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I think copyright only lasts for 10 years on PCB design in the USA. I think the harder thing would be mass producing a double sided etched PCB to the same standards as done up to the Mk IIC. As far as I am aware since technology has moved on, nobody produces PCBs this way anymore. For a MKIII...

Hey sorry for the slow reply. That makes sense I'm going off the original schematic here which deliberately contained errors so you're probably correct! Good spot

https://boogieforum.com/threads/mark-iic-to-c-steps-required-for-upgrade.83222/ https://boogieforum.com/threads/mark-iic-schematic-correct.74680/ (For reference this was an INFORMATION post and any repair work please send to Mesa if possible - being in Europe or Australia it's more...

If you're really asking to replace all PCBs in a Mark IIB... I'm really sorry but please give it to someone to repair who knows what they're doing. PCBs do not need to be replaced except in extreme circumstances. However, they don't exist anymore and generally can be repaired especially the...

Techincally the SP10 and SP11 can also be upgraded to C+ (the non reverb model boards) too (the R in the RP stands for Reverb). But yes IIBs usually have a RP9/SP9 and can't be upgraded to a C+ unless it was upgraded in the 80s/90s when Mesa still had the 10s and 11s in stock (they now have run...

My advice would be to buy a purple stripe (or anything else you want) and send it to Mike B to get whatever you want done to it. No-one else should be doing this unless you live on the other side of the planet. Even 'authorised' repair places. Just send it to Mike :) He'll be able to advise on...

Really nice job! Especially on the accurate layout too - if any info I put out there helped produce this even better. Any clips on how it sounds? I'd love to make up an RP10-A or RP11-A board one day using a double sided FR2 laminate with the original trace layout etc since Mesa don't reproduce...

The guy made up his own PCB which is really similar to the originals but not the correct material or traces so this will change the tonality of the amp a lot. You can't get the original preamp PCBs anymore as Mesa ran out and don't produce them anymore. Best bet is the IIB loop mod done by Mike...

The III+ mod is a Mike B specialty really. You can ship just the chassis to save weight/shipping costs and let Mike B do his magic. One simple thing you could do is check C516 - it's an orange drop that connects to a resistor (R238) that then goes to the presence pot. Start at the presence pot...

Just too much power going through it they didn't realise when they designed it. You need to replace it with a high W wirewound resistor. Say 3W or higher. That'll sort the issue for good. It's also what mesa do to both the IIIs and the IIC+s automatically when they go in for service - replace...

Hey Henz sorry I've not been here for a while! Could you let me know the differences between the sloclones and the other schematic so I can make changes as necessary. Regarding the negative supply I don't have a multimeter to check mine right now but this is from another post...

You have a factory IIC+ 60W with Reverb and EQ worth a small fortune (worth probably $2000-3000 but not sure on the exact market at the moment for the USA - xdg999 will be able to advise further on what he would pay for one as he buys quite a few). You should run a loop test though just to...

Yes. An upgraded C+ is a legit C+. All 'factory C+s' were IIC circuit boards that had the + mod done to them on the production line. End of discussion. However, it gets a bit more complicated. Basically if it has an SP11 or RP11 board it's 100% identical to a factory C+ regardless of when this...

No problem thanks Dave! I've put a new post up at the start that basically sums all the info up. Cheers! Stay safe everyone. Now to trace my studio preamp... :wink:

The IIC and the early IIC+s shipped out with the IIB schematic. Not sure why but that's just the way it was historically. I haven't compared the IIB and IIC from a circuit point of view but perhaps they are similar in certain ways? There could also be an element of stopping people copying the...

Can always hook up a multimeter in resistance mode to the pots with the amp off and check the difference in resistance as the knob is turned to check the pot is actually working properly within the limits it's meant to? If you can eliminate that as working correctly then maybe look around...

Thanks a lot I'll update that switching part on the schematic. Cheers :D

Also if you still have that picture of the bottom of the IIC+ PCB you could upload in a similar way I could kiss you right now! :lol:

AMAZING! Could you make sure the picture is given permission to view as it's not showing up (error 403), or alternatively use something like https://imgbb.com/ to upload. Many thanks in advance!!

There are NO official Mark IIC schematics out there. Sorry. These are the best you'll get and probably better if there were original ones as they include component layout and no deliberate mistakes... These seem to have gone under the radar somewhat but are on here if you look: RP10 IIC...