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-   -   DV-PF4E(UK) Power suppy repair (https://www.badcaps.net/forum/showthread.php?t=99744)

pintglass 10-10-2021 05:17 AM

DV-PF4E(UK) Power suppy repair
 
3 Attachment(s)
Hi
I'm trying to repair an internal power supply in a Hitachi DV-PF4E video/dvd combi player.

I've narrowed the fault down to Q1001 a N channel mosfet (2SK3566) which seems to be shorted, when powering the power suppy this takes out resistor R1043.

I don't have any of these mosfets but do have some FDPF5N50UT's would this be a suitable replacement?

I've attached the schematic for the DV-PF4E the power supply section being on page 88, I've also attached the datasheets for the mosfets.

pintglass 10-15-2021 01:35 AM

Re: DV-PF4E(UK) Power suppy repair
 
I've replaced the mosfet Q1001 with the same part as was installed originally, but resistor R1043 keeps failing going open circuit.
Does anyone know what other component could be causing this?

lotas 10-15-2021 12:45 PM

Re: DV-PF4E(UK) Power suppy repair
 
1 Attachment(s)
Quote:

Originally Posted by pintglass (Post 1077586)
I've replaced the mosfet Q1001 with the same part as was installed originally, but resistor R1043 keeps failing going open circuit.
Does anyone know what other component could be causing this?

Rather, Q1001 struck again, since you did not check the entire strapping of it, if Q1001 pierces, then it carries off the strapping, check these components.

pintglass 10-16-2021 10:03 AM

Re: DV-PF4E(UK) Power suppy repair
 
I found that the transistor Q1003 was shorted between base and emitter so I replaced that and changed Q1001 again, but I'm getting a loud buzzing I think from T0011 the power transformer and still getting no output.

pintglass 10-17-2021 07:25 AM

Re: DV-PF4E(UK) Power suppy repair
 
I do now seem to have output, the only voltage that seems low is the AL-30 all the others seem fine.
The buzzing is worse when the power supply is connected to the main board.

This text is from the service manual

When buzz sound can be heard in the vicinity of power circuit.

Check if there is short circuit on the rectifying diode and the circuit in each rectifying circuit of secondary side
and service it if defective. (D013, D014, D016, D018, D019, D1008, D1016, D1030, IC1002, IC1003, Q051,
Q053, Q055, Q056, Q058, Q1052, Q1053, Q1055)

Check if there is short circuit on the rectifying diode

Does this mean the rectifying diode's on the primary side?


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