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Need Schematic HY3005D SWITCHING power supply.

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

Reply to
mike
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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,

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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 ( snipped-for-privacy@teachspin.com) I can forward the pictures and stuff to you... maybe one of the 'wrong' pictures will be right for you.

George H.

Reply to
ggherold

Thanks for the offer. Not clear what you mean by forwarding pictures. The pix on the website look exactly like mine, on the outside. If you'd said switcher schematics...I'm in.

I did some investigation. It has two switchers running off the same filtered line input. One appears to run the digital readouts and power the op-amps. The other is the variable output supply. There's an 80-amp FET in series with the output that is always on. Not clear what it does. Maybe some kind of disconnect. They didn't do a very good job sanding the numbers off one of the ic's Standard quad op-amps. I was hoping they were duals with possibility of adjusting offset like they do in their linear supplies to get the current limit to go lower....no such luck. Never found the sense resistor. Probably buried on the output connector board.

The thing is on six boards all stuck in at right angles and gooped together with goop.

Works fine if I don't need the current limit to go below 130ma. Think I'll just leave it be until I trip over some schematics.

Thanks, mike

Reply to
mike

Well I don't have any schematics, but I did get some pictures and instructi ons for clipping 'this' diode to disable the short circuit protection 'feat ure'. I got a few wrong pictures/part numbers till we struck on the right one... So maybe one works for you. Or you could contact Sean at Mastech, p erhaps he will tell you what piece of the circuit to disable.

George H.

Reply to
ggherold

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