'74 Sony TA-1055 Recapping Project - diyAudio
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Old 1st April 2016, 05:16 AM   #1
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Default '74 Sony TA-1055 Recapping Project

Hi fellas,

I decided to start a thread about my project to do some parts replacement on this amp. I am looking for insights and suggestions from you, and maybe help others with similar project in mind. I'd like to start by saying a big heap of thanks to Bob (trileru) for walking me thru the entire process up until now. You rock big time.

So here's the amp:

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The board:
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Jonathan

Last edited by jwicaksana; 1st April 2016 at 06:47 AM.
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Old 1st April 2016, 05:21 AM   #2
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I did some cleaning on the amp, getting ready for recapping.

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Output transistors are not original, and one of four driver transistors is not original
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Transformer looks untouched, so that should be good
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First step is removing the transistors
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Jonathan

Last edited by jwicaksana; 1st April 2016 at 05:32 AM.
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Old 1st April 2016, 05:50 AM   #3
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We created a list of material, this is a placeholder post, I will update with the complete list.
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Old 1st April 2016, 08:19 AM   #4
Mooly is offline Mooly  United Kingdom
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So you are replacing all the transistors as well ? It should certainly be do-able but you may run into issues of both stability and also basic issues such as being able to obtain the correct bias current in the output pair. It looks like this is a fixed bias design and so its especially critical of the parts used. This is because of manufacturing differences between old vs new semis and the slightly different characteristics in things such as absolute turn on voltage.

Restoring old gear is great... if you dismantle it further then its even possible to wash the main PCB and chassis etc. Hot water and detergent. It would all come up like new.
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Old 1st April 2016, 09:18 AM   #5
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Mooly, I'm replacing 4 driver transistors and 4 output transistors, simply because the ones installed are not correct for this amp. There are smaller ones that I think I'll just leave as is. I'm replacing the caps as well, putting film caps in place of 'lytics, and also some diodes as well to be safe.
I'll see about removing the board altogether. Right now I'm fairly content with cotton swab and alcohol, working slowly around each part I'm replacing. Thanks for stopping by.
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Old 1st April 2016, 11:36 AM   #6
Mooly is offline Mooly  United Kingdom
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OK and good luck.

And when you power it for the first time use a bulb tester.
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Old 1st April 2016, 03:46 PM   #7
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Thanks Mooly.
The parts started to arrive, yay. A few things, the legs of the big caps were spaced at 7mm and the board is designed for 13mm. A few twist and turns with the plier and we're good. And the TO220 insulation kit I bought uses 3mm screw and the heatsink accepts something like 2.5mm? So that means a trip to the hardware store tomorrow.

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Old 1st April 2016, 06:29 PM   #8
Mooly is offline Mooly  United Kingdom
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Sounds like you are going to have some fun doing this Just take it slow and steady.
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Old 1st April 2016, 07:56 PM   #9
Trileru is offline Trileru  Romania
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Yeap. Also remember, unplug before working on it. Good luck and keep us posted with the progress.
Divide into steps, replace a set of parts, test the amp, then replace the next step, test it again. If you screw up, you have a small part count to check.
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Old 2nd April 2016, 04:36 PM   #10
kct is offline kct  Canada
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Looking really good, nice job. Just for the fun of it, see if you can pair the transistors a little bit.
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