LG Flatron L194WT-SFQ:AUSRQF
Okay, sports fans!
Our patient this time is an LG L194WT-SFQ:AUSRQF. The Pt presented - wait - this isn't student med...
This monitor was DoA, and plugging it in showed no soft-start or power. Dead as a doornail. After prying the front bezel off (and breaking three of the top tabs), removing the four screws on the back, and disconnecting the switchboard cable, panel header, and the CCFL plugs, the power PCB was removed.
See shots 01, 02, and 03. Shots 04/05 are close-ups of the Samxons by the HS. Shots 06/07 are of the bottom, and shot 08 is a side view of C206 (all the 25V caps looked okay, but better safe than sorry, right?). Shots 09/10 are of the AC input, and shots 11-13 show the HV/CCFL drivers and SOIC MOSFETs (which shows some discoloring on the PCB, but nothing unexpected. In fact, everything but those two Samxon 16V caps looked remarkably good. A quick in-circuit check of the MOSFETs and diodes read nominal, so none of those had to be ordered. Still, for reference, I shot photos of the ICs with my "tags" on them, as "lbl1-4".
As you can see, it's an AIP-0122 rev. D, made by Lien Chang. If you follow the plastic pointer up the board, you'll see the problem(s) in picture 3. Those are Samxon GF(M) series, known to be a bad batch. In PCB order, they are:
C203 - 680uF, 25V, 10mm dia., 21mm len. (use Digikey # P12390)
C202/6 - 1000uF, 25V, 10mm dia., 21mm len. (use Digikey # P12379)
C204/5 - 1000uF, 16V, 10mm dia., 21mm len. (use Digikey # P12366)
C207 - 470uF, 25V, 10mm dia., 16mm len. (use Digikey # P12388)
The Samxon caps at C101 (100uF, 450V) and C105 (0.47uF, 50V) are KM series, and looked good. The remaining Samxon GF(M) was at C103 (33uF, 50V), and feeds the FAN7601, so I'm guessing it doesn't see anything higher than 2X mains frequency (120Hz in my case), so I didn't replace it. I did, however, order the closest PanaFM to it, either Digikey # P12925 (33uF @ 35V) or #P12928 (56uF@50V). One is higher capacitance, but lower voltage (the FAN7601 shouldn't be seeing more than about 20V here, but you're still taking chances) - the other has the same voltage, but slightly higher capacitance. My gut instinct tells me they just used the GF(M) here because they had a bunch lying around. Since this is tied to the "soft start" feature, it merely acts a timing mechanism for the inrush current limiting for charging up those other GF(M)s.
So, about $4.50 of Panasonic (Matsushita) FM goodness later...
As you can see in shots "panfm1/2", the black-and-gold Panasonic FM goodness is all up in that. The "lone" cap at C206, by the SOIC MOSFETs, was the hardest to unsolder, only because they bent the leads of the cap before soldering it. The others just dropped (literally!) out once the second lead was hit with Solder-Wick (R). This is a single-sided board, and my trusty Radio Shack 30W iron had NO problem dealing with it. In fact, I was surprised by how well both the iron and wick handled the lead-free solder. I did mask out the "Pb Free" note on the PCB, as I used "LotsaLead" solder. Sue me, I'm NOT a "lead-is-dead-head".
After quadruple-checking my work, I re-installed the PCB, hooked everything back up (except the front bezel, as that thing really, really sucks to take back off), and... SUCCESS!
I didn't take yet-another-monitor-picture (yamp), but trust me. I ran it for about 90 minutes before calling it fixed. I'd estimate the temp wafting up the back at about 80F (~27C). No pops, crackles, or bad smells, either.
Hopefully, this helps anyone else with the same situation, or has really botched up their repair and needs a reference to get back on track. Thank you for playing along...
bipolar
Our patient this time is an LG L194WT-SFQ:AUSRQF. The Pt presented - wait - this isn't student med...
This monitor was DoA, and plugging it in showed no soft-start or power. Dead as a doornail. After prying the front bezel off (and breaking three of the top tabs), removing the four screws on the back, and disconnecting the switchboard cable, panel header, and the CCFL plugs, the power PCB was removed.
See shots 01, 02, and 03. Shots 04/05 are close-ups of the Samxons by the HS. Shots 06/07 are of the bottom, and shot 08 is a side view of C206 (all the 25V caps looked okay, but better safe than sorry, right?). Shots 09/10 are of the AC input, and shots 11-13 show the HV/CCFL drivers and SOIC MOSFETs (which shows some discoloring on the PCB, but nothing unexpected. In fact, everything but those two Samxon 16V caps looked remarkably good. A quick in-circuit check of the MOSFETs and diodes read nominal, so none of those had to be ordered. Still, for reference, I shot photos of the ICs with my "tags" on them, as "lbl1-4".
As you can see, it's an AIP-0122 rev. D, made by Lien Chang. If you follow the plastic pointer up the board, you'll see the problem(s) in picture 3. Those are Samxon GF(M) series, known to be a bad batch. In PCB order, they are:
C203 - 680uF, 25V, 10mm dia., 21mm len. (use Digikey # P12390)
C202/6 - 1000uF, 25V, 10mm dia., 21mm len. (use Digikey # P12379)
C204/5 - 1000uF, 16V, 10mm dia., 21mm len. (use Digikey # P12366)
C207 - 470uF, 25V, 10mm dia., 16mm len. (use Digikey # P12388)
The Samxon caps at C101 (100uF, 450V) and C105 (0.47uF, 50V) are KM series, and looked good. The remaining Samxon GF(M) was at C103 (33uF, 50V), and feeds the FAN7601, so I'm guessing it doesn't see anything higher than 2X mains frequency (120Hz in my case), so I didn't replace it. I did, however, order the closest PanaFM to it, either Digikey # P12925 (33uF @ 35V) or #P12928 (56uF@50V). One is higher capacitance, but lower voltage (the FAN7601 shouldn't be seeing more than about 20V here, but you're still taking chances) - the other has the same voltage, but slightly higher capacitance. My gut instinct tells me they just used the GF(M) here because they had a bunch lying around. Since this is tied to the "soft start" feature, it merely acts a timing mechanism for the inrush current limiting for charging up those other GF(M)s.
So, about $4.50 of Panasonic (Matsushita) FM goodness later...
As you can see in shots "panfm1/2", the black-and-gold Panasonic FM goodness is all up in that. The "lone" cap at C206, by the SOIC MOSFETs, was the hardest to unsolder, only because they bent the leads of the cap before soldering it. The others just dropped (literally!) out once the second lead was hit with Solder-Wick (R). This is a single-sided board, and my trusty Radio Shack 30W iron had NO problem dealing with it. In fact, I was surprised by how well both the iron and wick handled the lead-free solder. I did mask out the "Pb Free" note on the PCB, as I used "LotsaLead" solder. Sue me, I'm NOT a "lead-is-dead-head".
After quadruple-checking my work, I re-installed the PCB, hooked everything back up (except the front bezel, as that thing really, really sucks to take back off), and... SUCCESS!
I didn't take yet-another-monitor-picture (yamp), but trust me. I ran it for about 90 minutes before calling it fixed. I'd estimate the temp wafting up the back at about 80F (~27C). No pops, crackles, or bad smells, either.
Hopefully, this helps anyone else with the same situation, or has really botched up their repair and needs a reference to get back on track. Thank you for playing along...
bipolar
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