More Rodgers 321 Issues

[Vercus]

Hello again,
Seems like it's that time of the year again. Summer humidity causes numerous issues. Here's today's list:
1. Glock is back to doing phantom notes, despite previous repair. Seems like it's mainly top C.
2. Harpsichord plays, but only very faintly.
3. Numerous key contact issues, despite frequent cleaning.

If the harpsichord didn't play at all, I'd expect a contact somewhere, but the fact that it's faint has me confused. All other stops are ok. The glock issues was addressed before I got it, so I don't know the solution for that one.

As an aside, I'm definitely not impressed with the sound of the speaker cabinet it came with, and would like to hook up one of my full size Leslies. I have two 900s and one 760. I also have two Peavey SP1s I could use for the stationary side. That ought to let this thing rip! The problem is, I have no idea how to hook them up.

Any suggestions would be greatly appreciated. I feel like the organ is really not able to blossom right now, due to it's issues and the lousy Rodgers speaker cabinet. Think it's called ML-702, or something like that? It looks like a women's dresser, with a little styrofoam drum Leslie in one side, and a few speakers for the stationary side in the other. It takes up space, but sounds small and timid. I'm always using the organ with the shoe full open and it's still quiet.

-Jon

[johnbeetem]

[Usual advice caveat: this is free advice offered with no warranty or liability. It's mostly generic advice based on things I've seen or read about over the years.]

First, do you have schematics? I have a Rodgers 321C, and there are schematics for the Rodgers 321B and C in the Gallery.

The 321B/C schematics may be useful. Some of the boards may be the same (check board number) and others may be similar. At least you get an idea how things are supposed to work.

1. Glock phantom notes: The first thing I'd do is check grounding. On my 321C the power and ground connections for the Glock and the music desk go through a terminal block under the lid. Some of the lugs may have oxidized over the decades and need to be cleaned. Sometimes just unplugging and replugging a few times is enough to scrape off the schmutz. Otherwise contact cleaner might help.

If the problem is reproducible and you have a digital oscilloscope, you can probably track it down. EEs like to say that a reproducible bug is half fixed. My Rodgers 321C glock is circuit is on page 74 of my 321B/C schematics. There's a Glockenspiel Mark II on page 80, with variable expression.

2. Harpsichord plays faintly: The piano/harpsichord circuits are on page 65 of my 321B/C schematics. There's a level adjustment trim pot for the harpsichord. Pots can get dirty over the decades, so that's something I'd suspect. Note its current position, and then turn it back and forth a few times to see if that scrapes off the schmutz.

I have a vintage Sony stereo receiver/amplifier and it developed problems with the volume control. Changing the volume caused horrible noise bursts. I fixed it by spraying it with contact cleaner and turning back and forth. It took a few iterations. I used CRC QD Electronic Cleaner "Quick Drying Formula" which I got from a car parts store. Spray with power off and let dry before powering back on.

If it's not the trim pot, it may be one of the other components such as a transistor or capacitor. As always, looking at the signals with a 'scope is your best bet. I'm a computer engineer with enough 1978 vintage analog knowledge to be dangerous. Working with the 321C makes me feel like an undergrad again :-)

3. Contact issues: My 321C has very simple contacts. Each manual key has a pair of stiff wires (probably nickle-plated) which brush against a metal power rod (probably also nickle-plated). They make a wiping contact which should prevent build-up of schmutz. If you have reproducible poor contact, it would be useful to check contact resistance with a multimeter. One possibility is that the rod or the key contacts have lost their plating, allowing oxidation. If it's the rod, you can probably replace it.

Another possibility is a poor ground elsewhere. My 321C's power and ground wires are soldered in place, so no contacts except for the Glock and connections at the power supply. OTOH, soldered joints can deteriorate (particularly if defective when originally made) so some may need to be resoldered.

Hope this helps!

[D1gichip]

1. Glock is back to doing phantom notes, despite previous repair. Seems like it's mainly top C.

This may be due to rotted sponge under each striker causing the solenoid to stick.
There are capacitors that key each note. These go bad. Located on the glock PC board.

2. Harpsichord plays, but only very faintly.

Bad coupling capacitor in the harpsichord voicing circuit or in the preamp. Common in my experience. Could be a control pot, but the first time it is moved the problem should disappear for a while. Not much else except the audio control transistor for turning it on and off.

3. Numerous key contact issues, despite frequent cleaning.

The buss rods are not nickle plated. They are gold flash plated. Contacts also same. The buss rods get sludge from the surrounding the organ is in. The buss rods need to be gently buffed using some Deoxid or similar contact cleaner. I take a small piece of thin cotton material, like an undershirt type material, and spray the cleaner on that rag. Cut it so it is like 3/4" wide and about 4" long. Slide it between the contacts and the buss rod and run the rag up and down which will burnish/clean the buss rod. Number one cause of this problem. They are usually quite reliable, but if in a home with a smoker... they really get gummed up.

As an aside, I'm definitely not impressed with the sound of the speaker cabinet it came with, and would like to hook up one of my full size Leslies. I have two 900s and one 760. I also have two Peavey SP1s I could use for the stationary side. That ought to let this thing rip! The problem is, I have no idea how to hook them up.

You have had a ML-202 on that organ. A Rodgers built Leslie in a box. It is not supposed to be the main speaker. The Leslie part is only for the Tibia voice. Other half of the cabinet is a stationary cabinet for the "Main" part of the organ. They were NOT good sound! Passable at best IMHO. (I've been self-employed in the organ service business for the last 45+ years. Used to fly around east of the Mississippi River for Rodgers servicing organs for other dealers whose techs were having trouble getting organs repaired. It was fun!!)
Using a speaker designed for a PA system is not good. Wrong crossover frequency generally in all of them. You also do not want to put a midrange horn on the organ either. It will make it really harsh sounding. You should Rodgers Amplifiers for use with any speaker you put on the organ. They have a turn-on relay in them, and the input is optimized for the signal output from the organ. I own a Rodgers 321 right now. I also own a Rodgers 33E which is now run with Hauptwerk software. The 33E electronics got trashed. The new system allows me to play any type organ I want to play, whether theatre or classical, by downloading the organs from sample sets which people have compiled.

Any suggestions would be greatly appreciated................... It takes up space, but sounds small and timid. I'm always using the organ with the shoe full open and it's still quiet.

You could do very well with a separate subwoofer, and 2 Studio monitor type satellite speakers. I've done that combination many times over the years. The amplifier you need could be a standard 2-channel amp, but you will have to turn it on and off yourself, unless you add a power relay to turn it on from the organ console. Don't use less than 100W/channel, otherwise you will not get good performance from any speakers you use.

The Rodgers 321A is not a bad organ. There are MANY things you can change on that organ to make it even better than the factory built it.

All the best!

[John Vanderlee]

Since I was the one last worked on this one, I 'm sorry to hear those things cropping up. I can't judge much without being there, but I would check the volume controls on the amplifiers in the "dresser". They may be dirty. On the Glock - I also had some phantom ones. They were fixed by replacing the electrolytic and the transistor on each striker circuit - cheap parts. But to get into the Glock is a bit tricky. You should really look first how it is put together. I placed a long 12" wide board over the top of the open console to use as a bench/support. Be careful of the solenoids. the wires are very fine. If you decide to expand the sound system I have some of the Rodgers 100 watt amps that I'd sent to you just for shipping.
John

[johnbeetem]

Be careful of the solenoids. the wires are very fine.
John

Yes, it's very easy to hit a solenoid accidentally tear it off the PCB, breaking its wires.