Paul FenwickSep 27, 2025

Today I fixed a television out of spite.

One of the most common faults with modern TVs is a backlight failing. These are cheap to replace, and the tools to test them are cheap to obtain.

But the effort to get to the backlights? Oh my!

A TV that was made to be repaired would have a separate pane for backlights you could slide out, or some other access mechanism.

But today's consumer TVs require you to disassemble practically everything to get to the backlights. That means getting to them is a huge investment in time (for self-repair) or money (if you go to a repair shop and pay for labour). TV companies know that most people will just buy a whole new TV.

So today I fixed the TV out of spite. Not because it was rewarding, or for environmental or financial concerns (although all of these are valid). I fixed it because the company that made it did not want it to be easily fixed.

Show threadKerplunk

@pjf

Hi Paul, every saved device helps 🙂

Backlight fails are one common issue, as you say a horrible repair job.

Very common power supply capacitors failed due cheap crappy components and insufficient ventilation.

For anyone diy ing that job make really sure the mains connection is removed and capacitors in the supply are all discharged, especially the bigger, usually 400 volt ones, they can kill in an instant.

Even experienced technicians have been sloppy for the last time.

Sep 27, 2025 at 12:54pmWeb
Show threadGeorge DinwiddieSep 28, 2025
@Kerplunk @pjf It’s current, not voltage, that kills. In 1968 I hit the second anode of a color TV — around 30 kV if I remember correctly. It contracted my muscles so violently that it spun me around 270 degrees. Fortunately that arm was grounded on the side of the chassis so the current didn’t pass near my heart.
Show threadKerplunkSep 28, 2025

@gdinwiddie @pjf

Current kills yes, I was talking about ensuring large capacitors in a switching power supply are discharged, the voltage usually 400 is printed on them, easy to see. The capacity is not something many people understand.

The current capability is high and delivery with a pressure of 400 volts instant, even with very dry skin.

After opening the cover immediately discharge all larger capacitors using an insulated tool. Go round them again, check for voltage before working

Show threadGeorge DinwiddieSep 28, 2025

@Kerplunk
The voltage marked on a capacitor is what the dielectric can withstand, not the current charge of the capacitor. It could be charged to that voltage, but not likely as the circuit is usually designed with some room to provide reliability.

That said, a charged capacitor can really bite you, but it discharges quickly and unless it interferes with your heart rhythm is unlikely to do more than a skin burn, if that.

@pjf

Show threadGeorge DinwiddieSep 28, 2025

@Kerplunk @pjf

BTW, a cathode ray tube (TV CRT) makes a very high quality capacitor. The second anode is a coating on the inside of the glass. There's a similar conductive coating on the outside that is connected to ground for shielding.

I once picked up a picture tube that had been sitting on the bench for a week or more, and accidentally touched the second anode connection. That was from a black and white set, so was probably only charged to 12,000 volts or so, but it got my attention.