New to me Rodgers Exeter 770 help

[ej01550]

Greetings!
I've recently acquired a Rodgers Exeter 770 and am having issues with it.
Plugged the instrument in and the power button has no affect - will not turn off or on the instrument. If I press and hold the power button in the pedal board light comes on but not tab LEDs function and no sound.
Using the bypass switch on the amp the pedal board light illuminates but no LEDs function and no sound. In By-pass the Power button also seems to have no effect.

The dealer I purchased the instrument from swears it was working fine and that something must have come loose during moving.

Can any of you provide some ideas as to where I can start looking to resolve the issue before I break down and have to bring a Rodgers Tech to my house?

Thanks so much!
Erik

[Casavant Fan]

Was it working when you tried it? You did try it?? Did the dealer offer any kind of warranty or was this purchased “as is”? I kind of remember this model from wheniwas shopping in the early 89s.

[ej01550]

Alas I did not try it at the dealer. However being a respectable electronic organ dealer that installs organs costing 6 and 7 figures I believe their assessment to be accurate.

All wiring appears to be secure. A music lamp wire was not initially connected but that was quickly resolved.

[Casavant Fan]

You did not indicate the terms of sale, specifically any warranty that was offered, or not.

regardless, given that this is a dealer, I would put some pressure on him to check this organ out, especially as he represented that it was working at the time he sold it to you. Does this dealer represent Rodgers? If so, I think there is some added need for a showing of good will.

i hope it works out for you.

[ej01550]

Mystery solved!

After a had more time to really inspect each board I found the MIDI conversion board (which is piggy backed onto another board directly) was not seated properly. Re-seating the board solved my issue of it not turning on. I never would have thought such a simply thing would even prevent the instrument from powering on.
I'm now off solving apm issues.

For some reason I only get signal from CH3 which seems to be the low end / bass register. CH 1 and CH 2 are not sending any signal to the speakers. I have checked and re-checked the wire connections but - nothing. Argh

[toodles]

The MIDI board is in series with the microprocessor's data stream, so if it is not fully connected, a lot of the organ wouldn't function. There is a switch to bypass the MIDI data stream if it is not installed but that would not have been in play since the MIDI board was there and supposed to be connected.

What are "apm" issues--I am not familiar with that abbreviation?

Check for a headphone adapter or plug inserted into the headphone jack. That will mute the speakers, though I would expect the bass channel to be muted as well. I believe muting is done prior to the amplifiers.

[AllenAnalog]

I think "apm" is a typo for "amp."

[ej01550]

You are correct - AMP.
Sometimes the brain goes faster than the fingers.

- - - Updated - - -

The headphone jack is free - I confirmed the organ was functional once I was able to turn it on with a pair of headphones. Once you fully engage the headphone jack it automatically engages the Main Off tab.
I unplugged the headphones and turned off the Main Off tab to confirm speaker operation. Only the wire attached to CH3 is pushing signal to the speakers.

[ej01550]

So flying blind here....is there a way to adjust each channel input / output level? As I mentioned CH3 (Bass) seems fine. (Ironically the dealer said I would need a separate amp for the pedal voices and it's the one thing that plays fine). I can detect the faintest hint of sound coming from the speakers for the manual stops but I also get a slight hum as if the volume is already cranked up to the max. It's almost as if the signal coming to the amp is not strong enough.
Any help is appreciated!

Erik

[toodles]

Yes. See 770 Leveling Guide. The 770 does not have specific voices assigned to the pedal channel, except, perhaps, the 32 ft and 16 ft octaves of the unit voices. Each of the main channels has an adjustment to send its bass signal to the pedal channel. The 770 shipped with a separate pedal channel amplifier for mounting external to the console, but it is possible to be mounted internally. It's output, though, would not go through the output panel, but be taken directly off the amplifier.

[jbird604]

I think toodles provides the missing clue. The bass is working because it is coming from an amp that is mounted separately on the inside of the console. The rest of the channels would be using the 3-channel amp that is part of the power supply assembly mounted on the inside of the kneeboard. That amp is likely dead. One possible cause would be the 40 volts (or whatever it is) from the power supply that runs these three channels is missing.

There's a possibility too that someone intentionally disconnected this internal amp by removing the input or output connectors, which are, IIRC, four-pole molex connectors that snap into two different sockets on the amp pc board.

There are other possible causes, such as failure of the un-muting circuits, but many such causes are unlikely because they would also affect the bass channel. So I'm thinking that internal three-channel amp is the culprit, either missing its voltage supply or else having a plug loose or pulled off completely.

[ej01550]

The Bass AMP is not installed and I am not using Rodgers speakers. The only amp in the console is the three channel amp. Regardless of what speaker I connect to it - CH3 is outputting low end signal (32' 16' lower end of the 8' 4' stops - no treble at all). CH1 and CH2 are outputting high end but so faint you need to put your ear up to the speaker cone to hear it. I'm hoping I connected the speakers correctly - I assumed CH1 +/- = Speaker1 +/- and so on.

[toodles]

For the 3 channels, it doesn't matter which channel goes to a specific speaker as far as working--it might matter acoustically when you finally place the organ and speakers.

Since the headphone jack provides a good signal, then the problem is in the connection between the preamp outputs to the amplifiers and on to the speakers. Are you sure the speakers are good?

Any troubleshooting generally follows a signal from its source to the end of its journey--since the headphones prove the source is good, then it flows from preamp (where the headphone signal is generated and the other audio is mixed) to the amps, to the speakers. Start at one end and see where it is missing.

Also, check for fuses on the amp, connectors that aren't seated, and other mechanical issues.

[John Vanderlee]

For audio troubleshooting I found two tools very useful: one is a pocket signal generator set at an audible frequency like 400 Hz with clip leads which allows me to inject a signal along the audio path. With its variable output it will even (softly) drive a speaker! It's a quick way to follow the sound through the organ.
Another is a small powered speaker, like Yamaha, whose input I use with clip leads to see if there is a signal at all from the tone generators, and follow through the signal path as well to see where I lose it.

[ej01550]

Well the issue is resolved - kind of.

For some reason CH1 & CH2 only play then the Antiphonal ON is selected.
CH 3 plays regardless.

Is this a normal set up for this instrument? Seems strange - but at least it works!