Tandberg series 12
 

Just got one of these from Ebay.
Its in worse condition than I thought it was ! There are a number of missing parts - most of which I can deal with - screws and spacers.
Channel one did not playback …
The big problem is the ground connection broke off the 1-4 head ...it just fell off, not just the soldering but the entire connection.

I'll have a go at trying to solder it back but might be looking at getting another head.
Strangely the drive belt is okay!!

I have downloaded the service manual and circuit diagram.
Regards Paul

Re: Tandberg series 12
 

Tandberg made a design change to the 12 at serial number 2209550; prior to that the record/playback switch is an absolute beast to get to work properly, with intermittent connections and pops, clicks and scraping sounds as a result. It's not easy to get at either which makes renovation even more frustrating.

Re: Tandberg series 12
 

Yeah...…. I've gotta get that pcb out so I can clean the assembly... not looking forward to it ..
attempted to re-solder the wire to the 1-4 side of the head - no go, so may need another.
Bass / treble knob is also missing
Regards Paul

Re: Tandberg series 12
 

The bass and treble knobs are the same as on the models 1200X, 14 and 15 if that's any help.

Re: Tandberg series 12
 

See this recent thread. Had to fix one of these with very low output on one channel.
Incidentally I m now working on a somewhat bruised series 15 and the treble pot has had a knock, fortunately the wiper, track pcb, knob, thrust washer and shaft are there. Just the silver rear plate is missing so it falls to bits! I mention this as you may be able to reconstruct yours if all the bits are inside the machine.

Re: Tandberg series 12
 

Got the pcb out to clean the rec-pb-amp switches .. took loads of pics of the wires and where they go....

Re: Tandberg series 12
 

Does anyone have any more pics of the wiring of a Tandberg series 12?

Re: Tandberg series 12
 

I've plugged the rec/play pcb back in...…. so it's now silent ...I don't know if I have the switches clean enough yet or if I've reconnected a wire wrong....
****** typical..

Re: Tandberg series 12
 

See also PM.

By the way, forgot to ask, is there output from either of the rear line out sockets?
No output from speakers could be loose spade connectors (wire is very short on these as you will have seen) or broken wire on selector switch.

Re: Tandberg series 12
 

Good idea …...I'll check that - Paul

Re: Tandberg series 12
 

I have number 2207247.....

Re: Tandberg series 12
 

Problems found so far...…. playing back a known recorded on tape...Silence on channel 1, very quiet on channel 2. Switching channel 2 to amp allows very quiet channel 1 to be heard. Swapping speakers proves both work...

Switching to record makes channel 1 level indicator come on when the joystick is pushed into play …. channel 2's remains unlit.

Fuses test both okay …. speaker select switch appears to be okay....
Then lunch time ended ..
Regards Paul

PS i'm still not sure the famous slide switches are not clean enough yet …. I've used light sandpaper, flux remover and acetone so far

Re: Tandberg series 12
 

27volts are present, power amp hums when input is touched, other amp is still silent....

Re: Tandberg series 12
 

One of the amp PCB's has zero output ...anyone out there has any hints or tips on faultfinding……

Re: Tandberg series 12
 

From my experience, tin whiskers in the driver transistors is a fairly common problem, which causes the respective speaker output to go completely dead.

I've successfully cured this (at least for a while), by removing the respective transistor and 'zapping' it with 10 volts between the three leads connected together and case, as is a customary remedy. The whiskers will grow back eventually, but it can take several years.

Unfortunately, both the mechanical mounting and design of the heatsink arrangement make it a bit of an undertaking; I seem to remember the power transistors need to be desoldered before the heatsink for the driver transistors can be removed so the driver transistors can be got at.

Re: Tandberg series 12
 

ahhhh you mean the AD150 matched pair..... I have a matched pair of AD149's from a series 15.... rather than bothering to fix them, I'll just swap them over....
Regards Paul

Re: Tandberg series 12
 

well that was a waste of time …...no change

Re: Tandberg series 12
 

No, I was thinking of the AC127/AC128 pair in the driver stage just before the output transistors. They are mounted on a small heatsink; I can't remember if it's freestanding or bolted to the same heatsink as the output stage.

Re: Tandberg series 12
 

ahhhh those ones ......funny though I found a direct short on one of them from connection to body ...all other did not have this!!!! Ido have some output now but as the PCB only has volts and speaker connected I'm not sure you'd get an output without the treble and bass controls wired in
Regards Paul

Re: Tandberg series 12
 

Yep, that's the typical symptom. Since the body is in contact with the heatsink which is not floating it causes a short circuit which silences the amplifier.