What is the part number of the 8pin IC in primary circuit

The AN8054 is an integrated circuit used in the Casio Tone Bank M120 keyboard. If it has been blown off, you will need to replace it. An equivalent replacement for the AN8054 is the LM358N, which is a dual operational amplifier that can be used as a substitute. Other equivalent options you can consider include the LM741, LM7808, and LM324. It's always recommended to check the datasheet of the substitute IC to ensure it meets the specifications and requirements of the original IC.

You might thy going backwards from the output to the IC .have a good light and make yourself a pointer that is nonmetallic which you can track the copper strips on the circuit board without touching them. If you remove this IC from the board, be sure to wear a grounding strap to your hand or wrist, connected to the metal chassis.BE SURE TO REMOVE THE POWER CABLE BEFORE YOU BEGIN! Note the exact way you remove it. The number one pin will have a indented dot on the plastic case. Be sure to reinstall in the correct order. ALWAYS WEAR A GROUNDING STRAP TO HANDLE ANY IC! The static electric in your body can blow certain IC units. You can make you own grounding strap using an old metal watch band, a piece of flexible wire approx. two feet long and an alligator clip to attach it to the chassis. Hope this helps you and I hope I have not confused you.

Not sure about the KB-1, but many newer Peavey amps
( A Vyper for example)
have the fuse soldered to the circuit board.
If you're going to go through the effort of soldering, I'd suggest buying, and soldering in, a rear panel accessible fuse holder, so you only need to do it once.

For thwe best info, contact Peavey Customer Service. Here's the link-
peavey com

Contact Peavey toll free at 877-732-8391 or by email at [email protected],

It is possible one of the IC's failed.

You can apply an audio signal to the input and with a small amplifier with speaker you can trace through the circuit to locate which IC failed.

The input to the small amp split iattach 2 wires pr test least leads from a meter, ground the ground lead of the little amp to the mixer chassis, and then with the other wire/test lead trace the defective channel 1 IC at a time until you lose signal.

If you download the IC's data sheet, Most likely a 4558 typse, you can speed the testing by simly testing at the amplifier inputs and output of each section of the IC. When you lose the signal, you found the offending IC- use the other channel for compairison.

Digikey has a site search, so you can enter the number on the IC to find if they carry it, or a similar IC, and who makes it- on the item specification page there is a link to the datasheet. While they may not have all of them, they have quite a few.
http://www.digikey.com

It sounds like there may be an issue with the power amp section of your amplifier. When the distortion gets deep and saturated, it could be drawing too much current and causing the amp to shut down to protect itself. This could be due to a number of reasons, including a faulty power amplifier IC, bad solder joints, or a power supply issue.
You mentioned that you suspect the IC may be getting hot. If that's the case, it's possible that it's overheating and shutting down the amp. You may want to try cooling the IC with a small fan or heatsink to see if that helps. If it does, you may need to replace the IC or look into other cooling solutions.
It's also possible that there are bad solder joints or other issues with the power amp section that are causing the problem. If you're comfortable with electronics repair, you may want to open up the amp and take a look inside to see if there are any obvious issues. Otherwise, it may be best to take the amp to a professional for repair.

The integrated circuit that are used are specially programmed for Casio and are not available from electronics stores. They are usually surface mounted and require special tools and skills to replace. You would need to take this to a Casio service center to replace the chip if that is the problem. Frankly, it is UNLIKELY that is the problem unless you can see burn marks on the chip. Keybaord contacts are the usual failure and require cleaning.

It is likely soldered into the circuit board. It may be any of several part numbers such as 7805.

Try to read ANY number you can off the IC itself... the last two digits are the voltage... 7805, 7812, 7815 are common ones... There often is a production lot number... see if you can find the number ang et back to me as email.

Try googling " cross reference for " insert number on I.C." integrated circuit." Various manufacturers have identical replacements but with different labeling on them. Make sure you compare the functions of the pinouts to the original and mount it the same way. Also try contacting WDGreenhill.com. They have a lot of hard to obtain parts. Try checking their site.