View Cart (0 items)


Membership is FREE!
It is best to log in before posting. Anonymous posting is disabled.

GA3 mainboard parts

Hi everyone, my name is Tee from Malaysia. I am an organ player and enthusiast. I am looking for replacement parts for my Technics organ GA3. The organ is having a problem with booting - only the lights were on when the organ was switched on but not all o…

Viewing 1 to 8 (8 Total)
GA3 mainboard parts

KT2015

KT2015


Total Posts: 2
Joined: July 2, 2015

Hi everyone, my name is Tee from Malaysia. I am an organ player and enthusiast. I am looking for replacement parts for my Technics organ GA3. The organ is having a problem with booting - only the lights were on when the organ was switched on but not all other functions including the keys and the LCD. It was examined by technicians and found that part of the main controller board is not working. Apparently, Panasonic is not producing Technics organ parts anymore. I would really appreciate if there is replacement parts available eg. from other countries or expertise/suggestions on alternatives to repair, perhaps a modification using generic replacement components.

I am eager to hear from you. Tee.

Posted on July 2, 2015 at 8:57 AM
Display Messages: Threaded     Flat
7 Replies

admin

admin
United Kingdom

Total Posts: 1055
Joined: February 2, 2014

Re: GA3 mainboard parts

Hello Tee and welcome!

Components are fairly hard to get hold of unless you know an engineer who is willing to strip down a non-working machine for you.

On the Internet you can try W D Greenhill because they stock some components. You can also try Mike Barden if you can get through his security system lol. I can't phone him because I work full time and he only takes calls at certain times.

I'll ask our friendly Mr Tutt to look in on our thread and see whether he can shed some light on this.

http://www.tutt-technology.co.uk/...

Best wishes,
Mike

Posted on July 2, 2015 at 9:53 PM

davetutt

davetutt
United Kingdom

Total Posts: 166
Joined: January 12, 2015

Re: GA3 mainboard parts

Thanks Mike

Hi Tee

The problem generally concerns the circuit on the main logic board that sits over to the left side. Here you will find a small heat sink and some associated components that are a regulator that takes the 42 volt fed onto the board and converts it to something the logic can use. You will find a pass transistor, if I remember correctly its a 2sd958 on a small heat sink. This is a simple chopper circuit if I remember correctly. I should really look at the full circuit but its 00:30 in the morning here! With it is a surface mount comparator chip, a zener diode and a set of three transistors which again I think are something like 2sa1815. Your first replacement should be the electrolytic caps all around this regulator followed by the heat sink to220 transistor 2sd958 and the other three transistors. The power supply for the logic will not start unless all the other supplies are up and running and there is a mute circuit to think about too which is a 15 volt supply that comes in on the right of the board. Hope this gives you somewhere to start looking.
The display will not come on without the logic supply. There are a few other things that can cause this including damaged circuit protectors but from what you say in your message this is unlikely.
I have attached the important piece of the circuit to this post so hopefully you can read it and get an idea of what goes where.
Regards

Dave Tutt

Attachments: psu_section.jpg
Posted on July 3, 2015 at 12:35 AM

davetutt

davetutt
United Kingdom

Total Posts: 166
Joined: January 12, 2015

Re: GA3 mainboard parts

If you start working on this board please be very careful. It is a multi layer board that has many via links but the ones specifically around the regulator are difficult to unsolder without track damage. While you have the board out it is as well to also replace the two solder in batteries that maintain the organ settings. They will probably be past their best by now and it will save taking the board out again and risk damaging the flimsy ribbon connectors to attach to the power and output stage board.

Regards

Dave

Posted on July 3, 2015 at 12:48 AM

davetutt

davetutt
United Kingdom

Total Posts: 166
Joined: January 12, 2015

Re: GA3 mainboard parts

The main transistor, the to220 package on the logic voice board is likely to have cooked because the heat sinking is inadequate. This is a trait of many organs not just Technics and they are thus all starting to show the affects of many years run beyond their safe operating area. But then after 15 years or more it is unlikely that the designers expected the instruments to still be running!

Good luck. If you need more information let me know!

Regards

Dave

Posted on July 3, 2015 at 12:57 AM

davetutt

davetutt
United Kingdom

Total Posts: 166
Joined: January 12, 2015

Re: GA3 mainboard parts

Most of the logic / voice board is pretty much a tough old piece of hardware. It doesn't seem to have chip failure unlike some well known and much loved digital hybrid synths from much bigger companies. It will suffer remarkable abuse and still work which you would think is unlikely given that the audio output board next to it is rather more prone to op-amp failure, transistor failure, resistor failure and diode failure and all in circuitry that isn't running the higher voltages associated with the power output stage.

Posted on July 3, 2015 at 11:20 AM

KT2015

KT2015


Total Posts: 2
Joined: July 2, 2015

Re: GA3 mainboard parts

Hi Mike and Dave,

Thanks for the replies. Dave’s descriptions fit the technician’s diagnosis well that the main logic board located at left was not working but I have yet to check with him precisely which components were affected.

The organ was bought by my father in year 1997.18 years now! I played it all the while until several years ago when I was away to study.

Meanwhile I will check with WD Greenhill when we found which parts that are not working.

Regards, Tee

Posted on July 3, 2015 at 3:30 PM

davetutt

davetutt
United Kingdom

Total Posts: 166
Joined: January 12, 2015

Re: GA3 mainboard parts

Hi Tee

I have a feeling you will only be able to do a component level repair on the board. The components that are in this part of the circuit are all standard parts with nothing exotic or difficult to get. Almost any good quality component supplier either closer to you or here in the UK will be able to provide them. I'm sorry but I think you are closer to the supply of 2sd 2sa Japanese type transistors than I am. Mine came from my UK supplier,http://www.cricklewoodelectronics.com/... as they have always provided me with a good service.
Replacement boards are extremely rare and very expensive. Also the chances are that if you manage to buy one it will have the same fault as your original. Your organ is probably worth less than 850UKP but the board could cost you at least half of that. For the cost of a few transistors and capacitors and the time of a good electronic repair man you could have the organ back in business for 70UKP. Spare boards are usually removed from scrap machines and the only reason they become scrap is that something was wrong with them that the owner or their engineer couldn't fix!

Let me know how you get on!

Regards

Dave

Posted on July 3, 2015 at 4:42 PM