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

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Old 21st Aug 2009, 5:57 pm   #101
julie_m
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Default Re: Beloved Tandberg Series 15

Well done and a from me, too.
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Old 21st Aug 2009, 6:02 pm   #102
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Default Re: Beloved Tandberg Series 15

Could this also have cured your missing track?

Colin.
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Old 21st Aug 2009, 6:06 pm   #103
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Default Re: Beloved Tandberg Series 15

Yes , missing track now back!!!!

I've un-bolted the assembly, found one black ground wire loose hanging there.
now I've just got to find out where it goes....
Paul
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Old 21st Aug 2009, 9:41 pm   #104
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Default Re: Beloved Tandberg Series 15

Excellent Paul!
Glad it's sorted now.
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Old 22nd Aug 2009, 12:43 pm   #105
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Default Re: Beloved Tandberg Series 15

I don't suppose anyones got a full service manual for this model?

I'm getting to a point where it's dismantled totally, the boards are out, the track switch is out and think I may need a assembly drawing to put it back together!!!!

Paulus.d
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Old 22nd Aug 2009, 1:57 pm   #106
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Default Re: Beloved Tandberg Series 15

You'll be fine, it's just like a big jigsaw puzzle.

BTW, taking digital photos as you dismantle is a useful thing to do

Nick.
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Old 23rd Aug 2009, 1:54 pm   #107
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Default Re: Beloved Tandberg Series 15

Thanks Nick!!! LOL...

Joking aside, I did take photos so I should be OK. I'm just a bit tied up now with Little shop of horrors - I'm the plant puppeteer! So it might have to wait until Tuesday to get finished...Boo..Hoo! I'm taking a chance to re-wire and tidy up with some nice cable ties.

All I can say is thank you to all who have guided this project - you know who you are!!!!
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Old 23rd Aug 2009, 3:52 pm   #108
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Default Re: Beloved Tandberg Series 15

Great news!
I had a similar moment with a telly the oter day I was on the verge of scrapping - one duff transistor worth pence saved the set.
congratulations

PS. AFAIK I just have the schematic, will see if I have the full manual though.
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Old 24th Aug 2009, 7:00 pm   #109
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Default Re: Beloved Tandberg Series 15

Are you ready for this

If so, we'll proceed...

Spent all today carefully putting the unit back together - the new PCB's weren't indentical but a little reworking here and there, mostly in soldering wires directly to the boards because they had no connectors like mine. Anyways, all fitted - switch on - slight thump on power up - slowly raise the volume - no hum,no B-B-B, just a nice hiss (panic quick check to see if it's in AMP - NO).
Thread tape - press play - GO!!

Music comes forth...

Problem gone.

No , wait!!!!! New fault

As you raise the volume the volume lowers near the top end, then if you back off the treble volume increases to full. As I was panicking, I wiggled some wires near the track switch then 1-4 came on full volume, beautiful sound!!! but 2-3 no... took the track switch out, dismantled it, cleaned it, put it back now 1-4 gone low again, wiggling it to no luck stayed low. Switched the Pre-amp board back to mine - no luck.

I suppose it's 80% fixed.... 1-4 ok, 2-3 ok, but volume drops as you increase the volume?

I should check the solder joints on the Power amp PCB...and the wiring....and the voltages.....

Regards Paul

Last edited by Brian R Pateman; 24th Aug 2009 at 9:27 pm. Reason: Language!
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Old 24th Aug 2009, 9:37 pm   #110
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Default Re: Beloved Tandberg Series 15

Hi Paul,
Well, I think there's a possibility you may have some HF oscillation, which is killed when you reduce the treble. Does the volume level come straight up at one point on the treble control as you turn it?
Bearing in mind the volume came up when you moved the head wiring, I think the base concern is still with the track switch wiring.

Good luck!

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Old 25th Aug 2009, 10:39 am   #111
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Default Re: Beloved Tandberg Series 15

Yep thats how it seems to me - as treble hits lowest, volume suddenly seems to increase.
I did unsolder the 1-4 wire from the track selector switch and solder directly to pins 21,22 and 23 on the pre-amp pcb, bypassing the track selector entirely - but this made no difference. I also swapped back over the pre amp board - this made no difference either, if fact it was worse!!

I'll swap the Amp board this morning, then I'm off to hydrotherapy this afternoon.

Regards Paul
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Old 25th Aug 2009, 1:20 pm   #112
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Default Re: Beloved Tandberg Series 15

Swapping the amp board cured the problem just reported BUT brought back the motor-boating fault. At least I know now the motor-boating was my origional Power amp board....

Swapping these boards also changes the rectifier as one of the pcb's has a rectifier fitted to it - meaning my board has the separate rectifier...I have changed this rectifier too.

The power amp board sent to me by ilikevalvesme must have a fault too.

Regards paul
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Old 25th Aug 2009, 5:36 pm   #113
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Default Re: Beloved Tandberg Series 15

Which board is to be used with this machine and what has been changed on it. I'm a little confused and would like to know what's what before we go any further.

Cheers,

Steve P.
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Old 25th Aug 2009, 7:38 pm   #114
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Default Re: Beloved Tandberg Series 15

No problem, Steve!!!!!! It's called catching up!!!!!!
It's OK - I've just got back from hydrotherapy and it seems they've washed my brain!

'ilikevalvesme' sent to me a pre-amp, power-amp boards, a VU meter and transformer. The boards were a little different, mostly in being hard-wired to the pots and some minor circuit changes, however they did seem to have had 100% caps replaced.
I started by swapping the Pre-amp board - No change, perhaps slight drop in volume.
I then swapped the Power-amp board - still no change (I must have not noticed but there WAS a difference)
Then the transformer - Still not much change until I pushed up against the track switch then bang - normal operation on track 1-4. Stripping the deck I removed the track switch to find a black wire adrift.Finding where it went put 2-3 back in operation.

Then put the whole thing back together.

Just then a new fault was found - the motor-boating was gone but as you turned up the volume, the volume goes down!!??! Backing off the treble control made the volume go back up to norm.

So I swapped the boards around again, thinking the black wire off may have been the cause of the motor-boating and that the new fault was on the board sent to me by ilikevalvesme. Swapping the Pre-amp back was rubbish - that board is crap! swapping the power-amp board back brought the motor-boating back.

Ok? now here's the good bit!

Replacing everything back in - the new boards- all gets it back to the weird volume thing. Then a new message -

Hi Paul,
Well, I think there's a possibility you may have some HF oscillation, which is killed when you reduce the treble. Does the volume level come straight up at one point on the treble control as you turn it?

Made me think - where would you get HF oscillation?? on the erase head!
So I unsoldered the erase head wiring at points 26 & 27 and Bang - total normal, loud,clear music FINALLY.

Conclusion - the erase head bias is shorted to the play heads somewhere...from the Head to the track switch, because I've also wired the 1-4 head directly to the board and still had the fault. It must be the broken little bias pcb behind the head.....it had snapped off from the lugs that hold it in to the deck. I did check it to see if it had snapped off a connection or grounding point but no.

Anyway, I like to waffle and this is a record post for me!!! please give me your input. I'll be gone a bit of time now as Little shop begins tommorrow so will only check at night.

Regards Paul

Last edited by Paulus.d; 25th Aug 2009 at 7:57 pm.
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Old 1st Sep 2009, 10:58 am   #115
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Default Re: Beloved Tandberg Series 15

Hydrotherapy this afternoon to work out the stiffness after the Little shop plant job..so looking forward to the increase in brain activity and finally fix this thing!
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Old 3rd Sep 2009, 7:35 pm   #116
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Spent all afternoon checking the head wiring and the track change switch. Reassembled and switched on to test and......buuummp then silence. Every time you switch on you get bbuuumpp. No play-back. I really wish I'd have not brought this machine now... It seems you just get one and it works anymore...
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Old 3rd Sep 2009, 7:38 pm   #117
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Default Re: Beloved Tandberg Series 15

Do you get anything using it as an Amp only?

Check your wiring - it might be something silly you have done or a wire off. I think that track switch is to blame for a lot of this.

Cheers,

Steve P.
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Old 4th Sep 2009, 11:41 am   #118
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Default Re: Beloved Tandberg Series 15

Yep, you're right. Track switch wiring is all dry joints, broken wires and badly damaged. The actual wafer switches are OK but the wires are shot. This doesn't have any bearing on the new fault though it does it with the track switch not connected.

Does anyone have a diagram for the track switch? the circuit diagram is that clear as far as the track switch is concerned. The only alternative maybe to convert the machine from four track to two track? or devise a new method for switch over?

Lets get the boards working again and then decide...

regards Paul
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Old 7th Sep 2009, 3:20 pm   #119
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Default Re: Beloved Tandberg Series 15

you were right Steve - forgot one ground wire so the power amp was not grounded at all!!!!

OK - still when I connect the erase head, the playback volume goes right down. It's nothing to do with the track switch - the heads are connected straight to the pcb.
Could something be stuck so that the bias frequency is perminently on?
regards Paul
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Old 7th Sep 2009, 3:34 pm   #120
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Default Re: Beloved Tandberg Series 15

Head switching, or try adjusting the bias adjustment. Note where it was first though!

Cheers,

Steve P.
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