More pieces from custom ADC theater organ with TT-4 and TT-5 TG boards on eBay

[AllenAnalog]

The person selling the pieces of the custom ADC theater organ with TT-4 and TT-5 TG boards has now put the cage backplane up for sale for $999 on eBay. Not the whole cage but just the backplane. I cannot imagine anyone buying it, even at a lower price. What would you do with it?

And other than what michaelhoddy bought as spares for his TT-4 based organ I don't see any great rush to buy any of the other cage boards from this dismembered instrument.

[myorgan]

He won't find a buyer with them listed as a group. I'm afraid Michael might have spoiled him into thinking it was possible, so they'll probably languish there until they're taken down or destroyed.

Michael

[michaelhoddy]

Yeah- I don't know if I did the right thing. On one hand, I have a lot of TT-4 board spares now, which I feel like I should establish as some sort of public trust. On the other hand, I'm probably one of very few potential buyers that would know what these are, let alone buy them, and that has probably generated false hope, although I think on a per-board cost basis, it was fine. I am somewhat interested in the EG and DG boards on eBay that would make a complete set of spares.

I agree that the backplane is basically useless to anyone outside of the original organ.

[circa1949]

I suppose one question for you MichaelH, is whether those EG and DG boards ever fail. They seem relatively simple. Absent a massive overvoltage event (I'm sure you have your TT-4 organ protected with a good UPS/surge suppressor?) it seems like that circuitry should last forever? Maybe a question for our long time Allen techs like John or Andrew. My overall impression is that we've heard of MOS era boards just flat out dying way more than the ADC/MDS era boards?

[circa1949]

Yeah, that's a laughable price...especially for a custom organ, there would be no other organ to use it. In theory the backplane of a standard model has at least some resale value.

[circa1949]

EDIT: Although, now that I think about it, we know very little about the backplane configurations of these custom organs.  Which presumably have every card slot possible installed, and thus can have a full suite of cards.  Maybe the EG is always in the same set of slots, the DG always in another, etc.  As far as we know the addressing was always hard coded throughout the ADC/MDS era, right?  IN other words if you swapped one TT-4 for another, or one TG-8 for another, the stops literally move.  There's not a cage length 'bus' back there that is looking for the ID of an EPROM.  Maybe theater models needed a different # of EGs though because of the greater # of percussion stops? And so again the question is, how many universal era custom theater organs were there?  Probably very few!

It's a shame this guy hasn't posted the cage chart in any of his listings!

[michaelhoddy]

I know that you can mix and match TT-4s and DG and FG boards of the same numbers in the same slots, so there's no board or PROM-specific IDs. The different TT-4s just use the decay/release and pitch table maps of whatever DG or FG boards are in those slots. I have not worked up the courage to try a TT-5 in a TT-4 slot or vice versa.

And of course, the slots are hard wired on the backplane for their board type.

[circa1949]

Yeah I was pretty sure everything was 100% hard wire, but not sure sure. I have been afraid to swap around my W14s and see what happens, but the stops probably just begin being controlled by the wrong stop controls.
Once everything is 100% to my liking on the MDS-65 and I've learned all the pieces I need to learn (ha), I will use the MDS-45 as a test bed for some experimentation.