Eric,
Thanks for your help. I found that C13 is shorted out. What value capacitor should I use and how do I remove and replace a surface-mounted cap?
Positive voltages at V- and AV-
Re: Positive voltages at V- and AV-
According to schematic C13 is 0.1uF. Also it is paralleled with C14 and C15. How did you find out that faulty one is C13?Bill wrote:What value capacitor should I use
Basically you heat it with hot air and pick up with tweezers but if you don't have hot air gun, you can just heat it with soldering iron. The cap will stick to it and come off the board. To replace the smd with just a soldering iron is a bit tricky but I managed to do it a couple times. You place a smd on its place, hold it with tweezers or wooden toothpick and then heat its sides with soldering iron.Bill wrote:and how do I remove and replace a surface-mounted cap?
Re: Positive voltages at V- and AV-
Bill wrote:Eric,
Thanks for your help. I found that C13 is shorted out. What value capacitor should I use and how do I remove and replace a surface-mounted cap?
please note Corrected version for my post on 23/08/2017
Hello
Ok your board is new one, so here C13 is SMD, as i could see on your (poor quality )
So C13 would be a 0.1µF, and 50v on the 0805 smd size
http://fr.farnell.com/walsin/0805b104k5 ... dp/2496944
To do a good work, you need something like that to see what you do
http://i.ebayimg.com/images/g/RXEAAOSwa ... -l1600.jpg
Flux also needed to do a good solder too like that before soldering the new capacitor
http://www.ebay.com/itm/5pcs-BGA-SMD-So ... SweW5VaRks
It is possible to do without sure but you'll have to do it with special care. To extract old capacitor , you have to heat the 2 sides alternatively (and quick) to lift one side and after the other wiyh tweezers (if you don't have air gun)
Heating the two side alternatively permit to lift one side a few without breaking the capacitor and you need to heat enought to make it easy to lift the two sides without damage the two solder points on the card
(pcb)
if you have two litle soldering guns it is possible to put one on each side to lift it directly (but gently too...)
Then you clean the two solder points on the pcb with desoldering braid (tresse in french) and the gun to retire the old solder
https://www.jlelectroniq2.com/PBSCProdu ... %5FD%5FBwE
Put juste a few new solder to do the points clear and bright with gun, then it is ok to receive the new one capacitor smd
regards Eric
Re: Positive voltages at V- and AV-
I'm sorry but I may have been mistaken when I said C13 was shorted out. Petroid's comment about how did I know C13 was shorted made me re-examine what I was doing. I was testing the capacitors for continuity using a multimeter while the capacitors were still in the circuit which, according to what I just read on testing capacitors, is a not a proper test. Is that correct?
I redid my improper tests under a magnifying glass so I was sure where I was touching the meter's probes and both C12 and C13 indicated 0.03 M ohms while they were attached to the circuit board so they are not different in behavior.
I'm afraid to try to remove C12 and C13 for fear of messing up the board and/or them so I'll try the test with the resistor that Eric suggested in the same post as he suggested testing C12 and C13. Everything else in Eric's post tested out OK.
Thanks for the reference to the schematic. I didn't know that was available online.
I redid my improper tests under a magnifying glass so I was sure where I was touching the meter's probes and both C12 and C13 indicated 0.03 M ohms while they were attached to the circuit board so they are not different in behavior.
I'm afraid to try to remove C12 and C13 for fear of messing up the board and/or them so I'll try the test with the resistor that Eric suggested in the same post as he suggested testing C12 and C13. Everything else in Eric's post tested out OK.
Thanks for the reference to the schematic. I didn't know that was available online.
Re: Positive voltages at V- and AV-
No matter ! that's the job !!!
Like Italians say...10 times you measure...1 time you cut ! lol
Like Italians say...10 times you measure...1 time you cut ! lol
Re: Positive voltages at V- and AV-
No problem. They're right there on jye-tech website: http://www.jyetech.com/Products/LcdScope/e150.phpBill wrote:Thanks for the reference to the schematic. I didn't know that was available online.