Thomas Vox replacement transistors

[R.G.]

OK, this is making me a little nuts.

Years ago, I got a paper copy of the Thomas Vox transistor field replacement list. It's become untraceable in my moves.

Sometime in the last year, I found a scan of it on the internet. I saved that, too. It's apparently been lost in one of my computers. No amount of searching shows it up.

Does anyone know offhand where the scan is on the net?

Yes, I know... ops: ... I'm the one who's supposed to be watching these things.

The bipolars are not a problem. I'm debugging the preamps for that Super Beatle board set and the JFET I used is not biasing correctly. The circuit is right, has to be the JFET replacement. And I can't find my replacement sheet.

... I promise to take better care of it next time if I find it again. :lol:

[R.G.]

Never mind. Found it.

[tboy]

How 'bout uploading it here, R.G.? Then we'll all know where it is.

[Amp Kat]

I had a printed out copy I could have scanned for you if all else failed. I have one (846) with the original 5117's in it but recently did some mods to the other one and believe it or not ended up with NTE 289's and it is very suttle and smooth which is what I wanted. Oh well glad you found it and don't scare us like that RG.

[R.G.]

I had a printed out copy I could have scanned for you if all else failed. I have one (846) with the original 5117's in it but recently did some mods to the other one and believe it or not ended up with NTE 289's and it is very suttle and smooth which is what I wanted. Oh well glad you found it and don't scare us like that RG.

I'll try to improve my act. 8-)

The copy I found is a many-times photo-copied sheet that's barely readable. I got it back in the 1980 from an amp shop tech I sweet-talked when I was repairing my first Beatle head. It lists only parts from 86-5064-2 up through 86-5114-2, and has a page number "2" in the center of the bottom, so presumably there's a page 1 and at least a page 3 because we know the 86-5117-2 transistors exist. If you have the sheet with the 5117 on it, I'd sure like to see that. There are numerous references to numbered notes which are not on this page, which would be interesting in figuring out replacements. Quite a number of the replacements are no longer available: the 2N1302 is very much a dinosaur, and the DTG110 is a germanium power device that I saw one of in 1976. RCA 40xxx series will be hard to find too, because there is no longer an "RCA". 8-|

I tried to OCR the page after scanning it, but that turned out very poorly, so I'm typing. Many of the entries are listed for organ use only, so I'm only retyping the ones noted for "Vox".

[R.G.]

Ok. Did this in a bit of a hurry. New article at geofex (New Page 1) on what I got distilled out today. First item in "new at geofex".

Should clear up some things.

[R.G.]

Updated with output devices and rebiasing for silicon PNP info.

[52 Bill]

Thank you for sharing that information. Like always you are more than generous with your time, talent and research.

And I can't believe that you engineered new boards for TO preamps!

[Amp Kat]

Thought I printed the transistor sheet but could only find the Technology. May have it somewhere else as I know I printed it. Did find this and don't know if it will help but I'll keep looking.

THOMAS PARTS CATALOG

*Keyboard Systems Component Cross Reference Master*

[Enzo]

Those look like the old HAB guide, and Keyboard Systems sounds familiar as the source.

Looking around for the HAB might be fruitfull. It covered Thomas, but also Vox, Farfisa and some others we might find usefull. ANyone who made organs. Even yamaha and some Korg.

Like that screen shot on the second link, each part had an entry with basic specs, but you also got the same part part numbers for other OEMs, so if you were fixing an old Thomas organ and needed a 123-456-789 transistor, you m,ight find that a Vox 98-7654-321 was the same thing. And if you wanted to go that route, they even listed the ECG numbers.

At this point I dont care about old Lowry organ parts, but companies like Vox and Thomas used the same part numbers across their lines, so a Thomas 123456 would be the same part whether in an organ, a wah pedal, or a guitar amp.

[vintagekiki]

Thomas parts search for a Part by Part Number
http://www.organservice.com/SearchPart.htm

X-Ref - Thomas/Vox Transistor List and Field Replacement Chart. http://www.voxshowroom.com/northcoast/vox/schematics/btsch.html

[Enzo]

I note that the second link there, the NorthCoast offering, is SELLING the data. Not expensive and probably worth it. But not an online lookup for instant part ID.

[R.G.]

Organ service's Thomas transistor list did include the other devices above and below the devices I was missing, and also suggested industry numbers for most of them. I've now pithed that down to a cross to industry number, looked up the mostly-obsolete industry numbers, and found most of the ratings for the industry numbers. Next step is to find modern (that is, available as through hole parts today) replacements equal to or better than the commercial items.

I also entered a list of Thomas 86-5xxx-2 numbers as used by Thomas Vox amp model number into a spreadsheet, so I can figure out what parts are used in what amp. It's getting close to being usable.

[Enzo]

How many numbers are you missing? Listable or too many?

[R.G.]

Very few missing now. I have not yet sorted the 86-5xxx-2 to commercial list back into the listing of Thomas part numbers used by amp. Dropping out the devices not used in amps will substantially reduce the number of devices. I'll take another run tomorrow.