Mk II C PT Specs?

[Allen]

Hi everyone-

I was just wondering if anyone here might have specs for the MkII C/C+ power transformer, 100-162318. I have searched around the forum, but didn't find what I needed.

I have looked at Boogiebabies excellent thread "MkIIC+ Guide for Dummies" thread, which indicates my DRG IIC (later modded to +) came with the early 100 transformer.

60W PT - 00-162310 - 448V
60W Export - PT: X62-162318 - 448V
Early 100 - 100-162318 - 448V
Simul/60-100 Power - 105-162318 -483V+
- X101-162318 – Export - 448-460V
180W - 0180322 Coliseum - 500V+

Some early IIC+’s may have leftover 100 power transformers.

The voltage associated with the early 100 is shown at 448V, but I take that to be the "A" node B+ voltage rather than the actual high tension secondary AC voltage off the PT... am I correct in this understanding?


The HT secondaries on my PT measure at 340v AC on either side against the center tap.
The low voltage secondary tap measured at 60v AC.

Does that look about right for my transformer? Wall voltage here is 122-127v AC as I am about a block away from the electrical switch yard.


Thanks for any help.

Allen


P.S. For the record, DC voltages were as follows:

A=469v
B=469v
C=402v
D=360v (C --> D dropping resistor is 5.6k)
E= neg 59v
F= neg 49v

Pin 3 at power tube plates = 437v

 

[Boogiebabies]

Those 448V factory specs are under load.

Your numbers look perfectly normal with no load. Some 100's can go as high as 480V
and the 105's clock in between 505-510V DC.

 

[Allen]

Thanks BoogieBabies...

I just got back from my shop where I was doing some more testing with the amp on the bench.

Your information is right on the money. It was great to read that what I was seeing on the meter is in the ballpark.

Also, the voltages while playing the amp were different in class A than when in SimulClass. (Makes sense since in Simul there are two more tubes dropping voltage.)

In class A:

A=446v
B=446v
C=387v
D=347v
E=neg 58.8v
F=neg 49v

In SimulClass, the A through D voltages all fall down about 5v.

The amp sounds good, but maybe a bit darker than I remember it. Probably the filters are still a bit sleepy. I am hoping with continued play, they will wake up a bit more.

Thanks for your reply. It lets me rest easy.

Allen

 

[gts]

I was hoping BB would chime in and help you out!
Good to see you on the board Ed!

 

[dodger916]

I was hoping BB would chime in and help you out!
Good to see you on the board Ed!

Indeed!!

 

[Allen]

I really appreciate this board. You guys have kept me on track more than once.

On the subject of caps for the DRG, is there any preference these days? There are so many new choices today, like F&T, which I have used in other amps successfully. The 30u/500v cap they make is a little bit large to fit on the DRG PS board. They make a 220u that might fit. Their caps are rated at 105C.

The replacements I bought from Mesa in 2005 were United Chemicon Corp. I thought they were a decent cap. I can't remember what the originals were in this amp... Spragues?? I see Sprague does make a 30u 500v Atom, but I haven't found any 220u Atoms.

What is Mesa selling as a replacement these days? What do you guys like?

Thanks,
Allen

 

[Boogiebabies]

I really appreciate this board. You guys have kept me on track more than once.

On the subject of caps for the DRG, is there any preference these days? There are so many new choices today, like F&T, which I have used in other amps successfully. The 30u/500v cap they make is a little bit large to fit on the DRG PS board. They make a 220u that might fit. Their caps are rated at 105C.

The replacements I bought from Mesa in 2005 were United Chemicon Corp. I thought they were a decent cap. I can't remember what the originals were in this amp... Spragues?? I see Sprague does make a 30u 500v Atom, but I haven't found any 220u Atoms.

What is Mesa selling as a replacement these days? What do you guys like?

Thanks,
Allen

I only use the Mesa Label caps. Not too expensive and they are made in Virginia by Barker Microfarads.
You can get all 8 from Mesa for ease of shopping and peace of mind. I've done four cap jobs for board members here with BMI caps and have yet to hear back after three or four years of a failure.

The originals were sprague, but I can't name an American cap manufacturer other then Barker.
I think Sprague is made overseas as well now.

 

[Allen]

Thanks Roadking. That exactly the kind of first hand info I was seeking.

 

[Boogiebabies]

Thanks Roadking. That exactly the kind of first hand info I was seeking.

I had three Road King's. Hated two of the three.

 

[Allen]

Apologies BB. I mis-read your board status as your board name. Long day.

But out of curiosity, I read up on the Road King. How did they keep the circuit boards from baking??

Cool concept for a touring rig though.