1976 Trinitron flickering blue color

[Duke1921]

Hello everyone, I am new here. I have been a master electrician for over 30 years but am relatively new to electronics repair. I have an extensive retro console/game collection and have recently gotten interested in electronics repair. I’ve recently acquired an absolutely beautiful 76 Sony Trinitron and am currently attempting to make some needed repairs/adjustments. I already replaced about 30 electrolytic capacitors which have fixed a few of the issues but the one I am trying to figure out now is the blue color comes in and out randomly. The service manual suggests it may be one of three components: a transistor, a diode and an amp. Two of these components are under a shield that I am trying to avoid removing. Anyway, just thought I’d get some insight from some more experienced folks. Any thoughts? Thanks so much.

[zeno]

Look on CRT socket PCB. Most likely cold solder joints under
the transistors or the socket itself. Could be other things, start
easiest first.
Be VERY careful with this set. If you slip its often the end for it.
Long story !

73 Zeno
LFOD !

[Duke1921]

Originally Posted by zeno

Look on CRT socket PCB. Most likely cold solder joints under
the transistors or the socket itself. Could be other things, start
easiest first.
Be VERY careful with this set. If you slip its often the end for it.
Long story !

73 Zeno
LFOD !

I will take your advice. Thanks for the tip. I’ll let you know how it turns out.

[zeno]

Just thinkin.... Those transistors may be on the main PCB. Look for 3 identical
transistors with metal tabs & small parts. They are the place to look first
for missing or excess of one color. One each for R out, G out & B out.
Still check the CRT socket for cold PC cons. You can usually smoke out
cold joints with light tapping

C U later
Zeno

[Duke1921]

Originally Posted by zeno

Just thinkin.... Those transistors may be on the main PCB. Look for 3 identical
transistors with metal tabs & small parts. They are the place to look first
for missing or excess of one color. One each for R out, G out & B out.
Still check the CRT socket for cold PC cons. You can usually smoke out
cold joints with light tapping

C U later
Zeno

I found the transistor for the Blue and it is definitely discolored compared to the red and green. it has burn marks on the leads. I ordered an NTE replacement transistor and will install it as soon as it arrives. Thanks so much!