TG1000 2-track DAMAGE CONTROL

Sämtliche Tonbandgeräte bis zum TG 1020
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helloradio
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Registriert: 19.08.2014, 22:06
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TG1000 2-track DAMAGE CONTROL

#1 Beitrag von helloradio » 23.08.2014, 21:14

Hi
Probably I should be impressed with people who designed Braun TG1000.
My second example of this tape deck had in the past mega crash, maybe with the metal or cement floor.
The damages to the metal box/shell look small but you can imagine how big was the impact just to bend the corner of quite thick and sturdy metal and the top of the reel plate was bent more than 45 degrees. The head of one bolt just snapped off because if the tension. The bottom silver plate, where all the controls are, was bend up tearing of one of the meters. Of course more gentle things like tension arm was bent, counter and play buttons were broken. It took me some time and effort to open the box, flat screw drivers, pliers etc.
In the very beginning i turned on and both reels were turning but no play function I was not aware back then of the physical damages, they were not so obvious.
Inside I found bulb from the right tension arm hanging on the wires and glass broken, belt off the capstan motor. there were some short and light cracks around the bolt of the relays board. After shaking the whole machine, pieces of glass, radiator of one of the transistors, metal plate cover and spring for playback head,
button for the counter and the head of the bolt all fell out. I put the radiator back on the transistor and turn the machine on. Both reels although noisy were reacting to push buttons. Play button clicked some contacts in the relay, but the capstan motor was not turning and pinch roller arm nor engaging. I found lack of continuity in one of the traces going to the power transistor. I also checked traces around the bolt. capstan motor, brakes pinch roller arm started to work. I tried to straighten up the lock on the reel plate but with no success so I cut it off. Now I could put the tape on and see if the mechanism works. I was very afraid that one or both winding motors have something bend and were of axis but to my suprise not. I fixed right tension arm (this was very easy) but not bulb yet. Capstan motor became very noisy surely needed some grease. I moved tape recorder a bit to check something else and capstan motor suddenly is not working. Remember the gentle cracks around the bolt? there ere micro cracks in the solder's traces not even visible withe the magnifying glass. I found them by accident pressing the board with my hand and later by checking with continuity tester over and over again. Next I was enjoying works of the mechanism moving tape back and forth many times. After a few minutes in play mode I see the smoke coming from inside. 100 Ohm resistor in power supply section was burning his paint. I exchanged the resistor and the transistor next to it because showed on the meter as dead. Again PLAY works, tried to listen to tape but why not to record and listen the same time, coming in sound has lots of loud hum. Another 5 minutes and another smoke from the same place. Checking output voltage, 36V instead of 24V! This time new 3 transistors and new resistor. Back with nice 24V. Capstan motor does not move! Brakes, pinch roller move properly. FF and REV ok. Now time for audio check I know electronics were tortured with 36V, not much hope.
NO hum, no noise, very clean sound on both channels coming into tape deck. Very nice. Capstan motor please, please start turning. I touched gently and feel only warm metal shell but no whispering back to me.

At this point I feel very helpless because I do not know how to track things connected to capstan motor
I hope that some transistor gave up so I can fix it. Following diagram in service manual makes me only dizzy and with no ideas.


Darius

wickerge
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Re: TG1000 2-track DAMAGE CONTROL

#2 Beitrag von wickerge » 24.08.2014, 11:13

Hello Darius,
I do not no how familiar you are with the TG 1000 controls in the mean time. But a simple reason could be that no tape speed is selected. The capstan motor runs at different speeds according to the selection at the three push buttons, and if none is pushed, it doesn't run at all.

Best Regards
Gerhard

helloradio
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Re: TG1000 2-track DAMAGE CONTROL

#3 Beitrag von helloradio » 24.08.2014, 11:25

hello Gerhard
thank you for the suggestion
I am aware of necessity of speed button being pushed in.
no reaction to speed button change.
I am just wondering why the capstan motor is slightly warm after few minutes.

Darius

ps. I do a lot of reading about TG1000, just very excited about my new toy.

wickerge
Braun-Spezi
Braun-Spezi
Beiträge: 1167
Registriert: 26.05.2009, 21:52

Re: TG1000 2-track DAMAGE CONTROL

#4 Beitrag von wickerge » 24.08.2014, 11:59

Hello Darius,
I am not very familiar with the TG 1000, but two ideas (getting warm indicates that the motor is getting power):
- is the motor mechanically locked? You mentioned abnormal noise when first running it
- is there a capacitor producing a phase shift? It is a common error on TG 60 motors that these capacitors are defect.

Best Regards
Gerhard

helloradio
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Jungspund
Beiträge: 23
Registriert: 19.08.2014, 22:06
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Re: TG1000 2-track DAMAGE CONTROL

#5 Beitrag von helloradio » 24.08.2014, 13:01

So the latest news.

When all 3 speed buttons are off the capstan motor moves freely if I turn it with my fingers
but with any speed button ON, I feel strong magnetic field and can turn it a little bit and it jumps about 2mm forward.

My guess is that maybe one of the transistors (BC340) attached to the motor is broken.
The motor board is in horrible place just near the DIN sockets for phono radio etc. and I am not sure if I have to take apart the bottom part of the tape deck or there is another way.

also I would like to measure voltages on the motor itself but how to do it between chassis and the wire on the motor or between two wires on the motor itself?
Darius

wickerge
Braun-Spezi
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Beiträge: 1167
Registriert: 26.05.2009, 21:52

Re: TG1000 2-track DAMAGE CONTROL

#6 Beitrag von wickerge » 24.08.2014, 14:20

Hello Darius,
I had a look into the service manual and the capstan motor seems to be a DC-motor, so no capacitor involved. The rotating magnetic field is created on a part called Kommutierungsplatte, which is part of the motor. So probably your guess with the transistors is correct. According to the service manual they are numbered T3001 - T3004 and are of type BC 302 - 6, which can be replaced by BC 340.

Best Regards
Gerhard

helloradio
Jungspund
Jungspund
Beiträge: 23
Registriert: 19.08.2014, 22:06
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Re: TG1000 2-track DAMAGE CONTROL

#7 Beitrag von helloradio » 27.08.2014, 18:53

hello
It took me some time but I could not find in my town the right transistors so in the end I decided
instead of BC340 put BD139 which I had in my spare parts. I thought that it will be big hassle to solder them because the have different pin configuration but in reality it was very easy. I checked all six transistors on the control motor board (by using hfe option on my multimeter. Two BC340 were broken.
Now the motor is running again.

Darius

ps. a few new problems but restoration will continue.

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