17-04-2020, 10:06 PM
(This post was last modified: 17-04-2020, 10:11 PM by peter scott.)
Quote from Lawry-Johns, Television Jan. 1985
"This time he had a GEC set we didn't recognise.
It was a C2265 (Hitachi NP81CQ chassis) and it
took me some time to realise that what I took to be a
chopper transistor was in fact a chopper i.c. (IC90l,
STR441). So I studied the notes in the manual, hoping to
get a clue as to how to start the thing up. They did provide
a lead, and when I put the meter on R605/6 in the
chopper feedback line the set sprang to life. It frightened
the life out of me because the sound had been left turned
fully up. I turned it down and switched off. When I
switched on again the set remained dead until I prodded
around the feedback network - the chopper is a sort of
blocking oscillator arrangement. The set then came to life.
Until the meter probe slipped. There was a nasty flash
and the 2.54T mains fuse disintegrated. "Oh dear" I said.
Like a fool, I put another fuse in and tried again.
FLASH! I checked the strange STR441 and found it
short-circuit"
"This time he had a GEC set we didn't recognise.
It was a C2265 (Hitachi NP81CQ chassis) and it
took me some time to realise that what I took to be a
chopper transistor was in fact a chopper i.c. (IC90l,
STR441). So I studied the notes in the manual, hoping to
get a clue as to how to start the thing up. They did provide
a lead, and when I put the meter on R605/6 in the
chopper feedback line the set sprang to life. It frightened
the life out of me because the sound had been left turned
fully up. I turned it down and switched off. When I
switched on again the set remained dead until I prodded
around the feedback network - the chopper is a sort of
blocking oscillator arrangement. The set then came to life.
Until the meter probe slipped. There was a nasty flash
and the 2.54T mains fuse disintegrated. "Oh dear" I said.
Like a fool, I put another fuse in and tried again.
FLASH! I checked the strange STR441 and found it
short-circuit"
