Can you identify these boards? (Edit- apparently from an organ of some kind)

[WolfmanTech]

While digging out my HP 5005A, I ran across these interesting old boards deeper in the box of assorted parts, can anybody ID them or at least suggest a function? Mods- Hope this is the right forum for this! 1-4 are the largest board, 5-7 are the smaller board, and 8-10 are the smaller board that is a reduced version of 1-4. Neons, barrel-caps, disc-caps, resistor-networks(?), and an adjustable thing in a can, either an inductor or a capacitor. The numbers on the boards don't get me anything in google, so I know it's old! They have several other markings 'BAL-5', 'IK', 'B 177' 'B 164', 'B 156', and 'B 221'.
Capacitor marking 7032 probably means 32nd week 1970, so that gives us an approximate time period!

[Quarlo Klobrigney]

They look like some tone generator boards I have seen in a few organs. Probably a Baldwin or a Hammond from the 70's.

[rob77]

no clue what they might be, but the silkscreen showing the traces underneath is awesome 

[G7PSK]

With all those neon's it's either timing or oscillator circuits of some description.

[Gyro]

The neon boards look like ripple counters (frequency dividers).

[WolfmanTech]

Quarlo- There is a similarity to some Vox boards, yes- http://www.voxshowroom.com/us/organ/V301H4.html Thanks!

rob77- Isn't it though?

G7PSK- Possible, though google won't give me anything that looks similar. Thanks!

Gyro- Also possible, though again, google won't give me anything that looks similar. Thanks!

[Richard Crowley]

Google revealed several discussions of electric organs when searching on that Sprague circuit module part number.

[John Heath]

Neon bulbs were used in guitar amplifiers for low frequency tremolo effect. I could see an organ using the same circuit with neon bulbs but why so many??

[Brumby]

Reminds me of the insides of an old Hammond organ.

Plus, there's 12 identical circuits on this board ... and that's an octave.

[WolfmanTech]

John Heath- One for each circuit, thus prolonging the life of the bulbs, perhaps?

Brumby- Ah, good point!

[iampoor]

These look more like boards from a CONN organ. I have taken several of them apart, and have a box of capacitors just like those from the organ. They are most likely frequency dividers as stated previously.

Not sure about the bulb on each circuit tho. Usually the master oscillator would be modulated to create a vibrato effect.

[WolfmanTech]

So, now that they're roughly identified, anybody have an idea what function tests I could run? Just for fun, of course.

[Richard Crowley]

I would think the first order of fun (and possibly of practical use to others) would be t draw out the schematic diagrams so that you could get a feel for what the circuit looks like, what inputs and outputs it has, etc. etc.

[Brumby]

I would think the first order of fun (and possibly of practical use to others) would be t draw out the schematic diagrams so that you could get a feel for what the circuit looks like, what inputs and outputs it has, etc. etc.

My thoughts exactly.

[WolfmanTech]

I can get a start on that, since I have two(-ish) of each board I can depopulate one and get a clear pic of the bare boards and do a crude edit to list placement of each component, with values.
As for a proper diagram, I'm not sure I can be much use there as I don't know hardly anything about making them! But yeah, that'd be a good step towards being able to test/utilize them in some way.

[Brumby]

Do something like a PCB overlay - and there will be a few of us that could take it from there!

[WolfmanTech]

Well, they do have the nice feature of having the copper-side paths silk-screened on the component side! Would that help?

[Brumby]

That would be great.  For a start, you won't have to work with a mirrored copper side.

Depopulate one board and photograph it.  Then work out a way to mark the components using the second board - whether by print out and draw them on or use some image software.


If you're not sure how to go ... just try something and we'll guide you through it.