Need some help identifying electronic components (Vox Organ)

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Horace
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Need some help identifying electronic components (Vox Organ)

Post by Horace » Tue Oct 18, 2011 4:10 am

I'm restoring a Vox Jaguar, and one of the tone generator boards is only producing a faint whine. My current course of action is to replace some of the suspect components and bring it back to life (hopefully). I'm no expert so bear with me :?

I'm confused as to what value these ceramic capacitors are. 4700K and 2200K? I wasn't even aware capacitors were designated in kilo ohms.
Image

Second are these guys. Haven't seen anything like these before. They read "Ducati" 125V- pF +/-10%
The values vary: 68000, 47000, 10000. Any ideas?
Image

And then there's the Germanium transistors. I'm still in the process of finding some replacements.

Thanks for your time!

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V301H
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Re: Need some help identifying electronic components (Vox Or

Post by V301H » Tue Oct 18, 2011 6:16 am

Capacitors are measured in Farads. You will commonly find ratings such as Microfarads (uf) and sometimes Picofarads. The Ceramic caps in question are 4700 uf and 2200 uf. The Ducati caps are Electrolytics which are polarized with one terminal + and the other -. These must be installed correctly to function properly. The Electrolytic Capacitors are the component most likely to fail in vintage electronics and should routinely be replaced during restoration as their expected lifespan is about ten years. This especially applies to the large high voltage Electrolytic caps found in the power supply. There is usually no need to routinely replace transistors unless they fail or are operating marginally. Ceramic caps usually don't need to be replaced unless there is reason to suspect a failure. Resistors will sometimes change in value over time but generally don't need to be replaced unless there is reason to suspect a problem.
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Re: Need some help identifying electronic components (Vox Or

Post by nathanscribe » Tue Oct 18, 2011 11:34 am

I think you'll find those caps - the orange disc-shaped ones - are ceramic and rated* at 4700pF and 2200pF (pico-Farads) - which is the same as 4n7 (4.7 nano-Farads) etc. They're most definitely NOT 4700µF etc., and most definitely NOT polarised.

As for the Ducati caps, if you're sure they're labelled "pF" then those figures will be the picoFarad values - or 68nF, 47nF and 10nF respectively. They're rated at 125V and have a 10% tolerance either side of the nominal value (or 20% overall tolerance, normal for such things). As for material, I'd hazard a guess at polystyrene, but am not certain as I usually see those in lower values. Maybe polyester.

*One caveat about those Farad values - normally such caps are not marked with the value in figures, but with a couple of digits plus a multiplier of 10^X where X is the number after the first pair. So 472 would be 4700pF, for example. However, markings have changed over the years and older ones do use different methods - if you can measure them, do so, but I suspect those are the actual pF values marked there.

The letter at the end indicated tolerance, and K is 10%. I think the 3-digit/letter combo at the bottom indicate the dielectric (the material used to make the cap).

If you need to replace those resistors at all, you can still buy the carbon comp types (not carbon film, which are smaller) and they're likely to be 1/4 or 1/2 Watt. Germanium transistors - take a look at Towers' International Transistor Selector - your nearest reference library should hold a copy if they're worth their salt. My copy lists AC125 and 2N406 as alternatives, though I haven't checked their details. The STF351 is a low-gain PNP.

Hope that helps.

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Re: Need some help identifying electronic components (Vox Or

Post by pricklyrobot » Tue Oct 18, 2011 1:57 pm

There are lots of charts around for identifying capacitor codes. I find this one to be pretty well laid out and helpful: http://www.hamradio.cc/electronics/capa ... _chart.php
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Re: Need some help identifying electronic components (Vox Or

Post by Altitude » Tue Oct 18, 2011 9:20 pm


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Re: Need some help identifying electronic components (Vox Or

Post by pricklyrobot » Tue Oct 18, 2011 9:36 pm

Altitude wrote:http://www.electronics2000.co.uk/downlo ... #assistant is outstanding as well
That does look handy. :thumbleft:

Here's a good online one for resistors: http://www.hobby-hour.com/electronics/r ... ulator.php
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Re: Need some help identifying electronic components (Vox Or

Post by Horace » Tue Oct 18, 2011 11:23 pm

Thanks SO much guys. This information really helps out a lot. I'm going to try replacing the Ducati caps first and see if that solves the problem.
nathanscribe wrote: As for the Ducati caps, if you're sure they're labelled "pF" then those figures will be the picoFarad values - or 68nF, 47nF and 10nF respectively. They're rated at 125V and have a 10% tolerance either side of the nominal value (or 20% overall tolerance, normal for such things). As for material, I'd hazard a guess at polystyrene, but am not certain as I usually see those in lower values. Maybe polyester.
Does the material matter significantly? These were the closest available substitutes I could find:
http://www.mouser.com/ProductDetail/Kem ... PGPFAGs%3d

It pains me that I can't substitute a silicon transistor for the germanium one without redesigning the circuit. This vox's days seem numbered...

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Re: Need some help identifying electronic components (Vox Or

Post by nathanscribe » Wed Oct 19, 2011 12:01 am

In all honesty, I can't say how much difference it would make if you replaced a poly cap with a ceramic. It might be fine, it might suck. I'd always try to replace like with like, as near as possible - bearing in mind that some parts will have been chosen originally because they were cheap, or because they were available in the right size, not because they were great. Mouser do stock caps of that broad type - backtrack to Capacitors and search under Film Caps. There are pages and pages of them. Check the distance between the legs, as it can be awkward to fit very small caps into a widely-spaced position. If the voltage going through the circuit at that point is lower than 125V, you can get away with a lower voltage rating. If not, find the next higher.

As for replacing the transistors, test them if you can first. If I've learnt anything from digging around inside synths etc., it's that random replacement is a good way to waste time and money.

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Re: Need some help identifying electronic components (Vox Or

Post by V301H » Wed Oct 19, 2011 4:07 am

The Vox Showroom has lots of parts and info:

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

Vintage Vibe sells germanium transistors for Vox organs:

http://www.vintagevibe.com/c-8-vox-organ-parts.aspx

Ray Klos in North Wales, PA is an expert Combo Organ repairman. You can send him individual boards for repair.
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Re: Need some help identifying electronic components (Vox Or

Post by Horace » Thu Oct 20, 2011 5:45 am

UPDATE!

I discovered by looking at the circuit diagram that the E, D, D# board are all the same [E was not functioning correctly, only 1 faint tone that did not change across octaves].
After careful testing and swapping components back and forth from the D# board I discovered a faulty diode. Replaced with one I had lying around and ZIP ZAP the E board works now! I hope this helps anyone who may have this problem with a Vox Jaguar in the future. Also be careful of those walking bass contacts, all have to be grounded [neutral] for each subsequent bass key to work.

Thanks for your help, this information will come in handy in the future if other problems arise.

P.S.
V301H wrote: Ray Klos in North Wales, PA is an expert Combo Organ repairman. You can send him individual boards for repair.
I couldn't find Ray's contact information anywhere, it seems his website is defunct [http://home.att.net/~ray4376/music.html].

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V301H
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Re: Need some help identifying electronic components (Vox Or

Post by V301H » Thu Oct 20, 2011 6:09 am

Ray Klos hasn't had a website for quite a while. He fixed a 1965 British Vox Continental organ for me earlier this year and did a fantastic job.
His phone number last I knew is: 732-619-6594
e-mail: ray4376@comcast.net
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Re: Need some help identifying electronic components (Vox Or

Post by Altitude » Thu Oct 20, 2011 12:28 pm

V301H wrote:Ray Klos hasn't had a website for quite a while. He fixed a 1965 British Vox Continental organ for me earlier this year and did a fantastic job.
I'm sure ray would not appreciate you posting his phone and email on a public forum for all the spam spiders to scoop up..
Last edited by Altitude on Thu Oct 20, 2011 4:32 pm, edited 1 time in total.

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Re: Need some help identifying electronic components (Vox Or

Post by madtheory » Thu Oct 20, 2011 2:38 pm

Horace wrote: After careful testing and swapping components back and forth from the D# board I discovered a faulty diode.
Delighted you got it working! :) Congratulations on your diagnostic skills, very sensible approach. Replacing caps willy nilly is a fool's errand. And life's too short for such tedium.

We await your demos! :)

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Re: Need some help identifying electronic components (Vox Or

Post by V301H » Thu Oct 20, 2011 5:45 pm

Altitude wrote:
V301H wrote:Ray Klos hasn't had a website for quite a while. He fixed a 1965 British Vox Continental organ for me earlier this year and did a fantastic job.
I'm sure ray would not appreciate you posting his phone and email on a public forum for all the spam spiders to scoop up..
Even though he seems to be maintaining a low Web profile Ray Klos is still actively running a business. I provided contact info for that business which may otherwise be difficult to find. In fact, the same info can be found on the Web here:

http://theatreorgans.com/hammond/faq/sh ... isting.htm
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