Of Thratrons, French Soup, and a Dash of SCRs

Art Volz · Mar 14, 2002

Has anyone checked on the applicability of the recent 2 March 2002 posting at: http://www.metalworking.com/dropbox/Thyrathron_To_SCR_GE_SCR_Manual.pdf ? Consists of three pages from a GE manual.

I have a friend/local used machinery dealer who has about 5 of these dead butterflies--the tubes are shot--wondering if anyone has applied this GE conversion.

Art (What does this have to do with French Soup anyway?)

D. Thomas · Mar 28, 2002

That link doesn't work for me

J Tiers · Mar 29, 2002

I looked at it. That info has to be 20 years old, since GE isn't in that biz any more, AFAIK. Parts have changed a lot.

If I recall correctly, GE turned their semi division into RCA, that turned into Harris, Harris into Intersil, and finally Fairchild bought it. I know the RCA-Fairchild path is right, as we have used their stuff right along through it.

No reason why the replacement idea would not work, as the thyratron and thyristor are so close in operation. Thyristors are about the most rugged semiconductor device made, too.

I need to find a schematic and the thyratron numbers to give a decent opinion on a solution.

One issue is that thyratrons could stand a lot more peak voltage than a semiconductor device. Voltage ratings might need adjustment, since the 600 volt supply suggests a minimum rating for the thyristor in the 1000-1200 volt area, depending on exact circuit (push-pull, etc).

Art Volz · Mar 31, 2002

Does anyone know the thyratron tube numbers?

Art Volz · Mar 31, 2002

Corrected SCR URL:

http://www.metalworking.com/dropbox/Thyratron_To_SCR_GE_SCR_Manual.pdf

Tommy · Apr 1, 2002

Originally posted by Art Volz:
Does anyone know the thyratron tube numbers?

Tommy · Apr 1, 2002

Originally posted by Art Volz:
Does anyone know the thyratron tube numbers?

Schematic shows El-C16J. Mine has National Electronics brand NL-5665/C16J.

daryl bane · Apr 1, 2002

Originally posted by Art Volz:
Does anyone know the thyratron tube numbers?

C16J two each , the big un's

EL-1C one each, the one with the ST top,
shoulder type, antique looking, in the middle
below the C16Js. This one is for the all tube models, the sixties models just had the two big C16Js. Daryl

lc · Apr 1, 2002

What ARE you people talking about? I see the reference to tubes but regarding what and for what?

daryl bane · Apr 2, 2002

Without getting too involved, the Monarch EE
thoughout the 40s,50s 60s. used a very sophisticated (for that time) DC motor drive system. This involved vacuum tube technology, like a old 50s TV. It has some physically big tubes called Thyratrons. And it works real well. Did this answer your question?

lc · Apr 2, 2002

Yep. I figured it was EE stuff but nothing said was anything that mentioned something I recognized. Thanks.

J Tiers · Apr 3, 2002

Well, I checked around, as I didn't have the spec handy to hand.

Sounds like the C16J is a 16A 1200V thyratron, which means there is a good shot at a solid-state replacement. The exact circuit makes a difference as to the voltage rating required.
I seem to remember mention of 600 volt capacitors, which suggests that there may be something in the range of 500 volts DC present. If push-pull circuit, 1200 volts would be a minimum. Otherwise, 800+ volt parts should have sufficient margin.

There are also other possibilities as to parts, but I think the SCR approach is best. They are tough devices.

A solid state replacement sounds like a good idea, since the prices I saw for replacement tubes were from a low of $560 to a high around $750 per each. The SCR should cost under $15 in small quantity, and adapters and drive should not add too much.

If someone has a schematic of the beastie, that would certainly make it easier to decide whether relatively easy-to-find parts would be suitable.

J Tiers

Art Volz · Apr 3, 2002

ATTN: J. Tiers
Have schematic--please coord transfer: [email protected]

Art

Art Volz · Apr 4, 2002

I have posted Gary Hart's c. 1956 Monarch 10ee electrical schematic, potentiometer adjustments, trouble-shooting procedures, and parts list to the "dropbox" on metalworking.com on 3 and 4 April 2002:

http://www.metalworking.com/dropbox/10eeschematic.gif , http://www.metalworking.com/dropbox/10eeMonarchElect-1.bmp (will probably be changed to GIF), http://www.metalworking.com/dropbox/10eeMonarchElect-2.gif , and http://www.metalworking.com/dropbox/10eeMonarchElect-3.gif

Tommy · Apr 5, 2002

Schematics and instructions published by Art are virtually identical to those in the manual for my '58 EE, except for some fuse values. I have an additional schematic provided recently by Monarch that appears to be a copy of an original blueprint. Much more information on it, but some details around the edges have been obliterated. This schematic shows how to change connections for 230 or 460 volts on the anode transformers, but you will notice in the posted "electrical parts list" that different part numbers are given for 230 and 460 volt filament transformers.

J Tiers · Apr 5, 2002

I noticed that on the filament transformers too.
But the schematic implies that they are tapped for at least some voltage adjustment, since it shows some lines up on one side of the primary winding (the L2 side). Dunno how much.

They must be fair-sized, as the C16J seems to take 2.5V @ 31 A heater current, so that transformer has to be rated at least around 150W, and is probably over-sized on account of the LV wire size.
That said, I think I would put a boost transformer on them alone, rather than try to boost for the whole beast.

I posted some more info over on the Chaski board, replacement tube info etc.
The thyratron replacement looks quite practical, but needs some part sourcing and choices.

If you have an EE, the AC voltage across the points which are labeled A29 and A30, as well as across A24 and A25 would be helpful in specing suitable SCRs for the field and armature drives. I expect they are around 600 volts and maybe 400 volts (AC), respectively (300 and 200 volts either side of center tap) but I don't know that.

Thanks
Jerry

Art Volz · Apr 6, 2002

Tommy, do you think you can scan me the additional circuit stuff you have (GIF format preferrred) and I'll post it for everyone at metalworking.com?

Can you provide the voltage measurements that Jerry talked about in his last post?

Do you have any other circuit info--adjustments, voltages, etc.,--than what I already posted? There appears to be info missing--Gary's manual is parts and pieces, and not totally complete, of several different Monarch manuals.

Thanx--

Art (Houston)

Tommy · Apr 7, 2002

Art:

The schematic I have (Monarch part no. 20429)is too large for my scanner (approx. 13"x20"). Let me see if I can figure a way to scan it. In lieu of a scan I'll be glad to have a copy made for you, but am afraid it might lose more detail as it has obviously been copied many times before. Sadly, the whole right vertical column, which consists of voltage readings, and tune up and alignment procedures, already is unreadable.

D. Thomas · Apr 7, 2002

For future reference, if nothing else, a good digital camera, like a Nikon 950 (500 bucks maybe) will produce an image every bit as detailed as a scanner....so you can simply take a photo of blueprints or schematics too large to fit in a scanner.

Glenn Peterson · Aug 1, 2002

I found some short datasheets on the C16J and C3J by using this site's search function:

http://www.mif.pg.gda.pl/homepages/frank/vs1.html

Be sure to check the "include equivalent types" checkbox.

Glenn

[This message has been edited by Glenn Peterson (edited 08-03-2002).]

Of Thratrons, French Soup, and a Dash of SCRs

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