stillplayin1975

I'd not used my Neo Pak 3.5 for a couple of years. I've started using it again but it's started making terrible noises when i first turn it on. When I turn the amp on it makes a high pitched squeal like noise but this stops after about 5 mins and it returns to normal. I replaced the tube with a fab Harma Cryo but i'm still getting five minutes of ear splitting shriek that no control changing will stop. It seems to be coming from the amp and not the signal path. Any advice greatly appreciated? Many thanks, Alex[attachment=162183:IMG_2188.mov]