Ali express power supply. 10a. 30v. - Page 1
Forum section: electronics / repair

author: Australia-learn
author_rank: Contributor
timestamp: April 20, 2025, 11:16:15 pm
content: Hey guys. Got a wamptek or however u spell it 10a power supply here with a dead MCU. And display chip.I can't for the life of me figure out how to add photos here😅. They just wont upload!.Anyway the PS is running a TL494. Question is. Is there any way I can bypass the MCU, and just use a universal type display to run the 494? I understand ill loose all the OCP and stuff. That's no issue. I just need a varable current-voltage power supply.I'm some what know the 494. It's just looking for PWM correct? But is that to run the voltage or current?Any scematics kicking around? See if i can hack my own control into it. I won't be able to recover the firmware off the main IC is my bet 👎I'll try add some photos.Thanks

author: 5U4GB
author_rank: Super Contributor
timestamp: April 21, 2025, 10:04:54 am
content: No circuit diagram sorry, but a question based on that second photo: How?

author: Australia-learn
author_rank: Contributor
timestamp: April 21, 2025, 11:02:46 pm
content: Sorry, what do you mean? The terrible mess? I'm not sure i got all this stuff this way. Brought a bunch of stuff to bugger round with 🙂I got the power supply working with adjustbale voltage with just a pot. however can't seem to figure out the current control....Assume the 494 is sensing the voltage drop across a shunt or resistor.and this may be how it can control the current, However there is a huge shunt, a choke, and a bank of big resistors...🤷I've tried my hardest to understand op amps but nup just over my head at this stage....😅

author: thm_w
author_rank: Super Contributor
timestamp: April 21, 2025, 11:10:18 pm
content: Are you sure the MCU is dead?Its probably controlling the display, I assume, so if main MCU is not doing anything, then maybe nothing on the display at all.I doubt you'll find a schematic, but if you search "tl494 adjustable psu schematic" you'll find similar architectures.https://www.aliexpress.us/item/3256802964719977.htmlhttps://www.nuvoton.com/products/microcontrollers/8bit-8051-mcus/industrial-8051-series/

author: Australia-learn
author_rank: Contributor
timestamp: April 23, 2025, 04:44:41 am
content: Hi. Yes im positive. It heats up rapidly upon power up. The display chip is also fried. (Removed at seprate times to verify)So the whole front part is basicly toast. 👎.Definitely not worth the hassle however would be handy if i could get it somewhat working again using old parts I got here. I got a current/voltage display here. I also got a little PWM modulator. Just chinese crap but mabey could use that to control it? Hijack the 494? From my understanding I need to change the capacitance and voltage on a couple of the 494 pins.I'm not sure if the op amps have suffered from whatever happened to this. I am getting a saw tooth out of the 494. That's all I can see apart from auxiliry voltages. 🙂.But as I can't see what the original controller was doing, and there is a fair bit to this circut due to OCP and all that jazz. I'm not really sure how to get the correct signals/voltages in. I'll be sure to take out the transistors before messing with it😅💥