ultrasonic cleaner MH-060S, replacing transistors [fixed > broken again] - Page 1
Forum section: electronics / repair

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 01:18:26 am
content: Hi,i'm trying to fixthis same cleanerthe 15L version (MH-060S)It has 2 boards (see attached images).I marked the bad components on the main board: transistor, some diodes and a blown fuse.(i only know to test the voltage drop using the diode-function on the multimeter)The unmarked transistor shows a voltage drop of 0.3volt accros B&E. Maybe that one is Ok?(The second board has the exact same issue)Both boards having 2x SC3320 transistors.I've found them on ALI for much too cheap (link)But i'm probably better of buying proper ones.I've tried searching them outside aliexpres, but wasn't successful.But since i'm not so well versed in electronics,i'm hoping someone here can propose a proper replacement part and website for the EU? Any other suggestions are welcome as well.Thanks

author: fzabkar
author_rank: Super Contributor
timestamp: July 29, 2024, 01:47:45 am
content: AFAICT, the 2SC3320 was originally produced by Fuji Electric in the early 1990s.https://image.makewebeasy.net/makeweb/0/u8mVxmGkK/Document/_62_Fuji_Semiconductor_2SC3320_datasheet.pdf?v=202012190947https://pl-1.org/getproductfile.axd?id=8702&filename=2SC3320.pdfNowadays there appear to be numerous copies. Here are just a few:https://pdf.direnc.net/upload/2sc3320-datasheet.pdfhttps://www.unisonic.com.tw/uploadfiles/836/part_no_pdf/2SC3320.pdfhttps://datasheet.octopart.com/2SC3320-Inchange-Semiconductor-datasheet-15978868.pdfhttps://storage.ua.prom.st/2579499_c3320.pdfI wouldn't know what to recommend.Edit:BUV48 / BUV48A looks like a suitable substitute, but it is just as difficult to obtain from trusted sources. There are versions in plastic packages, but I would prefer metal.https://rocelec.widen.net/view/pdf/lvpyrsjj9z/ONSM-S-A0005942251-1.pdf?t.download=true&u=5oefqwhttps://www.mouser.com/catalog/specsheets/buv48.pdf

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 06:51:08 am
content: Thanks!Yours is cheaper than the NTE2311 i found(which is a bit overrated).Still shipment with those sites(farnell, tme, mouser) is substantial :/When i tried looking for a replacement myself, i was comparing thise properties:CE-current=400 CE-voltage=15A, BE-saturation voltage and try comparing switching times.Would these parameters be enough for checking?Like i saw darlington and biplair come. i believe darlington internally has more components and is used to have more gain? is it advantagious to stick to bipolair here?Did you compare more properties for this application?For fitting that other metal-package; i wouldn't know what heatsink to use.But what are the advantages of a metal case? much better heat dissipation i guess, or more?

author: fzabkar
author_rank: Super Contributor
timestamp: July 29, 2024, 07:01:28 am
content: I found the NTE part as well, but it cost $19.As for parameters, I would also compare hfe, in this case 10 (min), and the switching times. The ultrasonic cleaner is a tuned circuit, so the parts would have been carefully selected. A Darlington pair wouldn't be suitable, I would think.When you are testing the cleaner, I would let it run for a few minutes, then check the temperature of the transistors. I used to do this with line output transistors in CRT TVs. Fakes would run very hot while the genuine transistors would be relatively cool.

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 08:06:29 am
content: On this site, selecting the parameters starting with 15A i came as only available part to your BUV48A and it ships locally, so without customs feeshttps://www.reichelt.nl/nl/nl/transistor-npn-to-218-450v-15a-150w-buv-48a-isc-p6180.html?&nbc=1Looking at the PDF, the component not having printed parts number, and the next page has 2 pictures misplaced, doesn't give a good impression.Maybe a dumb question;Would you consider buying from this store? or would aliexpress be similarly trustable regarding authenticity?

author: wraper
author_rank: Unknown
timestamp: July 29, 2024, 08:21:57 am
content: LCSC has SC3320 from Chinese manufacturers.https://www.lcsc.com/product-detail/Bipolar-BJT_SPS-2SC3320T4TL_C462223.htmlhttps://www.lcsc.com/product-detail/Bipolar-BJT_SPTECH-2SC3320_C480012.html

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 02:56:50 pm
content: @wraperThanks for the links.In these datascheets, i see Vbe(sat) = (max)1.5V , but it doesn't seem to provide a 'normal' value for it.but the 4 transistors in my device read different for all of them;#VbeVbcVceMainboard left:0.0010.0020.001Mainboard right:0.30.50.52ndboard left:0.0010.0020.0022ndboard right:0.30.30.001Seems only 1 survived. i'm assuming it's better to replace all of them.

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 03:12:12 pm
content: i'm persuaded to go with the BUV48A since it seems to have double the voltage rating can handle 60 more Watts.Next choice to make:There's a storewww.reichelt.nlwhich has theBUV84A by "Inchange semiconductor", for €4,06 (4x + local transport fee) Total €23.18and there's a storewww.tme.euwhich has theBUV84A by "STMICROELECTRONICS"for €5,13 (4x + international transport fee) Total €32.50I'm not sure if "Inchange" is a reputable source, but the latter sounds familiarWhat are the odds i'm getting into trouble with the "inchange" one?

author: fzabkar
author_rank: Super Contributor
timestamp: July 29, 2024, 03:14:26 pm
content: I think the ST part is plastic.

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 04:39:26 pm
content: Quote from: fzabkarYou mean, the ST part is dodgy instead of the "inchange" one?otherwise, if you mean they both are plastic case.That's because i'm not confident enough to try a metal TO-3 case on the board and have another heatsink connected. i'm quite a newby and unfamiliar with the options.i guess metal one is more heavy duty(i'm a newby). but how do i get a proper heatsink fot it which fits? From what i see on mouser, those heatsink require quite some space on the board and screwholes as well.

author: wraper
author_rank: Unknown
timestamp: July 29, 2024, 04:52:22 pm
content: Using metal can transistors in 2024 unless replacing original metal can part is quite dumb for multiple reasons.

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 04:55:09 pm
content: @wraperHaha, ok.

author: wraper
author_rank: Unknown
timestamp: July 29, 2024, 04:58:48 pm
content: BTW PCB footprint also allows using TO-220 package which gives way more substitute choices. Somewhat higher thermal resistance does not matter at all as heatsinks/heat dissipation are not anywhere large enough for it to play a significant role.

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 05:06:11 pm
content: @wraperi've searched for Ice>=15A , Vce >=400 , but most casings i see are TO3 and only few are TO3P, on both TME and Reichelt. i don't find any TO-220?Regarding both suppliers of the BUV48A for the plastic versions, would both parts be same quality? (i added links in previous message) or is ony brand preferred?

author: wraper
author_rank: Unknown
timestamp: July 29, 2024, 05:25:55 pm
content: You're right. All 15A stuff in TO-220 seems to be discontinued. However you don't necessarily need 15A max either. Lower current rating would be fine as long as saturation voltage is low enough, gain at high current high enough and it's not too slow as what you should care the most about is heating not more than original.

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 05:35:17 pm
content: The PCB has a few big capacitors rated at 450V, and it has 2 big coils probably capable of generating a big current rush, so i'd rather have a sturdy component than another one that breaks down in a while.i don't mind getting the BUV48A. Only thing is, i don't want to buy bad look-alikes. Hence my question if either brand has better reputation. (or maybe both shops only have proper brands. i don't know)[edit:]I'll go with the TME website, because reichelt has the specs for BUV48 listed for its part BUV48A..

author: fzabkar
author_rank: Super Contributor
timestamp: July 29, 2024, 06:00:53 pm
content: Quote from: wraper on July 29, 2024, 04:52:22 pmWhy?

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 06:15:05 pm
content: Quote from: @fzabkari don't understand. The picture i posted isn't a metal package, is it?

author: fzabkar
author_rank: Super Contributor
timestamp: July 29, 2024, 06:19:04 pm
content: Quote from: htm on July 29, 2024, 06:15:05 pmDamn, I've confused myself again. Yes, you're right. Yours is plastic. If you do decide on a metal package, make sure that the heatsink is isolated from the circuit.

author: fzabkar
author_rank: Super Contributor
timestamp: July 29, 2024, 06:20:58 pm
content: Quote from: wraper on July 29, 2024, 05:25:55 pmThe MH-060S cleaner is a current design, yet its designer chose a 30-year-old transistor. ISTM that s/he would know best what works in that particular application. Otherwise, why not choose from a plethora of more common, potentially cheaper transistors? :-?

author: htm
author_rank: Regular Contributor
timestamp: July 29, 2024, 06:54:23 pm
content: Yeah, confuses me as well.. current design with a component hard to geti can't wait to try the thing with the new components..

author: fzabkar
author_rank: Super Contributor
timestamp: July 29, 2024, 07:01:32 pm
content: Some techs will use cheap substitutes to validate a repair, then replace them with the expensive parts once they are satisfied.

author: wraper
author_rank: Unknown
timestamp: July 29, 2024, 07:45:35 pm
content: Quote from: fzabkar on July 29, 2024, 06:20:58 pmBecause they cloned some decades old design without thinking too much? On other hand it's a Chinese 2SC3320, so might be because they could get it cheap and TO-220 footprint is for using say xxx13009 instead.

author: elektryk
author_rank: Regular Contributor
timestamp: July 30, 2024, 07:10:30 am
content: Quote from: wraper on July 29, 2024, 07:45:35 pmMJE13009 may be good starting point for debugging.BTW I tried to repair several ultrasonic cleaners, but some of them worked only a few minutes/seconds and burned another pair of BJTs, probably due to broken inductor, transformer or ultrasonic transducer itself.

author: htm
author_rank: Regular Contributor
timestamp: July 30, 2024, 11:12:58 am
content: @elektrykOk. thanks. not verry promising 🤒i'll have to find out how to test if inductor, transformer or transducers are defective..Regarding MJE13009 ; this one says 400V and 12A, while the capacitors on the board says 450V. Wouldn't the same voltage be smart?

author: elektryk
author_rank: Regular Contributor
timestamp: July 31, 2024, 11:46:30 am
content: 2SC3320 also has VCEO=400VFrom my experience MJE13009 are enough to drive 2 transducers 60W each.

author: htm
author_rank: Regular Contributor
timestamp: August 08, 2024, 10:08:40 pm
content: i've got an update and wondering what to do next;transistorsi ordered a few SC3320 from aliexpress.com(€3.08 for 5), ordered a few BUV48A(€4,24 for 1) from tme.eu and i salvaged 1 good transistor from the main board.Then i used my new component tester. Turns out the AliExpress ones are all seen as a Diode!? (see attached picture)How can that be? i mean, how wrong must the component be for the component tester to think it's a diode?transducersI measured the resistante between the two leads going to each set of 3 ultrasonic transducers. They show open loop.But when in 'voltage meter DC' setting and connect the black lead to the black probe, and tap the red wire with the read probe, then the measured voltage increases with approx 10mv per tap, until it reaches 400mV and it resets. That happens for both sets of transducers. Not sure what that says thoughwhat next?Should i just replace the broken components (transistors, fuse and diodes) and give it a go 🙈(after filling up the tank)or is it better to first check if the transformers/inductors are still Ok. i'm not sure how to go about it though..i have a simple function generator and a basic analog 10Mhz scope. Could i do something with that?

author: fzabkar
author_rank: Super Contributor
timestamp: August 09, 2024, 10:18:01 am
content: Perhaps the Ali parts have a C-E damper diode? I would perform a B-C and B-E diode test with your DMM.

author: htm
author_rank: Regular Contributor
timestamp: August 09, 2024, 07:46:14 pm
content: @fzabkarAfaik, the C3320 has pin layout: 1(B) 2(C) 3(E)The diode tests show:BCblack on 1, red on 2 = OLred on 1, black on 2= OLCEred on 2, black on 3 = OLblack on 2, red on 3 = 0.488VBEred on 1, black on 3 = OLblack on 1, red on 3 = OL

author: fzabkar
author_rank: Super Contributor
timestamp: August 09, 2024, 08:30:53 pm
content: Those Ali parts are fakes.

author: wraper
author_rank: Unknown
timestamp: August 09, 2024, 09:28:41 pm
content: Quote from: htm on August 09, 2024, 07:46:14 pmIt's an N-channel MOSFET, what you're measuring between pins 2 and 3 is an intrinsic body diode. Tester detects is as a diode probably due to high gate-source threshold voltage.

author: htm
author_rank: Regular Contributor
timestamp: August 09, 2024, 10:09:14 pm
content: @wraperI tested it. Indeed!The MOSFET is changing from Off to On from 4.1V to 5V.But why didn't the Component tester see it as a MOSFET? aren't most mosfets switching in that area

author: wraper
author_rank: Unknown
timestamp: August 10, 2024, 10:56:39 am
content: Quote from: htm on August 09, 2024, 10:09:14 pmMost modern ones have lower VGS(TH). Your tester probably cannot supply enough voltage or measure above some value below it. Or maybe its firmware has some quirks. I wouldn't outright trust what such testers automatically detect.

author: htm
author_rank: Regular Contributor
timestamp: August 10, 2024, 12:57:20 pm
content: Today i finished replacing the defective diodes and the 4 transistors.On both boards 1 transistor seemed ok, but i replaced those as well, just in case. I rather have them all be the beefy BUV48ADid a testrun of a minute, and..Thanks for all advice!

author: htm
author_rank: Regular Contributor
timestamp: August 14, 2024, 04:01:41 pm
content: .. he used it about 3 times, and then it quit on him again.i'll take another look at it, to see if the same thing happened again.

author: floobydust
author_rank: Super Contributor
timestamp: August 14, 2024, 08:43:22 pm
content: Check your model is likely the same as a Vevor, for repair and safety issues as well. I also mentioned it here:https://www.eevblog.com/forum/repair/vevor-30l-ultrasonic-cleaner-went-up-in-smoke-take-tranducer-out-of-series/msg5605060/#new

author: wraper
author_rank: Unknown
timestamp: August 14, 2024, 10:05:10 pm
content: As this has single layer PCBs I suggest thoroughly inspecting with magnification if there isn't some cracked solder joint. Sometimes it may be even not a crack as such but component lead not properly wetted by solder and moving within the joint that may look fine on a first glance.

author: fzabkar
author_rank: Super Contributor
timestamp: August 15, 2024, 12:08:12 am
content: Quote from: wraper on August 14, 2024, 10:05:10 pmThis is the reason that I was taught to always reflow the solder at inductors and transformers.

author: wraper
author_rank: Unknown
timestamp: August 15, 2024, 03:43:03 pm
content: Quote from: fzabkar on August 15, 2024, 12:08:12 amFBT solder joints were basically guaranteed to crack sooner or later in CRT TVs/monitors if manufacturer did not add rivets in the holes. It also amazes me how often I see single layer boards used in high vibration environment, it's just plain stupid.

author: htm
author_rank: Regular Contributor
timestamp: August 23, 2024, 01:34:20 pm
content: As promised, i checked the device which is broken again(picture attached).Basically, the small board was saved by the fuse. The larger board is broken again.Curious how both boards got damaged at the same time..