| Electronics > Repair |
| East Tester 5410+ not drawing current. |
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| Luv2Learn:
I bought a ET 5410+ from a bin store. I got it home and doesn’t work. It reads voltage when I hook up a source to it but when I try to put a load on something it doesn’t work. Just says 0 amps and watts and voltage stays same. I looked at the board and using a schematic from a member of this forum Morris6 I found some shorted resistors, 2 mosfets and a blown trace right by where the + side enters the pcb between p1 and p12. If I jump the trace the load kicks on but no way to control it. No matter the setting it draws as many amps as it feels like. Even after the OC protection shows it still pulls current with the trace jumped. Could be more issues but I am not an expert and have only basic knowledge of electronics. there is no noticeable burnt components on the board and it all looks perfect except the trace that is broke. Is it worth trying to fix or are the possible problems deeper than the ocean? I appreciate any help or advice from the brilliant members of this forum. the schematics morris6 made are the zip file. the page I edited is testing I did so far with shorted resistor and mosfets in red. I do have some troubleshooting tools. Multimeter, Soldering station with rework gun, DC power supplies, oscilloscope and a thermal image camera. ET5411Aplus-MAIN-Mosfet.pdf (751.2 kB - downloaded 40 times.) ET5411AplusSchematics.zip (827.77 kB - downloaded 36 times.) |
| MathWizard:
So it's not brand new right ? As long as none of the controller IC's got damaged, it should be pretty repairable. It's always a good idea to check the power supply section voltages. Was it Q10,11 and R112/113 that burned out ? With it un-powered, I'd check as many parts around there as possible, make sure the op-amps for those MOSFETs don't have any pins shorted to GND or anywhere else. Sounds like someone strained The ELoad too much, but something could just fail on it's own too, and then problems start snowballing. Check what some of the opto-couplers are doing, like U2,U3 on the MAINsense page. About 1V is a typical diode drop for the photo-diode. |
| morris6:
This ET5410+ of yours seems to have been part of a major overload event. The trace between P1 and P12 blown.., Oeps. May I suggest the following procedure? The system has six parallel current regulated channels. I would take out all the power mosfets and then check all the power supply voltages of the ET. When all power voltages are good measure the DRIVE voltage, pin1 on P8 or P3, and see if the voltage makes sense: +12 V for a no current command and -10 V for full current. You can use the V- bus as "zero" point. You observed the ET indicating the voltage of a hooked up power source. Now, if you put the ET in Constant Voltage mode and select a voltage setting just over or just under the voltage of your source, the DRIVE signal should change indicating that regulation is working. Now replace the power mosfets with known good ones, one by one, to find any faulty channels. Of course there will be some deviations, or maybe instability, if one or more channels are not active yet. Have fun, and good luck, Maurits PS. Power mosfets in the ET5410+ are IRFP250N. The schematic is for ET5411+ that has IRFPF50. |
| Luv2Learn:
--- Quote from: MathWizard on September 16, 2024, 07:03:44 pm ---So it's not brand new right ? As long as none of the controller IC's got damaged, it should be pretty repairable. It's always a good idea to check the power supply section voltages. Was it Q10,11 and R112/113 that burned out ? With it un-powered, I'd check as many parts around there as possible, make sure the op-amps for those MOSFETs don't have any pins shorted to GND or anywhere else. Sounds like someone strained The ELoad too much, but something could just fail on it's own too, and then problems start snowballing. Check what some of the opto-couplers are doing, like U2,U3 on the MAINsense page. About 1V is a typical diode drop for the photo-diode. --- End quote --- No it was not brand new. It was packaged like it was but the place I bought it from gets AMZ returns so sometimes things don't work but I paid $8.99 for it. Q4, Q10, R53, R70 were shorted out. Ive removed them so far. I will have to order some new MOSFETs and a resistor. I had 1 100k on a different scrap board that fit. I have not found any other problems yet. Thank you for your reply |
| Luv2Learn:
--- Quote from: morris6 on September 16, 2024, 07:42:49 pm ---This ET5410+ of yours seems to have been part of a major overload event. The trace between P1 and P12 blown.., Oeps. May I suggest the following procedure? The system has six parallel current regulated channels. I would take out all the power mosfets and then check all the power supply voltages of the ET. When all power voltages are good measure the DRIVE voltage, pin1 on P8 or P3, and see if the voltage makes sense: +12 V for a no current command and -10 V for full current. You can use the V- bus as "zero" point. You observed the ET indicating the voltage of a hooked up power source. Now, if you put the ET in Constant Voltage mode and select a voltage setting just over or just under the voltage of your source, the DRIVE signal should change indicating that regulation is working. Now replace the power mosfets with known good ones, one by one, to find any faulty channels. Of course there will be some deviations, or maybe instability, if one or more channels are not active yet. Have fun, and good luck, Maurits PS. Power mosfets in the ET5410+ are IRFP250N. The schematic is for ET5411+ that has IRFPF50. --- End quote --- Yes, I seen that the Mosfets are different. Otherwise everything else seems to be the same. Thank you for your time making the schematic and for your reply. I will buy some mosfets and work through your advice. It will be few days at least till I can start testing. I don't have the parts on hand. Thanks again! |
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