Hi all

Firstly big thanks to the forum, it's posters and especially Dillen. Thanks to you guys I have managed to fix BG 4000, BG4002 and a Beomaster 8000.

Back to the Beogram 4000. I bought it four years ago from ebay (faulty for £20!!). I had already fixed one 4002 so armed with the manual from here and reading the posts I brought it back to it's glory. I had worked well until about year ago it started to act bit crazy.

Tracking servo is erratic. With turntable on after few minutes (from 1min to 30min) the DC motor starts to twitch. Measuring from the motor leads I get voltage spikes both positive and negative. This normally ends when motor suddenly pulls the arm on full force to the middle ignoring the return switch. If record is on it pull the needle across the record making a horrible screetch. Motor keeps pulling on full force until power is cut. This eventually burned the H-bridge transistors on the boad, causing motor working only one way.

Thanks to Dillen's expertice and repair kits I changed all the caps and the H-bridge transistors. All is running better than ever, but still that twitching motor still persists with occasional fullforce pulling of the arm to the center. Don't dare to put record on before I got this one fixed

Problem most surely lies on the board where the H-bridge is.....then again could be also on the tracking control. I have been trying to measure/look/smell/probe/resolder but can't seem to pinpoint the problem. I have done all the tricks on the manual.

Does anyone have any ideas what might cause this problem or what to check?

Cheers guys!

-petri