C2621 IC Chip for Elegante

[dannicdem]

My Elegante 304100 needs 1 or 2 replacement C2621 IC chips These chips go into a socket on the Generator Board. There are four of them, I only need 2.

Does anyone one know if this Hammond organ has the C2621 IC chip(s)? The plan is to scavenge from this organ.



Thanks to the forum experts for the generous contribution of their time and knowledge.

Best!

Dan D.

[tucsondave]

I can't tell what model that is.
What happened since your post about the cipher that you now need two 440 keyer IC's?
Those were almost $100 back in 1985. I'd hate to think what someone would charge for one now.

td

[indianajo]

As far as I can tell from the Aurora schematic diagrams, Hammond LSI consoles and hammond LSI spinnets used the same 40 pin ROM IC's and top octave sythesizer. The ROMs were fabricated in huge production runs by a prototypical custom foundery, so probably they were all the same. I had literature from such a foundery, AMI, by about 1978. By the time the Elegante came out PMOS IC's were extremely obsolete, so Hammond must have bought a hundred thousand of them when they started the LSI models with the Concord: then kept using them for years. The -17 v and 5 v power supply is the tip-off to PMOS, IMHO.
I don't save pictures of the LSI spinetts below the Aurora, so I can't identify this one. It is a low end model, it only has one set of drawbars. LSI organs could process drawbars into sine waves due to the ROMs. I can't say for sure this is not a Acetone model, a divider organ, the color tabs were about the same, but I don't think the divider organs had drawbars. If it is a LSI Canadian built model the ROM ICS are very likely the same as the console. Where Hammond would save money on the spinet gen board, would be on the connectors and key wires. I suppose AndyG is out visiting family this weekend, or has a gig.
A scrap organ will be your best source of parts for these IC's. Have you changed to 100 uf caps on the level shifter circuits going into the demux board? if dried up the signal could ring and put stress on both the demux IC's (4052) and the ROM outputs. I think some posters have found blown up 4052's but one replaced the organ before learning how to fully use the scope.
Happy donor organ hunting. You're in old organ central, south Florida, and I hear there is an electronic disposal fee, so the price shouldn't be much.

[dannicdem]

Hi TD

Thank you so much for the interrest. The missing note problem had compounded into a cipher problem and continued to be sporadic. Since my technical skills are limited, I found an organ tech with lots of Elegante experience... an no parts who made the diagnosis and left me on my own to finish the repair, hence the parts request.

Yes! Those replacements are very pricy as such the scavenger approach to repair (and being patient) is the most economical way to keep the Elegante working. So, the parts acquisitions are the Top Octave Synthesizer and the C2621 IC chips. It is interesting to note that two of the C2621 ICs had been replaced previously as they are different manufacturers.

Also, the organ bench is a road map to past problems as the original owner saved all the old parts from previous repairs. You'd really appreciate knowing that the first issue for this organ (non-working rotary channel) and your fix as the the IC-1 on the 723 board was replaced. Why the tech didn't install a socket is beyond me.

Will post updates of the results.

With deep appreciation and gratitude to the experts who provide their time and experience,

Dan D.

[dannicdem]

Hi IndianaJo,

Thank you for your reply and generous sharing of expertise. I will soon have the model number and hope to get more information about this future donor organ.

I'd be very interested in learning about the 100 uf cap replacement of which you wrote (demux ICs 4052) and would be grateful for details: board identification and part(s) identification for replacement. I do have a scanned copy of the Elegante repair manual/schematics... the schematics are almost illegible.

Thank you again for sharing your time and knowledge.

Best!

Dan D.

[tucsondave]

Did you or the tech actually swap the 440 IC's to see if the problem moved to a different note?

td

[dannicdem]

Hi TD,

No the swap test was not performed, he seemed very confident. Am trying to acquire the 440 ICs. Have found a scavenger candidate: Hammond Composer model 146215. Does this have the donor parts?

Best!

DD

[indianajo]

246xxx was the number of Richard V's aurora. So I would suppose the 146xxx was similar. I don't know this.
I'm also assuming that spinnet and console generator ROM's are similar, but this is only a theory. They could have the same part number prefix, but have different programs inside. However, setup charge for a run of those AMI ROMs about 1976 was I believe $20000 with about a dozen sample parts resulting. So big reasons to make the ROM programs the same.
I can't read the aurora service manual I have the computer locks up after about page 20. Not enough memory or CPU or something. I think the demux is a "daughter" board plugged into the generator board, but that is going from memory. Look for 4052 14 pin IC's, that is the tip off of the demux board. I think RichardV's "all notes play at once" problem was caused by a blown 4052, but he bought a commodore rather than fix the aurora. Two other guys had the same problem, not as much conversation as Mr V.
Removing and replacing IC's is a ****. You have to cut the pins off the old one to pull them out of the board one at a time, without special **** IC tools. I reinstall IC's with phosphor bronze sockets when I cut one out, TE connectivity ones from newark. I don't like doing the replace IC job more than once. Phosphor bronze oxidizes a little less than tin or brass, although the standard HQ socket was gold plated (now very rare since the price of gold decatupled.)

[dannicdem]

Yes, the donor organ has the replacement IC C26231 440 chip. The only difference I see is the new chips are stamped: AMI 8428CGG while the existing chips are stamped AMI 8221MAA. I am wondering if there is any difference and seek the input of Forum members.

Thank you for your time and expertise.


Dan D.

[indianajo]

I'm afraid without a LSI Hammond My knowledge at that level is theoretical. I had some AMI catalogs and noticed the age of the first Hammond LSI organ- the whole idea that the 40 pin IC's were AMI ROMs was a guess up to this point. I would expect a suffix number to indicate different programs masked onto the ROM. There might be two, one for spinnet and one for console. There might be a lot more programs. With the cost of a run being so high, my guess was they were the same.
First, check the position of the power supplies pins on the IC's on the two organs. One slip one can short an output pin to a power supply and blow something up, so I would use a Pamona DIP clip to do that. I found at work that I could get scope probe hooks, or Pamona grabber hooks, over the pins of a DIP clip more stably than I could put any round meter pin on a DIP leg. That lesson cost my employer a new $600 board one time.
At one point there was a way to copy the programs out of ROM's by exercising all the combinations of the input pins, and reading the output of the output pins. Then one could program PROM IC's with the program. PROM ICs were ICs with a lot of fuses in them which could be blown by heat. At one time newark would perform this service for you for a fee. I am afraid those days are long gone. My employer used to have a "prom programmer" device we bought one year, but that whole lab was shut down and contracted out, with the resultant equipment hauled to dump in the rail car on one weekend after Friday shutdown.
Look at mcmelectronics.com website for some "workstation" devices and whatever. You can read on diyaudio.com tools and equipment thread about IC removal techniques. The new workstations for surface mount components may be entirely the wrong thing for removing IC's elegantly, but I could be wrong. I've been limiting my hobbies to electronic devices that used leaded components or vacuum tubes - for this reason. I don't have nearly the sounds available to me though, that an Elegante has.
If the power supplies are the same I would put a socket in the place of the bad IC on the Elegante and try the IC from the donor organ. Getting the IC out of the donor without cutting the pins is an exercise I have no expertise on. I would hope the entire board would be compatible at the connector level, but that is probably a faint hope if you are still asking questions.

[tucsondave]

Yes, the donor organ has the replacement IC C26231 440 chip. The only difference I see is the new chips are stamped: AMI 8428CGG while the existing chips are stamped AMI 8221MAA. I am wondering if there is any difference and seek the input of Forum members.

Thank you for your time and expertise.




Dan D.

Those are the manufacturing date codes.
For example: 8428= 28th week of 1984
A 440 divider/keyer is a 440 divider/keyer.

td

[dannicdem]

TD

You're the MVP! I'm feeling a little guilty cannibalizing this organ for parts.

Thanks for helping and sharing your knowledge and time.

Dan D.