Mark IIC+ - Guide for Dummies

[JOEY B.]

Yeah, I have seen that chart before... except this amp bears absolutely NO resemblance to a IIA except for the low serial.

If you look about 1/3 the way down on page 4 of this thread, you will see that Frank(dodger916) has a IIA>IIC+ upgraded amp. Yours could be something like his.

 

[igfraso]

I have a Mark II. which I believe to be a IIC, but the serial number is in the 38** range. As in, almost 10,000 short of where a IIC should lie.

As Joey B. says, it could be one of the few upgraded II-A.
By the way, what date does it have inside the chassis?

 

[nocluejimbo]

Yeah, I have seen that chart before... except this amp bears absolutely NO resemblance to a IIA except for the low serial.

If you look about 1/3 the way down on page 4 of this thread, you will see that Frank(dodger916) has a IIA>IIC+ upgraded amp. Yours could be something like his.

Interesting...

I supposed this could have been the case, but have never actually seen another example of such.

I have a Mark II. which I believe to be a IIC, but the serial number is in the 38** range. As in, almost 10,000 short of where a IIC should lie.

As Joey B. says, it could be one of the few upgraded II-A.
By the way, what date does it have inside the chassis?

I don't know where to find the date inside the chassis?

 

[JOEY B.]

I don't know where to find the date inside the chassis?

The upgrades that I have seen will have something like IIB>IIC+ written on the upper edge of the chassis to the left or right. The preamp circuit board revision is also a dead giveaway. It will be located at the far right of the preamp board when viewing from the rear of the chassis. Have you tried the C+ loop test?

 

[av8or3]

FWIW, a 100 watt C+ sold recently on e-bay had the
serial number 14,387. That's the closest one I've seen
to the end of the line. It was a DRGX.
Nice amp too......
See 'ya,
Jim

 

[SD Boogie]

I have a IIC+ with seriel 14,2xx. The chassis has D3 handwritten on both sides of it....any idea what I have? I dont see this code in the "Mark series for dummies" sticky

 

[lesterpaul]

..copied and pasted from the "Guide"...
You could get a standard 60 or 100 watt with no graphic or reverb so there are possible S, D and H only chassis codes. Any amp could have an export power transformer, so an X is possible as well. For example, SX, DX and HX.

A 15” could be added to the chassis code designating a long chassis.

The Number after chassis code –

This is the week of production.

 

[Skyless7620]

FWIW, a 100 watt C+ sold recently on e-bay had the
serial number 14,387. That's the closest one I've seen
to the end of the line. It was a DRGX.
Nice amp too......
See 'ya,
Jim

Don't mean to be nitpicking, but I'm pretty sure it was an HRGX. I know because I had the opportunity to buy it from a previous owner

Happy Holidays!

 

[mule#1]

Much Thanks for this original post! It helped me feel comfortable in buying my IIC+ this week!

 

[revgsmall]

New here, but a decades long mark series user. Great post, I must have a rare one. Mine DOES have the initials RCS on it. It is a 100/60 watt, non eq, non simuclass, serial # 13894. I had three of these amps at one time (when I was rich). Kept the best sounding one.

 

[nogalian]

Thanks a MILLION!!! Been looking for this info for a while. You should write a book! Hey you kinda did!!
Thank you for you incredible efforts!! :!:

 

[oyrgawd]

The Loop Test –

1) Plug your guitar into the Effects Return jack
2) Switch to lead mode
3) Turn the Lead Drive and Gain controls with a note ringing.
4) If they have NO effect on the volume and sound you have a+.

Can I get a clarification on this? I was looking at a IIC at a shop today. I didn't check the serial or look for a "+". I did do the loop test as listed above, but I'm not sure about step 3. With the guitar plugged into the fx return in Lead mode, the Lead Drive knob did nothing, the Lead Master was just signal/no signal as I turned it from zero, but Master 1 and Volume 1 changed level a lot. There's no knob labeled "Gain" though, so I'm not sure what the test's result is.

It's a 60-watt combo with EV, no reverb, no GEQ. Labeled Gain Boost versus Pull Deep.

It sounded pretty great but I'd have to bring my guitar in to decide. I'm a little worried I'd miss the 4x6L6s and Simul-Class from the III/IV/V but maybe not. I like the simplicity of shared controls again, coming from the V.

EDIT: Come to think of it, the knob tops were shiny and there wasn't a Pull Shift over the Bass, so it's probably a IIB. Does my test mean it might've been modded or is that normal IIB loop behavior?

 

[Rhoads]

I buy a Mark IIC two week ago serial 1229x export, EQ, all the thing that you can imagne ok the real thing !!! And date on it was 2/84 and i have a black Dot on the power ! I give more info about this monster ( i dont have the chance to try it, i work too much)

 

[rlhjr34]

My SR head arrives tomorrow. Would like to have the GEQ otion or even the Hundred watt version. You know what though it sure is better than wanting a C+ but not having one! I'll be adding a parametric EQ to the loop so I should be just fine. Can hardly stand the wait. Feel like a kid on Christmas Eve right now. 8)

 

[AZToo]

is a Boogie with a 4/20/79 chassis date most likely a Mark II? A?
Can this amp be modded to IIc+ specs?

 

[36-22-36]

The IIC+ Guide

The Schumacher Transformers –

The digits 606 are Schumacher’s EIA manufacturer code.

The digits after are the last number of the production year, example, 3 is 1983. The next two digits are the week of productions, example, 42 is the 42’nd week of 1983. It’s not the Fibonacci Sequence, trust me. EIA 606-342.

60W OT - T60-152019
Simul Output - SC-152019B – Simul-Class
180W - SD 190555 Coliseum

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.
[/b]

100/60W OT - T100-152019

Cheers

 

[Boogie-fever]

There seems to be a discrepancy here regarding the 2c+, simul-class output transformers. I want to get to the bottom of this...
I believe the proper simul-class output transformers are T100-152019, perhaps some of the 2c+'s had 562003's as well.

 

[Boogie-fever]

So as it turns out I was mistaken. The T100-152019 output transformer, is for a 60/100, amp.
Whereas the 562003, is the original simul-class output transformer used on the 2c+.
There's been some conflicting information on the Internet pertaining to this so I just want to clarify the info, after speaking with Mike B, today!

 

[gts]

So as it turns out I was mistaken. The T100-152019 output transformer, is for a 60/100, amp.
Whereas the 562003, is the original simul-class output transformer used on the 2c+.
There's been some conflicting information on the Internet pertaining to this so I just want to clarify the info, after speaking with Mike B, today!

You are still mistaken and/ or perhaps you misunderstood Mike.

The "562003" Simul-Class OT was introduced with and first used during the production of the Mark III and not on IIC's

The Simul-Class IIC+ had the "SC-152019B" OT.

Now some 60/100 watt IIC+'s may have been modded/ upgraded to a Simul-Class during the production of Mark III's
If this was the case it is very likely a "562003" Simul-class OT was used.

Fwiw the "562003" Simul Class OT and the "SC-152019B" Simul-Class OT have the same specs.

You can trust the info on the first page of this thread!! :twisted:
It is VERY Accurate and written by a VERY Knowledgeable and reliable source!!

So.... believe what you read here and not that "conflicting information on the internet." :wink:

 

[Boogiebabies]

Better late than never, the T100-152019 only has two primary taps so it could be used in a 60W, but it would be a tad over rated for the amp. The SC-152019B has four primaries, two for the 6L6 impedance and two for the EL34 impedance. If you look at the primaries on eith a 60W or 100W transformer they are red/red wires and jumped to the outer sockets with a wire on 100W models. The Simul OT is blue/red/red/blue, or one for each tube. As for upgrading a 60W to a hundred watt, I don't even think the factory would want to remove the power amp board and chassis punch two extra slots.