thomash
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Thank you Glitch for this advice. Meantime I sliced the front off this cartridge where the cantilever had broken off. Surprise surprise it is the same structure as the old SP6 with a little X stuck on rubber block and the cantilever secured to the X. The pole pieces are in a block of green rubbery stuff but they made this as a sealed unit unlike the old SP6 where the front comes off and gets replaced. If I can make a tiny X and secure a cantilever n needle to it, I can mount the X on the rubber and this thing will still work. If I touch pole pieces with ferrous tool, the speakers thump left n right. X structure n cantilever on SP6 is much too large to cannibalize otherwise I would buy one and get it on here somehow. If somebody made it farther than I have already, thank you for tips.
Mark I have multiple reasons for attacking this machine. It came to me only because owner had found it in junkpile from two generations ago deceased relatives and was ready to toss it in garbage. I stopped him and began what has now been a 2 month project. Mostly I wanted to prove a point: making an amazing old thing work again is a test of skill and analytic ability. Even if the old thing has been rendered obsolete. Right now the crude grafting of a needle to the generating member of the cartridge is working well enough to continue concept testing. It would be nice to find a OK lower end cartridge with intact needle for this at a cheap price out of dead broken machine. I would use it on one of my analog home systems as a gee whiz conversation piece.
I get that people’s intentions might be good and I hope mine are too. Words on a screen can be misinterpreted and I am sorry for mischaracterizing anyone.
Yesterday I did manage to get correct speed to go along with previously fixed power supply and arm control and muting problems. I did this piecemeal myself using only DVM and scope and general circuit advice theory from people not on this forum. A generic opto device from amazon is now in place held by a bread tie. IC3 and IC1 are new with sockets; the other ones are OK so far. My old ones might be OK; I replaced them being unsure of observed failures which turned out to have other causes. A couple dozen capacitors have been replaced as well. So I should be doing cartwheels.
The sapphire shank n stylus came to me broken with just a stub poking from cartridge. My first attempt to super glue a needle on resulted in poor sound and my second attempt to super glue a better needle on ended in disaster. My three choices are pay insane stupid money for replacement, cut this cartridge open with a dremel tool and try again to glue a stylus n cantilever on or adapt a lightweight small generic cartridge to the existing connections.
I fully expect to be talked out of two of those ideas but am all ears. Thank you.
It does not help matters when this machine has numerous modifications and changes not reflected on the meager service material more withheld than made available by B O. I am not a rich person and my skill level cannot be magically altered overnight so the insults ridicule and lecturing are not constructive. Thank you to the people offering ideas in a pleasant way and no thank you to the people who are going out of their way to attack me. Please stop doing that. I do not revere bang n olufsen. I tolerate it as a curiosity. I have fixed radios and tape recorders and amplifiers and television equipment on the job employed at TV stations. I fix stuff in people’s living rooms including turntables; stuff that was made in the old ways and with ready access to the connections. This thing is a rubik’s cube modified by rube goldberg and that is being charitable. Where does it say that devotion and adoration toward B O is required for membership here? Meantime I will continue to let myself be nickel and dimed with chips and sockets and transistors and capacitors in what I hope becomes a less quixotic adventure, not more.
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.
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.
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.
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.
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.
Hello: Hope OK to ask for help with a 8000 someone gave me out of a shed. I spent days getting new electrolytics in and reflowing solder joints on connector junctions and replacing the < > light bulb and rebuilding the lift plunger. It worked for a few hours then I lost +15 and the platter now spins wildly fast nothing will stop it. I even injected external +15 and regained some control over all the machine except platter speed which is like 100 rpm! The tacho wheel lost some of its traces which I drew back on and the IC is reading some pulses but still speed is utterly unregulated. Thank you for weighing in.
Hello: Adding to this as things happen; none of them good. I have lost +15V after I nearly had the thing working all correctly. The regulator has +20 going in, +20 on the base to Q18 but zero on the collector output. I am trying to learn how this is supposed to work but baffled. Can I temporarily just send the output of the bridge directly to the load with main power coming up on variac? Thank you.
At the risk of talking to myself, I submit for those interested that I got some response by crowbarring DC supplies into the beogram8000. I used two 9V in series and backwards for the NEG 15 plus a wall wart for the 5V and a regulated adjustable supply for PLUS 15. It now lights up on the display board with 0000 and the arm lights are on. It is pulling 18W from the wall on its own PT. I disconnected the three supplies before sticking my alligator clips in. This is somewhat encouraging so I might buy some electrolytics and see what happens then. Thank you.
In fact last night I DID remove the relay and determined what is what and am confident I now have the wires right. My plan is to just run the cartridge wires straight out the bottom and bypass the relay. Wonder if anyone out there has a main board available? Might be easier than trying to make this one wake up.
Thank you Glitch for image and info. There seem to have been changes though as my audio shields were in the center with hot L and R on either side. Right now having trouble figuring out the relay coil pins for the brown wire. Blue gray and black all seem to be ground but still in the dark as to the layout of this board.
I got the entire machine dismantled to expose the main board for service. In the course of tear down, the wires on the DIN connector have nearly all come off. I have studied the diagram of the plug and its little board but would like to see image of intact one or what the colors are in order starting with blue on far side. The diagram is far from clear and does not give colors. I did make a parts list of 12 electrolytics to get as starting point.
Hello Premiumverum and thank you. Glad to know no jumper needed on DIN connector. The second fuse on secondary side was not blown, only the one on primary side. My idea is to put external regulated supply to the main bus from outside just to see if the uProc will wake up. I have not yet exposed that panel under the buttons but hope to get at it from there. If I can get power to everything, then try volts at Q21 which seems to be main turn on command from the uProc. I fix vacuum tube vintage stuff but do not enjoy working on anything solid state.
