Sharp DVD player DV-740 gone bad

Assyst1606 · 26th October 2006, 12:51 AM

Got a Sharp DVD player model DV-740 that had gone bad. Switched on the wall plug, no standby light, unable to power up the unit. Suspect some components on the power supply board are dead. Any service manual, schematics & advice?
Thanks!

v-bro · 26th October 2006, 01:13 AM

My guess it's a smps, they tend to be quite complicated devices.

Repairing it might only be possible using a scope...

Leolabs · 26th October 2006, 02:47 AM

Quote:

Originally posted by v-bro
My guess it's a smps, they tend to be quite complicated devices.

Repairing it might only be possible using a scope...

Not really.DVD players' SMPSs are simple stuff.Bad symptoms are blown fuse,shorted semiconductors,opened circuit resistors,caps problems................

But Assyst,you need to open up the casing to check it.

Assyst1606 · 26th October 2006, 07:54 AM

I have checked & replaced some of the components but still it doesn't power up (no standby light on). I went to some of the local electronics shops but they can't identify some of the components rating. Perhaps a service manual & schematics might help.

clem_o · 26th October 2006, 08:21 AM

Don't have the schematic nor service manual, but from the picture it appears that there isn't any switcher IC?? Either that or it's under the board... you'll be very lucky if it's a 'discrete' switcher - good probability of getting it fixed.

Cheers

Assyst1606 · 26th October 2006, 09:10 AM

Hi, Thanks for the reply. The switcher IC should be the one near the big capacitor. I have changed that. I think the big capacitor maybe the problem. Now i recalled seeing some electrolyte coming out of the base.

clem_o · 26th October 2006, 10:02 AM

The big capacitor would be your mains filter. Mains power comes in, goes through some line chokes (Toko) and line capacitors (the blue ones), then into a rectifier (the four diodes near the two Toko). That should be a 350 or 400V electrolytic, maybe 220uF... Is there rectified DC on it? It should be about equal to (your line voltage * 1.414).

Cheers

Leolabs · 26th October 2006, 03:00 PM

You are lucky,dude

.It a Fairchild Power Switch(FPS) based SMPS that's definitely a stable stuff and easy to repair incase of failure.I suspect that the start-up resistor might be open circuit.But if so,PLEASE BE CAREFUL as the the electrolytic caps might store a few hundred volts of DC and make you jump around

.

Your part number should be the popular KA5x380R.I attached the link for your reference.

www.fairchildsemi.com/an/AN/AN-4141.pdf

BTW,is your DVD player based on a DVDROM and an ESS chipset???

DoomPixie · 26th October 2006, 03:11 PM

i have one of these dvd players also faulty.. but its different, mine the standby light comes on and all the voltages from power supply look ok.. i just cant get the thing to come out of standby :S
Owen

Leolabs · 26th October 2006, 03:13 PM

Maybe you got problem with the decoder board or the DVDROM.

26th October 2006, 12:51 AM	#1
Assyst1606 diyAudio Member Join Date: Sep 2006	Sharp DVD player DV-740 gone bad Got a Sharp DVD player model DV-740 that had gone bad. Switched on the wall plug, no standby light, unable to power up the unit. Suspect some components on the power supply board are dead. Any service manual, schematics & advice? Thanks!

26th October 2006, 01:13 AM	#2
v-bro diyAudio Member Join Date: May 2006	My guess it's a smps, they tend to be quite complicated devices. Repairing it might only be possible using a scope... __________________ Max. cone displacement can be several foot on any speaker!Too bad it can be done only once......

26th October 2006, 03:00 PM	#8
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	You are lucky,dude .It a Fairchild Power Switch(FPS) based SMPS that's definitely a stable stuff and easy to repair incase of failure.I suspect that the start-up resistor might be open circuit.But if so,PLEASE BE CAREFUL as the the electrolytic caps might store a few hundred volts of DC and make you jump around. Your part number should be the popular KA5x380R.I attached the link for your reference. www.fairchildsemi.com/an/AN/AN-4141.pdf BTW,is your DVD player based on a DVDROM and an ESS chipset???

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26th October 2006, 08:21 AM	#5
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Don't have the schematic nor service manual, but from the picture it appears that there isn't any switcher IC?? Either that or it's under the board... you'll be very lucky if it's a 'discrete' switcher - good probability of getting it fixed. Cheers

26th October 2006, 09:10 AM	#6
Assyst1606 diyAudio Member Join Date: Sep 2006	Hi, Thanks for the reply. The switcher IC should be the one near the big capacitor. I have changed that. I think the big capacitor maybe the problem. Now i recalled seeing some electrolyte coming out of the base.

26th October 2006, 10:02 AM	#7
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	The big capacitor would be your mains filter. Mains power comes in, goes through some line chokes (Toko) and line capacitors (the blue ones), then into a rectifier (the four diodes near the two Toko). That should be a 350 or 400V electrolytic, maybe 220uF... Is there rectified DC on it? It should be about equal to (your line voltage * 1.414). Cheers

26th October 2006, 03:11 PM	#9
DoomPixie diyAudio Member Join Date: Jun 2005 Location: Aberystwyth / Llanelli (wales)	i have one of these dvd players also faulty.. but its different, mine the standby light comes on and all the voltages from power supply look ok.. i just cant get the thing to come out of standby :S Owen

26th October 2006, 03:13 PM	#10
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	Maybe you got problem with the decoder board or the DVDROM.

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