IIB coli service Pt II

[electric mayhem]

"Honey do your filter caps have warts?"

 

[electric mayhem]

Here is 58x, an early coli I wasn't planning on replacing caps but when looking closely at them the bottom row looked like it was growing macroscopic version of the microscopic covid pictures.
Given that the long chassis IIB started at 550 after they retired the B serials for Mark II(A) and that the coli's start with Mark IIB one would think this was the beginning of the end of ears called the coliseum option for "Mark".
There is no chassis date and a pair of marker marks that I'll get to later and I'll gather all the cap dates too. I have 61x, a big brother with 10/5/81 date, a low number considering the IIB had been out for over a year.

 

[electric mayhem]

The silver Mallory 220uF caps in question you can see are from Thanksgiving 1980. I wasn't having problems with the amp but don't need an amp with covid spheres. Not bad for 43 years of service!

I think Mesa uses hot glue for caps, etc but this bank of 8 was loose and only the bottom row were growing out the positive.

So time to service another coli and I'll show some of the differences in the evolution of these IIB's.

 

[electric mayhem]

Since Mesa no longer sells the BMI e-caps it seems timely to make a note about the filters.

Last year I asked Mike a question about them along the lines of I'd rather keep them till they go bad. He said replace the white nylon cap ones and the rest are on me; sad news since there are so many of the white or off-white which I think applies.

So the red and the black (BOC!) capped caps pictured here on my Bass 400 are ok thankfully from that standpoint.

Maybe my leaking, not necessarily leaky, or close to leaking caps are one reason why MB said to get rid of these!

 

[electric mayhem]

Now going through several 30uF BMI's here, most were not acceptable for ripple current. Maybe BMI coming off the shelf was a good thing but other opinions are welcome.

Good thing someone already splurged on the ATOM's for the PS board at the turn of the century. From the prices I see on those they must use gold flake on the wrappings. I've noticed the 30uF filters often need replacing or have been replaced. It might be a good idea to up the V rating but I haven't looked to see what's out there.

Theresa on here mentioned F&T which I have not used but I see they are made in Germany which is usually a good thing.

And not that I plan to use them but do the price of "MOD" filters suggest they are no good? Just curious.

I hope ATOM's have excellent ESR/ripple specs for that price but does anyone have experience with other makes of filters known to have super ESR characteristics?

 

[electric mayhem]

The 220 uF 63V Siemens e-caps on the EQ3 board were cracking up on the positive side. They and the 10uF/63V have been replaced. The 220uF/63V caps from Mesa were Nichicon and I had some 10uF nichi's from Mouser.

The sliders were all busted when I got the amp. There is just enough to get your finger on them; it doesn't bother me and I don't care about resale since this one isn't going anywhere. I wouldn't mind having new sliders handy but the time to do that work would have been before putting new 220uF's in.

 

[electric mayhem]

The RP-8C looks a bit different than the other IIB boards I have.

I'll have to order some 25uF/25V for the 5 on there but the 30UF and 470uF/16V are changed. Like the K17x I've been working on I upgraded the 470uF to 25V since they are testing better than the 16V ones I got from Mesa.

The bottom layer of 220's is in.