On Saturday, September 21, 2013 4:12:58 AM UTC-4, mike wrote:
I picked up a HYelec HY3005D power supply and need to modify it.

The current limit won't go lower than 150ma.

The current limit latches up on a short.

This appears to be a known issue...I just wanna fix it.



A schematic would be far less effort than reverse engineering it.



I've found almost zero info on this supply on the web.

Sending me links to supplies with the same number, but

different configuration won't help.



This is a single 30V 5Amp variable supply with digital readout

of volts/amps.

Everything I've found so far is a linear supply with a big

line transformer.



This one's a SWITCHER.

Looks like an offline switcher.

There's another switching transformer (preregulator???) in the middle.

And a single-transistor linear pass transistor with a tiny heat sink.

Input power is approximately 20W greater than output power for

any range of volts/current.



Of course, they filed the markings off the IC's and covered a lot

of stuff with the goop they use to keep caps from flopping around

in shake.



Anybody got a schematic for the switcher version of the HY3005D?



Thanks, mike

Hi Mike, Well I thought we had the same supply... but I've got a HY5003D. And it's a linear supply. (Hmm going to the Mastech website, http://www.mastechpowersupply.com/va...ply/cat_6.html
they list yours as a linear supply?)

Anyway you might contact mastech..they helped me. (Well we did buy a bunch of the supplies.) I've got several emails from Sean at Mastech it took us a while to get the correct power supply identified. If you drop me an email
) I can forward the pictures and stuff to you... maybe one of the 'wrong' pictures will be right for you.

George H.