context: the other day, Ms Al128 was watching TV. I was in the room next door, suddenly a very hard whippercrackerish “peng” was heard followed by some deep human emotions from my better half (ahhh … the TV exploded!!!).
I had a very early feeling of what was going on and unplugged it … there was a faint “magic-smoke” smell coming out of it.
Shirley, “a cap on the power-supply board must have crapped out on me” (read this with the voice of a seasoned TV-repairman in your head, which I am NOT!!!).
FWIW: a 15 yo 32” Samsung plain vanilla TV-set, FWIW2: I just know enough about electrics/electronics to be really dangerous (but normally quite cautious (hate to be zapped) and handy with the soldering iron).
So today I open’ed her up …(repairman voice again) … and low and behold, things got confirmed.
Here a pic of the power-board (note the red arrow pointing to the blue cap):
the offending cap and its eruptive:
The Perp in close-up:
I fed the info into ChatGPT, but it kinda-sorta misread the markings (as 104 instead of 101) … what kind of ceramica cap. do I need? … ChatGpt’s last answer (after challenging it a bit) was:
Look for “Ceramic capacitor 100pF 1kV (or higher, e.g. 2kV) ±10%”.
Using a higher voltage rating is fine (and safer).
So what value of cap do I purchase? … any other input? … pls don’t try to talk me off the ledge, I am not willing to let go of a perfectly bad 15 y.o. $129.00 TV set …
Yes, 100pf at 1kv, you could probably go 110pf or so but dont go lower on voltage, as chatgpt said (good for you, chatgpt). Id guess it’s part of an RF noise filter, to keep the power supply “RF quiet”.
If you’re lucky, you’ll be treated to a light show and a small explosion!
(Happened to me while I was testing out add-in boards on old computers. One of the boards had a tantalum capacitor near the card-edge connector which immediately failed when powered on. It glowed a brilliant orange (like a neon light) for about 2 seconds and than popped like a ladyfinger firecracker.)
yep, thats my gameplan …. everything beyond an empirc smoke-test is above my electronics pay-grade (and willingness to invest in this fine piece of equipment) …
But advice (also the ones below) are duly noted and I shall plug the card in with a mindset that it might pop again …
to protect myself, I might even put on extra protective eyewear, or better yet, ask my little daughter tu plug it in …
Yea, it’s rare for a ceramic capacitor to fail, as the breakdown voltage for a ceramic cap is typically at least 2X the max rated voltage.
A search on CM804 came up with this page. Not the same part - it’s a 220 pF instead of 100 pF - but perhaps the schematic is similar. If so, the capacitor functions as a damper/snubber for the PWM controller (C5). In other words, a switched-mode power supply. So I would also look at the other components around the controller, especially the diodes.
successfully replaced the blue cap by an even bluer one of the same specs. Watched out for my eyes and held Golden Retriever Puppies between me and a potentially exploding tv set … and turned it on …
nothing (not even the red status-led) … seems that “something” upstream also crapped out (my highly uneducated guess) that PWM-Controller that @Crafter_Man linked to (model Sanken STR-W6053S in mine) that sits under the silver heatsink next to the blown up part…
well so I am somewhat miffled, b/c it was obv. not the low hanging fruit that was being waved in front of me.
What are possible next steps … (one I am debating: taking the whole shebang out to the curb, but then the thought of “it might just be a 2 dollar part - and I hate to see all that going to waste” kicks in)
I know that intellactually … however, emotionally it irks me to no end throwing an (otherwise) perfectly functioning machine away and contaminating our planet, when 99.9% of it is working perfectly.
Did I mention that I have a very nice 2003 Honda Fit parked in my driveway for 2+ years, that doesnt pass emmisions, but is otherwise in great shape - hasn’t failed me once.
Are you a long lost relative of my father (on whom be peace)? When we cleaned out the basement after he passed we found bathroom fixtures that must have been in the house when he bought it in 1946. “We might need that someday!”
