Pro Jr 3 Issue's

[Deadear]

I bought this great sounding little amp three months ago used. I would say it is less than two years old. It started to squeal recently. Took back cover off and the problem stopped. Why have they got metal tape on this back cover running very close to all the electrical components? Some of it was coming unstuck ,but not enough to ground anything. Also all the wiring is very hard and stiff probably due to heat off tubes. Opinions ?

[52 Bill]

The foil is there as shielding, to help reduce hum and radio interference. If it has come loose press it back down to the back panel. It should still be sticky on the underside of the foil.

The ribbon cables are made from very stiff wire, so heat really doesn't have much to do with the feel of the wires.

As for the squeal, that could be a bad tube, a bad filter cap or even how the ribbon cables are positioned in relation to the tubes. Try changing the positions of the first two ribbon cables and see if that helps. Remember that those cables carry high voltages so move them with the amp off.

[Drewline]

With the amp unplugged, make sure the ribbon cables are not touching the shielding on the back cover. After working on any of the HR series I take a plastic ruler & run it across the back of the chassis to make sure the ribbons are not sticking out to far. If any are push them very gently in.