Sony DVP-NS705V PSU repair (was SMPS diode replacement) - Page 1
Forum section: electronics / repair

author: aheid
author_rank: Regular Contributor
timestamp: December 26, 2020, 01:17:32 pm
content: The power supply on my old trusty DVD player died. It's a Sony DVP-NS705V, and with some very nice service manuals available I figured I'd give it a shot, even though I'm new to repairing.While plugged in, I measured an asymmetric voltage over the input rectification diodes of ~0.6V and ~110V, and being a flyback design my guess is that it doesn't start switching.After a bit of measuring I desoldered the diode D103, highlighted in yellow in the attached schematic (C111 is not populated on the board). Using the diode test up to 4V it measured open in both directions, and just to be sure I checked with my power supply up to 12V, so that one is burnt out.However that's a freewheeling diode AFAIK, so I guess with that gone it would have most likely broken the switching IC as well?What kind of replacement can I use for a D103? I have some standard diodes available, a standard fast rectifier?Any way I could test the switching IC on it's own? Haven't looked into flyback SMPS design, so not sure what kind of input it expects exactly.:https://www.manualslib.com/manual/790578/Sony-Dvp-Ns705v.html:https://industrial.panasonic.com/ww/products/semiconductors/powerics/ipd/models/MIP2E3DMY

author: fzabkar
author_rank: Super Contributor
timestamp: December 26, 2020, 06:51:35 pm
content: Datasheet for MIP2E3DMY:https://www.anion.ru/assets/files/pdf/MIP2E3DMY.pdfThe diode you need would be a 1000V fast recovery rectifier.This diode is used in a similar circuit (LC-65D90U):http://www.eicsemi.com/datasheet/ERA22_02_10.PDFhttps://diagramas.diagramasde.com/otros2/Sharp%20LC%20-%2065D90U.pdf

author: aheid
author_rank: Regular Contributor
timestamp: December 26, 2020, 09:45:00 pm
content: Thanks!So if I understand the controller correctly, if I hook up 6.2V to the control pin, and a (current limited) voltage across the drain-source pins, I should see a PWM waveform on the drain? Simple as that?I assume the 36V V_D(min) is for the controller to start operating?

author: fzabkar
author_rank: Super Contributor
timestamp: December 26, 2020, 10:45:58 pm
content: I think you might be right on all counts, but the datasheet really isn't helpful, at least not to me.

author: aheid
author_rank: Regular Contributor
timestamp: December 27, 2020, 01:32:48 pm
content: I desoldered the controller chip and wired it up for a test.The switching transistor seems ok-ish (zero leakage at 40V, body diode measured 0.6Vf) but the control pin sank the full limit of 50mA at 6V. As far as I can see the datasheet says it should max be on the order of a few mA. The chip didn't start either.According to the equivalent circuit (see attachment) there's primarily a couple of resistors between C and S pin, so I measured the resistance and it was 20 Ohm, explaining the current draw.So yeah I guess that means the controller chip is dead as well.I found some at AliExpress, looks totally non-original in the pictures but on the other hand not sure I want to replace this multiple-output board either...

author: aheid
author_rank: Regular Contributor
timestamp: March 09, 2021, 10:31:03 pm
content: The new switch mode controller came along, but all is not well yet.It outputs just a few volts between the "always on" rails.Since I don't have any isolated probes I don't feel comfortable hooking up my oscilloscope to the primary side to see if the switch mode controller is doing the right thing.But I figured I should be able to just take my bench supply and inject some DC current on the secondary side coils, no? Just to check if the secondary side is broken as well? Like between S2 and S3, S4 and S5?

author: ambrosia heart
author_rank: Regular Contributor
timestamp: March 10, 2021, 01:02:50 am
content: How to troubleshoot,see pm.I am now playing a game. No time to read a long composition.Tell me your result if you want.