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
G'day!
I have a 4002 that I've been slowly trying to fix, I managed to get a lot of it working but now i'm stuck :( Anyway the last thing i got working was the cool little B&o Light and it has inspired me to keep going!
So at the moment if I press Start, the needle will run all the way across the centre of the record. If I stop the needle at any point and press the button to lower on the record nothing happens.
https://vimeo.com/85705724
Any ideas?
Thanks,
Pete
There is a photocell in the B&O branded arm that senses if there is a record on the platter - the associated circuit can tell by the frequency of the ribs passing by the sensor as voltage pulses that acts a a blocking signal which prevents lowering of the arm on the platter. I suggest to measure that part; do you have the service manual?
Vinyl records, cassettes, open reel, valve amplifiers and film photography.
Thanks S øren, I just grabbed that and I'm having a look through, weirdly I can't seem to find anything on the photocell. Could it be "detector Arm Sensitivity"?
Could it be that the detector arm is not perfectly parallel with the platter? The light that shines out of the detector arm has to make a perfect round spot for the photocell to see it...( the photocell is right behind the light) It's just a thought, since if it's the case, it seems to me the the problem would be the opposite (ie, the arm always droping, even when there's no disc)
Okay great! there's something new happening now, another clue :) Looks like when I press the button to lower the needle it makes a little click sound. This only happens when there is a record on the platter so it must be picking up the record. seems like some part of the mechanism is failing.
heres a quick video showing the current state > https://vimeo.com/85791992
Loos like the clicking is coming form this mechanism (which feels kinda stuck actually).
That is the solenoid - when it fails, the arm stays up.
Peter
It sounds like a classic lubrication problem.
I suggest you study this:-
http://www.condoraudio.com/wp-content/uploads/Projects/BeoGram-4002-6000-Turntable-Restoration-Repair.pdf
Includes pictures of the lubrication points. You will need to dismantle the mechanism to clean out the dried lubricant. Just adding more oil is not sufficient!
Regards Graham
Great thanks for the link! I'll get to that and see how I go.
Hello,this is my first post here.I have the 4002 turntable in a shop now and the service tech informed me that my microprocesser is bad on the pcb and there is no way to replace it other than getting another table.Can anyone tell me if my table turns on and the tonearm travels across the platter and will even change speeds (from 33-45) but the tonearm will not drop onto a record,are these controlled by the micro? I would appreciate any info and advice.Thanks,Lawrence.
mietech55: Hello,this is my first post here.I have the 4002 turntable in a shop now and the service tech informed me that my microprocesser is bad on the pcb and there is no way to replace it other than getting another table.Can anyone tell me if my table turns on and the tonearm travels across the platter and will even change speeds (from 33-45) but the tonearm will not drop onto a record,are these controlled by the micro? I would appreciate any info and advice.Thanks,Lawrence.
Are you sure you are talked about a Beogram 4002? The Beogram 400x turntables were prior to the age of microprocessors. The Beogram 8000 and 8002 turntables do have processors.
-sonavor
sonavor,that is what I thought too.The tech told me that this cpu controls the logistics of the 4002.I don't know if he really knows what he is talking about or he is pulling my leg.He may have even damaged the pcb and wants me to pay for it.I just wanted some more info on my situation with my table. Thanks again,Lawrence.
The tech doesn't know what he is doing then. The 4002 is not controlled by a processor.I recommend you find a Beogram 4002 service manual for the "type" 4002 that you own. Even though you don't work on it yourself, it would be good to get better familiar with it. Beoworld has the manuals online for Silver level membership and above. What is the type of 4002 you have? The type is specified on a sticker underneath the turntable usually.
Thanks sonavor,my type is 5523 and I do have a manual.I got the manual on Ebay.I have looked through it.I have a lot to learn about electronics.I did remove the pivot axle from the dampner valve today and clean it from the dried grease and relubed and reassembled that. It seems to work a lot smoother but the tonearm will not drop.I see it working and hear the click sound but that's it.Thanks for the info.
Is that with or without a cartridge mounted on the tonearm? Check the balance of the tonearm and the control lever for the tonearm.I posted some Beogram 400x information here. Have you checked Beolover's blog on his Beogram 4002? He has links to it in this thread.