UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players

Notices

Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

Reply
 
Thread Tools
Old 10th Jul 2019, 3:39 pm   #1
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default 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
Paulus.d is online now   Reply With Quote
Old 11th Jul 2019, 8:44 pm   #2
ricard
Octode
 
ricard's Avatar
 
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,334
Default 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.
ricard is online now   Reply With Quote
Old 12th Jul 2019, 4:05 pm   #3
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default 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
Paulus.d is online now   Reply With Quote
Old 12th Jul 2019, 11:43 pm   #4
ricard
Octode
 
ricard's Avatar
 
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,334
Default 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.
ricard is online now   Reply With Quote
Old 13th Jul 2019, 12:46 am   #5
ben
Dekatron
 
ben's Avatar
 
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 5,377
Default 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.
__________________
Regards,
Ben.
ben is offline   Reply With Quote
Old 15th Jul 2019, 3:56 pm   #6
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default 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....
Paulus.d is online now   Reply With Quote
Old 24th Jul 2019, 10:23 am   #7
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default Re: Tandberg series 12

Does anyone have any more pics of the wiring of a Tandberg series 12?
Paulus.d is online now   Reply With Quote
Old 25th Jul 2019, 2:15 pm   #8
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default 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..
Paulus.d is online now   Reply With Quote
Old 26th Jul 2019, 10:46 am   #9
ben
Dekatron
 
ben's Avatar
 
Join Date: Aug 2006
Location: Madrid, Spain / Wirral, UK
Posts: 5,377
Default 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.
__________________
Regards,
Ben.
ben is offline   Reply With Quote
Old 26th Jul 2019, 11:14 am   #10
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default Re: Tandberg series 12

Good idea …...I'll check that - Paul
Paulus.d is online now   Reply With Quote
Old 26th Jul 2019, 1:06 pm   #11
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default Re: Tandberg series 12

I have number 2207247.....
Paulus.d is online now   Reply With Quote
Old 26th Jul 2019, 2:06 pm   #12
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default 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
Paulus.d is online now   Reply With Quote
Old 29th Jul 2019, 2:07 pm   #13
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default Re: Tandberg series 12

27volts are present, power amp hums when input is touched, other amp is still silent....
Paulus.d is online now   Reply With Quote
Old 5th Aug 2019, 2:03 pm   #14
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default Re: Tandberg series 12

One of the amp PCB's has zero output ...anyone out there has any hints or tips on faultfinding……
Paulus.d is online now   Reply With Quote
Old 5th Aug 2019, 8:03 pm   #15
ricard
Octode
 
ricard's Avatar
 
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,334
Default 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.
ricard is online now   Reply With Quote
Old 6th Aug 2019, 9:12 am   #16
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default 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
Paulus.d is online now   Reply With Quote
Old 6th Aug 2019, 1:22 pm   #17
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default Re: Tandberg series 12

well that was a waste of time …...no change
Paulus.d is online now   Reply With Quote
Old 6th Aug 2019, 2:37 pm   #18
ricard
Octode
 
ricard's Avatar
 
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,334
Default 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.
ricard is online now   Reply With Quote
Old 6th Aug 2019, 7:35 pm   #19
Paulus.d
Pentode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 248
Default 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
Paulus.d is online now   Reply With Quote
Old 7th Aug 2019, 9:45 am   #20
ricard
Octode
 
ricard's Avatar
 
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,334
Default Re: Tandberg series 12

Quote:
Originally Posted by Paulus.d View Post
... I found a direct short on one of them from connection to body ...
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.
ricard is online now   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 4:48 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.