Allen ADC Capture Board Questions - battery leakage

[thunderbird6]

I am about to help a friend with an ADC-2140 in their church where the nicads have leaked on the 3 Division Capture board (904-5682). The damage appears to be limited to the 9601 chip and I am experienced in cleaning up and restorring boards with battery leakage damage from my hobby of pinball machine restoration. However it would be helpful to know:

1) Is the organ usable without the capture board fitted (as this would take the time pressure off the repair)?
2) Does anyone have a schematic for this board (081-6530) as it would make it easier to bench test it after repair?
3) Has anyone successfully replaced this board with a DM-4 - is it really a plug-in replacement (in the event that the board is not repairable)?
4) Is there a proven alternative/replacement for the 9601 chip which doesn't look easy to obtain now in the UK?
5) Are there any other boards in the ADC-2140 with nicad time-bombs on them?

Many thanks for any help you can provide.
Keith

[myorgan]

I am about to help a friend with an ADC-2140 in their church where the nicads have leaked on the 3 Division Capture board (904-5682). The damage appears to be limited to the 9601 chip and I am experienced in cleaning up and restorring boards with battery leakage damage from my hobby of pinball machine restoration. However it would be helpful to know:

1) Is the organ usable without the capture board fitted (as this would take the time pressure off the repair)?
2) Does anyone have a schematic for this board (081-6530) as it would make it easier to bench test it after repair?
3) Has anyone successfully replaced this board with a DM-4 - is it really a plug-in replacement (in the event that the board is not repairable)?
4) Is there a proven alternative/replacement for the 9601 chip which doesn't look easy to obtain now in the UK?
5) Are there any other boards in the ADC-2140 with nicad time-bombs on them?

Many thanks for any help you can provide.
Keith

Keith,

There are some techs on the Forum who can answer all your questions, but I'll take a stab at a couple of them.

Yes, the DM-4 should be a plug-n-play replacement, and it now comes with solid state memory, so no batteries. No, Allen doesn't like to release the schematics of their organs, much less so with the individual boards or EProms. If you had the ability to replicate the chip in question, that may work, but I'd opt for the DM-4 replacement. There is a company here in the US that parts out Allen's boards--Daffer Organs. This link is for their DM-4 replacement, however, they do not have any presently available: http://www.dafferorgans.com/Store/ta...d/Default.aspx

I've never used any of my Allens without the capture board connected, so I could not answer your question.

I hope this helps you get started until the organ techs weigh in. Again, welcome to the Forum.

Michael

[Admin]

The capture board does not have to be installed for the organ to be playable. Of course, the combination action will not work. AFAIK, all the DM series boards are plug compatible. I have a four division DM-2 board available, but the battery pack was external on these.

Another alternative is to replace the board with a modern equivalent. I'm thinking of my (Zuma Group) DM MIDI Stop Controller which will provide bi-directional MIDI stop control. It runs in a standard legacy mode, using non-volatile on-board memory, in the Full MIDI mode, intended for use with VPO software that provide the combination logic, and a split mode where the board runs in the legacy mode, but still sends stop change and piston data as MIDI messages to external MIDI instruments.

[thunderbird6]

The capture board does not have to be installed for the organ to be playable. Of course, the combination action will not work. AFAIK, all the DM series boards are plug compatible. I have a four division DM-2 board available, but the battery pack was external on these.

Another alternative is to replace the board with a modern equivalent. I'm thinking of my (Zuma Group) DM MIDI Stop Controller which will provide bi-directional MIDI stop control. It runs in a standard legacy mode, using non-volatile on-board memory, in the Full MIDI mode, intended for use with VPO software that provide the combination logic, and a split mode where the board runs in the legacy mode, but still sends stop change and piston data as MIDI messages to external MIDI instruments.

Thank you to you and Michael for your prompt and helpful replies. Apologies that I just end up with more questions!

I thought I had read that the DM-2 wasn't interchangeable as it needed a separate battery and charging circuitry? I had found the DM MIDI Stop Controller and it certainly looks like a good upgrade but I know that they have very limited budget hence the desire to repair the board if at all possible (and I hate throwing things away if they can be repaired!).

When you say 'the combination action will not work' without the capture board, please excuse my ignorance as I am not an organist, but does this just mean that the memories for the stops won't work (which they currently don't anyway with the board damage) or does this mean something else?

Thanks again
Keith

[myorgan]

When you say 'the combination action will not work' without the capture board, please excuse my ignorance as I am not an organist, but does this just mean that the memories for the stops won't work (which they currently don't anyway with the board damage) or does this mean something else?

Keith,

The latter statement is true, not the former. Now that Admin has confirmed what I thought, he just means with the board out of the organ, the organ will continue to work, the stops will work when engaged, etc. However, the combination action that is currently non-functional will not work (i.e. setting pistons and retaining them in the organ's memory). The rest of the organ will continue to work as it is presently working.

I hope that helps.

Michael

[Admin]

I thought I had read that the DM-2 wasn't interchangeable as it needed a separate battery and charging circuitry?

Yes, that it is what I said, but otherwise, I believe they're compatible. You would have to wire a battery pack to the connector, but any adequate power source should suffice in place of the Allen battery pack (I've one of those available too.) A DM-3 or DM-4 would of course be a simpler and more preferable solution.

[thunderbird6]

Yes, that it is what I said, but otherwise, I believe they're compatible. You would have to wire a battery pack to the connector, but any adequate power source should suffice in place of the Allen battery pack (I've one of those available too.) A DM-3 or DM-4 would of course be a simpler and more preferable solution.

Thank you both once again for the excellent help. I will collect the DM-3 board as soon as I have tracked down a replacement 9601 and let you know how it goes. Hopefully I won't have to come back looking for a new board, but at least I know where to look now if I do.

Thanks again
Keith

[thunderbird6]

Thank you both once again for the excellent help. I will collect the DM-3 board as soon as I have tracked down a replacement 9601 and let you know how it goes. Hopefully I won't have to come back looking for a new board, but at least I know where to look now if I do. Thanks again Keith

I can confirm that the organ was perfectly usable without the DM-3 board fitted, although the cancel button no longer worked. I neutralised the battery leakage, cut off the damaged 9601 and a couple of ceramic capacitors and unsoldered the legs one by one, repaired the tracks which had been eaten away, and fitted the new 9601 chip into a couple of turned-pin socket strips so that the repaired tracks remain accessible for inspection. A coat of conformal lacquer over the repaired area and the job was done. Obviously the new batteries are fitted remotely now! After returning the board to the organ all of the memories were back in working order and the organist is very happy :) Many thanks to everyone who helped me in getting this sorted as it saved the church almost £1k for a replacement board and fitting. Keith

[myorgan]

Keith,

Thank you for posting an update. That is, indeed the information about your board repair is good to have, so we all know it can be done. Congratulations on a job well done!

Michael

[jbird604]

Yes, it is good to know that the job can be done. We still see a battery-damaged DM board now and then, though the usual fix is to get a DM-4 and toss the old one. It is surely worth the time and trouble to repair, if the board is otherwise OK.

[CarillonBells]

I always love seeing posts like this - the art (and savings!) of component level repair is FAR from extinct. Surplus parts can definitely be a good value, but they are still second to spending less than $10 to bring something expensive back to life.

[thunderbird6]

I always love seeing posts like this - the art (and savings!) of component level repair is FAR from extinct. Surplus parts can definitely be a good value, but they are still second to spending less than $10 to bring something expensive back to life.

One of my hobbies is restoring early electronic pinball machines. The batteries were normally mounted at the top of the boards so damage from leakage is often extensive, sometimes affecting 20 or more ICs, and replacement boards are effectively unobtainable. The key thing that I have learned from that is to cut the legs off the damaged chips as close as possible to the body and then unsolder them one by one. The tracks on these old boards lift easily and if you try to remove the chip in one piece, even with the right desoldering tools, you end up with an intact (but faulty) chip that you can then throw away and a board badly damaged from the excessive heat! Secondly it is worth buying a reel of 30awg kynar covered wirewrap wire to use for repairing/replacing damaged tracks. Keith

[myorgan]

Thunderbird,

Forgive my ignorance, but how do you re-program the IC chip to match the programming of the removed chip--especially once the legs are removed, or if the chip is compromised by battery corrosion?

Michael

[toodles]

You have to have special EPROM writing equipment and software; if the IC is damaged you might be able to connect soldering small wires to the remains of the legs, and rig up some sort of connection to a socket or circuit board that connects to the EPROM programmer. This is an activity more for designers and prototypers than for repair people (unless they do a lot of it).

Damage from corrosion may or may not prevent such repair.

You don't re-program the IC if it is damaged; if it is possible to read it, you copy its contents and write them to a new IC.

[thunderbird6]

Thunderbird, Forgive my ignorance, but how do you re-program the IC chip to match the programming of the removed chip--especially once the legs are removed, or if the chip is compromised by battery corrosion? Michael

Most of the ICs on most boards are standard, off-the-shelf, devices which can just be replaced with identical ones. Where you have custom programmed EPROMs or other custom chips then, unless the old one is working enough to read on a EPROM reader you need to have a binary file or access to the code from a good chip, or be able to obtain a pre-prorammed replacement, as Toodles says. In my experience with boards of this age (70s/80s) the EPROMS and other custom chips are often fitted in sockets and they survive all but the most extreme battery leakage, although the socket needs replacing. In the case of the DM3 board I was posting about, all of the chips are standard items, although some are quite hard to find simply because they are out of production - for example I had to source a replacement 9601 chip from Holland and the date stamp on the 'new' chip was older than the one originally fitted! Keith