Troubleshooting an old 24V charger

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rhills
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Troubleshooting an old 24V charger

Post by rhills » Thu, 25 Oct 2018, 19:34

Hi all,

I have an old 24V charger that died several years ago (no status lights, no charging) and I haven't had the time or the motivation to investigate until recently.

So, today I tried taking the lid off to see if I could work out what was wrong. The outside of the charger looks like this:
24V-charger-tecsup-baintec-lores.jpg
Tecsup/Baintech 24V charger
24V-charger-tecsup-baintec-lores.jpg (51.53 KiB) Viewed 1575 times
Initially misled by the big "Baintech" sticker on it, I worked out that the manufacturer is the French company Tecsup and I think the model is "Hi-tec", but of course they don't make that model anymore. Unfortunately their website doesn't have any legacy product manuals.

When I opened up the charger, I looked for obvious scorching but didn't see any.
24V-charger-tecsup-baintec-pcb-lores.jpg
Tecsup/Baintech 24V charger PCB
24V-charger-tecsup-baintec-pcb-lores.jpg (958.35 KiB) Viewed 1575 times
There are two fuses on board, the one in the 240V part of the circuit (PF1 near top right) and one in the 24V part of the circuit (unlabelled? right of middle, left of the Battery Earth connection. The 24V fuse was blown so I replaced that. The fuse on the AC input side has a small molten blob in the middle of the wire, but I can't see any break in it and the multimeter (on Diode setting) indicates that it hasn't blown.

With the new DC fuse, it still doesn't light up or produce any voltage on the battery output terminals.

What else can I check to try and work out if this charger is repairable? Can anyone see evidence on the PCB of something that has failed? After fuses, is there any component more likely to fail than the rest? Is the "blobby" bit on the AC fuse likely to cause malfunction?

Any suggestions/thoughts welcome.
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Re: Troubleshooting an old 24V charger

Post by coulomb » Thu, 25 Oct 2018, 20:23

rhills wrote:
Thu, 25 Oct 2018, 19:34
After fuses, is there any component more likely to fail than the rest?
Yes, the power semiconductors. In your case, the 4 diodes rectifying the AC near the top of your photo, the MOSFET or transistor that drives the "transformer" (likely to really be a multi-winding inductor, and the split in the core indicates this), and the output diodes. It looks like the main diodes are the three dual diodes at the bottom (D13-D15), and I don't know what the other three diodes (D16, D18, etc) are for. You should see around 0.4 - 0.5 V in the forward direction across most diodes, and OVF in the other direction. Depending on the circuit details, "transformer" windings can confound these readings.

Since it's so dead, I'd also check the Negative Temperature Coefficient resistor (the black thing at the top between the blue capacitors and the four diodes). It's a sort of surge suppressor; initially it has some resistance (tens or hundreds of ohms), but quickly gets hot and reduces resistance. This allows the large capacitors to charge gently. If it's open circuit or high resistance, that would stop the charger from starting.
Is the "blobby" bit on the AC fuse likely to cause malfunction?
I've seen it before, and this page says it's to make the fuse a slow blow type. Despite the NTC, it will still see a surge of current at start-up. The blob acts like a mini heat-sink for the fuse wire, delaying fusing for a fraction of a second, unless the current is way past its nominal fuse current. [ Edit: so that's normal and expected. ]

It looks like there is a 20-pin microcontroller in a socket. Extract the chip half way and re-seat a few times; contact might have gone bad.

After that, you need experience with electronics, and it's likely not worth the time to repair it.

All through-hole components; quite rare these days.
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Re: Troubleshooting an old 24V charger

Post by rhills » Fri, 26 Oct 2018, 01:17

Hi Mike, thanks for your reply
coulomb wrote:
Thu, 25 Oct 2018, 20:23
Yes, the power semiconductors. In your case, the 4 diodes rectifying the AC near the top of your photo...
OK, I checked these but am confused by my readings so maybe I'm not doing it right. With the unit plugged in to 240VAC, I used the 500VAC setting on my multimeter (the other AC scale was 200V) and measured:
D4 = 328V
D5 = 294V
D6 = 328V
D7 = 294V

all in the forward direction, and clearly much larger than the 0.4-0.5V you suggested I should be measuring. Either they are all cactus (seems unlikely, would all 4 blow together?) or I'm doing something wrong. Should I have been using the DC setting to measure these?
coulomb wrote:
Thu, 25 Oct 2018, 20:23
...the MOSFET or transistor that drives the "transformer" (likely to really be a multi-winding inductor, and the split in the core indicates this),...
I'm sorry, I'm not sure which component(s) you're referring to here. Is the "transformer" the large yellow-tape-covered cylinder in the black plastic frame in the middle of the PCB or something else? I couldn't see anything that I could identify as having a "split in the core".
coulomb wrote:
Thu, 25 Oct 2018, 20:23
...and the output diodes. It looks like the main diodes are the three dual diodes at the bottom (D13-D15),...
I didn't try and measure the voltage across these, do I use the AC setting or DC? And which of the 3 feet do I measure between? Also, it may not be obvious in the picture and may not be relevant, but these diodes have quite a bit of white-brown grunge around their feet - ? cooked flux ?
coulomb wrote:
Thu, 25 Oct 2018, 20:23
... You should see around 0.4 - 0.5 V in the forward direction across most diodes, and OVF in the other direction.
OVF? For Diodes D4-D7 I measured 0 VAC
coulomb wrote:
Thu, 25 Oct 2018, 20:23
Since it's so dead, I'd also check the Negative Temperature Coefficient resistor (the black thing at the top between the blue capacitors and the four diodes). It's a sort of surge suppressor; initially it has some resistance (tens or hundreds of ohms), but quickly gets hot and reduces resistance. This allows the large capacitors to charge gently. If it's open circuit or high resistance, that would stop the charger from starting.
Well this one at least I got right (I believe). I measured 13 Ohm which suggests to me it's OK based on your description.
coulomb wrote:
Thu, 25 Oct 2018, 20:23
It looks like there is a 20-pin microcontroller in a socket. Extract the chip half way and re-seat a few times; contact might have gone bad.
Well, that was very difficult to get at and in trying to prise it part-way out, I not only flipped it out altogether, but also bent several legs, two of them to 90° :x . Fortunately I managed to straighten the legs without snapping any and replace the IC in its socket without bending/damaging the legs further. Needless to say I didn't try reseating it again :oops:
coulomb wrote:
Thu, 25 Oct 2018, 20:23
After that, you need experience with electronics, and it's likely not worth the time to repair it.
It seems like I need more experience with electronics just to get through what you've described above, but hopefully I can get that done at least.

As a good quality replacement is likely to set me back many hundreds of $$, I'd like to resuscitate it if it is at all possible.

FWIW, while there are no lights, something clicks when I power the charger up.

TIA,

Rob
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Re: Troubleshooting an old 24V charger

Post by coulomb » Fri, 26 Oct 2018, 06:40

rhills wrote:
Fri, 26 Oct 2018, 01:17
OK, I checked these but am confused by my readings so maybe I'm not doing it right. With the unit plugged in to 240VAC, I used the 500VAC setting on my multimeter (the other AC scale was 200V) and measured...
Eek! I'm glad to know that AEVA still has a webmaster. Sorry, I neglected to say some really important things, that to me are really obvious, so I forget that beginners need to know them.

Chargers that connect to the mains contain dangerous voltages, that could lead to death. It's highly advisable that most if not all measurements be performed with the power OFF. For about a minute after the power is turned off, there will still be dangerous potentials from energy stored in capacitors.


Semiconductors are best tested with the power off, using the diode range of the multimeter. I assume that all multimeters have a diode range these days. The multimeter provides a tiny current from its battery to the device under test, and measures the voltage that results. For a forward biased ordinary diode, this should be about 0.4 - 0.5 for power types (the larger the power, the lower the voltage, really high power devices might read down to 0.35 V). In the other direction (reverse the muiltimeter leads), it should read infinite, usually displayed as "OL" for "OverLoad".

Diodes have an anode and a cathode. To forward bias a diode, you need the more positive voltage on the anode, and the more negative on the cathode. Usually, the cathode is marked with a band near one end; these are obvious on your two legged diodes in the photo (cathodes are all towards the bottom of the photo). Sometimes, two diodes are packaged together in one part; that's the case for D13-D15 at the bottom of the photo. Unfortunately, there is no consistency with anode and cathode connections with these; you have to find the part number and look up the datasheet. It may not be easy to see the part number in this case. But if you find about 0.4 V in one direction and OL in the other, you can be pretty confident that it is OK.

Usually, you need to test both halves of a dual diode independently. With three leads, two of the diode connections have to be commoned (they are connect to each other and share the same lead).

In your case, at least D13 appears to have the outer two pins connected together with thick printed circuit board track. It's a moderately safe bet to assume that the others are the same. With three of these, it's likely that the whole lot are paralleled, so you have six diodes in parallel. This is to share the current between them all. It looks like this is more than a three amp charger. So just treat all those bottom diodes as one diode, and use the middle and either outer pin to test. You should still see about 0.4 V one direction, and OL the other direction.
coulomb wrote:
Thu, 25 Oct 2018, 20:23
...the MOSFET or transistor that drives the "transformer" (likely to really be a multi-winding inductor, and the split in the core indicates this),...
I'm sorry, I'm not sure which component(s) you're referring to here. Is the "transformer" the large yellow-tape-covered cylinder in the black plastic frame in the middle of the PCB or something else? I couldn't see anything that I could identify as having a "split in the core".
Yes, the transformer is the large thing in the middle with the yellow tape. For whatever reason, it's nearly always yellow for inductors and transformers. The MOSFET or other transistor will be on the heatsink to the left of that transformer.

I meant to add a little about coils confounding diode readings. Coils of copper wire have nearly zero resistance. In operation, they have voltages induced into them, but it's not practical or safe to do this while measuring. So sometimes something will appear to be short circuited, when it fact it merely has a coil connected to it, and that circuit disturbs the reading. Usually, it's not practical to take the component out of circuit to test it. So you just have to use your experience (or mine, or others) to decide whether that part is going to be so affected, or not. Of course, other parts can also do this. The other common confounding components are the large capacitors. Where you expect to see OL across some diode or semiconductor junction, you might see a low voltage that slowly climbs and reaches OL in about 10 seconds. This is due to the large value (100 μF or greater) capacitor appearing to be a short circuit until it is charged up, where it becomes effectively open circuit. At the very low currents from a multimeter, it can take seconds for this change to occur. Again, experience will tell you if this is expected. As a rough guide, if you see this, treat it as normal unless and until other evidence says otherwise.
Also, it may not be obvious in the picture and may not be relevant, but these diodes have quite a bit of white-brown grunge around their feet - ? cooked flux ?
It's just flux. This is surprisingly common (to me at least) in chargers. I can't stand it and often clean it off with a cotton bud soaked in metho, but it's safe to leave it alone.
OVF? For Diodes D4-D7 I measured 0 VAC
By OVF, I meant overload, which on most multimeters will show as OL, as already mentioned. The fact that you don't see any AC voltage across those diodes means that they are not getting any power. Measuring AC across diodes gives you a rough indication of the voltage that they are blocking. If they aren't blocking anything, then they're not doing anything useful, either because they are short circuited, or because some upstream failure causes them to receive no power.
coulomb wrote:
Thu, 25 Oct 2018, 20:23
Since it's so dead, I'd also check the Negative Temperature Coefficient resistor...
Well this one at least I got right (I believe). I measured 13 Ohm which suggests to me it's OK based on your description.
Well done.
coulomb wrote:
Thu, 25 Oct 2018, 20:23
It looks like there is a 20-pin microcontroller in a socket...
Well, that was very difficult to get at and in trying to prise it part-way out, I not only flipped it out altogether, but also bent several legs, two of them to 90° :x . Fortunately I managed to straighten the legs without snapping any and replace the IC in its socket without bending/damaging the legs further. Needless to say I didn't try reseating it again :oops:
Presumably, that didn't make it come back to life, or you would have reported that. Good to know that it seems to be OK.
FWIW, while there are no lights, something clicks when I power the charger up.
That's an indication that power is getting at least part way through the path from mains to battery. I see no evidence of a relay. My guess is that the fan receives power briefly. It might not get it long enough to turn the blades noticeably, unless you are looking very carefully at it. The other possibility is the film capacitors, like the grey one near the connector where the mains lead comes in. These can often be acoustically active, and it's not clear to me whether this indicates failure or not. If you're interested, you could skim "The mystery of the faint crackling sound solved", where I describe Weber and I chasing this faint sound in another charger (an EV charger in this case). It could also be something arcing over. IF you can safely set it up without too much effort such that you can see under the board (it might even be above the board), you might be able to spot a tiny spark in a totally darkened room that goes along with the sound. This is obviously not good, and could be a root cause. Clearing away any accumulated dust (again using a cotton bud soaked in metholated spirits, many minutes after power is removed) might cure the problem. But more likely, it will have cause some part to fail.

You might be able to use Weber's trick, mentioned in the linked post about the mystery sound above. That is to use a large drinking straw or similar to act as a crude stethoscope, so that you can be more selective about where you are listening for the sound. Any sort of non conducting tube will work, perhaps a short piece of conduit.

Good luck with it, and please proceed with more caution. I note that slipped multimeter probes is a common cause of problems; I recently reprogrammed a processor from a car that lost several components, including the processor, due to slipped multimeter probes. With large through-hole components like this, it's less of a problem, but still worth avoiding.

[ Edit: fixed missing quotes; added a few paragraphs about identifying the transformer, and coils and capacitors affecting measurements. ]
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Re: Troubleshooting an old 24V charger

Post by Richo » Fri, 26 Oct 2018, 11:52

coulomb wrote:
Thu, 25 Oct 2018, 20:23
After that, you need experience with electronics, and it's likely not worth the time to repair it.
Usually in these cases I replace the active parts.
Its quicker than trying to diagnose random stuff.

My guess is
1. resonator - stops micro from running (Blue thing next to micro)
2. Output Power driver (on the heatsink)- blown from short / surge
3. Dead opto for feedback - no feedback, no output.

Otherwise if your in the metro area drop it off and I will have a quick squiz.

edit: wrong colour...
So the short answer is NO but the long answer is YES.
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Re: Troubleshooting an old 24V charger

Post by lobster » Fri, 26 Oct 2018, 14:43

Hi, I right clicked the Image of your front panel and Searched Google for image. On the results page, I added "tecsup hi tec" to the text box and found 14 images.

This is an old sales brochure link, it needs Jap to Eng online translate.

https://etech-japan.com/product/dokurit ... hitec.html

These 2 links are brochure PDFs

https://sed-wiki.inrialpes.fr/pub/Platf ... tterie.pdf

https://www.google.com.au/imgres?imgurl ... mrc&uact=8

If you search for "tecsup hi tec PDF" with your chargers name plate model details you may find an Online Manual.

The Manufacturer website has an online query page too. http://www.tecsup.fr/accueil/contact

Good Luck

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Re: Troubleshooting an old 24V charger

Post by rhills » Fri, 26 Oct 2018, 23:44

coulomb wrote:
Fri, 26 Oct 2018, 06:40
Eek! I'm glad to know that AEVA still has a webmaster. Sorry, I neglected to say some really important things, that to me are really obvious, so I forget that beginners need to know them.

Chargers that connect to the mains contain dangerous voltages, that could lead to death. It's highly advisable that most if not all measurements be performed with the power OFF. For about a minute after the power is turned off, there will still be dangerous potentials from energy stored in capacitors.
Thanks for the angst and the warning, Mike. Fortunately, I've been fooling with 240V long enough to have felt a couple of belts and not only survived them, but decided they're not very nice. So when I went about checking things with my multimeter with the unit powered up, I assumed everything was live with killable quantities of volts (including the metal case) and was very careful about where I probed, keeping all body parts well clear. That said, I did overlook donning some rubber gloves as an extra precaution, particularly silly as there was a large bag full of them less than a metre away :oops:
coulomb wrote:
Fri, 26 Oct 2018, 06:40
Semiconductors are best tested with the power off, using the diode range of the multimeter. I assume that all multimeters have a diode range these days. The multimeter provides a tiny current from its battery to the device under test, and measures the voltage that results. For a forward biased ordinary diode, this should be about 0.4 - 0.5 for power types (the larger the power, the lower the voltage, really high power devices might read down to 0.35 V). In the other direction (reverse the muiltimeter leads), it should read infinite, usually displayed as "OL" for "OverLoad".
Thank you for that succinct description. I'd always assumed the Diode setting just beeped to indicate a closed circuit and didn't beep when the circuit was open. I should have realised the numbers on the display meant something.

So, with my unit powered down for many hours to ensure residual electrons in the capacitors were at a minimum (and also because I was at work), my multimeter set to Diode setting, I measured the following (I'm guessing the units are millivolts?):
D4: 542
D5: 575
D6: 549
D7: 566

D16: 464
D17: 468
D18: 476

I'm guessing the differences aren't significant? My multimeter displays "1" for all diodes when I reverse the probe, the same as it displays when switched to the diode setting with an air gap between the probes, so I'm guessing "1" is its code for "OL"
coulomb wrote:
Fri, 26 Oct 2018, 06:40
Diodes have an anode and a cathode. To forward bias a diode, you need the more positive voltage on the anode, and the more negative on the cathode. Usually, the cathode is marked with a band near one end; these are obvious on your two legged diodes in the photo (cathodes are all towards the bottom of the photo).
Yes, a friend once told me to imagine the line on a diode as a "wall" blocking the electrons from entering that end. Works for me :)
coulomb wrote:
Fri, 26 Oct 2018, 06:40
Sometimes, two diodes are packaged together in one part; that's the case for D13-D15 at the bottom of the photo. Unfortunately, there is no consistency with anode and cathode connections with these; you have to find the part number and look up the datasheet. It may not be easy to see the part number in this case. But if you find about 0.4 V in one direction and OL in the other, you can be pretty confident that it is OK.
Those diodes are on the underside of the PCB and I'm hoping to avoid unscrewing the board from the case if I can, though I guess that will have to happen if/when I discover a defective component and have to replace it.
coulomb wrote:
Fri, 26 Oct 2018, 06:40
Usually, you need to test both halves of a dual diode independently. With three leads, two of the diode connections have to be commoned (they are connect to each other and share the same lead).
So, Diodes D13-D15 seem to have the middle pin as the common cathode. Measuring gives lower voltage than the previous ones, but much less variation:

D13: Left: 165 Right: 165
D14: Left: 166 Right: 166
D15: Left: 164 Right: 164
coulomb wrote:
Fri, 26 Oct 2018, 06:40
In your case, at least D13 appears to have the outer two pins connected together with thick printed circuit board track. It's a moderately safe bet to assume that the others are the same. With three of these, it's likely that the whole lot are paralleled, so you have six diodes in parallel. This is to share the current between them all. It looks like this is more than a three amp charger. So just treat all those bottom diodes as one diode, and use the middle and either outer pin to test. You should still see about 0.4 V one direction, and OL the other direction
Hmmm, should have read that before measuring them independently. Negligible resistance between the 3 left pins and between the 3 right pins confirms your theory. FWIW, measuring Diode voltage between the left leg of D13 and the middle leg of both D14 and D15 gives 194(mv?) in each case.

Oh, and the charger is rated at 10A DC so you're right, it is more than 3 :D
coulomb wrote:
Thu, 25 Oct 2018, 20:23
It looks like there is a 20-pin microcontroller in a socket...
Well, that was very difficult to get at and in trying to prise it part-way out, I not only flipped it out altogether, but also bent several legs, two of them to 90° :x . Fortunately I managed to straighten the legs without snapping any and replace the IC in its socket without bending/damaging the legs further. Needless to say I didn't try reseating it again :oops:
coulomb wrote:
Thu, 25 Oct 2018, 20:23
Presumably, that didn't make it come back to life, or you would have reported that. Good to know that it seems to be OK.
Yes, I meant to mention that it still wasn't working but you're correct to assume I'd have been whooping if it had come back to life :)
coulomb wrote:
Thu, 25 Oct 2018, 20:23
FWIW, while there are no lights, something clicks when I power the charger up.
That's an indication that power is getting at least part way through the path from mains to battery. I see no evidence of a relay.
Yes, I thought relay too but like you I don't see anything I recognise as a relay. Good thoughts about looking for fan movement when switching on (there was none) and also switching it on in the dark to look for any arcing, but none seen unfortunately. I've not tried to isolate the source of the click as my hearing is seriously defective and I don't localise sound well at all, even with the help of tubes, stethoscopes etc.

I might have to see if I can make my way to @Richo's place sometime and take him up in his generous offer to help out.

Many thanks,
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Re: Troubleshooting an old 24V charger

Post by rhills » Fri, 26 Oct 2018, 23:50

Hi Richard,
Richo wrote:
Fri, 26 Oct 2018, 11:52
Otherwise if your in the metro area drop it off and I will have a quick squiz.
Thanks for the thoughts and the offer, which I would like to take you up on at some stage.

I'll PM over the weekend and see if we can work out a mutually convenient day/time.

Cheers,
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Re: Troubleshooting an old 24V charger

Post by rhills » Fri, 26 Oct 2018, 23:53

Hi @lobster,
lobster wrote:
Fri, 26 Oct 2018, 14:43
Hi, I right clicked the Image of your front panel and Searched Google for image. On the results page, I added "tecsup hi tec" to the text box and found 14 images.
Thanks for the links, most of which I'd found in my own searches. I'd not thought of using the image to search, I need to remember to use that Google feature more! I may have to brush up my schoolboy French and use the manufacturer's contact page.

Cheers,
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Re: Troubleshooting an old 24V charger

Post by coulomb » Sat, 27 Oct 2018, 08:21

rhills wrote:
Fri, 26 Oct 2018, 23:44
Yes, a friend once told me to imagine the line on a diode as a "wall" blocking the electrons from entering that end. Works for me :)
But alas electrons flow opposite to "conventional current". But as long as you are imagining conventional current (from positive to negative), then that works. I hope I got that right.
So, Diodes D13-D15 seem to have the middle pin as the common cathode. Measuring gives lower voltage than the previous ones, but much less variation:

D13: Left: 165 Right: 165
D14: Left: 166 Right: 166
D15: Left: 164 Right: 164
So these may be Schottky diodes. These are acutally a semiconductor-metal junction, rather than the usual junction of two differently doped semiconductors. They usually break down at lowish voltages, like 40 VDC, so you can't use them on the mains side. But they have a very low junction voltage drop, often 0.2 to 0.3 V, and those readings seem OK for large Schottky diodes. So nothing stands out so far.

The last thing is to measure between various pins of the transistor on the heatsink, to the left of the transformer. If it's a MOSFET, you should be able to measure a diode between the drain (invariably the middle pin, and the case if a metal case is exposed), and the source (usually to the right of the drain, looking at the front of the transistor. The other pin is the gate; it is essentially open circuit (many mega-ohms), but will usually have a resistor from gate to source, typically 47 kΩ or 22 kΩ. But it could also be a bipolar (non-MOSFET) transistor, which should read like two diodes in anti-series. I could talk about base, emitter, and collector, but you don't need to know about those to test it as a pair of diodes. As with the other tests, these tests aren't testing the devices actively, but since they once worked and if they fail they often fail shorted (common) or open (less common), seeing diode-like voltage drops where expected is a strong indicator that it's still working.
Good thoughts about looking for fan movement when switching on (there was none) and also switching it on in the dark to look for any arcing, but none seen unfortunately. I've not tried to isolate the source of the click ...

I might have to see if I can make my way to @Richo's place sometime and take him up in his generous offer to help out.
Ok, so unless the transistor tests reveal a problem, that's your next logical step.
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Re: Troubleshooting an old 24V charger

Post by rhills » Sat, 27 Oct 2018, 10:38

Hi Mike, thanks again for your patience and detail,
coulomb wrote:
Sat, 27 Oct 2018, 08:21
rhills wrote:
Fri, 26 Oct 2018, 23:44
Yes, a friend once told me to imagine the line on a diode as a "wall" blocking the electrons from entering that end. Works for me :)
But alas electrons flow opposite to "conventional current". But as long as you are imagining conventional current (from positive to negative), then that works. I hope I got that right.
Ah, yes, I'm forgetting my secondary school physics, electrons are -ve and current flows from positive to negative, opposite to electron flow. So the explanation detail I had forgotten is that the line is "blocking" the current flow.
coulomb wrote:
Sat, 27 Oct 2018, 08:21
...The last thing is to measure between various pins of the transistor on the heatsink, to the left of the transformer.
What's not visible in the original circuit board photo above is the fact that there are actually two components bolted to that large heatsink, one either side, labelled T4 and D8:
component-t4-lores.jpg
T4
component-t4-lores.jpg (577.74 KiB) Viewed 1493 times
I'm guessing this is a Transistor, based on its PCB label. Googling its number (H8N80FI) turns up descriptions like "ST Power MOSFET N-channel enhancement mode H8N80FI transistor 800v 5.1A".

component-d8-lores.jpg
D8
component-d8-lores.jpg (689.89 KiB) Viewed 1493 times
I guessed from the D part of the label that this was another Diode, helped along by the diode symbol on its body :) . Google turns up a Mouser link for this and the linked datasheet confirms it as a "Fast Recovery Rectifier Diode". It measures 453mv (Diode setting on multimeter) in one direction and 1 in the opposite direction, so probably OK. Which is good as Mouser lists it as "obsolete" though I'd imagine there'd be a suitable replacement.
coulomb wrote:
Sat, 27 Oct 2018, 08:21
If it's a MOSFET, you should be able to measure a diode between the drain (invariably the middle pin, and the case if a metal case is exposed), and the source (usually to the right of the drain, looking at the front of the transistor.
So, I confirmed (above) that this is a MOSFET and using Diode setting, I got 471mv between the middle leg and the right one, with 1 when I reversed the probes so presumably that component is also OK.
coulomb wrote:
Sat, 27 Oct 2018, 08:21
The other pin is the gate; it is essentially open circuit (many mega-ohms), but will usually have a resistor from gate to source, typically 47 kΩ or 22 kΩ. But it could also be a bipolar (non-MOSFET) transistor, which should read like two diodes in anti-series.
Measuring between the left leg and the centre one (Gate and Drain) with Diode setting gives me "1" in both directions which I guess is no surprise given that it's not supposed to be a non-MOSFET transistor (double-negatives do my head in, but it seemed to be the best way to express that :( ). However, when I set my multimeter to the 20 kΩ range, I got a strange (to me) result where the display counted up steadily at the rate of around 1 kΩ per second until it went out of range. I repeated this with the multimeter on the 200 kΩ range and got the same result. I could try on the  2MΩ scale, but I'm not sure I could hold the probes in position that long! I suspect this steadily increasing resistance as a charge is applied might be expected behaviour, especially given that the diode side of the component seems to be working OK?

Thanks again for your input,

[ Edited Coulomb: removed extraneous [ quote ] tag. ]
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Re: Troubleshooting an old 24V charger

Post by coulomb » Sat, 27 Oct 2018, 13:02

rhills wrote:
Sat, 27 Oct 2018, 10:38
coulomb wrote:
Sat, 27 Oct 2018, 08:21
The other pin is the gate; it is essentially open circuit (many mega-ohms), but will usually have a resistor from gate to source, typically 47 kΩ or 22 kΩ. ...
The resistance should be seen gate to source, not gate to drain. So that's left pin to right pin.
However, when I set my multimeter to the 20 kΩ range, I got a strange (to me) result where the display counted up steadily at the rate of around 1 kΩ per second until it went out of range. I repeated this with the multimeter on the 200 kΩ range and got the same result.
This is due to a large capacitor. You should not see a large capacitance gate to source.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.

rhills
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Re: Troubleshooting an old 24V charger

Post by rhills » Sun, 28 Oct 2018, 23:55

Thanks again for your patience, Mike,
coulomb wrote:
Sat, 27 Oct 2018, 13:02
rhills wrote:
Sat, 27 Oct 2018, 10:38
coulomb wrote:
Sat, 27 Oct 2018, 08:21
The other pin is the gate; it is essentially open circuit (many mega-ohms), but will usually have a resistor from gate to source, typically 47 kΩ or 22 kΩ. ...
The resistance should be seen gate to source, not gate to drain. So that's left pin to right pin.
Ah. Well, now that I've measured the correct pins, I get 10.02 kΩ which I am guessing is likely to be OK.

Cheers,
Rob Hills
AEVA Webmaster
2014 Mitsubishi Outlander Aspire PHEV
Jul 2014 - Sep 2019
Total Petrol: 662.2L
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