TV Repair Questions? Ask a TV Technician
Yes, I just posted the issue yesterday, and would still like assistance. I did some additional troubleshooting that I can add as well.
I tried disconnecting the YSUS board, and then turning on power. The power stayed on (still no picture). However, when checking the 5V, V-A and V-S levels on the PS board with a VOM, the results were all off. When I reconnect the YSUS and try power again, the unit shuts itself off again.
In addition, I looked closely based on some recommendations, and found that 4 or 5 of the capacitors on the PS board may have some domeing.
V-A and V-S were very low, like a few volts. I don't have my data with me right now, but I thought one of them was supposed to be ~190 V. On the 250V VOM meter range, the needle barely moved on both. I was not sure if this was because of a load difference with the YSUS board disconnected however.
Also, the 5V reading was very high, like 10 volts or higher (needle past 10 V on the 10V range).
I can try readings using the back of the panel tonight, or all the way back to the ac input ground.
Yes, when YSUS was connected, the voltages would come up a few volts only before the power supply kicked off, and voltage dropped back to 0.
How likely is a new Ysus going to fix the issue (90%, 50%) and restore full functionality? Just looking for your best guess, not a guarantee. This is a ~$75 replacement for parts only (used/ refurbished!), not counting tax, shipping, and labor, and it's still basically a 4 year old TV (not even a new Ysus) when a new unit in this size is down to ~$400.
I also never heard if the slight "doming" of electrolytic capacitors on the power supply board is normal (especially based on output voltages) or if it's a possible concern.
Attached are some pictures of the caps on the ps board. Only 4 have indications of doming.
Attachments are only available to registered users.
Is there any benefit to installing a de-rated cap (rated for a higher working voltage from what I understand). The 5 bad ones are rated at 10V. So, in other words, would it be the wise thing to do to replace them with the next higher voltage, but all other specs the same (3300 uF, 105 degC rating, very low impedance, high ripple current)?
Separately, various forums have indicated there are known issues with bad caps from Samha in the early-mid 2000's timeframe, which is the heritage of these (WB series). I will be replacing them with valid substitutes from another mfg, such as Nichicon (closest spec match I found so far). It might be enough to just replace the bad ones, with new ones from a better source/mfgr, but at the same specifications.