I've still not found a solution. I'm jumping between the BM1990 and BM2400 Service manuals. This unit has the BM2400 main PCB, but BM1900 small PCB's, so it must have been one of the first BM2400's made. I disconnected the preamp one channel at a time, and the spike remained on the other channel. So it's not from the preamp section

I've done some tracing with the scope, but it's not conclusive. At all these points, with the scope set to AC - 20mV - 10ns, on the sine wave display, the tiny bump when switching UP, and the large jump when switching DOWN, is clearly evident. Components in (brackets) depending on PCB versions. I started on PCB3 at 3TR6 (3TR29) - voltages are

Hi all, I have just finished restoring a BM2400, almost identical to the BM1900. Complete recap, driver transistors, some diodes, etc. Full writeup to follow. All adjustments according to the Service Manual. There remains one problem. See the picture below. The is a momentary (1/2 second) worrling gargle when switching between the FM presets, in a certain

Hi Danny Check this page http://www.electronics2000.co.uk/pin-out/dincon.php Scroll down to the Phono/Aux diagram You can see that 3 pins are connected: Pin 2 - Earth, Pin 3 - Left channel, Pin 5 - Right Channel If you know how to solder, great, otherwise take this diagram to your local service center, and have them solder it for you. Menahem

Eugene I forgot to mention - the idle current adjustment is 12mV across ONE of the 2 Bias resistors on each channel. First set when cold, at lowest volume without speakers connected, and then play at reasonably high volume for 10 minutes thru speakers. Disconnect the speakers, set lowest volume, and readjust again for 12mV. Good for you that you support

OK, if you have no output voltage at the 7812 voltage regulator, it's clear that it's shot. Now, it's a simple thing to replace a voltage regulator, but before doing that, you need to determine WHY it failed. These voltage regulators do not fail willy-nilly. Assuming that the solder joints on the underside of the little PCB are OK, there

Eugene I'm glad to hear that! Can you tell us what the problem was, how you identified it, and how you fixed it? I'll be more than happy to help you out with the trimmers - I have good stock of the Bourns Cermet trimmers which you need for this BM3300. Do you want only the Amp Bias trimmers, or all the trimmers for the unit? Send me a PM to

Stewart, That solenoid is THE key to getting the whole operation started. Even if it feels that there is no noticeable friction, there still may be more friction than the magnetic field is able to overcome. Have you got "Silicone spray"? No WD40 or any other petroleum-based stuff!!!! Follow paragraph 5 about the spray. Reassemble the solenoid

Hi Stewart, Please download this article, go to Section 5, and follow the instructions exactly. Well-known manufacturing defect, with a cure! http://www.condoraudio.com/wp-content/uploads/Projects/BeoGram-4500-Turntable-Restoration-Repair.pdf Let us know how you get on. Menahem

Eugene I see that the rectifier diodes at the top, are not of the same type. I would recommend that all 4 diodes in a full-wave bridge are exactly the same. Here I would recommend 4x UF4007 silicone, or 11DQ10 Schottky's. Not to be rude, but NTE components are not always high-quality. I see that you use a lot of NTE in your repairs. A lot of their