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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 4th May 2020, 5:42 pm   #61
Paulus.d
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Default Re: Lockdown project - Sony TC-200

Hi guys , been to work today so just got back to it....Thanks for the circuit drawings ...that really helps loads.
Paul

Last edited by Paulus.d; 4th May 2020 at 5:47 pm.
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Old 4th May 2020, 5:59 pm   #62
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Default Re: Lockdown project - Sony TC-200

Quote:
Originally Posted by ms660 View Post
Next, in playback with the fault condition present check the voltages on V101 and X101...

V101 anode (pin 6) screen grid (pin 8) control grid with volume control turned up (pin 9) and cathode (pin 3)

X101 collector (junction of R105 & C104) base (junction of R104 & R103) and the emitter (junction of R107 & the +ve of C103)

Also determine whether the pre-amp transistor (X101) circuit is the early type (germanium transistor) or the later type (silicon transistor) as the expected voltages are different.
Can we assume that the Rec/Pback switch contacts are clean and making contact and that the tape path's ok?

When measuring the base and emitter voltages you need to know to at least one place after the decimal point on the meter, eg: if say on a higher range the meter says 7 volts but on a lower range it says 7.12 volts it's the lower range meter reading that's of interest.

Lawrence.

Right , I have possibly mixed up X201 for X101 .... so the OC140 is X101...

The readings are ....

Collector ...8.5v
Base ...8.8v
emiter..9.3v
Paul
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Old 4th May 2020, 6:04 pm   #63
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Default Re: Lockdown project - Sony TC-200

JUst for my own information I compared x201 with x101
collector 9.6v
base 13.8v
Emiter 9.6

The bases are different..
Paul
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Old 4th May 2020, 6:29 pm   #64
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Default Re: Lockdown project - Sony TC-200

Quote:
Originally Posted by Paulus.d View Post
Right , I have possibly mixed up X201 for X101 .... so the OC140 is X101...

The readings are ....

Collector ...8.5v
Base ...8.8v
emiter..9.3v
Paul
The transistor (X101) is a germanium type so the pre-amp circuit values should be as per the 1st schematic.

With transistors the emitter voltage should always be less that the base voltage and in the case of germanium types by approx. 0.1 to 0.2 Volts (approx. 0.6 Volts for silicon types)

As a final check, with the fault condition present measure the voltage between emitter and base of X101, -ve black probe to the emitter, +ve red probe to the base, do the same for X201 as a matter of interest.

Lawrence.
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Old 4th May 2020, 7:56 pm   #65
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Default Re: Lockdown project - Sony TC-200

x101 Emiter and base - .12 v X201 about the same.
Paul
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Old 4th May 2020, 8:29 pm   #66
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Default Re: Lockdown project - Sony TC-200

I would replace the transistor.

Lawrence.
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Old 4th May 2020, 8:39 pm   #67
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Default Re: Lockdown project - Sony TC-200

If I switch the transistors... then that should do the trick...
Are the original ones still available?
Paul
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Old 4th May 2020, 9:18 pm   #68
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Default Re: Lockdown project - Sony TC-200

That depends if the other transistor is ok or not and whether or not the transistor in Ch1 is faulty.

I don't know if the originals are still available, a quick search will usually prove yes or no.

Lawrence.
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Old 4th May 2020, 9:28 pm   #69
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Default Re: Lockdown project - Sony TC-200

Can be difficult to find these very old Germanium transistors, especially for a reasonable cost.

Would be worth asking the Forum on the "Sets, Parts and Service Information Wanted".
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Old 4th May 2020, 9:44 pm   #70
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Default Re: Lockdown project - Sony TC-200

Were you able to verify the number on X201 ?
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Old 5th May 2020, 10:40 am   #71
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Default Re: Lockdown project - Sony TC-200

X201 is Sony D64 .... Theoriginal component for the unit ....X101 is the OC140...

Does Tandberg series 15 have any compatable transistors? I have parts of that model
Paul
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Old 5th May 2020, 10:59 am   #72
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Default Re: Lockdown project - Sony TC-200

Swapping them made no difference..... sound still fades away.... Paul
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Old 5th May 2020, 11:36 am   #73
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Default Re: Lockdown project - Sony TC-200

The original X101/201 according to schematics is 2SD64, which is what your X201 Sony D64 is.

Your X101 OC140 as far as I can see is not an original, that is why I previously asked if there were any signs of its soldering having been disturbed.

I have not had time to check data sheets etc but according to radiomuseum.org (which is normally good) one of the equivalents for the 2SD64 is an AC176, which also according to radiomuseum one of the equivalents for the AC176 is an AC127.

Your Tandberg 15 should have a AC127 for transistor Q106 (in power amp stage).

There may well be many other Germanium transistors that would do, but it is always good ideally (if possible) to use the correct one or an equivalent.
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Old 5th May 2020, 12:02 pm   #74
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Default Re: Lockdown project - Sony TC-200

The soldering in this thing is awful...it looks like every joint has been reflowed badly and where i've just touched it the tracks are coming off the PCB...
Both of my transistors seem to be working...or alternatively are both damaged as swapping them did not cure the problem..
Ill dig out the AC127 and try it , just to be clear in my own mind..
Paul
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Old 5th May 2020, 2:05 pm   #75
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Default Re: Lockdown project - Sony TC-200

I've just cut the track at the wiper to channel 1's volume control and linked the wiper from channel 2 .....I can confurm the fault is only on channel 1's head pre amp ...
channel 2 is playing wonderfully .... I've also switched the head wiring too, so it's not the head.....
Paul

Last edited by Paulus.d; 5th May 2020 at 2:24 pm.
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Old 5th May 2020, 2:28 pm   #76
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Default Re: Lockdown project - Sony TC-200

Good work, you are doing well !
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Old 5th May 2020, 3:31 pm   #77
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Default Re: Lockdown project - Sony TC-200

Thank you... however keeping it playing while testing this has killed the Channel 1 pre amp..... there is now a very minimal sound from it ...
Paul
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Old 6th May 2020, 1:19 pm   #78
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Default Re: Lockdown project - Sony TC-200

Well, that's it..... Channel 1 is finally working normally All down to C109 50uf 15v cap across R107 ....
One last question, I'm I doing any harm allowing Channel 2 tpplay without an otput transformer
Paul
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Old 6th May 2020, 1:59 pm   #79
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Default Re: Lockdown project - Sony TC-200

Should be no problem, could remove the output pentode.

Cannot fully see how posts 75, 77 & 78 relate, but fantastic that you have fixed it, just need another output transformer now.
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Old 6th May 2020, 2:09 pm   #80
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Default Re: Lockdown project - Sony TC-200

The channel 1 sound came back after a couple of tries.... i found a 47uf 16v cap so tried it in there ...it's still playing now


woo hoo
Paul
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