Trinitron Horizontal Flicker
 

This 1989 KV-20TS20 Trinitron has a horizontal line flickering problem on all sources. They appear to be random. This is a still image for example. It's subtle but it's there. I'd like to fix it.

https://youtu.be/9x77Ha8or4A?t=8s

What is the source of the issue? Capacitors in the power circuit? Tapping the set for cold joints doesn't do anything.

You may have to slap it harder ! Still look for cold joints on the
hoz drive transformer. After that the hoz out & flyback area.

Cold joints on the H drive are common to most brands for many years.
when working on ANY set from the mid 70's on always resolder them.
If they keep up you could blow the HOT & power supply.

Your problem is very subtle so if its not a PC con it will be very hard to smoke out. You may have to wait for it to get worse or fails first.....

Good luck
73 Zeno:smoke:
LFOD !

Okay, thank you.

I am not experienced with electronics repair. Is there a book to get me up to speed?

For example, I think I know what a cold solder joint is (an intermittent connection due to cracked solder), but I do not know how to look for it or repair it. Perhaps it would be best if I practice on something else first.

This looks like a good starting point.

I took the set apart and tried to tap various areas of the board with a screwdriver to see if I could reproduce the issue, and I wasn't able to.

Then I noticed that the flickering seemed to be gone. I tried plugging only the TV and source into the AC socket, and the flickering remained gone. Perhaps another piece of equipment was causing interference in the power.

If it's anything like my old Trinitron, ALL the solder joints will be bad. Get yourself a REALLY good magnifying glass, and actually remove all the circuit boards and just look over every square inch of them under a good light (I prefer sunlight). Cracked solder joints ('cold joints') are usually very obvious when you can see them well. A good joint should be smooth and shiny, a bad one will have an actual crack in it, though it's hard to catch unless you're REALLY paying attention.

Problem areas on any pcb are anything large sticking up from the board (big caps, plug sockets, soldered-on riser boards) and otherwise anything that exerts physical stress to the joints.

Speaking of which, doesn't that TV have riser boards plugged into the main board? Maybe the contacts are dirty. Blow it out like a Nintendo cartridge.

Here are some photos of the boards.

https://p836iw.by3301.livefilestore....&cropmode=none

https://p80aja.by3301.livefilestore....&cropmode=none

When I took the back off, I vacuumed most of the dust off as well. The flickering has not returned yet. Next step is to plug everything back in one by one and see if the flickering returns.

Thanks for the advice about looking for cold joints, I will need it if Trinitrons are susceptible to bad joints.

With any luck it was just a fluke.

...

I tell you one thing: it's way too damn dusty in there. Blow a bunch of compressed air on everything. Dust can technically conduct electricity, depending on conditions.

high volumes of dust = a high hour set.

Or a low hour set that spent its life in an oppressively dusty environment. :yuck:

Once I dust out the inside with compressed air, is there anything else I can do for preventative maintenance? I've heard it's a good idea not to use sets when it's hot or humid because that can lead to cracked solder joints.

My old Panasonic works perfectly (and flicker-free for what it's worth) since '94, but did develop a bad joint in the vertical section about 10 years ago that had to be repaired as well as a sticking power relay. I never dusted it out until the problem had surfaced.

That was exactly it. I have isolated the flicker to the charger for my MacBook computer. When the charger isn't connected, the flicker disappears.

Some sets develop cold joints naturally with time...They sometimes don't size the heat sinks big enough. The chips will run cooler than their max operating temp and will work fine, but will be hot enough to cause thermal stress to the solder and or bring it to the edge of melting...Not much you can do about it but open it once every few years of service and check on it.

The flickering has returned. I’m almost certain it wasn’t there earlier. The only thing that changed is I dusted out the back again.

I tried plugging into three different outlets without success. Only one thing is connected to power, the TV, and it still flickers.

If it is an external power problem, how can it be remedied?

Voltage regulating power line isolation transformer.