High pitch Squeal with 2204

grazy · Post by **grazy** » Sat Dec 31, 2022 12:47 pm

I have an original 1984 JCM800 4104 combo with the 2204 50w amp. After playing it, for a while, I started to hear some distortion on some chords, then it squealed so loud I had to turn it off. I let it cool down, then set everything to 5, with preamp and MV set to zero. Plugged into high sensitivity, slowly turned preamp to about 2-3, then brought mv up....seemed okay for a while, and then the loud squeal again. I switched out each preamp tube..no change; looked at solder joints - all look okay. Any ideas? I am halfway thinking of buying a PTP board, removing and checking all components and then rebuild the whole thing -using as many of the original pieces as possible...but that is a big deal. Thank you for any troubleshooting suggestions.