MS3010D Bench supply repair - Page 1
Forum section: electronics / repair

author: RobUK
author_rank: Contributor
timestamp: January 26, 2019, 08:43:57 pm
content: Hi All,I purchased a MS3010D bench supply from ebay. Upon powering it on, pressing the "Power" button on the front of the unit, there was a loud band and flash, the power in the house went off. Upon inspection of the unit, at the sellers request, I found that the mains wires to and from the front power switch were running directly under the PCB. One of the legs from a component had pierced the live cable and sent 240v into the circuit. I believe it was pin 4 of the 817C optocoupler, which blew the bottom of the IC off and destroyed the track from pin 3 of the 817C which goes to pin 4 of the DK112 power controller. I have checked a lot of the components around these chips and along the traces and the Capacitors and resistors all seem in spec. Most tested in circuit, I did remove a few caps and tested them to make sure as they were in direct line of the 240V. I only found 1 diode at D10 coming off pin 2 of the 817C that is a dead short.The seller has refunded me for the supply and told me to keep it, so I'd like to repair it as a project. I am by no means an electronics engineer, I class myself as a novice, it is a hobby to me, I have recently repaired my Commodore 64, which went faulty about 25years ago and have always been interested in electronics, repairing gaming consoles and modifying them. The C64 was a learning curve for me. So after testing the basics, would it be feasible to repair this PSU by replacing the two IC's and the diode? Is there anything else I need to check/test? I have attached some images to look at.RegardsRob

author: fzabkar
author_rank: Super Contributor
timestamp: January 26, 2019, 08:56:22 pm
content: I would consider replacing the bridge rectifier as well.There is an application circuit on page 7 of the DK112 datasheet:https://p.globalsources.com/IMAGES/PDT/SPEC/955/K1120043955.pdf

author: RobUK
author_rank: Contributor
timestamp: January 27, 2019, 07:05:36 pm
content: Quote from: fzabkar on January 26, 2019, 08:56:22 pmThanks for the link, so it looks like I need an 11v 1/2W zener diode and four 1N4007 diodes. Any way to identify what the SMD diodes that are already installed in case they are different from that diagram? Also, there is plenty of room so would using normal through hole components make any difference as they are cheaper and easier to find, obviously they won't be going through hole? I found both The 817C and DK112 on AliExpress, anyone got any experience with the quality from there?RegardsRob.

author: fzabkar
author_rank: Super Contributor
timestamp: January 27, 2019, 07:57:20 pm
content: RS1M, Diodes Inc, fast recovery rectifier, 1A, 1000V, SMA:https://www.diodes.com/assets/Datasheets/ds15002.pdfThe diode marked "200A" might be 200V TVS diode, but I'm not sure.http://pdf1.alldatasheet.com/datasheet-pdf/view/513229/VISHAY/1.5SMC200A-E357T.htmlhttps://m.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_1_5smc_datasheet.pdf.pdf

author: Chris56000
author_rank: Frequent Contributor
timestamp: January 27, 2019, 08:02:37 pm
content: Hi!Rob, can I draw your attention to this post please?https://www.eevblog.com/forum/beginners/maisheng-ms-605d-power-supply/The chap's taken the trouble to draw it out in full to help everyone and he's done a nice job of it!I think replacing the DK112 and the opto, plus repairs to the blown lengths of print will be all you need!Note that the chap's unit is a 30V unit so there'll be differences in the main transformer and output cap. values and ratings but I think you should be OK with the chap's good work!Chris Williams

author: Chris56000
author_rank: Frequent Contributor
timestamp: January 27, 2019, 08:18:54 pm
content: PS!The diode marked "200A" is indeed a 200V transient suppressor type TVS diode, Power Innovations recommend the same in their application notes for their 8 pin DIL "TOPSwitch" chips - sadly the TOP series is NOT pin compatible with the DK112!Chris Williams

author: RobUK
author_rank: Contributor
timestamp: January 27, 2019, 08:34:42 pm
content: Quote from: fzabkar on January 27, 2019, 07:57:20 pmHi,Thanks for the reply. Those diodes you linked to aren't the same as the ones I tested. The ones I tested are glass type cylinders. Not really sure what you have linked me to and for what, i'm a novice when it comes to these things. Can you explain to help me learn?Rob.

author: fzabkar
author_rank: Super Contributor
timestamp: January 27, 2019, 08:41:11 pm
content: AFAICT, the damage appears to be localised to the primary (mains) side of the transformer. The glass diodes are on the secondary side.

author: RobUK
author_rank: Contributor
timestamp: January 27, 2019, 08:44:51 pm
content: Quote from: Chris56000 on January 27, 2019, 08:02:37 pmHi Chris,Thanks for taking the time to reply to me, that link is great, it appears to be the exact same as mine, mine is also 30v 10A supply. I will order the opto and DK112 from AliExpress. I will still need the Diode at D10, which according to that schematic is a 1n4148 smd. So I will find one of those. Are you saying the rectifier should be ok and to leave it?Rob.

author: RobUK
author_rank: Contributor
timestamp: January 27, 2019, 08:49:21 pm
content: Quote from: fzabkar on January 27, 2019, 08:41:11 pmIt's the glass diode on the right of Opto (D10) that I measured and was short in both directions, so that is the one I was going to change. I didn't realise the RS1M was a diode, so didn't check that. Maybe there are other things I need to check?

author: fzabkar
author_rank: Super Contributor
timestamp: January 27, 2019, 08:58:29 pm
content: That's bad news (about D10). I would now expect to find more failures on the secondary side.

author: RobUK
author_rank: Contributor
timestamp: January 27, 2019, 09:48:19 pm
content: I've just purchased 10 x 817c, 10 x DK112 and 100 x 1n4148 from AliExpress, really cheap.They were the smallest quantities I could get.I will do some more testing after the D10 Diode and see if anything else is damaged, fingers crossed nothing else is.Also, do you think it will be ok to power on the unit, as is, with IC's removed and test the rectifier output at BD2 or is there another way to test it?RegardsRob.

author: RobUK
author_rank: Contributor
timestamp: February 10, 2019, 08:18:50 pm
content: I decided to check the KBP206 rectifier. It appears to be dead. The positive side and the ac pin in either direction are open and the negative side and ac pin are short in both directions. I have ordered a replacement from aliexpress. The other components I ordered are yet to be shipped, so hopefully they will all come at the same time.

author: RobUK
author_rank: Contributor
timestamp: February 28, 2019, 08:59:49 pm
content: Update:The Dk112, 1n4148 and the 206 rectifiers have arrived, so I installed them tonight, just waiting for the 817 to arrive, I also bridged the burnt out pcb tracks. Hopefully they will arrive soon, itching to get this working as I'm currently stuck to using a converted AT Power supply, for 12v, 5v and 3.3v. The 12V is also fed into a quad output breadboard psu, one output being variable up to 12v.

author: emcay52
author_rank: Newbie
timestamp: February 06, 2023, 08:08:13 am
content: hi, can you send me pictures of the fets with aluminium cooler. i have removed them and misplaced need to know the numbers and the place they are soldered.thanks in advance.