1979 Mesa Boogie MK 1 Recap

[Aerostoon]

I am going to recap a 1979 Mesa Boogie MK 1 at the request of the owner. The caps test ok with my capacitance meter and ESR meter but I am sue these caps are the original ones and are 37 years old. There are three 30UF 500vdc and two 220UF 285vdc electrolytic caps. I have a copy of the original pink paper schematic. It looks like on the schematic that the two 220UF caps should be 60UF. Is it possible that Mesa changed things up and didn't update the schematic?

[Aerostoon]

Here is a photo of the caps. The writing in marker is from me.

[Aerostoon]

Here is a photo of the entire chassis:

[g1]

Yes it's quite possible. Mesa schematics are iffy on the best days. What do you have for the cap shown above the standby switch as 60uf/500V ? How about the one at the top to the right of the 33K ?

[Aerostoon]

Yes it's quite possible. Mesa schematics are iffy on the best days. What do you have for the cap shown above the standby switch as 60uf/500V ? How about the one at the top to the right of the 33K ?

The cap that looks like it is the one above the standby switch appears to be the large 220UF although the voltage on the cap is 285vdc which doesn't make sense.
The 60uf 350vdc cap indicated on the upper right of the schematic looks like a 40UF 500vdc one in the amp. It is connected to the 56K resistor off of the Fetron.

[Aerostoon]

The smaller yellow capacitor on the vertical circuit board is a 220UF 63vdc cap.

[g1]

It sounds like the MKII schematic may be a better match, at least for the power supply.

[Aerostoon]

That is very interesting. The values on the MK II schematic do match up with what is in this amp...