Rodgers 810

[arie v]

Hi,

I am working on transplanting a Rodgers 810, àn early '80s organ. It also is is a first generation Micasko technology organ.

Make a long story short, the organ was moved and worked fine. Yesterday after hooking up some speakers, I turned the organ on, but it would't stay on. BtW with this organ, you are given about 10 seconds to plug in a code.

I do have an early service manual, but doesn't say much about how this Micasko stuff works

Does anyone here have, any info on how to do diagnostics on these organs?

The Micasko system is based on some sort of a handshake between the CPU and the power supply. I should add there is a bypass switch, which I tried, but it didn't solve the problem.

TIA AV

[jbird604]

Arie,

I see that you emailed me about this and I failed to respond. Sorry, my friend. It has been a super busy week and I've not had as much time as usual to think on such things.

Considering that even Rodgers couldn't keep these Micasko organs going 38 years ago, it's surprising that you've found one that was actually working! I've never seen one. I sorta thought Rodgers recalled them all after a year or so of unrelenting hate directed at them by everybody who bought one. Or at least they all got traded in with very generous deals.

It sounds like the one you're seeing is one of the very few that actually worked. The current failure is probably not related to the fact that it's a Micasko organ, but some other more common failure. If the CPU board has a common Z80 microprocessor on it, you could try changing it out. They are, presumably, still available from many sources, and very cheap. I've changed out a few on CPU boards from later 80's serial keyed organs.

Also, it's worth checking to see if the batteries are dead. Not having any actual experience with Micasko, I can't say with certainty, but I guess the battery might be so dead that it is pulling down the entire system. Other than that, I can't think of anything beyond the usual standard routine maintenance -- pulling and re-seating all socketed chips and connectors wherever they may be found, verifying all the operating voltages, exercising any pots that exist in the digital portion of the system.

Perhaps one of the more knowledgeable Rodgers guys such as toodles or tuscondave will chime in an offer more specific suggestions. Good luck!

[arie v]

Hi John,

It was against my better judgement that I told the church that this organ at least played for the most part, and that the price was right. I knew about the problems Rodgers had with the Micasko organs.

Anyways, the organ did work until I rehooked up the speakers, turned the organ on, and it would not stay on.

Will be going there today and see if I can't get her going.

I may have to hook the previous organ to the speakers.

Thanks for your post.

AV

P.S. There is at least one other 810 in the Toronto area, ( I have serviced that one also), and I would not be surprised if there weren't 1 or 2 more that I haven't seen.

[toodles]

Unfortunately, I don't have any tech documents nor any personal experience with the first generation MICASKO organs. I suspect that the general theory of operation was the same as the LTG models (650, 740, 760, 770, 840, etc.) of the 1980's but I am sure some details vary.

I concur with JBird that the micro board itself is probably not the problem, and the batteries might be an issue. Though I would suspect that an issue with batteries wouldn't keep the organ from turning on unless they completely drain the power supply. the later models used a trickle charge, so current on those would be limited and shouldn't crash the supply, but on the early ones it might have been different.

Definitely look to the power supply as a source of the issue.

Have you tried disconnecting the speakers? Perhaps there is an issue with them that causes supply problems.

[NoTalent]

What is this

... you are given about 10 seconds to plug in a code.

stuff ?

Greg

[toodles]

It is an access code at turn-on to permit control of the combination action. Not one of Rodgers's best innovations, in my opinion--but, no keys to lose.

[tucsondave]

Actually you couldn't even play the organ without entering a code. The factory default was to press any "1" piston.
Access to playing and changing codes, but not the memories, was grated by entering 1, 2, 1, 3, 1, 4, 1, 5. This code is fixed in ROM so would not be affected by loss of battery backup.

The codes could be changed by activating a reed switch with a magnet and pushing some pistons.
You then put the magnet in a brown paper bag, went outside, flapped your arms, waved the bag over your head, and screamed like a chicken!

td

[jbird604]

Maybe Arie doesn't have a paper bag at hand?

[arie v]

Hi ya'lll

I managed to get the organ going again.

I disconnected the speakers at the amps (there are 5 amps on this organ), and reconnected them, and the organ fired right up. Strange that, because I hadn't touched that area before. That must mean that there is communication between the CPU and the analog output part of the organ, something I would not have expected.

I did do some voltage checks, and they seemed fine. Some of what I was trying to get at was impossible, as the console is in a pit, and the door only opens about 2'. It is no fun crawling around in there.

I found a small Lithium battery ( made in 1997) with a resistor in series obviously a replacement for the "D" cells that were originally in the organ. The voltage on the battery was zero V, so it will replaced.

Looking for information on the Micasko organs, I came across a couple of documents, one was called Micasko CPU - Theory of Operation, and a second one Micasko Servicing - troubleshooting guide. The service manual covers the following models, 810, 870, 270, 300, 900.

If somone wants this info., let me know. Makes for wonderful bathtub reading.

Thanks again for all the help received.

AV