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 experts,
my name is Dirk and I live in Germany near to Berlin. I purchased a Beogram 4000 not too long ago which worked nearly flawlessly the 10 first records I used to test the player. Then a problem occured, the solenoid for lowering the tonarm began to hum after pressing ON an the arm reached the record, but the arm did not lower itself. This fault didn't show everytime I tried to play a record but around 60% of my trials. Then it became worse and the arm didn't lower anytime.
I got me the service manual, but I have to say that I am not very experinced in electronics. At first I checked all mechanical adjustments, and saw that everything seems to be ok. the solenoid and the damper do not stick and are not blocked, If the rod coming from the solenoid is supported by hand, the arm lowers, and stays in the groove and the hum is gone. The illunination of the B&O Logo dims, when the solenoid is humming. If you press the tonearm movement buttons the arm lifts and the humming begins again if you release the button.
I checked the manual and found 0TR4, 1TR10 and 1TR11 as possible faulty parts. I ordered these transistors and replaced them yesterday but the player does behave the same as before.
I measured the voltage between C and E of 0TR4 with the player plugged in but out of operation, it was around 36V.
My equipment is poor, I have a DMM but no other measuring device. Now I am helpless and hope some one can assist me to find out the cause. Any help would be appreciated.
Thanks for your help in advance.
Dirk
Hi Dirk and welcome to the forum. Research these links on the Beogram first - Beogram 400x Project and Beolover's Beogram 4000 Blog. These turntables can have a lot of interesting issues. There are a lot of key mechanical and electro-mechanical adjustments to get in order. Those are usually the first suspects in the Beogram faults. If you intend on restoring the Beogram yourself I recommend going through each section and learning what everything does. It is well worth learning though and you will be able to keep the turntable operating at its best for years.
-sonavor
Sounds as if the solenoid doesn't get the activation voltage but merely the holding voltage.
Martin
Yep, fixed it. It was the leaf relay near the solenoid, the contact leaf had not enough tension to close the contact tight. Cleaning it and bending the leaf was the solution. Thanks to forum and especially Jacques and his anwer in the thread "
Now the arm lowers fine!
But I have a second problem:
The arm doesn't stay in "up" position, if you release the "Up"- button the tonarm lowers. The down button semms to be out of function.
Any thoughts.
Update:
The leaf relay doesn't work reliable anymore, I would like to change it. Are these available as spares or did someone replace them by modern parts.
Best regards
not that i know of but its quite simple mechanism and if you clean and use a fiber scratch pen you should be able to get it reliable again, the one on my beogram was broken in two when i got it but some araldite and some wires to replace the broken pcb traces and now works perfectly
Alistair
Thanks Alistair,
fixed it. Soldered the contactleaf out, brushed it with a fiber pen. Bend the leaf and soldered it in under tension....now it works perfectly. Did the same with the contact-springs in the tonearm-control "button", now the tonearm remains in the up-position until you press "down" - as it should.
Everything fine.
Best wishes