Help needed with '91 or '92 Mark IV short head

[aaronlyon]

Just received a Mark IV short head via eBay. SN: IV4027. See photos below. I hope you can answer some questions!

1. I suspect this head was rehoused in a third party cabinet, because there are no mounting points for the footswitch board, there is no room for the Mesa-direct reverb tank I bought, the AC fan is so large (or the case is so small) that it pushes one of the 6L6 tubes askew in its socket, and finally, the "Boogie" logo is screwed in at a slight slant. Was a Mark IV short head ever shipped without a reverb tank?

2. Page 17 in the manual shows that there are four sockets for power tubes, labeled A-D. And it says which tubes can be used in Class A sockets, and which in Simul-Class sockets. BUT the manual doesn't say which sockets are which! The previous owner has the tubes installed: EL34, 6A6, 6A6, EL34. Is this right?

3. Two of the POTs are bad. Fortunately, they're not the pull-switch type. R1 Treble and R1+R2 Bass. Can anyone spec replacements?

Thanks so much. This amp came at a good price, but it's turned out to be a project amp. Oh, well…I like projects!

-a

 

[aaronlyon]

Well. With the serial number, I found old posts here on the Boogie Board by the previous owner, "The Swank." That answered the question about the cabinet--it's not a Mark IV.

http://forum.grailtone.com/viewtopic.php?f=3&t=36594&p=263158#p263158

 

[MrMarkIII]

The manual describes the tube socket assignment on the previous page (16).
Yes, EL34s may be substituted for 6L6s in the outer Class A sockets.
Contact forum member "gts", he can make you a proper head cab.

 

[JimAnsell]

project? nah.
heres what you do:

1) take the chassis out of the cabinet.
2) burn that cabinet in the fireplace.
3) buy a rack kit or ask GTS about making you a headshell.


did you try cleaning those pots with contact cleaner yet?
try that before you worry about replacing them.
if you have to replace them, call mesa boogie, talk to customer service, tell them the pots that are bad, they'll send you new ones. might cost 5 bucks or so each, i can't remember, its been a while, but i've done it before.

 

[Boogiebabies]

Consider yourself spec'd !!!

 

[aaronlyon]

Excellent! Thanks, everyone.

 

[Mongo1]

Consider yourself spec'd !!!

Now that's a keeper!!!