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Viewing 1 to (35 Total) Technics SX-FA1 no load. Blue screen. |
United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
I just ordered both. I figured they aren't that expensive.
Thank you again. I'll keep you posted.
Just out of curiosity, if this doesn't fix it, do you think you might be able to do more, or is this basically what you would have done at this point?
Thanks,
Ken
Posted on February 21, 2018 at 8:15 PM
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United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
Thank you,
I am going to replace both and hope that this helps. I am really hoping this will work. I am dying to play this organ.
Thank you!
Ken
Posted on February 21, 2018 at 8:29 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: Technics SX-FA1 no load. Blue screen.
The power supply is pretty straight forward being a free running switch mode psu with a simple comparator and voltage reference circuit to keep it in check. The alternative is to get a 3 amp 5volt external supply, remove the components to isolate the circuit on the voice board and use the external one fed in at the stripe end of the diode next to the 1000uf cap. I often use a modified computer power supply from a standard desktop machine as it gives me +5v, +3.3v and several others and is ideal for most test situations. They are also very cheap compared to finding all the bits to try to make a linear one of suitable current and that would fit in the box. A standard one won't fit in the organ but there are flat ones used in rack mount computer servers that are suitable.
Posted on February 21, 2018 at 8:40 PM
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United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
Ahh,
Good idea. I am going to wait for the parts as they will be here maybe by the weekend. If that fails, I will take the Power Supply approach, and from what I am gathering remove the components that I have just replaced. The Diode I think you are referencing is the large Black one next to it? Is that correct?
Thanks,
Ken
Posted on February 21, 2018 at 9:48 PM
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United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
Hi David,
Can I put the ground of the computer power supply to the aluminum foil on the inside of the organ, or should it be placed somewhere else?
Thanks,
Ken
Posted on February 22, 2018 at 5:07 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: Technics SX-FA1 no load. Blue screen.
On a standard 24 pin output of a power supply the important ones are as follows:
You need to use the +5 volt from the power supply (three reds next to each other just pick one) and the 0v blacks (three next to each other the other side of the white wire) again pick one. If you remove the transistor on the heatsink you can then connect the red wire from the PSU to the stripe end of the output diode and the black lead to the other end.
To turn the power supply on you need a wire link between the power on green wire and any of the black wires.
Posted on February 22, 2018 at 9:09 PM
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United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
Perfect, I will give this a shot this weekend.
You are just absolutely amazing with your knowledge of this organ.
Thanks for being patient and extremely helpful.
Best Regards,
Ken
Posted on February 23, 2018 at 5:31 PM
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United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
Hi Dave,
I went ahead and did a little more troublshooting. For some reason when I checked Power to Ground with an ohm meter, I was getting a short. I removed the diode and plugged in an external power supply and low and behold!!
I have a working SX-FA1. I dont even know how to thank you sir. I thought I was going to be parting this out. But I hope it lasts a little while while I get to enjoy it.
Thank you and Best regards,
Ken
Posted on March 3, 2018 at 8:58 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: Technics SX-FA1 no load. Blue screen.
Hi Ken
That's good news. Its always difficult to do remote diagnostics as there are so many variables involved! Are you going to keep the external power solution or repair the on board circuit? I think it is totally acceptable to fit a permanent external replacement PSU as there is nothing special about the original and to be honest 90% of the Technics organs and keyboards are suffering similar faults because of age related failures which to some extent is due to poor heatsinking and an inability to keep things cool so you would expect failures at 20 years plus.
Best wishes
Dave
Posted on March 4, 2018 at 10:14 AM
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United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
I love a challenge so I will probably at some point repair it, but I need to get a new soldering iron.
I did find one ither issue now that I am going to have to try to figure out. All the pedals on the bottom don't work.. any thoughts on this.
Gotta say i am having fun with this thing. If I can get the pedals to work i am going to dig I to playing this. Just amazing how many sounds are in it..the small amount of buttons is very deceiving.
Thanks again!
Ken
Posted on March 4, 2018 at 3:05 PM
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United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
For those following along. 
So far, I have found there is another processor board in the bass pedal cabinet. I am only seeing 4 volts getting to the board, so I am not sure if that is enough to power it. Will go back to the main board and see if I can trace where the power is transferred to the pedal board through the pedal cable.
Will keep you posted.
Ken
Posted on March 6, 2018 at 4:24 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: Technics SX-FA1 no load. Blue screen.
There is a 100uf 6volt capacitor across the 5 volt supply in the pedal unit. If this is starting to get a bit tired the voltage drop down the cable increases such that the voltage at the ic2 processor on the pedals is then low. I would suggest you change that one and then check the voltage again. You may find the at the voltage drop across the choke on the pedal circuit board is rather high too. Best to swap the cap first and see what happens. Again, a 16 volt cap would be better than the 6volt one!
Its C4. There is also another cap here which is c6 across the reference voltage input for the ic. Its a 4.7uf and again needs to be a 16 or 25 volt device.
Let me know if this works
Dave
Posted on March 6, 2018 at 5:42 PM
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United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
Hi Dave,
I am actually only getting 4 volts out of the main board to the pedal cable. I am not sure if there is something else dropping the voltage, or is it just because I may not have a strong enough power supply.
Posted on March 7, 2018 at 8:38 PM
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United States
Total Posts: 21
Joined: September 6, 2016
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Re: Technics SX-FA1 no load. Blue screen.
Hi Dave,
I purchased a small 3 Amp 5 volt Switching Power supply for it, and everything appears to be working now. All pedals as well.
I just want to say a quick thank you to you again. Without your help, I would still be struggling with the organ, and may have at this point parted it out. I am glad I didn't.
Best Regards,
Ken
Posted on March 19, 2018 at 3:45 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: Technics SX-FA1 no load. Blue screen.
Hi there
Thats a really good result. Glad it worked for you! I would think an average external power unit should give you around 2 years life if it is permanently plugged into the mains but if it is switched through the organ mains switch it may well last a very long time. Great news. happy playing! Any other issues by all means let us know!
Regards
Dave
Posted on March 19, 2018 at 4:52 PM
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