Gulbransen Model D Issues

[Vince560]

Hello,

I recently picked up a Gulbransen Model D organ for free since I am interested in organ music and want to have one at home to practice on. That being said, I have a few issues with mine.

First issue is that only the vacuum tube stops make sound, and regardless of what combination I choose, they all sound the same. On the bottom of the keyboard it might sound more like a reed stop, as I go up the keyboard it changes to a more flute like sound. The chime/music box sounds still work.

Second issue is that all the F# keys and pedals make no sound. All the G's make sound however it obviously doesn't sound right, G tends to sound an octave higher than all the other notes.

I have experience with electronics however I am not sure where to start on an organ, and wanted to know if I could get some guidance on what the look at.

Thanks

[Jan Girardot]

Vince, if your new baby is, indeed a Model D, it is an extremely rare bird. According to my Gulb. info, only three were built, in 1957. It had individual transistor tone generators and was supplied with two Leslie tone cabinets, a model 100A and a model 100B . Does that sound like yours?

A photo would help. There were also models D1 (1964) and D2 (1965) that had two sets of generators.

To double check, I suggest you take a flashlight and look up under the keyboard deck (the part that overhangs your knees when playing) and find the model/serial number plate.

. . . Jan
the Organgrinder

[indianajo]

It sounds as if your F# master oscillator is not oscillating. These are the board with the square metal cans on them. DO NOT adjust the iron slugs inside to adjust the pitch. These were designed for that, but after ten or forty years, they rust in place and can be easily fractured, since they are sintered metal. check the paper capacitors in the oscillator circuit with a capacitor checker, to see if they are the proper value. For 1957, usually not, oxygen attacks paper capacitors not totally sealed with wax.
Resistors in that circuit can be checked with a DVM usually in circuit (on tube circuits) the higher value ones, 100k and up, tend to be attacked the most by oxygen and moisture. Again, the quality of the paint is important, a great stride forward was made about this time and resistors from AB and Sprague from 1961 and later are moisture stable, mostly.
Lastly there is the tube. Removing, erasing the pins and washing with alcohol, and reinserting, can solve a connection problem. If the is white inside instead of silver, the vacuum seal is broken and it is automatically bad. Other tubes, I tend to measure the plate, cathode and grid voltages versus the print, before declaring one bad. Read the safety sticky thread at the top to do this safely. (the Link works under Hammond thread, the link may not yet work here). tube testers sold these days tend to be emmision testers, which are no better than a DC voltage check in circuit. The Gmo tube testers are rare birds indeed, and the Triad one I have is broken, too.

[radagast]

Is this a church organ or a classical organ? This forum is for those types of organs. Or is it a home organ?

[Jan Girardot]

At this point, no clue, since we don't know for sure what model he has.

. . . Jan

[Vince560]

Sorry it took so long to get back to everyone. I have uploaded some pictures of when I picked it up. I said Model D because I thought that was the one that came with the AGO 32 note pedalboard. I'll take a look at the oscillator but I'm assuming it will have to be replaced. I forgot to mention that the G keys do the same thing as the F# keys.




- - - Updated - - -

It's a home organ, but it used to be in a church.

[Jan Girardot]

Vince, do us all a favor and find the model/serial number plate. As you are seated in playing position it should be on the under side of the keybed, the part that overhangs your knees, above your left leg.

Have you removed the console back yet? Take some pictures of the works.

While I am asking questions, what part of the world are you in?

. . . Jan
the OrganGrinder

[Vince560]

I looked where you told me and there is no data plate on the organ. I did start cleaning some of the parts inside.

Here are some pictures of the inside, it's still very dirty.

[Jan Girardot]

Question: were there small metal cans covering each of the lamps/light bulbs? Now we know it has a full set of the time-honored Tibia (Flute) individual transistor tone generators.
Have you pulled the kneeboard, yet? It could be that your F# and G keys are dead because the cables connecting the blackboard tone generators to the junction channel are just
unplugged.

Somewhere in there are (probably) some more tone generators which provide the string/reed/diapason voices. More photos, please! A full-width view of the back would answer several questions.

Again: what part of the world are you in?

. . . Jan
the OrganGrinder

[Vince560]

I'll get a picture of the entire back tomorrow. I live in Goldsboro NC. About 45 minutes south of Raleigh.

[tucsondave]

Looks like the standard additive flute voicing system with the buss rod turning magnets but possibly some filtering via the photocell switching.

In addition to what Jan said check to see if the all the lamps light at some point when various tabs or switches are activated.

Please be specific about functions that don't work. Words like "some", "most", or "a few" don't tell us anything to help with troubleshooting.
For example what is a "vacuum tube stop?"

td

[andyg]

Comparing the photos with Blue Book, this is the Model D (Classical) from 1965. Didn't jimmywilliams have a few threads on here about the 'theatre' version of the same organ? If so, there may be some useful info there.

[Jan Girardot]

I think you are right, Andy. This is where the water gets muddy: from the beginning, Gulbransen used two identifiers for each model, one for public use and another for factory use. For example, the model D-1 (white tabs) was the 1133 (1964) while the D-2 (colored tabs) was the 1134 (1965). Both had a set of individual transistor generators plus a set of transistor divider generators. The Organ Bluebook never got into the fine points.

To muddy the waters even further, in 1957 they had built a run of just three model D's, the 1102-1. The 1134/D-2 was also referred to as the 3rd version of the 1102-1.

Kinda makes you go cross-eyed, doesn't it?

. . . Jan

- - - Updated - - -

Dave, as I recall the lamps and ORP photocells were used to control only the Main (string/reed/diapason) voices. Of course, with the little can covers off, all those voices will play: what a racket!

. . . Jan

[tucsondave]

Look at photo # 2 of the inside. There's a paper label with "Walnut" printed on it. Could that also have the model number?

td

[Jan Girardot]

Good catch, Dave!

Also: just to the left of the large black edge connector is a label that appears to have "D 1104" on it.

. . . Jan