PSU from supermarket DVD?

[figge77]

Hi!

how would these powersupplys work in say a cd player to feed the dac with 5vdc and the op with +-12vdc? course i´ll recap it first since these units are of questionable quality.

reason i ask is that i do "get hold" of a lot of defective dvd players an this far i have just thrashed them for components such as 400v caps and some regulators and then throw the rest. often times its the laser or drive thats gone bad and ps is working.

another great source of stuff is all the damned tube vga monitors...

[Bakmeel]

Usually they are Flyback topology.

[figge77]

they are all switching mode supply´s,

and that means no good?

[wwenze]

Flyback is a type of SMPS topology.

And it reads cheap.

[figge77]

[i]And it reads cheap. [/B]

i see...well i am not chocked!

so how do i tell a "normal" switch-mode apart from this flyback?

are the chances higher to get a decent one in say a VCR?

[wwenze]

This is a philosophical question... if it is found in most low-power devices out there, is it normal?

[figge77]

good point!

[N-Channel]

FOlks,

I recently had a cheap (L.T. USD$30) DV player die on me. Turned out it was the cheap PSU- the player is fine. Verified this by plugging its main board right into the end of the ATX power connector for a 3 1/2" floppy. Fired right up!

Now, on the the "mod": The player's power requirements are +5V and +12V, both at 1 Amp (17W, total). Since I have no interest in re-doing the original AC-DC supply, I am doing a DC-DC converter so it can run off 12VDC. Should be straight-forward enough. Nat Semi has an App. Note on synch'ing two Simple Switchers together: a 100-200kHz LM2588 (100-200kHz, 5A Boost/Fly-back) to an LM2596 (150kHz, 3A buck), giving +5V & +12V out.

The only variation I plan on doing is to run the boost regulator as a SEPIC. Then I can run it off the car, or even a BIG battery in remote areas. (Don't ask why this scenario- looooong answer).

Yes, this is a switching solution, but I have worked with many SimpleSwitchers for audio applications in the past, getting excellent results, so this does not look like a problem. For the curious, the document is found here.

Just my $0.02 worth.

Steve

[Bakmeel]

Originally posted by N-Channel
(...)
The only variation I plan on doing is to run the boost regulator as a SEPIC. Then I can run it off the car, or even a BIG battery in remote areas. (Don't ask why this scenario- looooong answer).

(...)

Steve

Why?

(I have time for a long answer.... )

[N-Channel]

We show movies in a nearby park where AC power is not readily accessible. We run power from the AC/DC Genset I built (and posted on in the Power Supply Design Forum) a couple of years ago. DC for all the audio components (it's amazing what one can do with surplus car stereo equipment) and DVD player, and AC for the projo. We get excellent results both visually and auditorially.