Photo request: Mark IIC+ preamp circuit board

Mark I's, II's, III's and the almight IV

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woodbutcher65
Mark III
Posts: 193
Joined: Fri May 04, 2018 10:36 pm

Re: Photo request: Mark IIC+ preamp circuit board

Post by woodbutcher65 » Sun Nov 25, 2018 2:28 am

Don't even think about putting the tantalum caps in. There is no such thing as a tantalum capacitor that sounds good and when they go bad they become hard shorts.

Put in electrolytics instead, best of all, non-polarized ones.

Mesa uses those awful tants only because they are cheap and they offer a large amount of capacitance in a small package. They're still hot garbage.

jrb32
Mark III
Posts: 194
Joined: Wed Jan 31, 2018 8:32 am

Re: Photo request: Mark IIC+ preamp circuit board

Post by jrb32 » Sun Nov 25, 2018 12:07 pm

All IIC+s have military sealed tantalums on the cathode caps and an important .22uF one in the lead circuit that should be a T110. Are you really saying IIC+s sound bad and you would rip these out of a IIC+ ever came into your workshop and replace them?

I'm going for authenticity here. So would Mesa if they still had RP10/RP11 boards available. Stick with the original parts if you want it authentic. If I bought a IIC+ that had the wrong type of components I would correct it 100% without question regardless of how much of a POS tant caps are. The hermetically sealed ones seem to be fine I haven't seen any fail on me yet.

http://forum.grailtone.com/viewtopic.php?t=18617
All IIC+ cathode caps were tantalum or hermetically sealed tantalum. They never used electrolytic or ceramic disks.
http://forum.grailtone.com/viewtopic.php?f=9&t=49710
Replaced .22 cap on Pull Bright on Lead Master with Kemet T110 Hermetically Sealed

woodbutcher65
Mark III
Posts: 193
Joined: Fri May 04, 2018 10:36 pm

Re: Photo request: Mark IIC+ preamp circuit board

Post by woodbutcher65 » Mon Nov 26, 2018 11:19 am

I'm saying that you can always do better than a tantalum capacitor as far as tone goes. I think you will improve the sound of even a IIC+ by replacing those tants with something better sounding.

lovetoboogie
Mark II
Posts: 119
Joined: Tue Mar 25, 2014 10:14 pm
Location: New York City

Re: Photo request: Mark IIC+ preamp circuit board

Post by lovetoboogie » Mon Dec 10, 2018 8:53 pm

woodbutcher65 wrote:Don't even think about putting the tantalum caps in. There is no such thing as a tantalum capacitor that sounds good and when they go bad they become hard shorts.

Put in electrolytics instead, best of all, non-polarized ones.

Mesa uses those awful tants only because they are cheap and they offer a large amount of capacitance in a small package. They're still hot garbage.

This statement kind of caught my attention...

As a musician, amp and guitar tech of 30+ years with 100's of scratch builds and a custom amp builder...I would never encourage a vintage Mesa Boogie owner to "rip out" all the tants because they are crap or because Mesa Boogie was "too cheap". Molded tantalums started showing up in the late Mark IIA models and have been a consistent in all Mesa Boogie models. Tantalums are super stable at below their rated voltage, they don't need to be replaced unless they short(which is almost nil in the cathode bypass), they are super compact and help the real estate of a populated Mesa preamp board. I can't speak for Randall Smith or Mike B but the mindset at Mesa has always been durability and using components that don't fail. The pedigree and originality of older Mark Series amps are at stake with bad info on the internet. It might be prudent not to further that cause....

I might add I mean no harm or judgement of your experience. It is admirable to do period-correct work on old Boogies so I try to promote that.
Last edited by lovetoboogie on Tue Dec 11, 2018 9:32 am, edited 1 time in total.

jrb32
Mark III
Posts: 194
Joined: Wed Jan 31, 2018 8:32 am

Re: Photo request: Mark IIC+ preamp circuit board

Post by jrb32 » Tue Dec 11, 2018 5:39 am

I might add I mean no harm or judgement of your experience. It is admirable to do period-correct work on old Boogies so I try to promote that.
Definitely agree on this. If it was my own personal amp and I wanted to experiment and maintain these I'd be fine changing some caps but if I was ever to repair or maintain one for someone else or sell it on, definitely go for originality all the way!

I've finished a Mark IIC board view and schematic done from my SRGX '83 with RP10A board. Hopefully that will get you where you need to go.

IIC RP10A Schematic https://drive.google.com/open?id=1mpJFs ... 81rlggkt6M
IIC RP10A Board view: https://drive.google.com/open?id=1Lx0Ao ... V5IgEUf5cS

I'll do the same for the IIC+ RP10 once I do the upgrade.
Last edited by jrb32 on Wed Dec 19, 2018 5:26 am, edited 1 time in total.

User avatar
Authorized Boogie
Mark IV
Posts: 689
Joined: Wed Sep 08, 2010 4:12 pm
Location: Petaluma, California
Contact:

Re: Photo request: Mark IIC+ preamp circuit board

Post by Authorized Boogie » Tue Dec 11, 2018 11:42 am

lovetoboogie wrote:
woodbutcher65 wrote:Don't even think about putting the tantalum caps in. There is no such thing as a tantalum capacitor that sounds good and when they go bad they become hard shorts.

Put in electrolytics instead, best of all, non-polarized ones.

Mesa uses those awful tants only because they are cheap and they offer a large amount of capacitance in a small package. They're still hot garbage.

This statement kind of caught my attention...

As a musician, amp and guitar tech of 30+ years with 100's of scratch builds and a custom amp builder...I would never encourage a vintage Mesa Boogie owner to "rip out" all the tants because they are crap or because Mesa Boogie was "too cheap". Molded tantalums started showing up in the late Mark IIA models and have been a consistent in all Mesa Boogie models. Tantalums are super stable at below their rated voltage, they don't need to be replaced unless they short(which is almost nil in the cathode bypass), they are super compact and help the real estate of a populated Mesa preamp board. I can't speak for Randall Smith or Mike B but the mindset at Mesa has always been durability and using components that don't fail. The pedigree and originality of older Mark Series amps are at stake with bad info on the internet. It might be prudent not to further that cause....

I might add I mean no harm or judgement of your experience. It is admirable to do period-correct work on old Boogies so I try to promote that.
+1!! Sadly, there is so much misinformation presented as the number of internet experts multiply!
MESA/Boogie - Product Specialist/Customer Service - http://www.mesaboogie.com/support/index.html

jrb32
Mark III
Posts: 194
Joined: Wed Jan 31, 2018 8:32 am

Re: Photo request: Mark IIC+ preamp circuit board

Post by jrb32 » Mon Dec 17, 2018 11:25 am

RP10A IIC+ Schematic: https://drive.google.com/open?id=1dyC8z ... 3j4_4PnjHk
RP10A IIC+ Board Layout: https://drive.google.com/open?id=1Z0-2L ... 8XQX49nUWV

I'll do the RP11 soon. For differing values check this one:

IIC+ General Schematic with various component differences listed as much as I can:

https://drive.google.com/open?id=1ieTnM ... RIDwbLAcUQ

Should help anyone out there do maintenance if needed on their amp, but if you can send it to Mike B as always.

If you want to build a IIC+ clone board you should be able to figure it out from this.

Cheers,

Jon

discostu29
Bottle Rocket
Posts: 20
Joined: Sun Dec 01, 2013 3:14 pm

Re: Photo request: Mark IIC+ preamp circuit board

Post by discostu29 » Wed Feb 13, 2019 10:59 am

I have a IIC++ if your interested in photos and component values?

jrb32
Mark III
Posts: 194
Joined: Wed Jan 31, 2018 8:32 am

Re: Photo request: Mark IIC+ preamp circuit board

Post by jrb32 » Mon Mar 04, 2019 7:46 am


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