happily take a look at it.

Martin

I 2nd the non-trashing it approach (and if you still want to go that way i’m sure someone on here (myself included) would want to take dibs. Truth of the matter is you often need 2 units (one for use, one for parts) for anything in the 8000 series. Not only do you get spare parts, but they work as an in person roadmap for trouble shooting as well. I know it’s tempting to chase the dragon for the win trying to trouble shoot the individual boards/chips on these (especially a barn find) but they often cause more headaches than glory on what is already a rather idiosyncratic machine… trust me, I’ve been there- and if not me absolutely trust Martin’s post above, his opinion is the gold standard. If all of that hasn’t discouraged you I’d start looking on eBay (I know I know, but for their purposes it’s probably no harm). These have started to go from vintage to just old with an ever shrinking number of qualified service people in the last few years;  the parts unit market is reflecting this situation with whole units going for $100-150 (some even with cartridges) at auction. You  just have to keep an eye out. Any investment that stays under $250 and ends with a working BG 8000 will more than return its costs. Feel free to DM me if you want to walk through your current issues, there are a couple last ditch areas you can check I don’t see mentioned in your posts.

For many reasons I wish I were in Danmark to have someone who knows their way around it fix it but that is logistically impossible.  I feel lucky to have visited there 40 years ago.  Those memories will have to last the rest of my life.

As for this beogram 8000, I would have a better chance fixing it if the service information included scope traces and circuit description theory.  Today I hope to buy IC1 that is a quad op amp handling among other things the speed sensor from under the platter.  I got pulses going in and zero coming out.  It is a $3 part at my local store so the money continues to pour into this hole.

Hole?
Three dollars?
Honestly...

It's a general misunderstanding that a B&O service manual will tell you how to repair something.
It won't and it doesn't.
It tells you how the thing was built, it gives part numbers for ordering, adjustment procedures and a few hints here and there.
The rest is up to your technical education, and in this case also experience as this deck is not a good project for a beginner.

Please understand that it's neither the Beograms nor our fault, if you cannot repair your Beogram yourself.
Most of us here will do our best to help members in need with advice, guidance, ideas and perhaps even parts, - doing our
best - but we cannot take a guess at which part(s) you need to replace in this case, and we have no idea about the level of your skills.
Most likely, as I also told you in the PM, all of these decks will need a thorough restoration by now. There will almost certainly be several defective parts, broken connections and whatnots, often making it impossible to diagnose one single issue at a time.
When you have replaced the IC you may, or may not, have cured one issue. And with this cured, the next issue will become apparent. Working this way, it could take you two years.

Besides, many Beoworlders are located in northern hemisphere areas, - it's summer here, people are out and about, and the forum is very quiet.

And one more thing - and don't take this the wrong way, - I would like to help everybody the best I can, but
the "if you won't help me, I will throw it away"-attitude tells a lot about the lack of importance this job and the lack of value this Beogram has to you.
Surely, it won't see me upping my efforts.
My time will be better spent on something that will give meaning and value to someone.

As said before, Beogram 8000 is a great performing deck worth having repaired, or even restored, professionally.
Seeing as you are based in AZ/US, I would consider contacting one of the guys from Beolover.
What they charge I don't know, but most of these jobs usually end up in the EUR 300-500 range here,
and a well serviced Beogram, if also nice visually, can sell for up to twice that amount.

If you don't want to continue repairs, someone else surely will.

Martin

link

I would have a better chance fixing it if the service information included scope traces and circuit description theory.

Unfortunately, the service manuals often exclude any theory of operation" information. However, the datasheets for the individual chips frequently provide the needed information (or at least strong clues). It is common to see B&O using a reference design shown in the datasheet. This may or may not help, but is something else to try if you get desperate. Glitch