UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

ricard · 11th Jun 2019, 9:15 am

If the rec/pb switches have no tendencies to cause clicks and pops you most likely have one of the later serial numbers, above 220 9550, when they fixed the click and pop problem (only to have it return on the 1200X, 14 and 15). If so, congratulations are in order, as these seem rarer than the earlier versions. (Also, I'd be curious to know if the 1/4" connectors on the back are plastic or metal, as it seems the later ones have plastic connectors).

As for the amplifier troubles, the thing I'm thinking of is that since it's a stereo machine with two identical amplifiers and the amplifier PCB is easily accessible once the chassis is out of the case (and the metal shield covering the PCB has been removed), you could play a stereo tape with a known good balance between the channels, and use a signal tracer (another tape recorder in amplifier mode would suffice) to trace the signal through both amplifiers which should make it possible to pinpoint where the signal level drops.

I've had a couple of 12's over the years but haven't experienced amplifier problems other than tin whiskers in the driver stage of the output amplifiers, and the aforementioned rec/pb switch issues, so from my (limited) experience, I'd suspect a one-off component failure like a bad transistor or capacitor.

11th Jun 2019, 9:15 am	#2
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Tandberg series 12 If the rec/pb switches have no tendencies to cause clicks and pops you most likely have one of the later serial numbers, above 220 9550, when they fixed the click and pop problem (only to have it return on the 1200X, 14 and 15). If so, congratulations are in order, as these seem rarer than the earlier versions. (Also, I'd be curious to know if the 1/4" connectors on the back are plastic or metal, as it seems the later ones have plastic connectors). As for the amplifier troubles, the thing I'm thinking of is that since it's a stereo machine with two identical amplifiers and the amplifier PCB is easily accessible once the chassis is out of the case (and the metal shield covering the PCB has been removed), you could play a stereo tape with a known good balance between the channels, and use a signal tracer (another tape recorder in amplifier mode would suffice) to trace the signal through both amplifiers which should make it possible to pinpoint where the signal level drops. I've had a couple of 12's over the years but haven't experienced amplifier problems other than tin whiskers in the driver stage of the output amplifiers, and the aforementioned rec/pb switch issues, so from my (limited) experience, I'd suspect a one-off component failure like a bad transistor or capacitor.