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Help! Old Technics Digital Piano won't turn on

Posted By: mclemens68

Help! Old Technics Digital Piano won't turn on - 11/10/08 05:19 PM

Hi folks,

Hoping there's someone out there who can help me. I've got a 14 year old Technics digital piano that I bought back in 1994 for around $2500. The model number is SX-PX106, which is very similar to the PX103 and PX107 models.

Has worked great up until a few nights ago when pushing the power button wouldn't turn the piano on. There's a small red power LED on the face of the piano that does light up, but all the led indicators, metronome, etc on the top of the piano don't light, and no sound out of the speakers when pressing the keys.

Tried feeding audio into the line in jack on the piano to see if I could get sounds out of the speakers, but no dice. I can very faintly hear the external audio through headphones if plugged into either the line out or headphone jacks.

Definitely seems like something inside the piano has blown, but I'm hoping is something simple like a power supply that I can replace myself if I can isolate the problem (I work in the electronics industry so have some debug & electronic repair skill).

The key question is where to start to isolate the problem. Don't want to just start taking the piano apart without some guidance.

I know Technics (owned by Panasonic) got out of the DP market a few years back, and calls to Panasonic service & parts centers for some leads have been a dead end.

A google search has turned up a couple potential leads, the first is a potential source for the service manual . Have a question in to him to ask how big the manual is and if has detailed troubleshooting and schematics, but has anyone ever seen a service manual for Technics pianos that can comment?

The second lead is a guy in the UK that fixes old digital pianos. Only problem is he's in the UK and I'm north of Chicago, so not sure if would work to actually send him a problem board, but maybe I can ring him up to get some help if no other options.

Appreciate any other leads if anyone out there knows these pianos or knows a good source for parts, service manuals, or someone in the states who actually still services these.

Thanks,

Matt
Posted By: signa

Re: Help! Old Technics Digital Piano won't turn on - 11/10/08 10:03 PM

any technician who are familiar with circuit boards and has a voltage meter at hand would be able to help you to trace where the electronic current stops on your DP, such as some radio/TV or even PC repair guys. it sounds like some electronic component just stoped working. if such a component is replaced, then things will start working. if you say power signal light is still on, then something must be wrong from there on its wire path.

i'm just guessing, and know nothing about Technics.
Posted By: mclemens68

Re: Help! Old Technics Digital Piano won't turn on - 12/09/08 07:42 PM

Just an update on this,

I was able to locate the service manual, which has the schematics. I did find one problem in that off of the main power rectifier there are 2 voltage regulators, a +15v and a -15v. On my piano the +15v supply was not working, where the -15v supply was. The -15v supply goes to the LED on the front, which is why that still lights up. I was able to track down the +15v issue to a bad resistor at the input of the 15v regulator. Replaced this and now the 15v supply works, but still nothing from the rest of the piano (no lights, sound, etc...). Have verified that the 5v supply that powers all the digital logic on the Main and Control panel boards is there. Hoping these didn't get fried beyond repair when whatever took out the +15v supply occurred. Haven't gone further in the debug as had to move onto other things, but will probably get back to it in a couple weeks.
Posted By: Marty Flinn

Re: Help! Old Technics Digital Piano won't turn on - 12/13/08 08:58 PM

Call a couple of the larger sellers of new digital pianos in your area and ask for a technician reference.
Posted By: childressKlein

Re: Help! Old Technics Digital Piano won't turn on - 08/31/13 03:18 AM

Five years on, could you please report what - if anything - you did to have the 106 work again? I am having the exact same problem (also purchased it in '94). Funny, I always thought the first problem would be a mechanical issue... Thank you.
Posted By: MacMacMac

Re: Help! Old Technics Digital Piano won't turn on - 08/31/13 05:51 AM

You'll not get an answer. The OP posted twice in this thread. Soon after he posted one final time in the prices-paid thread, saying he'd bought a new P155 piano. He never posted again. His broken Technics piano is probably landfill.
Posted By: LesCharles73

Re: Help! Old Technics Digital Piano won't turn on - 08/31/13 06:21 AM

Realistically, it's probably the power switch or power supply unit. The best way to find out is to take a multimeter and find out where the power stops. If the unit has a fuse, that would be something to check as well.
Posted By: childressKlein

Re: Help! Old Technics Digital Piano won't turn on - 08/31/13 03:14 PM

Thanks macmacmac and LesCharles73 for your timely replies; sorry to hear the OP has left the forum. I used a DMM to check the fuse, which registers zero ohms (meaning OK, I understand). The red LED power and "touch sensitivity" normal and "Piano Grand" LEDs do light up. On occasion, the metronome number display also lights as either 40 or just dashes. It follows no pattern - sometimes they come on, sometimes they do no. The constant is that there is never any sound, except for one brief middle A that sounded just once. A visual inspection shows nothing discolored, mishapen, etc. (of course that doesn't necessarily mean everything is OK; obviously something's not). Would the above description still be consistent with a bad power unit? Thanks in advance for your thoughts!
Posted By: LesCharles73

Re: Help! Old Technics Digital Piano won't turn on - 08/31/13 08:20 PM

It could still be a bad PSU. Under or partial voltage can cause all kinds of weird things to happen. It would be nice to have some schematics or a service manual so you can confirm the voltage output of each transformer tap, but I don't know where in the world you could find one.

Another potential cause given your instrument's age would be leaky capacitors. They go bad with age and while they usually begin bulging and/or leaking, this isn't always apparent through visual inspection. Again, they can cause funky issues that may cause the gear to be "mostly dead" while still showing some signs of life. Caps are very cheap, but you'd need to be comfortable with soldering or know someone who is. To save money, you could just take the PCBs to an electronics repair facility. That way they don't charge as much in labor for taking the whole keyboard apart themselves.

I would have suspected the amp module/tone generator as well, but it sounds like the issue is somewhere else since you mentioned that the lights/indicators don't always behave correctly. It could be a processor issue in which case the keyboard is pretty much a goner, but my money is on the PSU or capacitors.
Posted By: childressKlein

Re: Help! Old Technics Digital Piano won't turn on - 09/01/13 02:19 AM

Thanks for this info. I trolled the web and found this http://music-electronics-forum.com/t31591/ where a poster back in 12/2012 describes pretty much the same problem I'm having. The initial transformer appears to be putting out about 20V, which according to the discussion in the other forum is normal. I am in Atlanta and found a shop that does electronic instrument repairs, so I will call them after Labor day and probably bite the bullet, at $80/hr... one last thing I may do is check those capacitors, which may require removing the amp board, since the Caps are mounted flush against the board, so I have no direct access to their terminals.
One last thing: on the main (green) board, there's an inductor (labeled 101) that has what looks like white candle wax next to it. A web search suggests this might be rosin from the original soldering. Doesn't look pretty, and it may have absolutely nothing to do with my problem, since I understand it's an insulator, but wanted to mention it anyway. Thanks.
Posted By: childressKlein

Re: Help! Old Technics Digital Piano won't turn on - 09/02/13 09:41 PM

Regarding my last comment on the white wax-like substance around a small inductor, a neighbor thinks it's insulation that's supposed to be there (makes sense due to the proximity to bare leads), so I will have to seek professional help. If it's $200-300 for a guaranteed job, I will accept, but anything more will probably put me in the market for something new... Thanks all.
Posted By: childressKlein

Re: Help! Old Technics Digital Piano won't turn on - 10/05/13 03:07 AM

Update:
Decided against spending $259 on a 19 y.o. piano and after seeing the improvements made since 1994, I purchased a Kawai CN34 today. I look forward to familiarizing myself with it over the next week or so, but already, I'm thinking that having my old Technics die is turning out to be a blessing in disguise, since the Kawai sounds and feels really good.
Posted By: iceporky

Re: Help! Old Technics Digital Piano won't turn on - 10/05/13 05:57 AM

Congrats on your CN34 purchase! I think you're in for a treat. :-)
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