Hi guys, i have a power supply with a shorted SR320 schottky diodes which is in parallel. Only 1 shorted while another is ok. So i removed the faulty one, the power supply is working fine now. SR320 is 3A 20V. I was thinking can i remove both diodes and replace SR340 as 1 diode as it is 3A 40V? Because i dont have SR320. Or can i replace both with SR340?
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replacing schottky diodes on a AV power supply
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Re: replacing schottky diodes on a AV power supply
Originally posted by stj View Postneither, your going to need 6A at 20v, not 3A at 40v
parallel diodes double the current, not the voltage
if you check my Ryobi charger thread, i replace a couple of diodes with a 25A to220 package part
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Re: replacing schottky diodes on a AV power supply
higher voltage is fine - infact with schottky's you really want 10x the running voltage.
https://www.badcaps.net/forum/showthread.php?t=54038
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Re: replacing schottky diodes on a AV power supply
Originally posted by DjKrish View Post6A 20V, noted, will try that. Cause i fitted the 3A 40V diodes, no power at all. When i fit back the single 3A 20V, its working again.
What exactly did you put in?Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
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Re: replacing schottky diodes on a AV power supply
Originally posted by budm View PostThat does not make any sense.
What exactly did you put in?Last edited by DjKrish; 08-28-2020, 07:55 PM.
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Re: replacing schottky diodes on a AV power supply
What happen if you test the SR340 and compared to the SR320 with you meter?Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
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Re: replacing schottky diodes on a AV power supply
Originally posted by stj View Posti dont understand where you got the numbers,
test the diodes with your diode-test on the meter - both directions.
while take off from board, these are the reading on diode mode
sr320 - 0.343v
sr340 - 0.164v
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Re: replacing schottky diodes on a AV power supply
both should be vf 0.55
https://cdn.badcaps-static.com/pdfs/...5f72338fd7.pdfLast edited by petehall347; 08-29-2020, 10:34 AM.
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Re: replacing schottky diodes on a AV power supply
Originally posted by stj View Postparallel diodes double the current, not the voltage
However, if the diodes are not built on the same physical die (as is the case here, where O/P has two separate diodes wired in parallel on the PCB), then one diode will run hotter than the other. When that happens, the forward voltage of the hotter diode will drop further, making the the circuit "prefer" to push more current through that diode, which will in turn heat up the diode even more. If this continues, thermal runaway may eventually kill the diode if the circuit has the capacity to push a sufficiently large current through it.
Because of that, I agree with what STJ suggested: use a single 6 Amp (or higher) diode/rectifier (and preferably Schottky type for lower losses.)
Originally posted by petehall347 View Postboth should be vf 0.55
https://cdn.badcaps-static.com/pdfs/...5f72338fd7.pdfLast edited by momaka; 08-29-2020, 12:50 PM.
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Re: replacing schottky diodes on a AV power supply
So when you install SR340 you say you no longer get the switched B12V?
When that happens, what Voltage do you get at the Cathode of SR340 with ref to circuit ground?
Is switched B31V present when that happen?
Can you also provide the full PDF of the service manual?Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
Comment
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Re: replacing schottky diodes on a AV power supply
Originally posted by budm View PostSo when you install SR340 you say you no longer get the switched B12V?
When that happens, what Voltage do you get at the Cathode of SR340 with ref to circuit ground?
Is switched B31V present when that happen?
Can you also provide the full PDF of the service manual?
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Re: replacing schottky diodes on a AV power supply
Originally posted by budm View PostSo when you install SR340 you say you no longer get the switched B12V?
When that happens, what Voltage do you get at the Cathode of SR340 with ref to circuit ground?
Is switched B31V present when that happen?
Can you also provide the full PDF of the service manual?
SR320 - 12v plus
B31V present
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