Hyena said:
If you can post a good picture of that area and the corresponding area on the bottom of the board, I might be able to figure it out.
Switch mode supply mod
- Thread starter Jeremy Harris
- Start date
If you can post a good picture of that area and the corresponding area on the bottom of the board, I might be able to figure it out.
mwkeefer
1 MW
fechter's help is the only reason I stopped overthinking the whole thing and figured it out, without his assistance I would still probably be trying to figure this out... That said, there are variances between different models of supply... all mine are S-350-R18-VAI, yours look to be S-350-R20 or somthing ... I can make that out but I couldn't see the TL494CN chip or the current control feedback loop (that fetcher spotted and made quite simple for me to understand!).
Fechter - yours is leaving Monday, it should go Priority and you should have it by end of business Tuesday. I got a bit slammed end of week with other projects and the usual family chaos and just couldn't get it done.
That said... on the units I have and have sent you.... Ive figured out how to get variable current from it, in addressable modes (ref v control signal, 40-50ma) to switch between various current levels. I have tested (prelim) using 2.5A, 5A and 9A rates from my 48 units reconfigured for 62.5v - I figure we can go a bit lower but there is some minimum duty cycle and I haven't measured temps durring testing yet, just made sure it worked on the prototype.
I kept the switching inputs limited to shorting a single rate at a time, this test unit defaults at 5A and has 2 control leads and a single ref VCC (from TL494CN) which the control leads are tied to for selecting 2.5 or 9A modes.
Knowing you have a scope, perhaps you will have time to refine this and see how low she will go. I figure for proper balancing using most (including yours) balancers / BMS systems, we need trickle mode right?
It's on a protoboard right now and done from the hip so give me a day or two to refine it just a bit and I will post the schematic (probably by the time you have your unit). The other concern is using units in series and/or parallel... the current limit switching gets a little more complicated in these cases (I think) but... it's workable.
-Mike
Fechter - yours is leaving Monday, it should go Priority and you should have it by end of business Tuesday. I got a bit slammed end of week with other projects and the usual family chaos and just couldn't get it done.
That said... on the units I have and have sent you.... Ive figured out how to get variable current from it, in addressable modes (ref v control signal, 40-50ma) to switch between various current levels. I have tested (prelim) using 2.5A, 5A and 9A rates from my 48 units reconfigured for 62.5v - I figure we can go a bit lower but there is some minimum duty cycle and I haven't measured temps durring testing yet, just made sure it worked on the prototype.
I kept the switching inputs limited to shorting a single rate at a time, this test unit defaults at 5A and has 2 control leads and a single ref VCC (from TL494CN) which the control leads are tied to for selecting 2.5 or 9A modes.
Knowing you have a scope, perhaps you will have time to refine this and see how low she will go. I figure for proper balancing using most (including yours) balancers / BMS systems, we need trickle mode right?
It's on a protoboard right now and done from the hip so give me a day or two to refine it just a bit and I will post the schematic (probably by the time you have your unit). The other concern is using units in series and/or parallel... the current limit switching gets a little more complicated in these cases (I think) but... it's workable.
-Mike
Hyena
10 GW
OK I dragged out the SLR, here's a pic of my unit
http://img44.imageshack.us/img44/6478/mws35048.jpg
Thanks guys
I've noticed it stays quite warm when just sitting there so I'm sure it'd reduce its life span.
http://img44.imageshack.us/img44/6478/mws35048.jpg
Thanks guys
Well the timer is set long enough that the current falls to 0, but atleast the PSU isnt powered up all night if I forget about it.mwkeefer said:
I've noticed it stays quite warm when just sitting there so I'm sure it'd reduce its life span.
Maybe it's actually an earlier model? On the board it says S-350&201. 2005-09-19. I don't know if that second number is supposed to be the date, if so it could be 4 years old. Although it looks like there is no SVR2 which suggests it may be the newer model ? Who knows...
GGoodrum
1 MW
Here's a shot of one of mine, which appear to be just like what Mike has:
View attachment S-350-24-01.jpg
In the upper right, I've circled R33 in red. On my 24V/14A S-350, R33 is labeled as a 750 ohm resistor. I measured it at 735 ohms. With it, the max current it tries to pump out is a bit over 20A. I added an 820 ohm resistor (810 measured...) to this one, in parallel, which brought the total resistance down to about 385 ohms. This dropped the max current to about 10.4A
Looking at yours, if I had to guess, I'd say R37 is the equivalent to R33 on our boards. The reason I say this is because on mine at least, R33 is the only one that was less than 1k ohms. I can't tell if your R37 is 29 ohms, or 290 ohms.
-- Gary
View attachment S-350-24-01.jpg
In the upper right, I've circled R33 in red. On my 24V/14A S-350, R33 is labeled as a 750 ohm resistor. I measured it at 735 ohms. With it, the max current it tries to pump out is a bit over 20A. I added an 820 ohm resistor (810 measured...) to this one, in parallel, which brought the total resistance down to about 385 ohms. This dropped the max current to about 10.4A
Looking at yours, if I had to guess, I'd say R37 is the equivalent to R33 on our boards. The reason I say this is because on mine at least, R33 is the only one that was less than 1k ohms. I can't tell if your R37 is 29 ohms, or 290 ohms.
-- Gary
Tiberius
10 kW
My 36 V ones look like the picture Gary just posted, with the blank SVR2 position.
R33 is 1K2 on one of them and 680 on 2 of them.
Nick
R33 is 1K2 on one of them and 680 on 2 of them.
Nick
tailwind
100 W
For comparison, S-350-48.
Greg
Greg
grindz145
1 MW
liveforphysics said:
I like where your going here but really, I don't think its worth shying away from less-stable chemistries completely. If Tesla can make a car with LiCo (a pretty volatile chemistry) work then we know its possible and sometimes theres good reason for it. There are tradeoffs for every chemistry and I think the most important issue is to have better BMS for the E-bike community. No matter what chemistry it is, its scary to see this cells without any thermal monitoring
Basically, thermistors are your friend, and with better battery design we shouldn't have to limit ourselves chemistry-wise, but LiPo definitely does have its benefits both performance and safety!
mwkeefer
1 MW
Hyena,
Would it be possible for you to scan the trace side? I need you to atleast remove a PCB so we can confirm there are no SMT resistors or components (there may or may not be) as some seem to have trace side components and some don't (but I can't tell by model revision yet).
Using what I know about the few model revisions I have access to, I can take an edumacated guess as to the configuration which you will need to test with a DVM continuity meter or trace by eye to confirm (or post the scan of the trace side).
[Stock Configuration]
R37: 390 ohm, 5% resistor
R21: 10K ohm, 5% resistor
The unit I have worked with the most and now it appears Tailwinds unit as well (thanks for the pics Tailwind, good to get further reference on various models in here) all seem to have the roughly identical componentry and circuits (the guess part) but the TL494CN has a particular connection schematic and so ... between that knowledge and the experience with my own units (with Fechters help!) I can posit a likely workable solution:
Between our models, R21, 33, 37 locations are all within the same rough spacing.... in my PCB R33 is the current adjustment resistor, R37 feeds the unpopulated variable current part of my circuit and to the best i can work out (hopefully fechter with a scope will help sort this out). It seems the other models have a simliar configuration but in your model I think it's just been reversed... so for your unit, R37 is the limiting resistor and R33 would feed the unpopulated component section (still want to figure this part out).
Test this out using a DVM contuniuity meter (beeps when shorted):
R37 (gold most side) should connect to pin #15 on the 494CN
R37 (orange most side) should connect to pin #16 on the 494CN
If you would also take an incircuit reading on the R37 that would be helpful too.
Assuming this is correct(and that your supply is electronically identical with this change at input)... add a second 390ohm in parallel and you should reduce your current by 1/2 the output. This is approx. and assumes no trace side components.
This is a picture of my model with the TL494 section outlined, see the positioning of the R33 and R37 relative to your own. R21 is a high value (as is mine.
Hope this helps!
-Mike
Would it be possible for you to scan the trace side? I need you to atleast remove a PCB so we can confirm there are no SMT resistors or components (there may or may not be) as some seem to have trace side components and some don't (but I can't tell by model revision yet).
Using what I know about the few model revisions I have access to, I can take an edumacated guess as to the configuration which you will need to test with a DVM continuity meter or trace by eye to confirm (or post the scan of the trace side).
[Stock Configuration]
R37: 390 ohm, 5% resistor
R21: 10K ohm, 5% resistor
The unit I have worked with the most and now it appears Tailwinds unit as well (thanks for the pics Tailwind, good to get further reference on various models in here) all seem to have the roughly identical componentry and circuits (the guess part) but the TL494CN has a particular connection schematic and so ... between that knowledge and the experience with my own units (with Fechters help!) I can posit a likely workable solution:
Between our models, R21, 33, 37 locations are all within the same rough spacing.... in my PCB R33 is the current adjustment resistor, R37 feeds the unpopulated variable current part of my circuit and to the best i can work out (hopefully fechter with a scope will help sort this out). It seems the other models have a simliar configuration but in your model I think it's just been reversed... so for your unit, R37 is the limiting resistor and R33 would feed the unpopulated component section (still want to figure this part out).
Test this out using a DVM contuniuity meter (beeps when shorted):
R37 (gold most side) should connect to pin #15 on the 494CN
R37 (orange most side) should connect to pin #16 on the 494CN
If you would also take an incircuit reading on the R37 that would be helpful too.
Assuming this is correct(and that your supply is electronically identical with this change at input)... add a second 390ohm in parallel and you should reduce your current by 1/2 the output. This is approx. and assumes no trace side components.
This is a picture of my model with the TL494 section outlined, see the positioning of the R33 and R37 relative to your own. R21 is a high value (as is mine.
Hope this helps!
-Mike
Hyena
10 GW
For Sale:
S-350-48, good for parts :x
I didn't end up pulling the board out, I figured it was in the too hard basket to unscrew everything with the case mounted fets / transistors. I had a spare 500ohm resistor which I dropped across R37 in parallel dropping the resistance from 380 odd to 240 odd. This worked and dropped the current down from 12 amps to around 7 amps which is perfect but made a very angry noise in the process - you know that high pitched, hissing/arcing type noise. I removed the resistor, having heard that sound in past in power supplies seconds before they let out the magic smoke and decided to hack at the shunt instead. I cut the middle out and held a piece wire in there and the current read 6 amps. That was good enough for what I wanted (a charger for a friend) so I soldered the wire in there, turned it back on and BOOM. The fuse blew +/- a big flash of light from something else near by. I inspected the board but couldn't see any burnt components. I replaced the fuse with some fine wire to test it again but she's dead as a door nail. SHIT!
I have no idea why it blew, it was happy enough 30 seconds earlier and I hadn't changed anything else.
Bugger, now I have a dead power supply and have to buy and wait for shipping on another for my friend.
When I get time I'll pull the board out and photograph the underside for you Mike - if it's still of use to the cause ?
S-350-48, good for parts :x
I didn't end up pulling the board out, I figured it was in the too hard basket to unscrew everything with the case mounted fets / transistors. I had a spare 500ohm resistor which I dropped across R37 in parallel dropping the resistance from 380 odd to 240 odd. This worked and dropped the current down from 12 amps to around 7 amps which is perfect but made a very angry noise in the process - you know that high pitched, hissing/arcing type noise. I removed the resistor, having heard that sound in past in power supplies seconds before they let out the magic smoke and decided to hack at the shunt instead. I cut the middle out and held a piece wire in there and the current read 6 amps. That was good enough for what I wanted (a charger for a friend) so I soldered the wire in there, turned it back on and BOOM. The fuse blew +/- a big flash of light from something else near by. I inspected the board but couldn't see any burnt components. I replaced the fuse with some fine wire to test it again but she's dead as a door nail. SHIT!
I have no idea why it blew, it was happy enough 30 seconds earlier and I hadn't changed anything else.
Bugger, now I have a dead power supply and have to buy and wait for shipping on another for my friend.
When I get time I'll pull the board out and photograph the underside for you Mike - if it's still of use to the cause ?
mwkeefer
1 MW
Post the underside pics but don't assume it's 100% dead.
The reason I wanted to double check the PCB was to see if that resistor was in series or parallel with any other resistor which could cause a multiplier effect for the whole circuit.
We may be able to fix it if you didn't fry the transformer.
-Mike
PS: I too have a fried 48v unit, probably similar cause.
The reason I wanted to double check the PCB was to see if that resistor was in series or parallel with any other resistor which could cause a multiplier effect for the whole circuit.
We may be able to fix it if you didn't fry the transformer.
-Mike
PS: I too have a fried 48v unit, probably similar cause.
Tiberius
10 kW
One thing you might like to try
Photograph both sides of the board, then in photoshop, flip one picture over, make it semi transparent and graft the two pics together.
You will have to deal with the distortion to get them to line up properly. But if it works its a lot easier to work out the circuit.
I've managed this before with small boards, but not tried it on something this side.
If you can't make a good composite picture, just printing one of them on a transparency could help a lot.
Nick
Photograph both sides of the board, then in photoshop, flip one picture over, make it semi transparent and graft the two pics together.
You will have to deal with the distortion to get them to line up properly. But if it works its a lot easier to work out the circuit.
I've managed this before with small boards, but not tried it on something this side.
If you can't make a good composite picture, just printing one of them on a transparency could help a lot.
Nick
mwkeefer
1 MW
Nick,
Great tip - I hadn't thought of trying to do that but if you image them on the same camera setup with same range then it should work with little to no error. To bad there isn't an illustrator for PCBs (automatic tracer/router)... would make reverse engineering very simple.
Hyena - since my unit isn't giving me issues as I have it configured I hadn't thought about the maximum voltage input for the TL494 and maximum current. I am fairly certain that we need to electrically account for the higher than range voltages with a compromise of the other side of the reference amplifier circuitry to prevent this from happening on other models (as I said, Iblew a unit up early on).
Seems fairly odd that these will produce so much more current than rated for, at close to 600w you would think the engineers putting them out would have limited max current to a safer (ie: closer to rated) level.
-Mike
Great tip - I hadn't thought of trying to do that but if you image them on the same camera setup with same range then it should work with little to no error. To bad there isn't an illustrator for PCBs (automatic tracer/router)... would make reverse engineering very simple.
Hyena - since my unit isn't giving me issues as I have it configured I hadn't thought about the maximum voltage input for the TL494 and maximum current. I am fairly certain that we need to electrically account for the higher than range voltages with a compromise of the other side of the reference amplifier circuitry to prevent this from happening on other models (as I said, Iblew a unit up early on).
Seems fairly odd that these will produce so much more current than rated for, at close to 600w you would think the engineers putting them out would have limited max current to a safer (ie: closer to rated) level.
-Mike
GGoodrum
1 MW
mwkeefer said:
This is what has me puzzled as well. These do apparently have CC limiting, even if the adjustable feature is not implemented, but the limit is set higher than the rated output. What is the logic behind setting it about 35-40% higher than the rated output?
Mike, have you figured out yet what makes the S-320 model different? I know it is supposed to be UL/CE-approved, but why this model?
-- Gary
mwkeefer
1 MW
Gary,
How do you mean "why this model"
The S-420 will be coming and I believe there are S-600 also on the block, the 320 and 600 have been UL/AU rated but the Meanwell tech specs list the S-420 as pending.
I'd be willing to venture a quick guess here (assuming I understand the why this model bit)...
If you attempt to pull below the rated load from these, they seem to be quite happy providing stable and close to rated/calibrated voltage. Im assuming that they were designed with the intent of powering equipment which would be "under" the rated consumption nominally.... things like stereo equipment, etc which may need transient bursts of current.
I also assume that to meet UL/AU certification (still don't have an S-320, a few due this week to eval) - they needed to derate the units to 320w and provide a much better current limiting function - If I recall the anual from top of head, the 350s are rated at 130% as being over current so... 7.3A rated becomes 9.48 A, this holds fairly true with my findings durring testing (I think maximum current I get to now is 8A with R33 cut by 1/3) and with initial testing where the unit was pushing 9.5A or so into my batteries.
I assume they did the normal chinese engineering bit on these and just use the same PCB for more than just the S-350 series (fairly obvious).
I have been working on limiting duty cycle via varying the oscillator circuit and also via the OUTPUTCONTROL line from the TL494CN chip... with limited sucess (not quite the outcome I expected but NO blown supplies from testing) and I think that to perform the modification for voltage range and extend it, we also need to recalibrate the sensing circuit around U2 the opamp which then feeds the error amplifiers of U1 the 494 via R33 (or 37 in some cases, probably other combinations too)...
Actually I have a PCB in front of me now... I'm tracing out and transposing to Protel Schematic for reference.
*Edited - Update:
On my particular unit, R33, R21, R37 (if populated) and joined blades of SVR2 all tie together. R33 and third pole of SVR2 goto signal ground (the UC ground by various paths), R21 goes to C18 and then on to U1 pin #3 (COMP). The joined side of R33, R21, R37 and R34 goes to U1 pin # 15 (V2-).
The remaining unpopulated D18, R46, Q7 are used as part of an overcurrent detection or limiter when the remaining adjustment circuit is in place.
That said... at your own risk, and only on S-350-R17VAI version of the S-350-48 Meanwell supplies:
Remove R33, replace with R37 and SVR1... be sure to calculate the impedance of the combined circuit so that it remains above a safe level where you have tested with a hard wired resistor with a load.
-Mike
-Mike
How do you mean "why this model"
The S-420 will be coming and I believe there are S-600 also on the block, the 320 and 600 have been UL/AU rated but the Meanwell tech specs list the S-420 as pending.
I'd be willing to venture a quick guess here (assuming I understand the why this model bit)...
If you attempt to pull below the rated load from these, they seem to be quite happy providing stable and close to rated/calibrated voltage. Im assuming that they were designed with the intent of powering equipment which would be "under" the rated consumption nominally.... things like stereo equipment, etc which may need transient bursts of current.
I also assume that to meet UL/AU certification (still don't have an S-320, a few due this week to eval) - they needed to derate the units to 320w and provide a much better current limiting function - If I recall the anual from top of head, the 350s are rated at 130% as being over current so... 7.3A rated becomes 9.48 A, this holds fairly true with my findings durring testing (I think maximum current I get to now is 8A with R33 cut by 1/3) and with initial testing where the unit was pushing 9.5A or so into my batteries.
I assume they did the normal chinese engineering bit on these and just use the same PCB for more than just the S-350 series (fairly obvious).
I have been working on limiting duty cycle via varying the oscillator circuit and also via the OUTPUTCONTROL line from the TL494CN chip... with limited sucess (not quite the outcome I expected but NO blown supplies from testing) and I think that to perform the modification for voltage range and extend it, we also need to recalibrate the sensing circuit around U2 the opamp which then feeds the error amplifiers of U1 the 494 via R33 (or 37 in some cases, probably other combinations too)...
Actually I have a PCB in front of me now... I'm tracing out and transposing to Protel Schematic for reference.
*Edited - Update:
On my particular unit, R33, R21, R37 (if populated) and joined blades of SVR2 all tie together. R33 and third pole of SVR2 goto signal ground (the UC ground by various paths), R21 goes to C18 and then on to U1 pin #3 (COMP). The joined side of R33, R21, R37 and R34 goes to U1 pin # 15 (V2-).
The remaining unpopulated D18, R46, Q7 are used as part of an overcurrent detection or limiter when the remaining adjustment circuit is in place.
That said... at your own risk, and only on S-350-R17VAI version of the S-350-48 Meanwell supplies:
Remove R33, replace with R37 and SVR1... be sure to calculate the impedance of the combined circuit so that it remains above a safe level where you have tested with a hard wired resistor with a load.
-Mike
-Mike
Tiberius said:
I did something similar to that with Mike's power supply. Take the bottom picutre and mirror it so it matches up with the top picture. I just did a side-by-side, which was good enough for the small area involved.
Hyena: yes, we really need to see the bottom side of the board to properly see what's going on. Too bad you let the smoke out. That's worthy of a guinea pig award
Hyena
10 GW
Awe, the fried guinea pig award, now I HAVE to investigate further
OK as requested here's the pics.
Firstly, here's where mine let the magic smoke out!
Here's a photoshopped overlay (probably have to open in a new window with the forum settings)
and another one where I've fiddled with the transparency to make the tracks clearer
Also, what's this black 2 legged component here? Is it a hall sensor ? If so could fiddling with that be an easier way of altering the current ?
I also noticed the zener diode under the main transformer is actually 2 together in series (PIC )- is everyone elses like that ?
OK as requested here's the pics.
Firstly, here's where mine let the magic smoke out!
Here's a photoshopped overlay (probably have to open in a new window with the forum settings)
and another one where I've fiddled with the transparency to make the tracks clearer
Also, what's this black 2 legged component here? Is it a hall sensor ? If so could fiddling with that be an easier way of altering the current ?
I also noticed the zener diode under the main transformer is actually 2 together in series (PIC )- is everyone elses like that ?
mwkeefer
1 MW
That 2 legged component is a thermistor of sorts and triggers fan (should cause throttling too) when temperature exceeded a certin limit.
-Mike
-Mike
Hyena
10 GW
Ah ok. I forgot to mention before, I checked the board over for what might have gone wrong to cause the underside of that tranny to blow like it did. I couldn't find anything obvious so soldered up the blown track and leg, replaced the fuse and tried again. BIG boom and flash, fuse gone again and a puff of magic smoke from elsewhere around the middle of the board. So I think it's officially dead now!
Back on the topic of the geniune meanwells, Mike have you found yours to be stable now at 62.5v ? What sort of voltage range do you have ?
Was adding another zener the only mod necssary to get it running ? (I can't remember which thread it was you posted about doing it) I'm thinking I'll grab a genuine meanwell and make a variable power charger with it, from 10S to 15S (or ideally even down to 5S for charging individual packs) If the R33 mod is working happily in your meanwells I'd add a pot on the top of the case for current control, one for voltage and keep an eye on it all with a $25 turnigy wattsup meter clone. The bits can all be neatly flush mounted in the top of the case too
Back on the topic of the geniune meanwells, Mike have you found yours to be stable now at 62.5v ? What sort of voltage range do you have ?
Was adding another zener the only mod necssary to get it running ? (I can't remember which thread it was you posted about doing it) I'm thinking I'll grab a genuine meanwell and make a variable power charger with it, from 10S to 15S (or ideally even down to 5S for charging individual packs) If the R33 mod is working happily in your meanwells I'd add a pot on the top of the case for current control, one for voltage and keep an eye on it all with a $25 turnigy wattsup meter clone. The bits can all be neatly flush mounted in the top of the case too
mwkeefer
1 MW
I believe the input transformer was blown - that's what I think is wrong with mine.... when a fuse goes, there is always a reason. I "may" take one of the transformers off of another unit (24v I have spares of) and transplant it to my blown 48v board... I doubt they are all having the same tapped voltage but I could be wrong....
With regards to R33 being stable... well it hasn't blown up but begins to make an awful racket then durring my last charge (which started at a nice 7.2A rate @ 58v and stayed there until it hit 60v) once 60.5 was reached the curent jumped up to 8A @ 60.5 and 8.09A at 60.8v
Tapering began about 62.1v and continued to follow a fairly linear taper from 8A to 5 then within 3 or 4 minutes it was at 1.8A output.
Ive currently breadboarded (soldered) the R33/R37 and SVR2 portion and the voltage adjust... also relocated ZD1 and finally added test points into the unit... I am about to go ride WOT for a few miles to run the pack to nominal 3.3v per cell (3.93v per cell lowest pack I have right now) and I will begin testing again...
One thing I forgot to mention I have also move the R35->R48 portion of the circuit to the breadboard and incorporated a 12 turn pot to raise the impedance.
[Test #1]
Using default R33/37, 35 and 38 values what is the immediate current when charging the pack at 49.5 (within rated limits) but with the supply voltage set to 62.2v/62.3v
This will be a brief test of just a few seconds... But this will in all effect be the factory settings.
I will measure the various test points and collect readings.
[Test #2]
If I recall properly the 48 would go to 57 or 58v stock... I will change the cutout voltage to 51v (well within the range of a stock meanwell)
Again I will measure all points while test charging.
[Test #3]
I will again set the R33 for 360 ohms (what I have mine at now) and cutout voltage to 51v and test (I know the outcome of this but not the test point voltages)
[Test #4]
Here I will raise the impedance of the R35/38 values in the same porportion as the R33 decrease... and then retest.
[Test #5]
This time it will be the test 4 mods but configured for 62.2v cutout
again I will measure all test points.
My theory is the burst I am seeing and possibly the harmonic noise is due to
1.) The unit putting out too much power
2.) The two current feedback circuits are out of balance.
I am guessing the unit handles the transition from CC-CV and then the second part of the circuit takes over for the control of current. If this is true it explains the 1A spike back to where it would have been if charging at default power of 9A or so... right at the beginning of the CV portion?
We will see = )_
-Mike
PS: Hyena - fixing is not soldering a bad trace (BLOWN) and putting a new fuse in.... fixing involves a DVM with continuity, voltage and impedance testing at a minimum = )_
I doubt we can fix it now *maybe stevo or methods could.
-Mike
With regards to R33 being stable... well it hasn't blown up but begins to make an awful racket then durring my last charge (which started at a nice 7.2A rate @ 58v and stayed there until it hit 60v) once 60.5 was reached the curent jumped up to 8A @ 60.5 and 8.09A at 60.8v
Tapering began about 62.1v and continued to follow a fairly linear taper from 8A to 5 then within 3 or 4 minutes it was at 1.8A output.
Ive currently breadboarded (soldered) the R33/R37 and SVR2 portion and the voltage adjust... also relocated ZD1 and finally added test points into the unit... I am about to go ride WOT for a few miles to run the pack to nominal 3.3v per cell (3.93v per cell lowest pack I have right now) and I will begin testing again...
One thing I forgot to mention I have also move the R35->R48 portion of the circuit to the breadboard and incorporated a 12 turn pot to raise the impedance.
[Test #1]
Using default R33/37, 35 and 38 values what is the immediate current when charging the pack at 49.5 (within rated limits) but with the supply voltage set to 62.2v/62.3v
This will be a brief test of just a few seconds... But this will in all effect be the factory settings.
I will measure the various test points and collect readings.
[Test #2]
If I recall properly the 48 would go to 57 or 58v stock... I will change the cutout voltage to 51v (well within the range of a stock meanwell)
Again I will measure all points while test charging.
[Test #3]
I will again set the R33 for 360 ohms (what I have mine at now) and cutout voltage to 51v and test (I know the outcome of this but not the test point voltages)
[Test #4]
Here I will raise the impedance of the R35/38 values in the same porportion as the R33 decrease... and then retest.
[Test #5]
This time it will be the test 4 mods but configured for 62.2v cutout
again I will measure all test points.
My theory is the burst I am seeing and possibly the harmonic noise is due to
1.) The unit putting out too much power
2.) The two current feedback circuits are out of balance.
I am guessing the unit handles the transition from CC-CV and then the second part of the circuit takes over for the control of current. If this is true it explains the 1A spike back to where it would have been if charging at default power of 9A or so... right at the beginning of the CV portion?
We will see = )_
-Mike
PS: Hyena - fixing is not soldering a bad trace (BLOWN) and putting a new fuse in.... fixing involves a DVM with continuity, voltage and impedance testing at a minimum = )_
I doubt we can fix it now *maybe stevo or methods could.
-Mike
heathyoung
100 kW
Thats not an input transformer, thats part of the suppression network to stop noise and spikes making it back to the mains. It can be bypassed (naughty) but it will work. Its a common-mode suppression choke with the two windings wound so that they cancel out the interference.
Hello!
I also have a Meanwell S350-R12 from 12-2007. The voltage range is now at 34V- 40V.
There are three shunts. I want to increase the voltage perhaps to max. 50V or so, and reduce the current from 9,7A to 5A. I have found ZD2 and ZD3, but cannot find ZD1?
R25 looks like 2k7, R33 is 470 ohm.
I also have a Meanwell S350-R12 from 12-2007. The voltage range is now at 34V- 40V.
There are three shunts. I want to increase the voltage perhaps to max. 50V or so, and reduce the current from 9,7A to 5A. I have found ZD2 and ZD3, but cannot find ZD1?
R25 looks like 2k7, R33 is 470 ohm.
mwkeefer
1 MW
ZD1 is under the big yellow transformer.
-Mike
-Mike
Hyena
10 GW
I posted a pic of the ZD1 location 2 days ago - here it is
You'll probably have to remove the circuit board from the case to get access to it
That same angry buzzing, arcing sort of sound I described previously ?
I look forward to hearing the outcome of your testing. These power supplies are pretty cheap in the grand scheme of things, but not cheap enough to keep blowing up!!
You'll probably have to remove the circuit board from the case to get access to it
mwkeefer said:
That same angry buzzing, arcing sort of sound I described previously ?
I look forward to hearing the outcome of your testing. These power supplies are pretty cheap in the grand scheme of things, but not cheap enough to keep blowing up!!
Bah, be grateful I didn't use duct tape to try and fix it
mwkeefer
1 MW
it would not have fried if u used dect tape =)_
-mike
-mike
First I added to ZD1 a zener diode with 19V to my 36V PSU. I could not see which value the original zener has, but I think it is 39V.
R25 next to the pot is 2K7 - I did not change it to 2k2 - should I do it?
The original pot I changed to a 5 K 10 turn.
The first test : max 40V
!!??? This is the same voltage before I did the mod!
