Power Supply Failure - Page 1
Forum section: electronics / beginners

author: rbleth51
author_rank: Contributor
timestamp: April 04, 2020, 03:14:50 pm
content: Hello all. This will be my first of hopefully many posts. I am new to the electrical world. I started out in mechanical engineering, but life has thankfully led me to the EE world.I have been given a CIC brand PS-1930 DC power supply that had failed. I believe it is one of the many rebadged HY3003D units. When powering up with all 4 adjustment knobs at "0" I get 0.00 on the current display and -00.5 on voltage.The real problem comes as soon as I advance the current limit up. As soon as I adjust in any real amount of current the relays click and voltage jumps to 55-56 on the display. This is confirmed on 2 different meters.When I fist opened it the only obvious issue I found was a cap with a bad solder joint (loose), the one circled in the pic. I touched it and after putting everything back together it appeared to function correctly for about a minute. Then right back to 56V. All of this is open circuit, no load.Can anyone suggest how to proceed to troubleshoot. I have a decent assortment of test instruments and a decent iron. I am only 8n my 2nd semester of school for EE so am very green. But I will really appreciate any and all advice and help. Thanks!

author: xavier60
author_rank: Super Contributor
timestamp: April 04, 2020, 09:18:37 pm
content: Difficult without a schematic.Using a suitable load, test to see if the Constant Current side functions properly.Does it have CC and CV indicator LEDs?

author: Manul
author_rank: Super Contributor
timestamp: April 04, 2020, 09:57:10 pm
content: Looks like voltage control loop went out of control. Probably lost feedback.If after reassembly you saw a unit working correctly - that is important. Based on that, let's call this failure intermittent. It means, that there is probably nothing permamently damaged.For strange intermittent problems you may:1. Shake wires, connectors.2. Poke components with plastic stick.3. Flex PCB slightly.4. Do thermal stress: warm up components with hot air (not too much obviously), cool down with freeze spray.Normally, you want to do these things on a unit while it is working to observe any changes, so take huge care and safety!!Maybe there is more of these bad solder joints, maybe unit experienced excesive vibrantions. Sometimes cracked solder joints are not visible by naked eye (but often react to poking or thermal stressing). Take very good look in the control board for any components which might be affected by vibration - standing, massive components which are not fixed or glued. Also in the areas where components experience thermal cycling (areas which get hot when in operation).Also sometimes bad electrolytic capacitors cause random instability (not very likely in this case).Can be glue used on PCB (some of these glue get conductive with time).Good luck troubleshooting.

author: rbleth51
author_rank: Contributor
timestamp: April 04, 2020, 09:59:50 pm
content: xavier60,It does have CC anc CV indicator LEDS. When hooked to a large resistance load (and old heating element) it appears that CC is working. As I ramp up the current knob (fine and coarse) the CC LED stays lit for quite a while. Eventually it goes out and voltage rises to around 45V. It is supposed to be a 30V, 5A power supply. The current reading on the display did track pretty close to what my meter was reading it to be. Voltage does the same. But rotating either of the voltage adjustment knobs has no effect. I can't see any obvious problems (blown components, puffy caps, burn marks, loose wires, etc.). But that doesn't mean there are none, I could be just not seeing them.I was kind of hoping someone here could point me toward a schematic. Although I am not skilled enoough as yet for it to be a real big help, it would certainly be of some assistance. I Googled the HY3003D and found a schematic, that to my eye, greatly resembled what I have. The pots for adjusting the current and voltage were of the same value, 1k and 6.8k for fine and course. I am not sure if I am allowed to post the schematic I found here or not.Thanks.

author: rbleth51
author_rank: Contributor
timestamp: April 04, 2020, 10:02:49 pm
content: Manul, I have tried a lot of those suggestions, but definitely not freeze spray. I don't have any or any substitute at this time. I will look into getting some keyboard cleaner or something I can use like that next time I am out. I will certainly go everything again following your suggestions. Thanks!

author: xavier60
author_rank: Super Contributor
timestamp: April 04, 2020, 10:20:53 pm
content: Yes, post the schematic.

author: rbleth51
author_rank: Contributor
timestamp: April 04, 2020, 10:28:23 pm
content: This is the one. Like I said, not sure if it is exactly mine, but to the best of my limited knowledge it is.

author: james_s
author_rank: Super Contributor
timestamp: April 04, 2020, 10:28:35 pm
content: I have no familiarity at all with this particular power supply but...Does it by chance have the option of Kelvin sensing of the voltage outputs? IE instead of monitoring the output voltage internally, some PSUs have separate inputs where you can connect wires to sense the actual voltage supplied at the load which compensates for any drop in the wires. If you accidentally set it up to do this without having those sense wires connected then it will behave very much like you are seeing.

author: rbleth51
author_rank: Contributor
timestamp: April 04, 2020, 10:33:35 pm
content: james_s, I wish, but no, no such option. This is just a cheap Chinese unit by the looks of things. Just the three outputs on the front (+), (GND), and (-). The only things on the back are AC in, the fuse, and the 110V/220V switch, which is set to 110V. And I am plugged into a 110V outlet.

author: james_s
author_rank: Super Contributor
timestamp: April 04, 2020, 10:40:51 pm
content: Well I would start then by testing the pass transistor(s) on the heatsink to see if one of those is shorted, and then see if you can work out the feedback path in the regulator circuit.

author: Manul
author_rank: Super Contributor
timestamp: April 04, 2020, 10:51:37 pm
content: Now when you have schematic you can first check internal supplies, that is always a good thing. I saw +12, -12, -6 and two isolated 5 volt supplies (so check on C9 and C19).Also voltage on a wiper of 6.8K pots, does it change while adjusting.

author: rbleth51
author_rank: Contributor
timestamp: April 04, 2020, 11:04:55 pm
content: james_s, I am pretty sure the answer is no, but is there any way to test the power transistors in circuit? Or am I warming up my Hakko and de-soldering them?

author: rbleth51
author_rank: Contributor
timestamp: April 04, 2020, 11:09:08 pm
content: I left the unit switched on for about half an hour after I poked, prodded (all with plastic stick), shook, and wiggled with no changes. A bit after shutting it down I noticed that the larger PCB had a very hot spot on it, pretty much too ho to touch. It was under the heatsink for the KA7812 voltage regulator. I would imagine it is supposed to get quite warm (needs a heat sink) but is that hot a probable sign of failure? Any good way to test?Thanks a ton!

author: Manul
author_rank: Super Contributor
timestamp: April 04, 2020, 11:11:57 pm
content: Special interest whould be to measure voltage on capacitor C13A. Or, if it is more simple - between negative out and W5 pot wiper. What kind of voltages it shows, if you set some current and then try to rotate voltage pot from min to max?

author: Jwillis
author_rank: Super Contributor
timestamp: April 04, 2020, 11:13:37 pm
content: Quote from: james_s on April 04, 2020, 10:40:51 pmThat would be my best guess as well. One or all the power transistors are blown shorted.

author: Manul
author_rank: Super Contributor
timestamp: April 04, 2020, 11:14:20 pm
content: Quote from: rbleth51 on April 04, 2020, 11:09:08 pmWell, is there 12 volts out on C3A (220uF 25v capacitor). If yes, do not worry much for now.

author: Manul
author_rank: Super Contributor
timestamp: April 04, 2020, 11:16:09 pm
content: Transistors should not be dead if CC works, and also it was observed to be working for a minute or so and then failed again.

author: xavier60
author_rank: Super Contributor
timestamp: April 04, 2020, 11:35:35 pm
content: I hope the schematic matches, it will be a great help although a bit confusing to me.The CV LED is included in the path of the CV regulation loop. If it goes open circuit, the output voltage will go uncontrollably high.

author: Jwillis
author_rank: Super Contributor
timestamp: April 04, 2020, 11:43:03 pm
content: Quote from: Manul on April 04, 2020, 11:16:09 pmIt will do that because the low current from the darlinton pair that drive the power transistors. If those power transistors are shorted then the current from the darlinton will pass through them . When a threshold current is detected at R15 the LM324 kicks the relay on . This puts the full voltage across the blown power transistors. Full voltage ends up at the output.

author: xavier60
author_rank: Super Contributor
timestamp: April 04, 2020, 11:49:08 pm
content: The possibility of the CV LED causing the problem can be tested by bypassing it.Next is to see how accessible the CV op-amp is, N1.

author: Manul
author_rank: Super Contributor
timestamp: April 05, 2020, 12:05:04 am
content: Quote from: Jwillis on April 04, 2020, 11:43:03 pmSo if I understand correctly, you are suggesting that in CC mode (kinda working, as OP said) darlington was an actual voltage dropper and not 3055?

author: rbleth51
author_rank: Contributor
timestamp: April 05, 2020, 12:49:24 am
content: Manul I do have 12.36V on that cap, I believe. It is labeled C3 on my board, but it is across the output and ground legs of the the voltage regulator and is rated 25V, 220u.What is my best bet for testing the transistors? I am assuming I need to remove them from the circuit to do it.

author: Manul
author_rank: Super Contributor
timestamp: April 05, 2020, 01:02:57 am
content: Quote from: rbleth51 on April 05, 2020, 12:49:24 amThat is great. Please look at the reply #13 and also reply #17 (is CV LED working or no?) I whould say, that is control issue, not bad transistors.

author: rbleth51
author_rank: Contributor
timestamp: April 05, 2020, 01:09:54 am
content: Manul, the CV LED does not appear to be working. Unfortunately my schematic reading skills are more than a but lacking at this time, and my boards ar not labeled identically to the schematic. The W5 pot is one of the 2 6.8k pots, but would it be the one for adjusting current of voltage? Sorry for all the newby questions.

author: Manul
author_rank: Super Contributor
timestamp: April 05, 2020, 01:19:37 am
content: To test for bad transistors in this case you can simply measure resistance between main input capacitor C6A "+" side and positive output of power supply. Turn off unit before doing that. Also let capacitors discharge.

author: Manul
author_rank: Super Contributor
timestamp: April 05, 2020, 01:24:34 am
content: Quote from: rbleth51 on April 05, 2020, 01:09:54 amIf CV LED is never lit, it may mean that it is something broken with it as xavier60 noted. And he also suggested a test - to bypass this LED.

author: Manul
author_rank: Super Contributor
timestamp: April 05, 2020, 01:30:15 am
content: Yes, I was talking about measuring voltage between negative output and voltage control 6.8K pot wiper. How is it changing when going from min to max?

author: rbleth51
author_rank: Contributor
timestamp: April 05, 2020, 12:10:05 pm
content: As far as I could measure I saw no change of the voltage on the wiper as I rotated the pot. I will pop the board out or try to get better access to it and try again. But I was reading 55V-56V on my meter the whole time. I will also try to bypass the LED and see if it brings any change.

author: Manul
author_rank: Super Contributor
timestamp: April 05, 2020, 01:04:45 pm
content: Quote from: rbleth51 on April 05, 2020, 12:10:05 pmWell, maybe you just found fault. Your measurment should mean that there is no connection between 6.8K and 1K pots, 6.8K pot is broke, 1K pot is broken, or 1K pot is not connecting to negative output.

author: Manul
author_rank: Super Contributor
timestamp: April 05, 2020, 01:09:10 pm
content: If you observe W5 pot in the schematic, you can see that one side goes up througth some resitances to +12. Another goes down to W7 1K pot (fine adjustment) and down to negative output of your unit. This down path from W5 must be checked really good.

author: rbleth51
author_rank: Contributor
timestamp: April 05, 2020, 07:36:58 pm
content: I removed both the 1k and the 6.8k pots from the current adjust side of the board and both seem to function correctly according to my meter. I have solid continuity between the output pad for the 1k pot and the negative uotput of the unit. Looking through the connections I do not see any problems, although there still could be some.When checking the pots in circuit, just out of curiosity, I found some strange behavior. I realize this could be due to in circuit effects, but it made me wonder if it indicated issues further up the line in the circuit. Once pot showed no change at all when adjusting. It was like the was a short across it. But as I said, out of circuit it seems normal. Could this be an indication of a bad cap, like C13A in the schematic? Unfortunately me ESR meter will not be arriving until mid May so I have no way, that I know of to test them. I would like to just preemptively replace all the electrolytic caps, it is cheap enough I think, with good brand new ones. But I don't know enough about caps tp be sure I am buying the right replacements. I can obviously match voltage rating and capacitance, and make sure I get at least the same temp rating. But I don't know what "Series", "Grade", etc. to get.Any thoughts on any of this? Thanks again for all the advice. I am always learning and looking forward to the day when I can give back and help someone else.

author: Manul
author_rank: Super Contributor
timestamp: April 05, 2020, 08:52:59 pm
content: So you want to say, that the output of the unit is always at ~45v (+- does not matter) and the voltage between negative out and W5 wiper (I called it point "X") always stays at ~55v (again, +-) ? Like is shown in the schematic down below?

author: xavier60
author_rank: Super Contributor
timestamp: April 05, 2020, 10:15:28 pm
content: Voltage readings of all pins on the op-amp could be useful. Readings must be with respect to the positive output terminal.

author: rbleth51
author_rank: Contributor
timestamp: April 05, 2020, 10:41:26 pm
content: Manul, the voltage was 45V with the large load attached. It is 55V open circuit.

author: rbleth51
author_rank: Contributor
timestamp: April 06, 2020, 08:43:58 pm
content: xavier60, I am assuming you are referring to the UA741CN chip? There are 2 of them on the board. Or the LM324?

author: xavier60
author_rank: Super Contributor
timestamp: April 06, 2020, 10:10:23 pm
content: Quote from: rbleth51 on April 06, 2020, 08:43:58 pmJust the UA741CN,N1 it does the voltage regulation.

author: rbleth51
author_rank: Contributor
timestamp: April 06, 2020, 10:19:44 pm
content: Which one? There are 2 seperate chips. Or both?

author: xavier60
author_rank: Super Contributor
timestamp: April 06, 2020, 10:22:52 pm
content: N1, if the schematic matches.

author: rbleth51
author_rank: Contributor
timestamp: April 06, 2020, 10:44:53 pm
content: I pretty sure it was going to be N1. The schematic does appear to match in this area. This will be with all 4 front panel knob adjustment pots turned all the way up (during proper function max current, max voltage). Positive lead pf meter to positive output of power supply, negative lead of meter to pin.Pin 1: 6.21VDCPin 2: 4.5mVDCPin 3: -2.41VDCPin 4: 6.27VDCPin 5: 6.27VDCPin 6: -11.65VDCPin 7: -12.23VDCPin 8: -3.6mVDC

author: xavier60
author_rank: Super Contributor
timestamp: April 06, 2020, 11:04:36 pm
content: Quote from: rbleth51 on April 06, 2020, 10:44:53 pmYou should have had your black probe on the positive terminal.It just means that polarities of the measurements are transposed."Pin 3: -2.41VDC" is very close to the 2.5V reference voltage from the TL431.It means that there is an open circuit somewhere along the string that includes R40.Set the voltage control to some mid point for further testing.

author: Manul
author_rank: Super Contributor
timestamp: April 06, 2020, 11:13:24 pm
content: xavier60, I'm sorry, I added confusion with my doubt about original schematic. I will delete it. OP confirmed that his version is more correct.

author: Manul
author_rank: Super Contributor
timestamp: April 06, 2020, 11:34:43 pm
content: I started doubting schematic because things do not add up. Based on a constant voltage on W5 wiper, I made a conclusion, that there should be missing connection to negative terminal, but rbleth51 said that he checked it and it seems ok. I noticed that on another schematic W5 is a current control pot. So yeah. Things do not add up, but original schematic confirmed to be "correct" one. Except that obviously it is missing ground on 741 negative input

author: xavier60
author_rank: Super Contributor
timestamp: April 07, 2020, 12:06:39 am
content: Voltages on all 3 pins of W5(6.8K) might be useful. WRT positive terminal.

author: rbleth51
author_rank: Contributor
timestamp: April 07, 2020, 12:15:34 am
content: Voltage control set to approximate mid point. Meter leads swapped for correct polarity.Pin 1: -6.2VDCPin 2: -4.4mVDCPin 3: 2.44VDCPin 4: -6.25VDCPin 5: -6.25VDCPin 6: 11.69VDCPin 7: 12.3VDCPin 8: 0VDC

author: rbleth51
author_rank: Contributor
timestamp: April 07, 2020, 01:07:07 am
content: Black probe to positive output still, Red probe to W5 pins:Pin going to W7: -56VDCWiper/Center Pin + Reamining Pin: 2.4VDCThese two pins are connected by a trace on the PCBThere is only a few mV change on any of the pins as the pot is rotated stop to stop.

author: Manul
author_rank: Super Contributor
timestamp: April 07, 2020, 01:17:02 am
content: Quote from: rbleth51 on April 07, 2020, 01:07:07 amPot W5 has broken (disconnected) arm. Lower one, which goes to W7. Solder joint or internal failure of the pot.

author: Manul
author_rank: Super Contributor
timestamp: April 07, 2020, 01:23:39 am
content: If it is internal failure it means they are shitty ones. Replace all four.

author: eblc1388
author_rank: Frequent Contributor
timestamp: April 07, 2020, 01:52:52 am
content: Quote from: rbleth51 on April 07, 2020, 12:15:34 amrbleth51, can you confirm the circuit connection on N1 pin#2 is as shown in the attached image? If that is the case, then N1 pin#2 and #3 should be about zero volt w.r.t. the positive output terminal.Judging from your voltage readings, it points to faulty W5 as Manul had said above. Please unsolder it and check its resistance carefully.hope this helps.

author: rbleth51
author_rank: Contributor
timestamp: April 07, 2020, 02:17:52 am
content: From the very beginning when this unit came into my possession not working I wondered if the pots may have been to blame. But as I dug into it the reason that caused me to believe it was proven wrong. I sure hope that it is that simple though.Pulling the 1K off to measure will have to wait for morning. It is time for bed and the wife is already irritated about this unit and the time I am spending on it.I would like to replace all 4. I searched around the other day and was unable to find a 6.8K replacement. The 1k seemed easy enough. I am also unsure what to look for in them as far a specifications go, other than resistance. I have attached a couple pics. Sorry about the poor quality, I was rushing and my hand was not steady. I am fairly sure I can track down the 1K eventually. But the only 6.8K's I have found have a very different form factor. Anyone have any ideas?

author: Manul
author_rank: Super Contributor
timestamp: April 07, 2020, 02:36:48 am
content: Well, I said that it is path to negative output to be checked, and the W5 pot is itself part of this path. It will be 6.8K broken (or a solder joint on PCB). Form factor looks standard, should not be hard to order.

author: xavier60
author_rank: Super Contributor
timestamp: April 07, 2020, 03:02:29 am
content: Old trimpots commonly develop a dead spot where the wiper has been sitting. Working it after applying some lubricant can be a permanent fix.I use PAO oil. Any high quality wax free oil should also be suitable like sewing machine oil. I just happen to have lots of PAO at hand for aircon repairs.

author: eblc1388
author_rank: Frequent Contributor
timestamp: April 07, 2020, 03:29:32 am
content: Quote from: rbleth51 on April 07, 2020, 02:17:52 am6K8 carbon film variable resistor is rare and might only be available from AliExpress in China. Your other option will be wire wound type which is both large in size and expensive. As the last resort, you should be fine to use a 10K variable resistor instead for W5 with W6A changed into a 2K multi-turn resistor as shown.

author: Manul
author_rank: Super Contributor
timestamp: April 07, 2020, 10:49:13 am
content: 10K pot will be fine if you also change R16 470 ohms resistor to something like 750 ohms resistor. That would be easiest solution. And then W6 can be adjusted to have the exact max point (30v output).

author: rbleth51
author_rank: Contributor
timestamp: April 07, 2020, 01:38:49 pm
content: That looks like my best option. 6.8K carbon film pots that match my form factors are near impossible to find. But 10K are everywhere. Any suggestion for wattage rating on the pots?

author: Manul
author_rank: Super Contributor
timestamp: April 07, 2020, 02:16:28 pm
content: Max pot power dissipation in this circuit will be around 90 mW. So rating should be more. I guess all of them in this form factor will be rated for a lot more.

author: rbleth51
author_rank: Contributor
timestamp: April 08, 2020, 12:51:38 am
content: I have ordered replacement pots, 10k and 1k. I also ordered a 750k resistor to replace R16. In the meantime I am going to start working on getting all th electrolytics specked out and ordered. I might as well replace them all while I have it all apart.Thanks so much again to everyone for all the help and advice. I will post my results after the parts show up and I solder them in.

author: james_s
author_rank: Super Contributor
timestamp: April 08, 2020, 06:51:57 am
content: Why mess with the capacitors? Linear power supplies are typically gentle on caps, I have 40+ year old devices with all the original capacitors. I've seen a lot of instances where someone shotgun replaced a bunch of perfectly good capacitors with cheap crap.That said, this being a low cost power supply the capacitors may be poor quality off-brand stuff to begin with.

author: rbleth51
author_rank: Contributor
timestamp: April 08, 2020, 09:01:05 pm
content: Yep, these are cheap no name Chinese caps. I am going to order Rubicon or Nichicon. They are cheap enough for the amount I need and I will order extras to build up my part stockpile some.

author: james_s
author_rank: Super Contributor
timestamp: April 09, 2020, 04:33:19 am
content: Rubicon and Nichicon are some of my favorites as well, Panasonic also seems to be quite good. Fix the fault before you mess with the capacitors though, doing one thing at a time makes it easier to know if you've messed up somewhere.

author: rbleth51
author_rank: Contributor
timestamp: April 09, 2020, 09:38:39 am
content: That is the plan. I am just going to spec them out and get them ordered while I wait for the other parts to arrive. Should be here by the weekend. I have plenty of time given we are quarantined here.

author: rbleth51
author_rank: Contributor
timestamp: April 16, 2020, 09:46:11 pm
content: Well, I found the culprit. The pots were not at fault after all. I was twisting things around to get a better angle to solder when this caught my eye. It was kind of hidden and I missed it when inspecting before. Changed it our and everything works fine. The hole did not look like the pic when I found it. I did a little digging after I got it out. I am guessing the brief moment of functionality I saw after I initially opened it up and put it back together was what finished this diode off for good. It was across one of the relays. The picture isn't the best, but you easily get the idea. Thanks again to all who helped and offered advice.

author: xavier60
author_rank: Super Contributor
timestamp: April 16, 2020, 10:08:57 pm
content: Quote from: rbleth51 on April 16, 2020, 09:46:11 pmThings need to make sense and that doesn't. The voltage measurement you took earlier pointed directly at the Pot as bring the cause of the loss of regulation. Is the diode across a relay coil?

author: Manul
author_rank: Super Contributor
timestamp: April 16, 2020, 10:19:32 pm
content: Quote from: rbleth51 on April 16, 2020, 09:46:11 pmWell, that must be just coincidence. Maybe the pot just got into contact accidentaly, so it started working (and it will fail one day again). Makes no sense. First, these diodes do not experience big stress, so how it failed? Second, even with a failed relay diode it whould not have the symptoms you seen (which was clearly feedback loop problem).

author: Manul
author_rank: Super Contributor
timestamp: April 16, 2020, 10:23:31 pm
content: And if this diode is toast like that, control transistor should be too. Maybe it is mechanical damage. By the way, I just saw, that you ordered 750k resistor to replace R16. It should be 750 ohms, not kiloohms.

author: rbleth51
author_rank: Contributor
timestamp: April 17, 2020, 12:19:39 am
content: Wow, I am really stepping in it lately. First, Manul, 750K was a typo. I must have had K on my mind. I did get 750 Ohm. And you are all correct, as you knew you were. It was one of the 6.8K coarse adjustment pots. I had the 750 ohm soldered in and the two 10K pots as well when I saw the diode. I got excited and changed it. Then I powered up to check and it was working. I did not stop to think things through. Of course that diode across the relay would not cause the problem I had. But I have been in quarantine to almost 4 weeks now and very sick for three of those along with the wife. Not sure if we had Covid as there are not enough test kits, so no test unless you are bad enough to be admitted to the hospital. But the doc was pretty sure that is what was up.Anyway, I will admit my foolishness. I got excited. Powered down and waited for the caps to bleed off. Then swapped everything, but the diode, back to original. You know what comes next. Back to the same 56V on output problem. So out the 6.8K's and original resistor come and back in the 10K's and 750 resistor. Imagine this, it works great. Time will tell, but is has run longer now than it has since I owned it.At least I learned a lot. Now I just need to find a carbon film 1K that matches the form factor of the originals so I can get those replaced too. They feel a bit crusty and I have nothing like what was mentioned before to lubricate them. I am surprised how hard a time I am having trying to find replacements at places like Digikey and Mouser. The shaft is 6mm diameter, the back can is about 16.4mm diameter and it is about 24.4mm from the back of the can to the tip of the shaft, about 9.75mm from the tip of the shaft to the thread. I have found a few close, but all had some detail that made it not work. The picture is of one of the 6.8K's. All four were the same form factor.Thanks again everyone.

author: james_s
author_rank: Super Contributor
timestamp: April 17, 2020, 12:25:57 am
content: Quote from: rbleth51 on April 17, 2020, 12:19:39 amI hate that. Don't feel too bad, it happens to the best of us sooner or later. I've ordered the wrong order of magnitude resistor probably half a dozen times over the years.

author: rbleth51
author_rank: Contributor
timestamp: April 17, 2020, 12:29:01 am
content: I ordered the right one, lol. I just got excited and typed it wrong in my post.

author: Manul
author_rank: Super Contributor
timestamp: April 17, 2020, 12:53:01 am
content: Hope you all get fully well with your health. Wish you all good.Congratulations on your power supply. Also, you should change that diode. Is that relay clicking when it should? In general, such a failure like you had is very dangerous. Imagine if you power some nice electronics with your supply and it suddenly goes out of regulation and gives 50V. There would be sad consequences. So finish your repair with care and solder everything good.

author: rbleth51
author_rank: Contributor
timestamp: April 17, 2020, 01:42:12 am
content: The diode was changed as soon as I saw it. Just need to get the 1K pots sourced now and I still want to go through the electrolytics. And thank you for the well wishes!

author: max.wwwang
author_rank: Frequent Contributor
timestamp: April 17, 2020, 09:34:35 am
content: Nice. You got it sorted. Congrats.You got no excuse not to become a decent EE thanks to your good gears!