UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Hameg HM307-3 Cleaning and Repair

OldTechFan96 · 25th May 2019, 10:24 pm

X final amplifier measurements (the acceptable range is 84.1V-90.1V):

C of TR113- 112V
C of TR114- 96V

Both are unbalanced, like the Y amp.

R181 and R182 measure spot on out of circuit. The voltages on TR111 and TR112 are correct.

CRT section investigation:

85V missing on E of T354. R368 was O/C. Replacing it restored E voltage.

-8.9V was found on pin 4 (-590V--680V) of the CRT. The focus potentiometer has a partly broken inner ring. It is still partly attached. I have glued it.

All of the other voltages are present. The are either a bit too high or a bit too low.

I'll see if the pot is salvageable in the morning.

25th May 2019, 10:24 pm	#29
OldTechFan96 Octode Join Date: Jul 2017 Location: Newcastle Upon Tyne, Tyne & Wear, UK. Posts: 1,186	Re: Hameg HM307-3 Cleaning and Repair X final amplifier measurements (the acceptable range is 84.1V-90.1V): C of TR113- 112V C of TR114- 96V Both are unbalanced, like the Y amp. R181 and R182 measure spot on out of circuit. The voltages on TR111 and TR112 are correct. CRT section investigation: 85V missing on E of T354. R368 was O/C. Replacing it restored E voltage. -8.9V was found on pin 4 (-590V--680V) of the CRT. The focus potentiometer has a partly broken inner ring. It is still partly attached. I have glued it. All of the other voltages are present. The are either a bit too high or a bit too low. I'll see if the pot is salvageable in the morning.