GW GPC-3030 power supply - Page 1
Forum section: electronics / repair

author: LA2BPA
author_rank: Newbie
timestamp: November 02, 2024, 10:17:45 pm
content: Hi,I have a GW GPC-3030 power supply. It has three channels, two of them is adjustable (master/slave).The master channel seems to be working as it should, however the slave channel is not.The output voltage can't be adjusted, it just stays at 32V whatever i do.I have checked op-amps, transistors, diodes and potmeters in the regulator circuits.Any ideas?

author: Harry_22
author_rank: Frequent Contributor
timestamp: November 03, 2024, 10:33:56 pm
content: Hi!Could you attach a photo of PCB. I think I have a similar device.

author: LA2BPA
author_rank: Newbie
timestamp: November 10, 2024, 10:08:30 pm
content: Here is a couple of images of the unit. Frontpanel, main pcb and a bird view.

author: wraper
author_rank: Unknown
timestamp: November 10, 2024, 10:12:31 pm
content: Measure voltages in operation. Start from measuring if potentiometer actually adjusts the voltage on its wiper terminal.

author: Poroit
author_rank: Frequent Contributor
timestamp: November 11, 2024, 06:16:20 am
content: This may help if you don't already have a copy.Page 5 gives you a Circuit Arrangement.

author: Smokey
author_rank: Super Contributor
timestamp: November 11, 2024, 06:39:54 am
content: I have two of these. One had a problem on the slave channel that I quickly tracked down to a failed power diode across the output. Grabbed something from the junk bin and was back in action. Had to erase the "NFG" from the front panel once I got it working again.

author: wraper
author_rank: Unknown
timestamp: November 11, 2024, 12:19:26 pm
content: BTW, as it has single layer boards, it's not necessarily a bad component. As these boards have on hole metallization, solder joints are prone to cracking.

author: Harry_22
author_rank: Frequent Contributor
timestamp: November 11, 2024, 01:44:33 pm
content: Quote from: Smokey on November 11, 2024, 06:39:54 amPlease enlighten me, is it a common tradition to write like "No Freaking Good" on faulty devices?Quote from: LA2BPA on November 02, 2024, 10:17:45 pmI have mostly the same PS.If we can't find a schematic diagram for it, this will help.

author: Grandchuck
author_rank: Super Contributor
timestamp: November 11, 2024, 03:44:01 pm
content: I have a HY3005F-3 which might be similar. I have attached a schematic.

author: Harry_22
author_rank: Frequent Contributor
timestamp: November 11, 2024, 04:04:33 pm
content: Quote from: Grandchuck on November 11, 2024, 03:44:01 pmYes, many thanks! Seems mostly the same.

author: Smokey
author_rank: Super Contributor
timestamp: November 12, 2024, 07:59:38 pm
content: Quote from: Harry_22 on November 11, 2024, 01:44:33 pm...close enoughThat was pretty much the universal warning markings that something was broken by the grey beards I learned from. I still have a few partially working pieces of equipment in line for repair with "NFG" above some function or another. (That's right! I'm talking to you Keithley 196 resistance mode!)

author: LA2BPA
author_rank: Newbie
timestamp: November 12, 2024, 09:19:54 pm
content: I've found the problem. A cracked pcb track on the front panel board.

author: Harry_22
author_rank: Frequent Contributor
timestamp: November 13, 2024, 07:56:45 am
content: Quote from: Smokey on November 12, 2024, 07:59:38 pmYes, grey beards will not give bad advice.PSNow in every service