| Electronics > Repair |
| HP E3610A Power Supply - Current not displaying / Voltage not changing |
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| F4:
I am having an issue with an E3610A repair. Does a schematic exist for the display board? Its not in the service manual. My issue is that the current display is always blank. It displays intermittently when set cc button is pressed and then goes blank again. All characters on the display work. At startup it flashes all the chars. The second symptom is that I get 15v at the output terminal and the display is unresponsive to the voltage dial. Both voltage and current pots have been checked. I cannot determine if the issue is the display board or the main board. I have tried testing the 4 transistors, swapping the 3 mainboard chips with a known working unit, cap replacement, and testing resistors/diodes around the current areas of the schematic. All voltage rails are spot on after the recap. Does anyone have the display board schematic? There seems to be 2 different display boards for this model, one having an extra pin and the older one without. 10 for the newer boards, 9 for the older. Anyone experienced a similar problem as this with one of this series (3610, 11, 12 etc)? Thanks! |
| F4:
Here are a couple of pics of the older style display board, looks like 1991. |
| wn1fju:
I don't have the display schematic, but I did have an E3611 that was behaving quite erratically. It is a known issue that the electrolytic capacitors on the main board leak, possibly from an inability to deal with the ripple or possibly from heat. In any event, they have a nasty habit of not only visibly leaking and possibly destroying traces on the board, but also leaking beneath the cap where you can't see it. If you haven't already, remove and inspect all of the electrolytics on the main board. Scrub the mainboard clean several times. Closely examine the board for any damaged traces and buzz the traces out with an ohmmeter if in doubt. This may not have anything to do with your display problem, but it might prevent additional problems in the future. |
| pqass:
--- Quote ---I cannot determine if the issue is the display board or the main board. I have tried testing the 4 transistors, swapping the 3 mainboard chips with a known working unit, cap replacement, and testing resistors/diodes around the current areas of the schematic. All voltage rails are spot on after the recap. --- End quote --- Before embarking down the repair rabbit hole, you could just attach a multimeter (set to DCV) on the output terminals, then another multimeter (set to DCA) in series with the positive terminal, a power resistor(s), and the negative terminal. Twiddle the voltage and current knobs and see if your multimeters agree (with the built-in display and confirms ohms law) with the chosen power resistor(s) attached. Then you'll know which of the power supply regulation or the built-in display is the issue. |
| F4:
--- Quote from: pqass on December 05, 2024, 01:12:11 am --- --- Quote ---I cannot determine if the issue is the display board or the main board. I have tried testing the 4 transistors, swapping the 3 mainboard chips with a known working unit, cap replacement, and testing resistors/diodes around the current areas of the schematic. All voltage rails are spot on after the recap. --- End quote --- you could just attach a multimeter (set to DCV) on the output terminals, then another multimeter (set to DCA) in series with the positive terminal, a power resistor(s), and the negative terminal. Twiddle the voltage and current knobs and see if your multimeters agree (with the built-in display and confirms ohms law) with the chosen power resistor(s) attached. Then you'll know which of the power supply regulation or the built-in display is the issue. --- End quote --- I have done something similar, the voltage knob does not respond to turning it on the display or the output. I get 15v on the output consistently. Current knob is also unresponsive. |
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