Disklavier

Update on the Piano Power Off  #15 "PWR OVER” Error on a Mark II GH1B 
Grand DKC100R with MU50 after about 30 Seconds of Play.  

I ran the Error History, here are the results:
Sensor LED ON error #8 Count = 094
Sensor Not Connected #9 Count = 085
Piano Power Off (PWM OVER) #15 Count = 039

I removed the power supply and dis-assembled it, and ran tests on all the 
Output Voltages and inspected all components for signs of Overheating, 
Leakage, cold solder joints and Failure.  The Power supply tested out as 
normal, in fact looked rather New.

I replaced the incoming power cable, and power strip with a premium grade 
replacement.

I read all the service manuals, and studied all of the schematics, block 
diagrams, Error Descriptions, and Troubleshooting manuals.

The DGP1/DGA1 service manual on page 60 gives this description of the 
Error Under the PK-CTL Board – Protect Function:

No Message Condition Contents and Countermeasures

15 Piano Power Off The keyboard & sustain, soft / shift pedal 100V (120V 
for Grand) of power to Keyboard and pedal drive OFF.   
(PWM OVER) playback stop.  Playback function cannot One or more key drive 
transistors have become too hot and the
be restored until the drive transistor(s) protect circuit has activated. ® 
Check the drive board
has/have cooled down sufficiently and 
the power has been turned off,then 
turned back on.

The DGA1XG Service manual lists the PK-CTL Board Part Number as VU691100 
for the DGH1BXG model
The Block Diagram shows a Thermo Protect F1 on the Gate Array with inputs 
from Thermostats on the Drive A, B and Pedal Units.  They all look like 
there are in series to Ground,
so the opening of any thermostat will signal the thermal protect to 
shutdown the piano.

Tomorrow, I am going to adjust the Pedal Solenoids, the Half pedal 
settings, the pedal linkage gaps, and put a meter on the Thermostat line 
to see if it opens during play.

It kinda makes sense that there maybe something wrong at the pedal unit, 
because it was removed during the move.  The pedal Solenoids are huge, so 
I can understand
If they are creating a lot of heat on a drive transistor at 120VDC, enough 
to trigger a thermostat overheat.

Schematics have been very helpful as well as component adjustment info and 
error information.

Will let you know of the progress…
 






From:  "Brad Harper bharper33@yahoo.com [disklavier]" 
<disklavier@yahoogroups.com>
Reply-To:  <disklavier@yahoogroups.com>
Date:  Tuesday, December 30, 2014 at 5:13 PM
To:  <disklavier@yahoogroups.com>
Subject:  Re: [disklavier] Service Manual and Schematics for MarkII DKC100R

 
 
 
 
   

Hi Carol,

I did disconnect that harness, and reconnected it, and it was loose when I 
first checked it.  I also did a check that spencer suggested, which is to 
record a run of the keys, and then playback only that to see if it stops 
at a certain key.  The problem is now it has progressed to not playing 
anything.

Brad…

From:  "Carol Beigel carol@... [disklavier]" 
<disklavier@yahoogroups.com>
Reply-To:  <disklavier@yahoogroups.com>
Date:  Tuesday, December 30, 2014 at 4:47 PM
To:  <disklavier@yahoogroups.com>
Subject:  Re: [disklavier] Service Manual and Schematics for MarkII DKC100R