Thanks to all the helpful posts about blank monitor problems. I have dual 1955 monitors, one died & was replaced in warranty. The 2nd (original) just died (a bit over 3 yrs old). Fuse PF801 blew (BEL MS 5). Q805 (8-pin MOSFET on bottom side) Si4431 CDY was toasted, burns under it and 2 traces burnt & lifted off of PCB. I cleaned the carbon burned spot under Q805, added some tiny Kapton tape pieces (for insurance) and replaced the 4431. ( the "lifted" traces were still useable). Found one shorted C5707 (Q809) and replaced it (and the good one near it) with 2SC5707 transistors. Re-soldered LOTs of bad joints around the transformers & caps. Put it together. It blinked on momentarily, but still had a problem (blank screen). Searching some more I found a bad transistor Q803 (near the bad Q805) was burned and tested bad. The SOT-23 transistors marked "WO4" are NPN 3904 transistors (MMBT3904 or equivalent)). The ones marked "to6" are PNP 3906 transistors (MMBT3906 or equivalent). I didn't find any other bad ones. Problem solved! Monitor works great! I plan to open up the newer monitor and check the solder joints in it, too.
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Re: HP 1955 / BENQ 48.L1A02.A00 repair
1.- CongratulationsOriginally posted by bobbyth
2.- Welcome
3.- If possible, post pics as reference for future issues with the units.There are 10 kind of people in this world: those that understand binary, and those who don't.- ASUS ROG Maximus IX Code
- Intel Core i5-7600K 3.8GHz
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2 x Acer KA240H + 1 Vewsonic VP2130 21 (a cap replacement job
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Re: HP 1955 / BENQ 48.L1A02.A00 repair
My name is Ron, is it possible to purchase a new new Benq 48.L1A02.A00 invertert or power board for a HP 1955 monitor, and if its possible where can I purchase some?
Thanks. Ron.Comment
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Re: HP 1955 / BENQ 48.L1A02.A00 repair
Manufacturers of computer components usually don't offer parts just complete replacement when under warranty.
These monitors are going on 6 years old now even if parts were available they aren't anymore.
Besides the new board would be made with the same crappy solder joints and caps as the old one it would just fail again.Elements of the past and the future combining to make something not quite as good as either.Comment
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Hi:
I am trying to repair this amplifier that I've bought as faulty. I've found some transistors damaged, the ones where I am drawing a red circle.
With the final transistors not yet installed (the expensive ones), I've started to measure some voltages:
Where I am supposed to have 1.12V (base Q524/Q523) I am reading -42V..................both channels don't seem ok.
Where I am supposed to have -1.12V (base Q526/Q525) I am reading -44V..................both channels don't seem ok.
I removed and tested Q514,Q516 & Q513,Q515 but the analyzer... -
I had a Sundown SFB-8000D amp come into the shop yesterday that wasn't giving any output. The guy who brought it in said he bought it off some crack head on Facebook marketplace for a good price, but bought it knowing it was broken. Apparently the original owner was cutting out the transistors to the right of the ones pictured whenever one would blow and take the output out. Best I can figure he also cut the legs on the S5 and S6 ic's as well and soldered them back together.
My problem is Sundown decided in the factory to remove the original markings on the IC's and now I can't figure... -
Welcome badcaps, repairing a Crosshair 15, in need of transistor specifics. Received a broken laptop that's was perfect for repair, threw away the looser transistors in a haste... Should and could have salvaged them.
In any case, I will be posting all my discoveries to this forum as a thanks in advance. Thanks in advance lol.
P.S. If anyone is familiar with such things, as in, If anyone knows that MSI uses one or one of a few types of transistors when marked with a number please let me know how I can find more specifics before I start throwing hail marys. -
Hello,
While ago I replaced those big filter caps to that amplifier. After that started to happen. I connected the amplifier normally to the mains and almost immediately several transistors burned out. I really didn't do anything else (at least on purpose) than replaced those big caps C801 and C802.
After that I replaced those burned transistors (I can't remember exactly what they were) and measured all the others, and now everything should be ok. But, when I power up that amplifier part with two bench power supplies connected in series there is obviously still something... -
Hello everyone,
I've got a Benq power board of a XL2540K monitor which suffered from a power cut and is since defective / won't turn on. It's got obvious defects, some blown resistors, some burning around the drain pin of a MOSFET...
... and some 6-pin IC I struggle identifying, that is driving said MOSFET.
The IC is labeled as IC601, so someone with a circuit schematic could probably identify it really quick, unfortunately I can't find the schematics.
In other power boards of Benq for which I did find the schematics, IC601 is an 8-pin NCP1200 PWM controller - I suppose...
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