Looking for a 1967 Vox Jaguar schematic

[DrGonz78]

Not sure exactly what I have here, as it is not in my possession yet. I do know it is from 1967 and is a Vox Jaguar Organ. I do know I have various Vox Continental schematics. Just checking to see if anyone has some info on this keyboard. Also, I do not know if it is a heath kit version or what. I will find out more once it is delivered. Thanks in advance to anyone that might be able to point me in the right direction.

[Sock Puppet]

I found this link: http://music-electronics-forum.com/t9222/

and some general info here: Combo Organ Heaven: Vox-Jaguar

Which might help. Good luck.

Oh, this too: http://www.voxshowroom.com/uk/organ/V304_PS.html

[vintagekiki]

Vox Jaguar schematic

http://music-electronics-forum.com/t9222/#post73640

http://www.vintagevibe.com/misc/Vox%20Jaguar.pdf

http://www.reinout.nl/?page_id=80

[DrGonz78]

Thank you so much you guys! I had found a lot of these pages already, but it is good to document it on this site for all. I could not load the vintagevibe schematic at first but eventually got it. So that will prove to be my guide while working on this beast. Thanks again!

[DrGonz78]

So anyway I have found the power supply of this Vox Jaguar to be good. I started working on this tonight... I have found that there was a plastic rod that was preventing the mid to higher keys from making contact. I put the rod back where it belongs and those keys are working now. This is a Vox Jaguar 304E2 made in Italy and it sounds great even while now functioning completely. The mid to high keys are not the ones giving me trouble now. It seems it might be something in the divider circuit...



I know I should create a new thread for Maintenance issues and not in the schematic section, but I am gonna just post this here anyway to keep all questions on the same thread...

My real question here is about resources for parts really. I have a bad Flute Flat Top Rocker Switch that need repair or replacement...


I might be able to jimmy rig this switch and make my own solution. However, if can't fix this rocker switch, does anyone have an idea where I could find a replacement part for this switch? I want to fix this switch before I start trouble shooting the few keys that are giving me trouble. Most of the organ is working now but just need some advice on where to find good source for replacement parts, if needed. Got to get all the rocker switches in good working order then I will trouble shoot the few key that are giving me a hard time. Thanks guys!

[DrGonz78]

So I used a Guitar E string and fixed the Flute flat top rocker switch. It technically works as it makes continuity in the circuit but still something is not right with the circuit. The switch functions now but only in a mechanical way(continuity and rocker switch function), but not circuit related function. The flute setting still does nothing (no sound) as far as all the other switches are concerned but I will get to that later. I got bigger fish to fry first.


Basically, I have a problem with the four A# keys. Probably a divider circuit problem on the A sharp generator. Could be a lot things at this point and I really have no great skills to solve these problems. I am learning anyway and I will keep trudging along... When I first turn on the organ I have gotten the four A# keys to work after some intensive cleaning of the bus bar and related contacts for the all the keys contacts. The problem is after about a minute of play the A# keys start to fail, starting with lowest in the octaves and working it way down till I only have the very high note working all across those A# keys. The lowest bass note barely even sounds and when I hear it so faintly it is that of higher pitch ring frequency only. So, after reading up on how to trouble shoot this problem I have come to the conclusion that it is the divider circuit on the A# Oscillator board that is failing. It starts with the higher note and sub-divides down the octave to generate the lower keys. When organ if first turned on the lower keys are the first to go after a minute or so. This is all making sense, so I pulled out the A# generator board. I inspected it and tested parts just willy nilly. No complete shorts in any of the Germanium transistors, but that does not mean they are still good. To make sure I cleaned the hell out of the board and soldered up all the connections on the A# oscillator board. After doing this it seems that I can play the four A# keys a bit longer before they start to fail, but still those keys fail in a bout a minutes time.

So I guess I will need to keep cleaning the heck out of this thing... Also, I am gonna research more and figure out what part to change out on the A# generator board... My question to all here is... Has anyone some guidance or advice...? I mean to tap into the experience and recommendations of anyone here that worked on organs of the vintage persuasion. Really having some fun working on an organ and have never touched one of these before. Plz anyone out there will full schematics or advice help! lol...

[Jazz P Bass]

I would start with the main tone oscillator on the A# note.
The master oscillator circuit used a germanium transistor, several capacitors and a tuning coil.
Check Q1 at the collector pin. See if that is where it is dying.

Nice link:http://www.voxshowroom.com/uk/organ/V304_generator.html

[52 Bill]

I would start with the main tone oscillator on the A# note.
The master oscillator circuit used a germanium transistor, several capacitors and a tuning coil.

Jazz is right, start at the master and work down from there. Unlike the Continental all of the keys play a premixed combination of octaves. If the note dies completely, then look at the master osc. If it's just the lower octaves, start at the first divider and work down through each octave.

Play the highest A# and listen carefully to the signal when it dies out, does it die out completely or is it just the lower octave? If it dies completely I'd just replace the master osc. transistor and see if that cures it.

[DrGonz78]

Thanks Jazz for the schematic and to both you & Bill for the advice. I will first plug in the unit and turn it on and about minute of playing the A# keys the lowest bass not stops working. You can hear(very lightly) a high pitch but it almost silent. Then a few seconds later the the next lowest A# will drop and on down the line. Actually, the three highest A# play a high pitch note as if they are identical to the highest A#.

I was pretty sure that the tone generator transistors were the first to suspect. I will try some more tests on those later tonight, thanks again you guys!

[DrGonz78]

So I have to plead bit of ignorance here... I am not sure which leg is the collector... I researched a bit on the net to find a datasheet on the SFT351 transistor but have questions about which leg is the collector. I added a pic here showing what I thought might be the pin layout for the SFT351 layout in reference to the schematic of the tone generator board that Jazz had uploaded. I think I might be confusing the base with the collector. Please let me know if I am close.


These are SFT 351 Germanium Transistors... Anybody have some resources to find replacements or advice on this matter? I did find this one the 322 germanium and that looks like the most reliable bet. What do you guys think?

Vox Organ Germanium Transistors

On the bright side I did test for 15vDC coming into the A# tone generator board and it was good. I also managed to find a loose wire on bias pot near the rocker switches. So, now I have the flute rocker fully functional now and the flute sounds are working again!

[Jazz P Bass]

Have you read the next two pages?
The VOX Showroom - The V304 Vox Jaguar Organ - Tone Generator
They describe how the separate tones are combined.
I think you may be jumping the gun on the transistors.
It very well may be a bad cap.
The pinout that you drew is correct.
Collector to base will read 47K.
Base will read 22K to ground, collector 49K.

[Jazz P Bass]

I found another good repair link: Studio

[52 Bill]

Actually, the three highest A# play a high pitch note as if they are identical to the highest A#.

I was pretty sure that the tone generator transistors were the first to suspect. I will try some more tests on those later tonight, thanks again you guys!

If all of the A# notes play the same as the highest one, then the problem is in the dividers and not the tone generator.

The tone generator creates the highest note and then is divided in half, over and over again to create the lower octave notes. If they all play the same, then the divider flip flops are not working correctly. Start with the first one and work your way down the line.

The germanium transistors in these are not critical at all, if you can find any source for reasonably rated devices buy them and use them. They are basically working as switches so there will be no real audio mojo lost by using a different part number.

Typical problems with the dividers are bad transistors, bad caps and bad resistors. Get out the meter and dig in.

[DrGonz78]

Well just a quick little update:

Q1
C to B = 35k and starts dropping a bit
B to Ground = 39k and starts dropping a bit
C to Ground = 3.9k and holds steady

R1 = 2.5k should be >>> 2.7k
R2 = 35k should be >>> 47k
R3 = 27k should be >>> 22k

It was too hot in my shop today to go out and solder any legs out of circuit... I basically will double check those resistors out of circuit in the next couple of hours. Just wanted to post what I have so far measured so far in circuit. Which is not a very good start... I think a lot of these resistors could be drifting but will check them out of circuit soon.

Also, what is the best way to test some these capacitors on this board?

Thanks again for all the help!

[DrGonz78]

Pulled up a leg on the R1-R3 and got these measurements...

R1 = 3.3k should be >>> 2.7k || In Circuit>>> R1 = 2.5k should be >>> 2.7k
R2 = 53.7k should be >>> 47k || In Circuit>>> R2 = 35k should be >>> 47k
R3 = 27.05k should be >>> 22k || In Circuit>>>R3 = 27k should be >>> 22k

I measured Q1 again with R1-R3 removed from the circuit using diode setting:

First way across>>>
Red probe on Collector and Black probe on Base = 0.141v
Probes reversed on collector and base = OL
Red Probe on Collector and Black probe on Emitter = OL

Second way across>>>
Red probe on Emitter and Black probe on Base = 0.146v
Probes reversed on Emitter and base = OL
Red Probe on Emitter and Black probe on Collector = OL

So to me it looks like Q1 is fine... Is that what you guys think too? Also testing a lot of the transistor in the same way makes realize Jazz & Bob are right that it might not be any of the transistors. I have been looking at the resistors now but still have no clue about these caps other than to just replace them as they are way old. I don't want to shotgun anything but I have read that these caps going bad makes it real hard to troubleshoot in general. I really think it is the caps too now.

Most of the guys on organ repair sites were saying that look for transistors first then caps then (less of the times) the resistors. I guess I am pulling up a few to see the resistance accurately.