400bh circuit board

[Cvbella22]

Hello, I'm not very familiar with this equipment. Does anyone know how long it would take to switch out a circuit board inside of the 400bh mark4 series? I recently sold the 400bh online and the guy called several hours later saying that it didn't work and made a loud noise. Upon further inspection, it would seem that the circuit board that is now inside of the unit is not matching the number that corresponds to this specific unit. I have a 1980 and the serial number for the amp traces back to 1971. I read the forum about the serial numbers before 1990 falling within a decade of the production date. However the serial number on the circuit board that is now inside of it is traced back to 1995. I would really like to get an estimate as to how long it would take to switch them out. Thank you.

[j0nsnell]

I have been repairing Peavey, Marshall, WEM, Laney, Orange, HI WATT, Fender and many more makers amplifiers since 1970 and have never had to replace a circuit board. If you tested it before the sale, what has your customer done to make it stop working I wonder.
What is wrong with the board and why do you want to change it?
Repair it.
If you can't, take it to some one qualified to repair it as there will not be any spare boards available for a 30 year or older amplifier.
If you are UK based, I can repair it for you.