Meanwell RD-125-2412 versus RD-125-1224 - Page 1
Forum section: electronics / general

author: RustyShackleford
author_rank: Regular Contributor
timestamp: August 14, 2018, 05:03:48 am
content: These are both dual-output switching power supplies, with 12vdc and 24vdc outputs. I can't figure out the differences, and the datasheet mostly gives hints.https://www.meanwell.com/Upload/PDF/RD-125/RD-125-SPEC.PDFIt looks like the load regulation is better for "channel 1" (the first of the two designators in the part name after "RD-125-"). There is also suggestion that only channel 1 has adjustable output voltage (a range is listed for it, but not for channel 2').Maybe I've already answered my own question, but I wonder what else there is ...

author: helius
author_rank: Super Contributor
timestamp: August 14, 2018, 06:20:27 am
content: It is typical for multi-output switching supplies to regulate most precisely on only one of the outputs, because the user requires that output to be more stable, for instance in a mixed analog/digital device the analog supply should be more cleanly regulated than the digital supply.

author: RustyShackleford
author_rank: Regular Contributor
timestamp: August 14, 2018, 11:36:25 pm
content: Quote from: helius on August 14, 2018, 06:20:27 amThanks. Similarly, do the you interpret the datasheet as saying that only Channel 1 has adjustable output voltage ?

author: helius
author_rank: Super Contributor
timestamp: August 14, 2018, 11:59:06 pm
content: Quote from: RustyShackleford on August 14, 2018, 11:36:25 pmYes. In the picture you can see there is only one V+ ADJ on the unit, probably a single-turn cermet pot. It makes sense to only provide adjustment of the higher precision output voltage—anyway, it is a "set it and forget it" type of adjustment.

author: RustyShackleford
author_rank: Regular Contributor
timestamp: August 15, 2018, 04:48:58 am
content: After all that, it turns out I can get both a 100watt 12vdc unit and a 100watt 24vdc unit, for the same price (in Meanwell's LRS series). Not as compact, but I don't care right now.Since you seem to know about these ... Two similar (smaller) Meanwell units just died on me (I think I might've shorted 'em together briefly, but it was just after a lightning bolt came very very close to the house, so who knows). Anyhow, when I power either one up, the voltage comes up and immediately drops out (over many seconds if there's no load). Is that something recoverable ?

author: helius
author_rank: Super Contributor
timestamp: August 15, 2018, 05:12:00 am
content: I don't know. These types of supplies should be short-circuit protected, although they arenotadvertised as crowbar protected.This means that back-feeding higher voltage into the outputs may cause damage.

author: RustyShackleford
author_rank: Regular Contributor
timestamp: August 15, 2018, 05:42:26 am
content: Quote from: helius on August 15, 2018, 05:12:00 amYeah, but they both got whacked. The lightning bolt didn't even make the lights flicker, though it knocked out the whole neighborhood's cable for a day or so. But they're not stone dead, and the symptoms are remarkably similar. It's a head-scratcher ...

author: capt bullshot
author_rank: Super Contributor
timestamp: August 15, 2018, 06:34:01 am
content: Quote from: RustyShackleford on August 15, 2018, 04:48:58 amLightning damage can be very obvious (direct hit) or quite subtle if the strike was e.g. some 100m in distance.Your symptom looks like the main regulating path is damaged, so the output voltage rises above the maximum and the over voltage protection kicks in (which just shuts down the primary side controller until the next power cycle).

author: RustyShackleford
author_rank: Regular Contributor
timestamp: August 15, 2018, 09:01:49 pm
content: I can replace 'em both, with ones with somewhat higher power, for $30 or so. Just wanted to check if it was something simple.