Filter Cap Replacement - 1984 Mark II C+

Pre Recto days. Boogie modified Fenders, Mark I-IV, Dual Calibers, etc

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DrewV
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Filter Cap Replacement - 1984 Mark II C+

Post by DrewV » Sat Jul 22, 2006 12:12 am

:D Hi All, I have a Mark II C+ which I bought NEW from the factory in 1984. It's a Blond / wheat Super Sixty combo with graphic and 'verb with a 150w Black Shadow. I also bought the road casewhich has kept "The Amp" looking showroom clean, near mint condition! It's time to replace the filter caps. One of the 220uf 300v caps is spittin out tobacco juice! They were replaced about 15 years ago at a shop here in Austin. There are another 4/ 30uf 500v 'blue' caps that are original Mesa "Made in USA" caps, 3 on the power supply board and 1 on the preamp board. All the 30uf 500v caps look good, although the one on the preamp board has the letter "R" written on it with a felt tip pen as well as a 1/4" green stick-on dot on it (?). My questions: 1) Should I replace the 30uf 500v caps? 2) Is there a "better" or "best" cap to use for a replacement rather than the stock item? 3) Where do I buy the replacement capicitors? 4) While I'm in there should I replace anything else?
Thanks
DrewV
This amp has been my faithful gigging pal for 22+ years

BPski
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Post by BPski » Sat Jul 22, 2006 1:28 am

Call Mesa and get the caps from them. I replaced all my Boogie's filter caps and got them right from Mesa. They are U.S.A. made and are exact replacements. While you are under the hood check all of the other electrolytic caps including the cathode bypass caps. Check yours out. Have fun!!!

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Post by DrewV » Sat Jul 22, 2006 1:54 am

Thanks - will do Monday when they are back in the shop....... dv

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Post by stokes » Sun Jul 23, 2006 4:17 pm

I would also suggest changing all the electrolytics.I changed mine (same amp) in '96 and just ordered a new set from New Sensor.I dont know what Mesa charges,but I paid $66. for the 2-220mf/300v and 4-30mf/500v.These caps are not pre-formed,I think Mesa may be able to do that for you,if you cant do it yourself.You may pay a little more but if they are pre-formed it is worth it.I dont believe in leaving caps for more than ten years even if they look okay,when they blow they make quite a mess not to mention what they might take with them.By the way the 30mf's are Sprague and the 220mf are German made F&T's.I believe Mesa uses Illinois for the 220's and Sprague for the 30's.Dont use the Jap caps in that amp,they are cheaper for a reason.

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DrewV
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Post by DrewV » Sun Jul 23, 2006 9:38 pm

Thanks,
I did some checking yesterday and found a couple IC 220uf 300V's and 4 Atom 30uf 500V's at thetubestore.com for $44.85 with shipping. I count another 7 electrolytics in various places. I also want to change out the cathode bypass caps, but I am kind of having a hard time identifying them on the preamp board. I know they are 25uf 25V, but I can't find anything marked like that. What I am seeing is: '5' black 3/8" x 1/8" components that look like they could be capacitors marked as follows: "226K" underneath that is "6V with a "+" towards one end and underneath that the number: 8319. I would say this has to be them? This is my first cap job so I'm a little cautious!
dv

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Post by BPski » Sun Jul 23, 2006 9:52 pm

That'd be them. I don't think they are electrolytic though. They are probably tantalum. Leave them alone. Just replace the electrolytic caps. Have fun!!!

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Post by DrewV » Sun Jul 23, 2006 10:31 pm

That's what I'll do then! Thanks again for the info...dv

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Post by stokes » Sun Jul 23, 2006 10:32 pm

Thats a good price.I would get the F&T 220's.I think they are a better quality than the IC's.Just my opinion.I paid 2x what thetubestore is asking.The two small 75v caps on the power board are the bias supply caps you want to change those also.Dont mess with thos preamp cathodes on the board like BP said they arent eloctrolytics.Be careful-lots of volts there.Make sure you drain them caps.

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Post by DrewV » Sun Jul 23, 2006 11:23 pm

thetubestore.com doesn't have that great of a selection of caps, none of the smaller 7 caps, but apparently the price is good on what they do have. The caps on this power supply board are 47uf/63V if I'm not mistaken. They are the only other caps on the psb besides the 220's and 30's.. I've been checking the DC on the filter caps. They have been draining over the last few days and are down to + 10V on the 220's and +14V on the 30's. They should hit zero by the time the replacements get here. I won't be messing with the bypass caps..no signs of damage or discoloration. The circut boards looka little cruddyand could use a clean up. Boogie On...dv

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Post by DrewV » Mon Jul 24, 2006 3:26 pm

I went ahead and got the F&T 220's. About $3 more a cap. Mouser.com had the rest of the smaller caps & a high ohm power resistor for about $9 including shipping. I'll post when the amp is done. thanks dv

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Post by stokes » Mon Jul 24, 2006 4:42 pm

I assume the "7other electro's" you refer to are for the EQ,I dont have EQ in mine and dont have these smaller ones.But if they are on the preamp circuit board I would clip the old ones off close to the cap so you leave a nice length of lead from the board and you can solder the new ones right to the wire-its easier than trying to desolder and resolder directly to the PCB.Good idea for the larger caps as well.Hate those PCBs but love the amp.

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Post by DrewV » Tue Jul 25, 2006 12:35 am

there are 2/ 47uf63v on the powersupplyboard, 1/ 470uf16v on the preamp board, 2 /220uf63v and 2 /10uf63v on what I think is the graphic eq board (it's mounted on the side of the chassis, near the input.

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Post by stokes » Tue Jul 25, 2006 12:41 am

Yea thats the EQ board,so it looks like you have 4 more caps than mine,all on the eq board.

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Post by DrewV » Tue Jul 25, 2006 1:56 pm

I've found a sprague orange drop cap running parallel with a resistor that is next to the 4th preamp tube socket (called the gain boost footswitch circut on the schematic) that has turned brown but doesn't look disfigured and is not leaking. the value is sprague 715P .005-400V. As far as I can see, it's the only 715P in there.Should I replace it?

stokes
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Post by stokes » Tue Jul 25, 2006 2:56 pm

If it isnt leaky then I would leave it alone.I have a drawerful of orange drops that are brown and have never been used.Just discolored.

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