Gulbransen Rialto II

[DJMAC]

Hello. Recently saved a Gulbransen Rialto II model 6018 from a church near me. They said they remember it working until the plug was severed, Then it was abandoned in a storage closet for many years. I repaired the plug and the lights came on and the Leslie started spinning, but not a peep out of the organ. With the help of a very generous member of this forum I was able to obtain a service manual. I am obsessed with getting this organ working, and like all of us, have a lot more time at home to tinker. While reading through the manual and realizing just how daunting of a task this may be, I noticed this entry:
"EXTERNAL SPEAKER OUTLETS : The twelve connector contains completely processed signal. When external cabinets are NOT USED, the jumper plug which is installed at the factory must be inserted in this socket. If it is removed, the organ will be inoperative."
There is a 15 pin, a 12 pin, and a 6 pin external speaker cabinet outlet on the back of the organ. Nothing is plugged in to any of them.
If anyone could shed some light on what the factory jumper plug is and what it looks like, and where to obtain one, I would be very grateful. Don't want to get my hopes up too high, but wouldn't it be great if something so simple got this thing playing again?
Thanks

As the Rialto II isn't a dedicated electronic theatre organ, I've moved the thread to Home Organs, where your question should get a better response.

We do have some Rialto II owners on the forum and it's shouldn't be too hard to find out how the 12 pin jumper plug is wired. You can then hard wire the socket, should only be a few soldered connections. Andy G - Moderator

[andyg]

A fully working Rialto II can make some gorgeous sounds, let's see if we can get it up and running!

[jimmywilliams]

Hi Dave, glad the Rialto II manual worked out for you. I just dug mine up this evening.

OK Look at the colors of the wires that come into the back of the 12-pin connector - the one in the middle. Ignore the 6 pin and 15 pin connectors; don't do anything with those - unless you ever get the external speaker set that is.

Now back to the 12-pin connector. Refer to page 18-2 in the service manual. This is a diagram of the 12-pin connector from the rear - but to avoid confusion look closely at the wires going to the back of this plug. You will see the wires are in colored pairs - each color is for one of the 6 audio channels.

For each pair there is a preamp output and an amplifier input. Using the external speaker hookup kit would intercept the the preamp signal. So right now without the 6-way jumper assembly plugged in, each of these 6 audio channels is "open" as the preamp signal has nowhere to go.

So for each of these same-color wire pairs, you just need to bridge the gap..

Before making things too complicated, you can try a simple proof of concept by manually jumpering the color pairs - You can use any sort of jumper wire you can wedge into the connector holes - make sure it is insulated wire though - you don't want any bare metal shorting anything out - just strip off enough to fit snugly into each of the holes . Make absolutely sure you are jumpering to/from the same color wire!

I would not recommend ever cutting the wires off the 12-pin connector and just bridging them them that way. That would make things "easy" actually - you just need 6 wire nuts and you're done. But then it would be very difficult to ever use the external speakers - should you ever come across them. In fact I'm very surprised the church did not have them laying around somewhere - who knows maybe you can track them down. Anyway I'm a big fan of keeping things as "stock" as possible.

Anyway, jumper from/to the holes as follows. Remember if you are looking at the diagram the numbering is from the "Rear view" but I guess that means the back side of the connector? I don't know what it is relative to. If so everything will look "reversed" if you are looking at the back of the organ. Be careful. Just be sure to orient yourself correctly - that's why I suggested focusing more on the colors of the wires.

Black wires: Main channel 1 (connect pin 1 to pin 2)
Brown wires: Main channel 2 (connect pin 3 to pin 4)
Green wires: main channel 3 (pin 5 to pin 6)
Blue wires: Main channel 4 (pin 7 to pin 8)
Violet wires: Tibia channel (pin 9 to pin 10)
Yellow wires: Pedal channel (pin 11 to pin 12)

Give that a try - see how that all works out. Just be sure to only bridge the same color wires, ONLY work with the 12 pin connector, and never have any bare wire exposed and touching other wires, crossing, etc.

If that works we can look into making some sort of permanent connector - I may have some spare molex connectors in the basement but there are so many possible sizes, variants, etc. we would need very specific info. It is not always easy to find the exact replacements.

Good luck,
Jimmy

[DJMAC]

Thank you Jimmy, for once again taking the time to help me. Your instructions were so clear that even a beginner like me couldn't screw it up.

I connected all the appropriate pins, wire color to wire color, but alas, no sound. Then I removed the wires, and realized I had messed with all the settings except the volume pedal, which was on the low side during my test, so I wired it all back up and tried again with the volume pedal up, and still no sound. Oh well. At least I can check something off the list. Then I began wondering "If I was an organ tech, what would be the next thing I would investigate?" Then I wondered if there was a book that would walk me through the likely steps, or even an old "How to become an organ tech" book. So, of course I searched it on the forum and found a thread about books, that all sound really interesting. Saw the name Forrest M. Mims III and was pleased, because when the organ arrived I remembered someone had given my son the Electronics Learning Lab - A Complete Course In Electronics with Workbook 1 and 2 and all the equipment and parts, when he was far too young for it, and I got it out and started working through it. I knew right after opening up this organ, I was going to have to pay a lot, or learn a lot, to get it working again. I was hoping to do a little of both. I found a guy a couple of towns away that has been working on organs for many decades and services my area, so I thought with his initial help, I could get at least get an idea of what needed doing, and see if I could do any of it. But then the world shut down, and who knows when a service call will be an option again? So, I guess I'm going to learn electronics and keep bugging you guys with questions. Thanks again.

[geoelectro]

First thing is always, check the power supply. There are several DC voltages generated by the power supply that are distributed across the organ. Use a meter to verify they are there. (check fuses and regulators if any are missing)

I then check for any amplification. If I can find a place to touch and get hum, (like the preamp board, filter board etc.) I can then signal trace with my hands.

In low voltage electronics, you can touch circuits without being shocked. Most voltage levels will be 15 to 20 Vdc or less. Except on the power amplifiers! You may encounter plus and minus 30Vdc or more. That's a 60Vdc difference. That in itself wouldn't hurt you but best to stay within the preamp size voltages of plus and minus 15Vdc. (estimated)

Once I have a hum point, I can keep one finger there and with a small screwdriver in my other hand touch pins on the tone generator board to hear if the tones are being generated. If not, then troubleshoot the generator. Voltages, bad dividers etc.

At this point if you have hum and tones, you very likely will be able to get it going eventually. You just have to trace the signal flow from tone generation to output and see where it breaks down.

This is a brief description of troubleshooting. You verify DC voltages essential in circuits working. Check for amplification which can be used in troubleshooting. Check tone generation which is essential for any sound.

BTW...the drum machine isn't tied to any tone generation so it could possibly work even if all keyboards sounds do not. It would verify certain sections were working like the amplification and whatever DC voltages it uses.

Geo

[DJMAC]

Thanks Geo.

I appreciate your advice on troubleshooting. I'll report back if I have any luck.