[Solved] VIPer53 chip (PSU) blown in an air conditioned unit - Page 1
Forum section: electronics / repair

author: nuno
author_rank: Frequent Contributor
timestamp: April 04, 2017, 05:37:03 pm
content: Hello all,I'm trying to fix an air conditioned unit which is totally silent. I opened it up and found this VIPer53 chip from ST (datasheet) blown. This is a "PSU controller", on the AC-DC converter. I see no other components with fault signs nor blown fuses.My question is, do you think something else may be blown? I've tried to fix another AC-DC converter once, that had the controller chip blown, but it kept blowing as soon as I plugged the "fixed" board to mains (in this converter I think the problem was the transformer, the ferrite was cracked, which probably changed the transformer characteristics).Many thanks for any input you may have.Update: corrected chip's nameUpdate: added "" to the post's title and here'sthe link to the closing post.

author: RayRay
author_rank: Frequent Contributor
timestamp: April 04, 2017, 06:16:47 pm
content: Quote from: nuno on April 04, 2017, 05:37:03 pmProbably.Looks can be deceiving, and you should never presume that just because a component looks okay, then it really is!Everything needs to be properly tested.

author: nuno
author_rank: Frequent Contributor
timestamp: April 04, 2017, 06:34:33 pm
content: Yes... I've been poking around the chip, and there's a diode that seems to be open. SMD in the most tight place, of course, and with that "hard yellow epoxy" hiding more components. Humm :\ ... There are also some "diode-looking" components that kind of behave like diodes, maybe they have something in parallel, but I've never seen such diodes... on the forward direction they drop only a few 10 tenths of mV ... I'm going to try to find the schematics.

author: strawberry
author_rank: Super Contributor
timestamp: April 04, 2017, 06:42:53 pm
content: Check Viper53 Drain pin RCD clamp network capacitor for droped capacitance ( this fault will blow it instantly) if there is not capacitor then ~180V zener clamp.Check if VDD bias voltage circuitry is ok Dried electrolitics or damaged small rectifier diodeCheck mains electrolytic, may cause Viper chip to overheat at nominal loadIf that pasesd and there is clicking noise/pulsating voltage present, check secondary capacitors and feed back circuitry.

author: nuno
author_rank: Frequent Contributor
timestamp: April 07, 2017, 02:25:18 am
content: I removed the dead VIPer53 chip and did some measurements and reverse eng. on the converter block, with the help of VIPer53's datasheet application example; schematics below.Except for the electrolytic caps which I haven't measured yet for ESR (don't have an ESR-meter, but have fungen & scope so will try next), the only part I think is broken (besides the Viper chip) is D34. This diode isn't in the example application and is never suggested by the datasheet. It's a SOT-23 part with the marking WT3, then 98 in vertical text; some sites say it's a BZX84-C2V4 zener, but the datasheets say a different marking for this part in this package... any suggestions?The RCD clamp network looks good, all 3 parts measure well.The VDD circuitry is more complex, with a snubber for D38 (a fast diode), alternate path through D45/R157 (power the Viper at startup while the big 220uF C22 charges?) and a 7805 to power something else in the board. D44 and D45 measured funny (0.6V fw, 1.9V reverse), D38 measured shorted; then I removed D38 from the PCB and it measures good, as well as D45 which also measures good now. I suppose the loop through the transformer and 7805 affects the diode test; D44 still reads funny... I was now looking again at the schematics as I write this and I don't see a reason for D44 to read funny...By Vfw and physical aspect, D44 and D45 are probably 1N4148 or similar.Thanks!update: replaced the schematics by a "tidier" one, same functionalityupdate: corrected chip's nameUPDATE: See the updated schematics further down in this thread:schematics2019/06/17: Schematics updated by biank88, seehis postbelow.

author: noidea
author_rank: Unknown
timestamp: April 07, 2017, 04:19:57 am
content: Post a couple of photos of the board, component and solder sides please

author: nuno
author_rank: Frequent Contributor
timestamp: April 07, 2017, 07:48:27 am
content: Everything is crammed in tightly and conformal coated and there's "hard epoxy" holding the caps and almost embedding some of the SMD comps. Had a hard time trying to reach the SMD components with the DMM's probes

author: nuno
author_rank: Frequent Contributor
timestamp: April 10, 2017, 11:54:46 pm
content: Ok, so I found another faulty component. I measured ESR of the electrolytic caps around the transformer's primary (T3) and found C91 (2.2uF 100V) of the compensation network with 21 Ohm ESR. If it were this alone, it wouldn't probably matter as there's a 2K resistor in series, but then I remembered that the capacitance is also probably reduced, which was confirmed: it measured 1.2uF. Same area as the busted (supposed) 2.4V zener diode. I compared the readings on this capacitor (already out of the circuit) with a 25yo unused 2.2uF 50V electrolytic, which gave 2.2uF and 3.2 Ohm ESR (both tested at 200KHz with a fungen and a scope).By biggest doubt now is the diode D34; can it really be a 2.4V zener diode? VIPer's working is a bit over my head, but the datasheet says there's a short-circuit / overload protection mechanism that kicks in when COMP reaches 4.35V, which it wouldn't reach with a 2.4V clamp in there.Quote from: VIPer53's datasheetOn the other hand, my experience with small value zeners is that they don't have a very sharp knee.

author: nuno
author_rank: Frequent Contributor
timestamp: April 11, 2017, 12:32:11 am
content: Quote from: nuno on April 07, 2017, 02:25:18 amAhh!!... I misread the datasheet, there's in fact a marking WT3 on SOT-23 meaning it's a BZX84-C2V4 (China made, 5% tol 2.4V zener).

author: nuno
author_rank: Frequent Contributor
timestamp: May 25, 2017, 08:51:39 am
content: Quote from: strawberry on April 04, 2017, 06:42:53 pmAfter replacing the chip and 2 damaged components around it, it's no longer "dead"... now it's clickingNext stop is to look at the sec. caps and feedback circuitry then. Another PCB reverse eng. task

author: stj
author_rank: Super Contributor
timestamp: May 25, 2017, 02:16:43 pm
content: if it's pulsing, check the output rectifier diodes.also any small electrolytics on the primary side.

author: nuno
author_rank: Frequent Contributor
timestamp: May 25, 2017, 02:33:26 pm
content: Quote from: stj on May 25, 2017, 02:16:43 pmElectrolytics on the primary are covered. So adding the output rectifiers to the check list, thanks... This board is a big PITA to work on, no schematics and this part of the circuit is a mix of SMD with big electrolytics, I sometimes don't even have space to put a DMM's probe nor the soldering iron, had to remove a cap or 2 just to reach certain parts

author: stj
author_rank: Super Contributor
timestamp: May 25, 2017, 02:56:17 pm
content: i made probe extensions for that scenario using large medical needles.you can of course buy long thin probes - but who wants to wait for the post!looking at your photo, you need to remove the brown glue - it slowly becomes conductive!!(it's also acidic)

author: nuno
author_rank: Frequent Contributor
timestamp: May 25, 2017, 03:06:17 pm
content: Quote from: stj on May 25, 2017, 02:56:17 pmWell insulated, I hope!Quote from: stjJeeez.... any safe alternative to mechanical removal?

author: stj
author_rank: Super Contributor
timestamp: May 25, 2017, 03:53:14 pm
content: unfortunatly no, small flat screwdriver + long-nose pliers is my method.

author: nuno
author_rank: Frequent Contributor
timestamp: May 25, 2017, 04:14:28 pm
content: Humm... not sure if I'm going to take the risk... the stuff is rigid and some of it is hiding SMD parts

author: wraper
author_rank: Unknown
timestamp: May 25, 2017, 04:25:53 pm
content: Quote from: nuno on April 10, 2017, 11:54:46 pmfor 2.2 uF it's OK-ish ESR.

author: nuno
author_rank: Frequent Contributor
timestamp: May 25, 2017, 06:26:26 pm
content: Do you think so? My 25 year old unused 50V 2.2uF electrolytic has 3.2 Ohm... and besides, the 2.2uF cap measured 1.2uF, 45% down from nominal value, way out of spec. I just replaced it. The 2V4 zener in "the same area" was also fried (open).

author: nuno
author_rank: Frequent Contributor
timestamp: May 25, 2017, 08:36:05 pm
content: It's not clicking in my bench(according to A/C technician it was clicking when installed at the A/C unit...).The circuit has no "explicit" feedback from secondary to primary side (uses the transformer). There doesn't seem to be any ruined capacitor nor rectifier. Measurements at the secondary after the rectifier show that when I plug it in, it looks like it's trying to raise the voltage but stays only at about 3 - 4V (should be at least 12V), then after some time it kind of quits and the voltage slowly drops to zero; viper53 gets quite hot, so I suppose it's thermal protection kicking in. I think my next step is to remove the transformer in order to better check all components around... any other suggestions?

author: wraper
author_rank: Unknown
timestamp: May 26, 2017, 07:12:51 am
content: Quote from: nuno on May 25, 2017, 06:26:26 pmYes I do. It's on the high side but even some new, especially ultrasmall capacitors are like this.3.2 ohm is on the low side. What I do think, you have a cheap LCR meter from ebay. They don't use 100kHz sine wave to measure capacitance, as it is in decent meters. But some sort of charging/discharging IIRC. It may result in wrong measurements, especially if capacitor is leaky or you try measuring in circuit.

author: nuno
author_rank: Frequent Contributor
timestamp: May 26, 2017, 11:42:21 am
content: I measured ESR (on both caps, and others too) with a function gen and a scope, outside of the circuit.

author: nuno
author_rank: Frequent Contributor
timestamp: May 30, 2017, 01:03:08 am
content: I think I'm starting to get somewhere. The DC-DC where this VIPer53 goes supplies power to several sub-circuits, both with the converter's secondary but also with his primary. Looks like one of the primary fed sub-circuits has a reverse power supply polarity protection diode in parallel (still only a suspect), and this little guy is shorted (had to cut a few PCB traces to find it). I repaired the converter but this short is still preventing it from working, having the behavior I described above (unable to keep output voltage, then thermal protection kicking in). This is going to take me time... the little b@st@rd is under a huge heatsink where a bunch of stuff is attached

author: noidea
author_rank: Unknown
timestamp: May 30, 2017, 05:34:34 am
content: Quote from: nuno on May 30, 2017, 01:03:08 amHave you had a good look at the components loads that are connected to the board? you are way more advanced than I am as far as component level fault finding and repairs but I also live breath eat sleep inverter driven AC units and 99 times out of a 100 the SMPS is the innocent victim and it's what's connected to it that has caused the failure.

author: nuno
author_rank: Frequent Contributor
timestamp: May 30, 2017, 10:49:41 am
content: Man, this is by far the most complex thing I've ever tried to repair!Indeed... even with "thermal protection", "overcurrent protection" and all that... the guys still fail under a bad (shorted) load.I couldn't find a schematic for this board (an ELECTRA outdoor DC inverter controller from an Airwell DCI 50 A/C, with just a few years! They don't sell the board anymore), so I've been reverse-engineering the PCB as I go (and finding some mistakes on my part, the partial schematic I left above is not 100% correct, I'll have to update it later). There's a few loads fed by the auxiliary winding (from C22), spread all over the PCB. Resistance from C22+ to C22- is below 0.5 Ohm. To find the responsible I did a binary search cutting the positive rail until the culprit zone was isolated. I isolated one leg of the diode, but since I can't see the other side of the board yet because of the heatsink, I don't know if there's something else connected there...After all the work, I hope it's just the diode... I've been thinking and I may be able to cut it out without removing the heatsink, then I'll know... and being a small diode, I'll put a replacement on the unobstructed side of the PCB (nice that the designer put silkscreen on both sides of the PCB, at least for most TH components; on the other side... there's things like vias going to nowhere).There's one other "little thing" that worries me a bit, but I don't know if it's normal. The VIPer53 runs a little hot even with a very small load... it stabilizes near 60ºC. The PCB all around is darkish, even the box cover on the copper side of the PCB has an isolation plastic that is darker in that area, so I'm not sure this really is a "bad" design or there's another problem waiting for me to fix the diode.

author: noidea
author_rank: Unknown
timestamp: May 30, 2017, 11:02:31 am
content: Please post a photo of thewhole boardcomponent and solder sides as well as the block wiring diagram that was on the unit.As per previous post what have you done to check the loads connected to the board?

author: nuno
author_rank: Frequent Contributor
timestamp: May 30, 2017, 11:22:42 am
content: Checking the loads is not "under my jurisdiction", I only have the controller for attempt repair, so I didn't check them, but will take care of making it happen (if not yet done). The diode is in the compressor motor driver area (3 phase AC). I'll post photos later.

author: noidea
author_rank: Unknown
timestamp: May 30, 2017, 03:02:32 pm
content: Sorry to be so blunt before, I am from the AC technician side originally who has developed some understanding of electronics.Is this the model you are trying to fix the board on?http://lh.airwell-res.com/sites/default/files/imported/Airwell/c61/p146/SM_DUODCI_1_A_1_GB.pdf

author: nuno
author_rank: Frequent Contributor
timestamp: May 30, 2017, 03:12:39 pm
content: No, it's this one (DCI 50, outdoor unit):http://lh.airwell-res.com/sites/default/files/imported/Electra/c16/p56/SM%20LEX%20DCI_25to72_1.E.1%20GB.pdf

author: noidea
author_rank: Unknown
timestamp: May 30, 2017, 03:44:06 pm
content: OK, will wait to see your photos too

author: nuno
author_rank: Frequent Contributor
timestamp: May 30, 2017, 05:52:45 pm
content: Photos...

author: nuno
author_rank: Frequent Contributor
timestamp: May 30, 2017, 06:40:53 pm
content: I was able to remove the diode without removing the heatsink. It's a zener diode, 1N4746A, 18V 1W. It's shorted. The short on the board went away. Now looking for a replacement in the local stores.

author: nuno
author_rank: Frequent Contributor
timestamp: May 30, 2017, 11:06:03 pm
content: Soldered a 1/2W 18V zener just to test. It worked*(some relays clicked, uC came up and started doing its hw tests)... for about 10s, then it switched off and doesn't turn on anymore. Zener still ok. Zero Volt at VIPer53's supply pins. Tomorrow will take another look...*I have only the board and the big choke coil

author: noidea
author_rank: Unknown
timestamp: May 31, 2017, 05:03:38 pm
content: Quote from: nuno on May 30, 2017, 10:49:41 amHi NunoI was reading back through your posts whilst looking at the the data sheet for the Viper and it seems that the circuit is similar to the Primary regulation reference design in the data sheet which makes numerous references to Vcc being 15vdc. You also mentioned that there are sub circuits connected to the primary of the Viper.I was wondering if there is any continuity from the Orange wire of P6 the OFan connector to any part of the Viper circuit and where?The DC fan motor connected to that harness uses 15Vdc on the orange wire to power the internal circuit board of the fan motor and in many cases failure of the fan motor Vcc is what causes damage to the SMPS. The same 15v Vcc voltage is often shared to supply a 15V Vcc to power the controller section of the IPM / Power Transistor IC (U2)PS I don't envy your task that board is crowded compared to the ones I look at every day, the company I work for uses about 1.5 times the size PCB for the same circuitryHTH and please forgive me if I am wrong

author: nuno
author_rank: Frequent Contributor
timestamp: June 02, 2017, 10:06:17 pm
content: Yes, this board roughly implements the primary regulation reference design, and I've used it as a reference to do the reverse-engineering. There are no "shorts" (anymore) on the primary, and yes, it supplies the OFAN and the compressor motor's driver circuitry. The blown zener diode shorting the primary feeding the viper was on the compressor's driver (the rectangle you mention, in the last photo, if you look carefully at the right of it, you see can see where I cut 2 traces to isolate the zener).I disconnected all power going out to OFAN etc but converter still not working, then while trying to measure Viper's Vcc on the cap (C94)... probe slipped, big bang with tiny fireball and some nice smell. I have very little experience with high voltage powered circuits, but I was prepared for such event with some personal protection equipment so no human flesh was harmed. Blew D34, D44 and probably the Viper, so I replaced them (have not yet inserted the new Viper, to ease other component tests; maybe it was already blown from previous tests) and tested the other components, including C17 which I had not tested yet (it's ok).I also isolated C70 from the other 3 huge caps to test it's ESR, and it's ok. There has always been the correct voltage (300-something V) at this cap.So... I don't know where to go from here, so I'll put the new Viper in and test it again, if it still doesn't work then I'll throw the towel. The PCB is also starting to show "fatigue" from so many soldering and desoldering. I'll test first with no other loads (OFAN, ...) on the Viper's primary. Maybe the transformer is ruined (shorted winding loops; there are no open windings), I don't know how to test it and even less how to get a replacement (googling for the number written in to it turns up zero results). I measured the windings resistances, it's on the updated schematics below... have no idea if they look good or not.2019/06/17: Schematics updated by biank88, seehis postbelow.

author: nuno
author_rank: Frequent Contributor
timestamp: June 03, 2017, 08:00:53 pm
content: It may be working after all... It just happens that the guy sleeps from time to time and the 1st time it happened, after I replaced the shorted zener diode, I thought something went wrong and just disconnected it right away to avoid further damage... then I did the short when probing. On my test of today, since I was throwing the towel anyways, I just let it turned on after it "went off", and started looking at the temperatures, measuring VIPer53's Vcc (this time with a proper connection) and... suddenly the guy poped up ON again... then I just waited and it keeps turning ON for a while, sleeping for a while, repeat. When ON it has 14.8V on the VIPer53's Vcc, when sleeping it has near 10V.Now I have to find a replacement zener and then we'll see if it works when back to the A/C unit...

author: noidea
author_rank: Unknown
timestamp: June 05, 2017, 04:29:19 am
content: That's great news Nuno.Sorry to sound like a broken record but you must stress to the technician that he needs to test the fan motor before fitting the board back in the unit. If they are not familiar with testing DC fan motors I'll post some information for you.Too many times I am speaking to technicians and they ask "what is the whining /squealing noise" coming from the new board they have just fitted. Unfortunately it's the sound of the smps dying as they've not tested the motor properly

author: nuno
author_rank: Frequent Contributor
timestamp: June 05, 2017, 11:04:42 am
content: No problem, thanks. I've spoken to the technician about that, he apparently does know how to and does test motor windings, but I don't know how far his knowledge goes. Any information you can provide will be appreciated, thanks.

author: noidea
author_rank: Unknown
timestamp: June 05, 2017, 05:38:38 pm
content: The biggest thing he needs to be aware of and I find confuses most people is that you are not testing the motor windings themselves. The fan motors are actually a little three phase motor with an internal driver board inside the casing so when you test them you are testing the circuit board not the windings. Here's a couple of photos of a DC fan motor from another manufacturer and the pinout of the Electra motor from the wiring diagram. I'm not sure of the Electra motor but in most of these motors the driver circuit board is completely encapsulated and you can't see what's in there. Fortunately on the motor I have the circuit board is accessible when the cover is prised off.Different manufacturers use different colour codes on the leads and on this one they refer to the Earth as Ground but they are all pretty much the same. There is a 300-350 Vdc supply (Vdc), ground, a 15Vdc supply (Vcc), a speed input signal approx 0-7vdc (Vsp) and a RPM feedback (Vsp) which is x pulses per revolution.When you test them the best way to do it is using diode check mode on a DMM and I always test with Red meter lead to Ground first then reverse the test and are looking for readings something like belowBetween Vdc - Earth/Gnd you should get about 0.8-1.0v / OpenBetween Vcc - Earth/Gnd you should get about 0.4-0.5v / >0.8v or OpenBetween Vsp - Earth/Gnd you should get about 0.8-1.0v / OpenThe same reading both ways is obviously a bad signI have never bothered testing the Vfg / gnd as most times the failures are between Vdc, Vcc or Vsp when tested to ground.Feel free to ask if you have any other questions.

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 08, 2017, 02:16:42 am
content: nuno;first of all, I want to congratulate you on attempting to repair something thatnever was designed to be repaired.Replacing electronic boards wholesale is not what I consider a repair.Unfortunately, in our throwaway society, this is becoming more and more common.

author: nuno
author_rank: Frequent Contributor
timestamp: June 11, 2017, 02:11:21 am
content: Thanks schmitt. This is actually a job, but I do enjoy to fix, and do fix, a lot of stuff, although I rather much be designing something new. They don't sell this board anymore, so the owner would have to replace the entire A/C system, some 700€ value just the hardware. It really sucks, in every imaginable way, having to throw away a big set of perfectly working stuff because of a cheap tiny faulty component. The amount of time I poured into this will never be paid but I do enjoy the ride, and is knowledge that may be useful in the future.I may still have a gremlin. I found out that the period on/off behavior I described earlier in the thread isn't actually true, it did that because of this gremlin. At some point it simply stopped turning ON when powered. I found out that the oscillator on the VIPer53 wasn't running (flat line at the OSC pin). I couldn't think of anything else besides a broken solder so I reflowed the solders at the R and C setting the frequency and it came back to life. However, the next day in the morning, the 1st time I powered it it came up but turned off after a minute, then back on again and it has always worked since. It has been hotter here since that morning - so I'll have to cool the controller down and see if it has an affect. I suspect the OSC pin on the VIPer53 is not well soldered, the board is a bit "beaten" by now and I can't get there properly with my soldering iron - I was already thinking of buying a new one anyway, so here's a good excuse

author: nuno
author_rank: Frequent Contributor
timestamp: August 02, 2017, 01:21:48 pm
content: I reflowed some of the VIPer53 joints and tested the board at a lower temperature. Didn't fail since, and it's now been working for a few weeks in its final system, so this repair was successful so far.I'll never know the exact sequence of events that led to the destroyed components, but the fix consisted of the following:-> Reverse engineering of parts of the circuit, including the full low voltage output PSU (based on VIPer53).At the compressor's circuitry:-> Replaced D52: 1N4746A, 18V 1W zener (was shorted, shorting the primary output on the low voltage output PSU's output).At the low voltage output PSU:-> Replaced U15: VIPer53 (DC-DC converter controller) (was blown to pieces).-> Replaced D34: BXZ84-C2V4, 2V4 zener (compensation network) (was open).-> Replaced C91: 2.2uF 100V (compensation network) (was 1.2uF ESR=21 Ohm).-> Retouched solder joints at the VIPer53's oscillator RC components (SMD).Additionally:-> Removed some of the yellow gunk.-> Restored the conformal coating in the PCB areas I had removed it because of the repair.Thanks to all in this thread.2019/06/17:Schematics of the PSU

author: r_d_m
author_rank: Newbie
timestamp: August 14, 2017, 08:03:22 pm
content: Hi nuno.I have the same (garbage) board in my ACTomorrow I will receive my components (viper53, diodes, etc...). In your last post you talk about the oscillator but I can't see where he isI have a yellow garbage everywhere on the board. Can you tell me where is the oscillator?Other question... can I replace diode D34 (SOT23) by a tube zener diode (C2v4)? The BXZ84-C2V4 have one leg disconected.Thanks,David Teixeira

author: nuno
author_rank: Frequent Contributor
timestamp: August 15, 2017, 04:17:10 pm
content: I'm referring to the capacitor + resistor that set VIPer53's oscillator frequency. It's the SMD components at the center left of the 1st photo ofthis post above. There are 2 "sets" of 1 capacitor and 1 resistor in that board area, I can't remember exactly what's the right set that sets the VIPer53's oscillator frequency. At least one of the sets may be under the yellow gunk.If it's the same diode reference but only different package I don't see any problem. The SMD version only uses 2 package pins, that's why the other is "disconnected".

author: r_d_m
author_rank: Newbie
timestamp: August 15, 2017, 05:00:31 pm
content: Quote from: nuno on August 15, 2017, 04:17:10 pmThanks nuno.I've found the resistor and the capacitor under the yellow junk (dammit yellow junk).When I recieve my order, I will post my results here for all people.I've two AC's. My brand is "Equation" but the main brand is "Airwell" The board say "ELECTRA"!!!In other AC, the problem isn't in "this board" but in MSMP board. Here, some capacitors and the Viper53 needed to be replaced. The transformer T3 was also deadI made one experience: I removed the transformer T3 and I connected an external transformer (12 DC) on output. After that, I connected the negative pole to a negative pole on primary side (on primary side have one bridge retifier). I was also change the thermistor near Viper53. Works like a charmRegards,David Teixeira

author: biank88
author_rank: Contributor
timestamp: June 14, 2019, 08:59:24 am
content: Thanks Nuno for your immense effort to put down a schematic for this hell made ac/dc converter. I happen to have the same exact board and I've managed to repair the AC/DC section thanks to your schematic. I just want to note thatthe RC pair indicated in your schematic is not correct; in fact for an operating frequency of 100KHz the values should be R22: 6.8KOHm and C93: 2.2nF. I've updated your schematic with the correct values. Also, in the attachment there are two pictures showing the pcb top area near the Viper53 chip, before and after the cleaning, where you can see the silkscreen values for the smd RC pair (R22 and C93).Bye

author: nuno
author_rank: Frequent Contributor
timestamp: June 16, 2019, 11:03:52 pm
content: Hello biank88, glad you find the information usefulI've updated my posts to point to your updated schematics, thanks!Cheers!