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

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.

On 9/23/2013 1:37 PM, wrote:
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.

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

On Monday, September 23, 2013 5:17:37 PM UTC-4, mike wrote:
On 9/23/2013 1:37 PM, wrote:

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.
snip

Well I don't have any schematics, but I did get some pictures and instructions for clipping 'this' diode to disable the short circuit protection 'feature'. 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, perhaps he will tell you what piece of the circuit to disable.

George H.