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
Tonight I fixed my BG 8000. It now works but I just notice it's missing the weight adjust slider that goes on the outside of the arm. So until I can get one of those I won't be able to adjust the speed of the up and down cueing. Other than that, it works fine. Ran it through all it's paces and all button work fine. It looks like the weight is still in the arm but just missing the outer plastic slider. Maybe I will try to set the weight with a tooth pick and with a sure VTF scale.
I resoldered the main PCB the other night. Tonight I resoldered all the wires that run to the MPU box and resoldered all the caps resistors next to the cable and on the other side. Resoldered the replacement cap and made sure it was connected ground properly and to the casing. I also reseated the CPU.
After all that I hooked everything back up and plugged it in and at first it briefly went back wards when it was plugged in to the AC Receptacle but there was no humming anymore and I noticed the table was in standby mode. put a record on and hit play and everything worked fine except from the arm dropping a little too fast.
Now I can fixed these tables! :)
If I can set the weight via the Shure VTH scale then I will try to adjust the lowering function.
I just wanted to say Thank You to everyone for their help and info!
Well done.
But I think that the problem with the arm dropping too fast has nothing to do with the weight. I have a Beogram 8002 with the weight slider in place - and the arm is also dropping too fast. I think that I once read in an older thread, that this could also be some electronic issue. However, I'm not quite sure about that, and hope that someone else who has repaired those Beograms can tell more about it.
Good job.
Regarding the set down speed of the tonearm, I don't see anything in the BG8000 or BG8002 service manual regarding an adjustment for that. Can anyone shed any light on that?
Hmm - I did a Little research in the archieved forums, and found this. As far as I can see, the problem was not solved - but there is an explanation of how it works.
http://archivedarchivedforum2.beoworld.org/forums/t/38670.aspx
Steffen: Hmm - I did a Little research in the archieved forums, and found this. As far as I can see, the problem was not solved - but there is an explanation of how it works. http://archivedarchivedforum2.beoworld.org/forums/t/38670.aspx
Thanks for finding that archived post. It's a good starting point. I have some BG8000 and BG8002 units in my backlog so I'll use the next one I work on to measure the arm lowering circuit.
Congrats for your repair... that deck is awesome!
Lately a similar problem appeared on my deck: The arm drops but there's a delay. and it drops like a brick! It does not happen all the time though.. I may think that the coil is doing it's job. But since winter came and with it the cold the dryness etc.. I think that the arm is only stuck where it is because of old greases or oil. The service manual talks about putting oil in the back of the tonearm, but I don't really figure out where exactly. I should have taken more photo of the back. Just to think that I have to open this deck again, for what is probably just a temperamental problem, gives me headaches !
As a complement of information, here's the article about the lifting and lowering of the tonearm. It's from the "Technical product information" of the Beogram 8000. I might upload the whole thing someday on this site.
Guillaume
NiceThanks Guillaume.
Hi Hamacbleu,
Thank You! It was a good learning experience for me. Also Thank You for posting this brief explanation on what this circuit is and how it works. That's all I needed to get me going.
I may add a .22uf or .33uf cap in parallel and see what I get as far as drop speed. I don't really want to open this table back up and take everything out to fix that part but will do it once and for all so I won't have to do this again. I suspect the resistors are out of tolerance but I will find out when I pull each one and measure it.
I didn't resolder the cable for the tonearm where I found that short. maybe I should have. I will resolder that on Saturday when I have some more time.
Hopefully I can get that tonearm drop working perfect this Saturday and sit back and listen to this table. This will be my Everyday table!
Make sure to take pictures :)
I have never been able to solve this particular problem on two Beograms.
I tried adding a capacitor four years ago to no avail. If the cap is too big (say 2uF) the relay never triggers. Too small and it has no effect.
Jacques
Hi Chartz,
Could you please explain what steps you did when you were working on that lowering circuit? Did you only change the cap or did you check out the whole circuit? maybe that sensor that is connected to the output line may be causing some of this issue/s. Maybe some of the resistors were out of tolerance, those can affect timing delay of the circuit. I will take a look at it with a scope and see exactly what the IC is doing and if the transistors are doing what they are supposed to.
The weird thing is out of all the YouTube videos on the 8000, 8002, and TX they all showed the same thing except for one or two tables that lowered slightly slower but not by much.
I'm just waiting for my 7 PIN DIN to RCA connector to come in so I can start listening to this table. I already set the platter height and VTF. I will be cleaning up the table and removing that old adhesive to put the new epoxy or 3M tape to hold the lid for the 45 adapter compartment and aluminum surrounding for the platter. Also I will try to epoxy the shinny metal underneath the cover below the tonearm. that's all I need to do.
Once I get it all set up correctly, I will do a side by side shootout with my Teres 255 table, ET-2 tonearm, and Shelter 901 cartridge and see how good the BO BG 8000 really is compared to the big boys of turntables with linear tracking arm. Should be interesting! :)
I saw the post on Vinyl Engine about how the Beogram 8000 totally kicked butt on the Technics SL1200. that says a lot!
Oh that old post of mine! I had forgotten! The techie was sold thereafter.
I checked every component around that circuit, I even replaced the op-amp, and yes I did play with the resistor too. All to no avail. But you are right, many decks on Youtube do show that defect. At one point I figured this could be an arm lubrication issue, but no, it is not.
Even Martin and Tim could not help, and that is saying a lot!
Wow, still couldn't get to work? Then this definitely a hard one! I will give it a crack and hopefully I can find what is going on. If this circuit worked properly when the table was new it should work properly again. The only thing that could change would be that moving coil or the other two circuits affecting it.
Now that you have used your BG 8000 with the arm dropping the way it is now, have you had any issues with broken stylus or cantilevers due to this fast dropping of the arm? I know it doesn't look good but if it not damaging the cartridge in anyway then maybe it's something I can live with.
I use that one regularly with an SMMC20EN
The funny thing is that it doesn't always drop. Sometimes - but seldom - operation is normal.
I just noticed that this schematic in this technical note is different from the circuit in my Beogram 8000 Service manual. Mine has R61 10k ohm resistor between R58 220K resistor and pin 6 of 1IC1. Also the supporting circuit is a little different too. So there seems to be different revision schematics and PCB's.
Well, the technical information brochures are very early versions of circuits. The various service manuals I've come across show the same values as in the production models.
You should not worry too much here.