200S Power Tranny

Rick Erickson · 10-08-2006, 02:49 AM

I need a power transformer for a Sunn 200S that I'm restoring. Anybody here know where a suitable replacement might be found, or have a current production part # for say, a Hammond PT that comes close?

RE

Tom Phillips · 10-08-2006, 03:36 AM

Rick,
The specs for the secondary windings of the PT originally used in the 200S were:
410-0-55-410, 200ma; 5V, 3A; 6.3V, 4A. You will most likely need to derive the bias with a resistive divider since I doubt that many manufacturers include the bias tap in their off-the-self models.
HTH,
Tom

Ray Ivers · 10-08-2006, 04:11 AM

Rick,

Sorry about the price:

http://www.mercurymagnetics.com/page...og/MM_sunn.htm

Ray

Tom Phillips · 10-08-2006, 05:29 AM

WOW! That price would make me consider re-winding the old one.

Tom Phillips · 10-08-2006, 05:45 AM

Rick,
I found the Hammond model 378X power transformer. It's almost dead on for the 200S specs including the bias tap. $138.62 from Mouser. See http://www.mouser.com/catalog/627/1580.pdf
Tom

Tom Phillips · 10-08-2006, 05:29 PM

Hey Rick,
I found another source. Triode eletronics makes clones of the original Dynaco P-782 power transformer that Sunn used in the first 200S amps.
Check out http://www.triodeelectronics.com/mq782.html
The listed price is $99. Pretty good compaired to the MM $300 price.
What do ya think?
Tom

Rick Erickson · 10-09-2006, 07:56 PM

Wow - Thanks Tom & Ray. This is for a restoration I'm doing for Mike Lull, owner of Mike Lull's Custom Guitars in Bellevue, WA. [www.mikelull.com The original transformer was replaced with a Stancor P-8170 TV PT which was physically too large and was leaking wax all over the chassis from running too hot. I will look into the Dyna PT replacement, or the Hammond - one of those should work. I recently hot-rodded a 100S for Mike, who is a very good Bass player, using KT90 power tubes and a slightly modified preamp circuit. A customer saw it in his shop on top of a 200S cabinet and gave him the 200S amp to match his cab..

RE

soundmasterg · 10-12-2006, 07:31 PM

I've heard some very good things about the Triode Electronics transformers. If I had to replace the one in my 200S, that would be the first place I would go.

Greg

Rick Erickson · 10-12-2006, 07:43 PM

Quote:

Originally Posted by soundmasterg

I've heard some very good things about the Triode Electronics transformers. Greg

That's the one I ordered. Will let you know how it works when I get it installed.

RE

Amp Kat · 10-29-2006, 03:39 PM

Just got two in for a Fisher 300 and they look real nice so I'll let you know as well.

Mr. dB · 10-29-2006, 09:55 PM

Quote:

Originally Posted by Rick Erickson

I need a power transformer for a Sunn 200S that I'm restoring. Anybody here know where a suitable replacement might be found, or have a current production part # for say, a Hammond PT that comes close?

That amp uses the Dynaco MkIII iron and power amp driver circuit, no? I'd look at Triode or Angela or Curcio or any of the other places that support Dynaco hobbyists.

Or just find a Dynaco MkIII and harvest it for parts. There's jillions of 'em out there, so the hifi boys won't get too upset if a few are lost to make guitar amps. For the price of one Mercury Magnetics power tranny, you should be able to find a ratty old MkIII and get the power, output and choke, and maybe even a working Cornell-Dubilier 4-section twist-lok cap, and the whole 6AN8A driver stage on a circuit board.

Mr. dB · 10-29-2006, 10:04 PM

http://cgi.ebay.com/Dynaco-MkIII-mk2...QQcmdZViewItem

Rick Erickson · 11-25-2006, 12:28 AM

I got the Triode PT. It dropped right in to the Sunn 200S chassis. I installed a 32x32/500V dual can where the original twist-lock quad cap was. This became the 3rd & 4th filter stages. I used (4) 100uF/350V caps in series pairs to make the first two stages of filtering - first stage-choke-2nd stage. This has worked well for me in the past and allows the use of a solid state rectifier plug in place of the 5AR4 rectifier for a stiffer supply and higher B+ voltage, which is nice for a Bass amp. The owner had me install a pair of EI KT-90 tubes and arrange the impedance taps of the OT for max. output. The amp now delivers 90W RMS into 8 or 4 ohms via the 16 & 8 ohm OT taps. The KT-90's seem to be comfortable running into half the impedance typical of EL34's or 6550's. It will be interesting to see if the transformers can handle the increased power, but the customer doesn't care if it blows up. I love customers like that.

RE

Tom Phillips · 11-25-2006, 01:10 AM

Rick,
Thanks for the update.
Glad to hear that it seems to have worked out well.
Tom

soundmasterg · 11-26-2006, 08:58 PM

Glad to hear that Triode transformer worked out for you Rick. On my 200S I didn't even bother with a can cap...I just left the stock one in place and disconnected it, because I didn't want to deal with cost in the future since discrete parts are so much cheaper. I went with slightly larger values too, and series connected the first two stages like you did, and I'm using a solid state Weber Copper Cap. It works and sounds great!

greg

10-08-2006, 02:49 AM	#1
Rick Erickson Senior Member Join Date: Jun 2006 Posts: 257	200S Power Tranny I need a power transformer for a Sunn 200S that I'm restoring. Anybody here know where a suitable replacement might be found, or have a current production part # for say, a Hammond PT that comes close? RE

10-09-2006, 07:56 PM	#7
Rick Erickson Senior Member Join Date: Jun 2006 Posts: 257	Wow - Thanks Tom & Ray. This is for a restoration I'm doing for Mike Lull, owner of Mike Lull's Custom Guitars in Bellevue, WA. [www.mikelull.com The original transformer was replaced with a Stancor P-8170 TV PT which was physically too large and was leaking wax all over the chassis from running too hot. I will look into the Dyna PT replacement, or the Hammond - one of those should work. I recently hot-rodded a 100S for Mike, who is a very good Bass player, using KT90 power tubes and a slightly modified preamp circuit. A customer saw it in his shop on top of a 200S cabinet and gave him the 200S amp to match his cab.. RE Last edited by Rick Erickson; 10-09-2006 at 07:58 PM. Reason: Bad Link

10-29-2006, 03:39 PM	#10
Amp Kat Senior Member Join Date: Jul 2006 Location: Baton Rouge,LA Posts: 1,062	Just got two in for a Fisher 300 and they look real nice so I'll let you know as well. __________________ KB

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10-08-2006, 03:36 AM	#2
Tom Phillips Senior Member Join Date: Jun 2006 Location: California, USA Posts: 676	Rick, The specs for the secondary windings of the PT originally used in the 200S were: 410-0-55-410, 200ma; 5V, 3A; 6.3V, 4A. You will most likely need to derive the bias with a resistive divider since I doubt that many manufacturers include the bias tap in their off-the-self models. HTH, Tom

10-08-2006, 04:11 AM	#3
Ray Ivers Lifetime Member Join Date: Jun 2006 Location: Connecticut Posts: 442	Rick, Sorry about the price: http://www.mercurymagnetics.com/page...og/MM_sunn.htm Ray

10-08-2006, 05:29 AM	#4
Tom Phillips Senior Member Join Date: Jun 2006 Location: California, USA Posts: 676	WOW! That price would make me consider re-winding the old one.

10-08-2006, 05:45 AM	#5
Tom Phillips Senior Member Join Date: Jun 2006 Location: California, USA Posts: 676	Rick, I found the Hammond model 378X power transformer. It's almost dead on for the 200S specs including the bias tap. $138.62 from Mouser. See http://www.mouser.com/catalog/627/1580.pdf Tom

10-08-2006, 05:29 PM	#6
Tom Phillips Senior Member Join Date: Jun 2006 Location: California, USA Posts: 676	Hey Rick, I found another source. Triode eletronics makes clones of the original Dynaco P-782 power transformer that Sunn used in the first 200S amps. Check out http://www.triodeelectronics.com/mq782.html The listed price is $99. Pretty good compaired to the MM $300 price. What do ya think? Tom

10-12-2006, 07:31 PM	#8
soundmasterg Senior Member Join Date: May 2006 Location: Cornelius, Oregon Posts: 669	I've heard some very good things about the Triode Electronics transformers. If I had to replace the one in my 200S, that would be the first place I would go. Greg

10-29-2006, 10:04 PM	#12
Mr. dB Junior Member Join Date: Oct 2006 Posts: 3	http://cgi.ebay.com/Dynaco-MkIII-mk2...QQcmdZViewItem

11-25-2006, 12:28 AM	#13
Rick Erickson Senior Member Join Date: Jun 2006 Posts: 257	I got the Triode PT. It dropped right in to the Sunn 200S chassis. I installed a 32x32/500V dual can where the original twist-lock quad cap was. This became the 3rd & 4th filter stages. I used (4) 100uF/350V caps in series pairs to make the first two stages of filtering - first stage-choke-2nd stage. This has worked well for me in the past and allows the use of a solid state rectifier plug in place of the 5AR4 rectifier for a stiffer supply and higher B+ voltage, which is nice for a Bass amp. The owner had me install a pair of EI KT-90 tubes and arrange the impedance taps of the OT for max. output. The amp now delivers 90W RMS into 8 or 4 ohms via the 16 & 8 ohm OT taps. The KT-90's seem to be comfortable running into half the impedance typical of EL34's or 6550's. It will be interesting to see if the transformers can handle the increased power, but the customer doesn't care if it blows up. I love customers like that. RE

11-25-2006, 01:10 AM	#14
Tom Phillips Senior Member Join Date: Jun 2006 Location: California, USA Posts: 676	Rick, Thanks for the update. Glad to hear that it seems to have worked out well. Tom

11-26-2006, 08:58 PM	#15
soundmasterg Senior Member Join Date: May 2006 Location: Cornelius, Oregon Posts: 669	Glad to hear that Triode transformer worked out for you Rick. On my 200S I didn't even bother with a can cap...I just left the stock one in place and disconnected it, because I didn't want to deal with cost in the future since discrete parts are so much cheaper. I went with slightly larger values too, and series connected the first two stages like you did, and I'm using a solid state Weber Copper Cap. It works and sounds great! greg

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