cheap 5v and 12v source

[wilykat]

I have an LCD monitor, I really liked it but the power supply has gone out. It is a known issue with SOYO DYLM24D6 and SOYO had gone out of business long ago so asking them for replacement part is not possible. I have seen aftermarket replacement power supply but they are from Chinese site Taobao and I really don't want to try and go through them or depend on a 3rd party service to handle communication and payment.

I have already checked, the problem is not the capacitors but on the primary side, something is shorting out, blowing fuses instantly. Since the 2 large IC on primary side are not easily replaced, I thought I'd try to build a replacement power from scratch. I also thought of building it in a way that the bulk of it is outside rather than inside the monitor, basically making it easier for power supply to stay cooler, and easier to replace in the future.

The pinout is documented and it required 24v, 12v, and 5v. 24v (min 2.5A) is just for the backlight inverter, 12v (a few milli amps) and 5v (about 1 amp) is used for the video board that is separate from the power board.

I happened to have a 24v 4A power supply brick which suited me fine since it'd be the outside power source. I'd like to figure a way to get 12v and 5v on the cheap side. 12v to 5v is easy to get, those are common for use in cars such as USB adapters/chargers (many don't comply with USB spec max of 500mA anyway). That leaves 24v to 12v converter. I tried to get DC-DC converters from Amazon 3rd party sellers over a month ago but I never got them. Since I only need a few mA for 12v circuit plus about 1/2A more to power 12v-5v converter, any idea what can I build or a source in USA that is more reliable than 3rd party sellers on Amazon? I'd prefer not from eBay, too many low priced converters are very cheaply made and some of them are so cheaply made they may not be to spec or even safe to use.

 

[alec_t]

Any old PC power supply will give you 12V and 5V.

 

[wilykat]

Any old PC power supply will give you 12V and 5V.

Even when stripped down, any old PC power supply won't fit nicely inside the small space in the monitor and I'd rather not have a bunch of wires hanging from the back. Thanks for the idea though.

 

[skimask87]

https://www.ebay.com/itm/Repair-Kit-Soyo-Topaz-DYLM24D6-LCD-Monitor-/330499791194

 

[wilykat]

Capacitors Only, Not the Entire Board.

Wouldn't help me

 

[ronv]

If your handy you could build one like this:
Or you could buy a couple of wall worts for the 5 & 12.
Or give in to Ebay.
Or use a couple of linear regulators with heat sinks, but they might get a little big. (but easy)

 

[The_Penguin]

Why not try to repair the supply? If it's blowing fuses instantly it should be fairly easy to find a shorted component.
Probably a shorted rectifier or FET.

 

[skimask87]

It is a known issue with SOYO DYLM24D6

Right, it's a known issue with a known cure for that issue. Swap out the rotten caps...which are provided in that re-cap kit linked above.

I have already checked, the problem is not the capacitors but on the primary side

How do you know this? What kind of tests did you do? A plain multimeter doesn't do the job in these cases.

, something is shorting out, blowing fuses instantly.

Which is one of the symptoms of bad caps.

I thought I'd try to build a replacement power from scratch.

$14 for the re-cap kit. Can't build a power supply for that.

The pinout is documented and it required 24v, 12v, and 5v. 24v (min 2.5A) is just for the backlight inverter, 12v (a few milli amps) and 5v (about 1 amp) is used for the video board that is separate from the power board.

You're missing the part about the 600v required for the backlight.

 

[tcmtech]

A lot of the USB adapters are rated for 24 volts input so that they can be used in commercial trucks that have 24 systems.

As far as 12 volts at a few ma is concerned a simple resistor and properly sized zener diode to shunt excess voltage would work just fine. That or a common 3 terminal regulator IC.