Mark IIC to C+ Steps Required for Upgrade

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Mark III
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Mark IIC to C+ Steps Required for Upgrade

Post by jrb32 » Fri Nov 30, 2018 10:53 am

So I've been going through the steps required to the C+ upgrade on my '83 IIC with the RP10A and I just wanted to share how ridiculous these are! I have no idea what Mike B was on back then but if you think it's just a few component changes or an FX loop/Reverb swap think again.

I've counted just under 40 steps from looking at pictures of an upgraded RP10A and comparing them to some schematics of the IIC I based on the chipaudette ones to try and get my head round it all. I also drew up a corresponding board layout. It involves V2A and B being swapped around completely, traces being destroyed on the board, jumper wire and hook up wire everywhere.

I don't really want to post a step by step guide, especially for those in the US who can send this to Mike B (sending to Petaluma is not really a viable option for me), but definitely everyone appreciate the hard work and effort required to do the + upgrade and the genius that went into this creation.

I'll stick up a board layout and schematic for the RP10A and RP11A boards for maintenance and general information in the next few weeks. This is for the C and the C+ for the RP10A and the C+ for the RP11A (I don't have any information on an RP11A C and would be guessing). If anyone wanted to do the mod work themselves (or even downgrade to a C if you wanted) you can analyse them both but I'm not doing a step by step for dummies guide or anything to stop people destroying their amps if they don't know what they're doing. I just think it's nice to document these 30+ year amps as much as possible for the future.
Last edited by jrb32 on Mon Dec 17, 2018 4:22 am, edited 1 time in total.

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Re: Mark IIC to C+ Steps Required for Upgrade

Post by JD » Wed Dec 05, 2018 3:40 pm

That would be very cool
Mesa Boogie Mark 3++ RGX 60W
Axe fx 2
Mesa Boogie Quad Preamp with C+ Mod Ch1 C++ Ch2
Mesa boogie Studio pre with C++ Mod by Mike B
Mesa Boogie Studio pre with C++ Mod

Mark III
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Re: Mark IIC to C+ Steps Required for Upgrade

Post by jrb32 » Tue Dec 11, 2018 5:34 am

RP10 IIC Schematic: ... 81rlggkt6M
RP10 IIC Board View: ... V5IgEUf5cS

RP10A IIC+ Schematic: ... 3j4_4PnjHk
RP10A IIC+ Board Layout: ... 8XQX49nUWV

Hope that helps someone out there do some maintenece/repair if needed.

If you're looking into doing a C to C+ upgrade there are a load of wire placements and moves you need to sort too so don't think you can just do these changes to the board it'll work. It won't. Don't even try unless you know what you're doing. ALWAYS send it to Mike B if possible.


Last edited by jrb32 on Mon Mar 04, 2019 10:40 am, edited 2 times in total.

Mark III
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Re: Mark IIC to C+ Steps Required for Upgrade

Post by jrb32 » Mon Mar 04, 2019 7:43 am

RP11A IIC Schematic: ... l8qHdo5nji
RP11A IIC Layout : ... 8LQ627h54b

RP11A IIC+ Schematic: ... D8matOy4qY
RP11A IIC+ Layout: ... KH6Vb7VAwj

The IIC schematic for the RP11 is the best I can get it without tracing one first hand. Looks like there is some weird stuff going on with the Lead Pull Bright as opposed to the RP10 board, but is very similar to the RP10 preamp wise apart from that. It also has all of the EQ, automatic treble shift, V2A/B rearranged and power section already at IIC+ specs. Like it was designed with the + upgrade in mind. It would make sense from a production point of view that the RP10 was the one that Mike B and Doug West originally modded and made the RP11 easier to upgrade with a lot of C+ features already done. That way the customer could choose easily between the C or the C+ far easier. There's the SP10 and SP11 boards as well but they seem similar in layout to the R versions (R meaning Reverb) from what I have seen. I've written on here that it doesn't really fit the Winter 83 timeline and makes more sense this would have been done Summer 83 in time to get a PCB redesign put into production (the IIC RP11s appear from around October 1983 with a lot of the + features already done). Could just be coincidence though and something that was being developed at the time but it seems unlikely. Just my thoughts! I'm probably wrong.

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Mark II
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Re: Mark IIC to C+ Steps Required for Upgrade

Post by TiPiMods » Sun Apr 21, 2019 3:02 am

thanx, great info & schematics
Boogie MkIIB, MkIII red stripe, Caliber 22+, Studio Preamp
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Kitty Hawk Standard, KH Junior
Marshall: 73 JMP Super Lead, 6100 Anniversary, 2555 Silver Jubilee
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