Ferrus power fp250-710 power supply repair (mystery part) - Page 1
Forum section: electronics / repair

author: super7800
author_rank: Regular Contributor
timestamp: August 08, 2021, 09:49:44 pm
content: Just got an osciliscope for cheap, the nicolet accura hv100. Owner said it was smoking, so immediately removed the power supply for testing. Seems to use a standard pc power supply. Powered it up, and sparks came flying out of the chip pictured. Obviously catastrophic failure lol. Of course, the chip part number is now unreadable. Does anyone know what chip it is, or a way for me to find out? Thanks.

author: amyk
author_rank: Super Contributor
timestamp: August 08, 2021, 11:53:19 pm
content: See if you can find the top, it should still be somewhere in the case.Otherwise you'll have to reverse-engineer the circuit to determine what it was supposed to be.That said, I've never seen sintered glass diodes in a PC PSU before.

author: super7800
author_rank: Regular Contributor
timestamp: August 09, 2021, 04:09:56 am
content: Thanks. I had already looked, but I looked even more and found the top. I had thought it had shattered or shot off somewhere. It was a top223p. I'll order a new one, and hope it fixes the issue.

author: perieanuo
author_rank: Frequent Contributor
timestamp: August 10, 2021, 08:32:07 am
content: yep, top's are not TOP, i noticed the same myself on some burnt power supply

author: super7800
author_rank: Regular Contributor
timestamp: August 24, 2021, 11:33:01 pm
content: Purchased a new part, and the power supply worked! For about 20 seconds. Perhaps it was counterfeit, but it failed in the same way as before so I don't believe that's the issue. I have ordered 10 more from a different seller.I'll look at the datasheet, and start testing other components. It was a very violent event with both, I actually saw the second one fail, it let out quite some pretty lights lol. Does anyone have any suggestions? I'll look at the other components and report back if I find or don't find something lol. Thanks.

author: amyk
author_rank: Super Contributor
timestamp: August 24, 2021, 11:48:59 pm
content: Check if the transformer may have shorted turns.

author: m3vuv
author_rank: Super Contributor
timestamp: August 25, 2021, 07:03:18 pm
content: why not hack a pc psu for testing to find out if the scope is ok,or did the psu blowup because of a fault on the scope?

author: super7800
author_rank: Regular Contributor
timestamp: August 29, 2021, 09:37:45 pm
content: I haven't had a chance to test the transformer for shorted turns, but I will shortly.The power supply failed partially when it was installed, and once I removed it failed the rest of the way. The second time it was completely disconnected, only attached to a pc psu tester (just power switch and led indicator, no load). It seems to be a very common failure for these scopes, since every mention I found on this thing mentioned power supply issues. I will see about hacking a pc psu, probably just to test the pc side of things, but it has very weird current requirements. Thanks.

author: perieanuo
author_rank: Frequent Contributor
timestamp: August 30, 2021, 12:03:26 pm
content: verify caps also, transformer it's not easy to testi doubt it's the new ic the faulty component

author: lazyman
author_rank: Contributor
timestamp: August 30, 2021, 01:19:38 pm
content: It's simple PSU, Check all components, capacitors, diodes.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 31, 2021, 09:36:00 pm
content: Hi,This board that you are working on looks like a standby power. The input to the supply is red lead, +ve and the black lead, -ve. With a power factor correction stage there will be about 370V between those leads.The board should be pretty close to the TOP223p datasheet or application note. I would try and trace out the schematic.These will be connected to the main electrolytic capacitors in the power supply. Given the age of the power supply I suggest that you measure the ESR or simply replace the main electrolytic capacitors.Regards,Jay_Diddy_B

author: Thedarkmade
author_rank: Newbie
timestamp: September 14, 2023, 04:07:36 pm
content: Hello evreyone, I've the same issue, but I know this part is a TOP223P. Replaced by The TOP223PN, who is the same but the leedfree to comply with the ROHS, but it's the same datasheet.I switch it with a new one but the part break explode instantly with the power ON. I'm trying to find out the root cause, but it can be really helpfull if you can tell me what's you've found on your side.By the way the R106 on the power supply is completly exploded to and I can't figure what's the R value can be. Anyone have the schematic of this power supply, or the value of this resistor ?

author: amyk
author_rank: Super Contributor
timestamp: September 15, 2023, 12:21:16 am
content: Check for other shorted parts nearby.Also, a variac, or lacking that, a "dim bulb" tester may help with troubleshooting without blowing more parts.Given that it appears to be a standard PC PSU, and quite a low-rated one at that (only 250W), if you can't fix the PSU you may try substituting a regular PC one.

author: factory
author_rank: Super Contributor
timestamp: September 15, 2023, 07:58:51 pm
content: SMPS and variacs are not a good combination, lower line voltage equals higher current through the switching transistor.Some PSUs had/have auto line voltage detection for 110V/230V, if you are in a 230V area and you go from 0V to 110V and it sets for the 110V operation (doubler circuit), it would fry once you get head towards 230V.Modern PC PSUs don't have a -5V output, also old PCs didn't require high power PSUs.R106, is actually open circuit or just burnt? measure to confirm. Could the small cap near the TOP223 be open/dried out?David

author: Vovk_Z
author_rank: Super Contributor
timestamp: September 15, 2023, 10:03:39 pm
content: Quote from: Thedarkmade on September 14, 2023, 04:07:36 pmHave you replaced all the small electrolytes on the board?

author: Soheil8877
author_rank: Newbie
timestamp: November 18, 2024, 08:59:23 pm
content: Where should I order one of these ?Where did you get this from ?

author: fzabkar
author_rank: Super Contributor
timestamp: November 18, 2024, 10:37:20 pm
content: Mouser and Farnell stock the TOP223PN.