The “passionate life” of an old electronic organ technician.

BALDWIN D911 (Circa 1990)   Diagnosis and repairs

BALDWIN Howard D911 top and back open

Location :  St-Leon Le Grand Parish’s church near Amqui, Quebec, Canada. 260 km return trip from 

Rimouski, Qc. my home base.

First call:  April 1^st 2015, (not an April’s fool day joke) Temp. was -20 deg C. (That’s cold)!! Easter is approaching and the organ must be repaired ASAP.

Problem reported:  1)instrument does not keep user presets in memory, factory presets are OK.

2) Organ locks up and requires shut down. When power is turned back on, it  plays normally until you hit a (any) user preset, then it locks up again.

Repair:

Found memory backup battery dead, replaced battery 3vdc. (CR2032). I had doubts about the replacement battery, it was not fresh,   it was the last one on the shelf at the local 7-11 ...

Note: Battery was changed in 2007 and a new battery holder (support)  and a CR2032 battery was installed, it lasted about 8  years, not bad!

I  turned  the power back on and then reprogrammed users presets immediately!

Note: if you touch any user presets before reprogramming them, it will lock up again and you will have to shut off the organ, remove the battery CR2032 and reinsert it again, then turn the instrument back on.

Done that:  It played fine finally and beside the scratchy potentiometer on the expression pedal, it sounded OK. I played for about 30 minutes and then, I cleaned up and closed the organ. Turned on and off half a dozen times, it kept the user memories ok. Voltage reading on the 5vdc power supply  test OK but  the heat sink runs hot like Hell. I remember this is normal for this organ but I don’t like it, that BDW83C  NPN Darlington power transistor(U1) is way too hot for my liking, there should be a fan cooling the bugger!! Or a bigger heatsink!!

A 3 hour service call plus 260 km trip all that for 280 can$, of course not paid before 15 days by check. (I am too expensive?)

Second call: April 21^st2015

Problem reported:  Organ  makes  poping noises when turned on and locks up! I asked the lady at the church to call me using a wireless phone while sitting at the organ and I made my diagnosis by asking her to turn the instrument on while  I was able to listen to the organ when it came on, (I heard a poof) I knew right away I had a real problem, I suspected the 5 vdc supply!

April 23^rd 2015: Here we go again, 260 km return trip from my home base, and it is snowing, temp. is +2 deg C.

This time, I will bring with me a couple spare Darlington Power BDW83C and a fresh pack of CR2032 batteries.

Back at the church  23 days after the first call.

The D911 BALDWIN Organ is switched on, it powers up, it makes a pop and it locks up and does not respond, stoptabs  on or off, no sound.

Note: Turn the power off and unplug the organ.

I removed the top, the roll top, the top back panel and the bracket above the vertical boards on the treble side of the organ, I removed the CPU board, the first vertical board on the left.

 I replaced the CR2032 battery. I replaced the board on the mother board connectors.

Note : You have to be very careful to insert the board on the right way, be careful before removing the CPU board, look carefully where the pins should be and  ground yourself, watch for static electricity. If you are on carpet flooring, discharge your body on a metallic object before touching the boards. You can never be too careful!

Note:  Take pictures with a camera if you want to remember something like:  parts layout, wirings, cable colors, etc... it is always useful, take written notes also.

Plug the ac cord, turned switch on and right away reprogrammed user presets.  All stoptabs work properly,  all  looks fine and the organs plays well.

I checked the U1 heatsink and it’s getting hot by the minutes, I can barely keep my fingers on it.

I wiggle a wee bit the U1 heathsink  and “poof”,  it makes a loud pop and the organ goes into a lock up!

That’s it! Now I know! One of the 3 pins on the Darlington transistor has a cold joint and intermittently does not make contact and the 5vdc supply is affected.  This could have been caused by the excessive heat on this part and by expansion and cooling of the related circuit!
Time to remove the power supply board and have a look and see! The fun starts!!

Time to Power off , unplug the ac cable. Remove the green tie wires  keeping the wiring in place, unplug the large black cable in the middle and then, remove the black, red, yellow and green, yellow, blue, brown, make sure each wire is marked where it should go on a diagram on a piece of paper. Be careful, they have to go back at exactly the same place on the connectors.

Remove the 4 large screws holding the PSU board on the shelf.

 Do not remove the small screws around the board  holding the little plastic frame under the PSU board.

Lift the board gently, pushing the wires aside, be careful! Expose the bottom... of the board and locate the 3 pins of the Darlington Power transistor. Remove the nut, lock washer and bolt keeping the transistor on the heatsink, this is not easy.

Unsolder the transistor and remove it, you should inspect the copper circuits to make sure there are no break! Insert the new U1 Darlington Power BDW83C and solder carefully, inspect your job. That’s it! Re-connect and re-wire every cable and wires. Inspect for the last time before trying to see if it works.

Remove the CR2032 and re-insert it, plug the ac cable and turn the instrument on! If it powers up and does not make the pop noises, try a few stop tabs, it should play, reprogram the 5 user presets right away with basic settings. If it all works fine, feel the 5 vdc heatsink , it’s feeling warm already. Then the ultimate test!!! Wiggle the heatsink slightly, no noise and all is fine! You made it. Screw the 4 screws holding the PSU board on the shelf, attach all cable and wires.

Play on the organ and test all settings.

The scratchy control on the expression pedal can be help a bit, if you don’t have a replacement  potentiometer (it’s a 22k pot),  just pump that pedal every second for 2 minutes and I guarantee you the problem is gone for now...but for how long??

Close up and get out of there before it quits again, just joking!

Don’t forget your tool kit, your hat or your boots!

And don’t make the bill before 30 days, just in case!

How much should I charge?? What do you think?

Gilles

BALDWIN D911 Power supply board

Darlington Power Transistor heatsink in the middle with new transistor installed and old one in front

I might translate this text in french if I get to it someday! Sorry les amis français! 

It took me more time to write this article than to effectuate the repair.

I wrote this article has a guide to repair the D911, this is my own experience and I am not responsible if you screw up...

 Be careful or better yet! Call a technician with experience not the church caretaker, please!!