Warning about A-BF - Page 1
Forum section: electronics / testgear

author: ArCoN
author_rank: Contributor
timestamp: January 19, 2023, 11:23:01 am
content: Hi AllJust want to give a fair warning about this company.brought a one of there "big" psu (CSY600-6) almost a year ago.https://www.aliexpress.com/item/1005001385711811.html?spm=a2g0o.order_list.order_list_main.132.a0951802Lu5xtBfirst power up, around 100v 5-6A, the power board blow up, one of the power transistors literally caught on firei did not put much thought in that, shit can happen. they send me a new power board.Got it assembled and started the test of the psu when i got to around 300v it blew up again...so i got a closer look and realised they used 2 x 0603 resistors as the input divider for 600V, wtf :/They obviously don't know what they are doing...I still don't have a working psu and they don't respond to me anymore.I just want to know how to calibrate the unit, apparently a hard question to answer.$1000 down the toilet!...B.R.

author: rsjsouza
author_rank: Super Contributor
timestamp: January 19, 2023, 12:00:15 pm
content: I am sorry to hear about your predicament. Did you take any photographs of the board before/after the failure event? Perhaps there might be a way to fix this in house.Designing a 3600W HV power supply is no walk in the park - especially at the advertised prices.

author: ArCoN
author_rank: Contributor
timestamp: January 23, 2023, 06:51:14 am
content: HelloI have pictures afterThe problem is if there is some firmware calibration there needs to be done.B.R

author: ArCoN
author_rank: Contributor
timestamp: January 23, 2023, 06:51:52 am
content: more

author: ArCoN
author_rank: Contributor
timestamp: January 23, 2023, 06:55:06 am
content: more

author: TurboTom
author_rank: Super Contributor
timestamp: January 23, 2023, 07:23:37 am
content: Interesting: 3.6kW SMPS without PFC??I expected even for an obscure chinese manufaturer, this would be a little too much! Apparently not... Sorry for your loss.

author: tszaboo
author_rank: Super Contributor
timestamp: January 23, 2023, 09:05:47 am
content: So they are relying on the PCB to place force on the transistor below it, when screwing it down to the threaded hole on the heatsink. You remember when in university they told you that PCBs are especially good to be used as a compression spring?This sort of bullshit. You only need to make a hole to place the screw through the PCB and place a few standoffs.

author: ArCoN
author_rank: Contributor
timestamp: January 23, 2023, 11:06:21 am
content: Quote from: TurboTom on January 23, 2023, 07:23:37 amIts up the hill

author: ArCoN
author_rank: Contributor
timestamp: January 23, 2023, 11:12:11 am
content: Quote from: tszaboo on January 23, 2023, 09:05:47 amPCB is the best spring!I actually have a question, when the power mosfets is mounted is it normal to put thermal grease between a thermal pad?B.R.

author: rsjsouza
author_rank: Super Contributor
timestamp: January 23, 2023, 11:57:16 am
content: Wow, thanks for sharing the photographs. The blown "compressed" transistor and its collateral damage to the PCB tracks is particularly brutal.Quote from: ArCoN on January 23, 2023, 11:12:11 amIf I understood your question correctly, you mean applying thermal grease on the transistor and then using a thermal pad? That should not be needed, as the silicone pad already molds to the metal quite well - however I have seen both scenarios.

author: nctnico
author_rank: Super Contributor
timestamp: January 23, 2023, 12:11:43 pm
content: Quote from: ArCoN on January 23, 2023, 11:12:11 amNo. It is a sign people don't know what they are doing. The silicone thermal pads don't need grease. The grease actually makes it worse and on top of that, many don't know how to apply it properly. As a side note: I've seen people apply such a thick layer of thermal grease under a module that it got warped so much that it broke when it was bolted down.

author: hpw
author_rank: Frequent Contributor
timestamp: January 23, 2023, 09:29:49 pm
content: Quote from: ArCoN on January 19, 2023, 11:23:01 amalso the requiredCEmarking must be visible, legible and indelible.

author: Martin72
author_rank: Super Contributor
timestamp: January 24, 2023, 12:17:00 am
content: QuoteThin, very thin...The thermal paste is only used to fill the unavoidable unevenness of the heat sink and the back plate of the semiconductor.If you are aware of this, then it also becomes clear that "too much" paste has an opposite effect.The same applies to the pads.It presses into the unevenness and thus fills up, if you now use paste on top of that, the heat transfer increases.It is frightening how often this is ignored, even and especially by "professional" manufacturers.

author: thm_w
author_rank: Super Contributor
timestamp: January 24, 2023, 02:05:56 am
content: Yeah I probably wouldn't drop 1k on some no-name PSU.0603 rated for 75V continuous so 300V is not good.. assuming its not due to some other failure.However, I did buy their $100 torque driver, and its working well so far:https://www.aliexpress.us/item/2255801110882961.htmlAutomatically stops when the torque limit is hit.

author: ArCoN
author_rank: Contributor
timestamp: January 24, 2023, 06:17:44 am
content: Quote from: thm_w on January 24, 2023, 02:05:56 amin hindsight it probably wasn't that smart, I also looked at some well-known ones, but they are 10x the price and way over my budget. but at least they have worked as expected.Glad to hear something works. I did also buy a laser level from them, it also works for now at least.very cheaply made, but that's to be expected, I guessB.R,