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Viewing 1 to (9 Total) Technics PR350 no sound from any keys |
United Kingdom
Total Posts: 4
Joined: February 24, 2017
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My father has a PR350 which has just developed a fault in that none of the keys play any sound. Pressing demo, or rhythm accompaniment produces sound. Anyoune have any ideas?
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Posted on February 24, 2017 at 2:24 PM
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United Kingdom
Total Posts: 360
Joined: June 8, 2014
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Re: Technics PR350 no sound from any keys
Hi Andrew, First of all I would recommend doing a Factory Reset , unfortunately this will remove any settings you have adjusted to your personal likings.
This should remove any corruptions in the basic setup and put us on a level playing field. Then at least if it does not clear the problem Please come back for more advice.
To do a Factory Reset on a PR350
Turn OFF the instrument.
While Holding Down the first 3 left Rhythm Buttons, Turn on the instrument.
This will have now reset the instrument and hopefully fixed the problem.
Best regards John.
Posted on February 24, 2017 at 4:49 PM
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United Kingdom
Total Posts: 4
Joined: February 24, 2017
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Re: Technics PR350 no sound from any keys
Hello John,
Many thanks for your suggestion to try a reset first. I tried the reset but it made no difference. The PR350 is my Dads who is approaching 90 but still keeps active playing at home after 75 years of playing in jazz, dance and swing bands. I would dearly like to fix it for him as soon as I can?
Kind regards,
Andrew
Posted on February 25, 2017 at 8:18 PM
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United Kingdom
Total Posts: 360
Joined: June 8, 2014
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Re: Technics PR350 no sound from any keys
Hi Andrew Firstly we have reset the piano now as this has not solved the problem I will pass you onto our resident engineer. Where in the UK are you based ?. I will pass on you problem on to him and hopefully he can come up with a solution.
Regards John
Posted on February 25, 2017 at 8:36 PM
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United Kingdom
Total Posts: 4
Joined: February 24, 2017
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Re: Technics PR350 no sound from any keys
Hi John,
We live in Stroud, Gloucestershire
Regards,
Andrew
Posted on February 25, 2017 at 9:26 PM
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United Kingdom
Total Posts: 360
Joined: June 8, 2014
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Re: Technics PR350 no sound from any keys
Hi Andrew, I have pass the details on to David Tutt, no doubt he will he will be intouch in due course,Dave is based in Kent but realy knows his stuff
Regards John.
Posted on February 25, 2017 at 10:15 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: Technics PR350 no sound from any keys
Hi there Andrew
Sorry about the delay in commenting here.
If you want to try and fix this yourself then I can suggest at least a couple of things that might help you. I wouldn't advise anyone without the necessary skills in electronics to delve too far into the workings of any piece of electronic equipment but it may be that the fault is actually just a plug loose which with some very delicate care can be fixed.
First thing, when you did a reset did the display change state? Think it should flash a couple of times but there are no messages that are displayed. I am wondering if the reset actually worked or if it was skipped because of another issue. You can always do another reset and see what happens.
My concern is that the keyboard encoder chip is not connecting to the main voice board. There is a lot of conversation between these two parts especially at start up. If the start up process fails then no key will make any sound.
I would think that if it is a physical fault it may be that the key frame may have become disconnected from the main voice board. It is only a 12 way connector only about 4mm x 30mm so is relatively easy to plug in but I would be very careful as it isn't a replaceable part as there are no spares. If you are adept with a screw driver you can at least take the top off and have a look at both ends of the cable. The main circuit board end is connector CN4 in the bottom left corner. If in doubt you can always send me a picture before you go too far. The other end o the cable is actually under the key frame which requires you to remove the screws that hold it in (5 of them under the front of the piano and I think 3 at the rear of the key frame) and lift it up from the back taking care not to damage the cable. The cable is plugged into the middle left of the printed circuit board under the key frame. A gentle push should tell you if it is plugged in properly.
Put things back together and see what happens. If all is well you may have a working instrument again. Beyond that there is probably not a lot you can do without a visit from either myself or at least someone with the necessary skills to fix it or at least diagnose the problem and see if a fix is possible. As I say there are no spares to speak of. All the electronic hardware is either custom and hence no longer available or relatively standard parts that are extremely difficult to replace as is always the case with this sort of technology.
Regards
Dave
Posted on February 26, 2017 at 11:32 PM
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United Kingdom
Total Posts: 4
Joined: February 24, 2017
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Re: Technics PR350 no sound from any keys
Hi Dave,
Many thanks for the reply and suggestions. Apologies for not replying sooner!
I went down to Dad's today to try and have a look at the PR350 as per your suggestions. I don't have an issue with removing covers and taking a look as I am a qualified electrician (although my additional City & Guilds electronics module was 35 years ago so I don't do anything more than look at printed circuit boards for any obvious signs of damage such as burnt components or blown fuses).
Firstly, the reset procedure doesn't do any flashing. I hold down the three left hand buttons of the rhythm and turn on power button. No lights appear until I release the three buttons, then all relevant LED's light up and the tempo display comes up with 120, it does not flash.
I then removed the top and inspected all internal boards and connections which were all seated correctly.
I checked continuity on the three glass fuses on the 'mains in' board and all three were fine.
I removed the key frame and checked the plug CN4 underneath and that was also fine. The wiring looms all looked to be in good order with no visible signs of damage.
On checking with Dad, the day the keys failed, it was a gradual decline- it started with some keys not working and when I got there to take a look, we could only get one or two to make a sound, then nothing at all. As I said earlier in this thread, the demo sounds all work fine as do volume and balance controls.
The only thing I haven't tried is plugging headphones in yet, which I will try next time I visit Dad (he doesn't use head[phones and never has on the PR350.
I am at a bit of a loss now and am wondering what sort of cost a diagnosis and repair would be versus trying to find Dad an alternative second hand machine with similar functions and sound quality.
Any help/advice gladly appreciated.
Kind regards,
Andy
Posted on March 1, 2017 at 7:58 PM
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United Kingdom
Total Posts: 166
Joined: January 12, 2015
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Re: Technics PR350 no sound from any keys
It could be then that the keyboard encoder chip has failed. It is unlikely but with all the semiconductor hardware out there there has to be a few that fail in service.
I don't think I have a set of replacement pcbs that work with this machine as this would probably be the best point to start. However, one thing you could try is to change the crystal on the board on the keyframe as from what you have said if there was a gradual drop off the timing is obviously upset and that will have a knock on effect to all the rest of the function of the instrument. This is a small (in this case I think its blue) component right on the edge of the board alongside the gate array chip with three legs and its something of a special but a standard 2 pin 14.7mhz crystal may well work if you want to try it. Its delicate of course so if you don't want to!!!!! It would be soldered into the outer two pcb holes.
As to a replacement keyboard I have one here that is probably going to end up on sale sometime soon if I can cure the couple of intermittent faults it has.
Regards
Dave
Posted on March 3, 2017 at 8:06 PM
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