Some help dating this Mark IV

[Rampage]

I am just wondering if the date on the inside of the amp is the build date. I've got a picture:

Would this mean May 24th, 1991 build date?

 

[Boogiebabies]

That is the date that the circuit board was completed. Generally, the rest was finished within the same month or one later. It's probably a 6/91 MK IV A. The final tech date shoud be written in red marker on the power transformer.

 

[Rampage]

Thanks Boogiebabies!

 

[Boogiebabies]

No problem. I geuss your 1994 MK IV A is now a 1991. I always wondered since I have a late 1993 MK IV B.

 

[Rampage]

That is what I was wondering. When I bought it I was told that it was a 1994 model so that is what I always went off of. So I was kind of surprised to see 1991 inside the Mark IV. Would that make this the second year then?

 

[pmb]

Quite offtopic, but what are the opamp-style components.

 

[z28lt16]

Rampage may I ask where you got that date from. Ive looked around inside my amp and cant find a born on date. I found a stamped serial # though.

My amps kinda a frankenstein I guess being switched from a combo to a head. Previous owner thinks he purchased sometime in 1992.

 

[Rampage]

I have a picture of the inside of the chassis. I marked where I found the date (right side red rectangle):

 

[Boogiebabies]

Quite offtopic, but what are the opamp-style components.

Those are in the switching circuit ie: footswitch, LED's, LDR's and relays. They are not in the signal path.

 

[z28lt16]

so kinda flipped over, upside down, torn apart basically. Looks like on the right side.

Thanks for pic there Rampage

 

[Rampage]

so kinda flipped over, upside down, torn apart basically. Looks like on the right side.

Thanks for pic there Rampage

To get it here is what I had to do:

1. Unscrew all four mounting screws on top of the Mark IV and remove them totally so you don't scratch the face when putting it back in.

2. Put your hand under the chassis and push up will simultaneously pulling it out the back of the headshell. Be aware of the RCAs for the reverb tank.

3. The circuitry will all be exposed. The signature is on the very end of the circuit board. It is the end on the side of the Mark IV that has the external switching jacks.

Removing the tubes makes everything a lot easier. Also be safe and leave the amp unplugged overnight before you do it to dissipate the charge left in the caps (blue D battery looking things).

It also helps when you detach the front of the headshell after you pull the chassis. Mine was held on with velcro and I just put it back on after I reinstalled the chassis in the head.