Yeah, I went in guns blazing and should have just lifted the pin.... I must have been thinking I could find the short by the smell of magic smoke or the heat of a dying chip!
Nice repair & nice meter, had problems with the buttons on a Marconi Sig gen, used some carbon loaded paint designed to repair tv remotes & still works fine two years latter. Also the rf output was on the back so re routed it to the front with semi rigid coax
Good idea! I've already bought a replacement membrane and might have a follow on video properly fixing these issues, but the conductive paint is definitely a way to go if you can't get the replacements. The Feedback Loop repaired a fluke scopemeter's membrane keyboard by making a thin FR4 PCB to replace the membrane which I thought was quite clever, as they're extremely cheap from pcbway/jlcpcb provided you don't mind the CAD time.
Thanks! Just email me at youtube@bansci.com. I haven't used the email much yet so ping me here too and I'll check the spam folder. Good luck with the repair, maybe comment what you found failed for future fixers like yourself to find.
Nice video and a nice channel. I got a 4418B (single channel version). After the video i checked the battery voltage but it is still 3.2V. What memory is supplied from that voltage? The cal memory or just the user settings?
Found the answer in the service manual: "It is advisable to replace the RAM battery A2BT1 every three years. If the battery fails or drops below 3 V the RAM will lose the following information when power is disconnected from the meter: Unit Serial Number Revision letter of Processor Card Unit Option User defined setups User defined sensor calibration tables"
Thanks! You've got it right, its only an inconvenience to not have the battery working. The cal tables are nice for older sensors, and I think preserving the serial number is probably for when you have several of the meters on the same GPIB bus so you can tell them apart. As an interesting side note, the motherboard actually indicates what SRAM chips are actually backed up by the battery with a white box and text in the silkscreen. Not sure why though, perhaps to warn repair techs that there may be 3.3v on them so don't start shorting pins?
I can't remember exactly how but it was a very painful process, I think the plastic clips over something meaning you have to flex it out, very nerve wracking when you have aged and brittle plastic!
The battery could have been easily unsoldered from the underside of the board in under a minute. You can replace the exact same battery with mounting by searching on digikey. You have brown outs because that's the original 20W supply which they stopped using in later productions. You can find 40W or higher for them on eBay. Hope this helps.
I tried desoldering the battery from below but I had issues getting enough heat in, so clipping the battery out first was the easy option. I'd also already ordered the replacement battery (with the wrong connectors) before taking delivery of the meter, so I went with what I had. About the power supply, interesting to note they have different versions, I'll take a look at the 40W version and maybe measure the existing units peak draw. My issue was definitely the broken hex inverter though, the power controller was giving the all clear signal but it was not being correctly inverted. I even ran the system from my lab supplies to be sure. Might do a follow up on this when I finally get back into the lab after COVID lockdown and replace the hex inverter!
Sure, can you describe anything else? Does the power light come on at all? If the light is not on, you need to check the PSU. It is always on, so you should be able to measure it's voltages on its connector. If the light is on, then it might be in your reset circuit like mine. Also check the very top of the display for an error code like The Signal Path saw.
@@bansci thanks for your reply. voltages 12 v,-12 v , 5 v , battery 2,9v are ok . The stand by light is ok .when I press the power button notting happened.
@@radiotvrepair1059 OK it sounds like my issue, you need to check the voltages on the reset pins on the MCU (to see if you have an issue with brownout control like me), and verify the clock in and out is working on the MCU (to see if its the clock), finally, you need to see if there's memory bus activity and the voltages of that, to see if its bad memory like The Signal Paths' one.
@@bansci I didn't work with my power meter a month ago. before yesterday when I turned on my meter it does not want to start knowing that it works well before. can humility do that because I'm in a place where the percentage of humidity is very high.
@@bansci Thanks to the schematics I got from you I was able to get my meter working again in no time. My channel B sampling board failed during the self test. Turns out the 2.5 volt reference voltage was shorted by a 100nF decoupling capacitor (C30). Thanks again for your help!
Hi, can you please share with me the schematcs file too? Just got a unit with a weird symptom, if a plug the AC cable while pressing the power button it turns on and works as expected, after that I can press the power button to turn it off, but it then won't turn on if I press the power button again, I have to unplug the AC cable and repeat... Regards.
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And I thought I was the only one who blew open parts rather than lifting pins LOL Great video, TNX 4 the upload! 73
Yeah, I went in guns blazing and should have just lifted the pin.... I must have been thinking I could find the short by the smell of magic smoke or the heat of a dying chip!
Nice repair & nice meter, had problems with the buttons on a Marconi Sig gen, used some carbon loaded paint designed to repair tv remotes & still works fine two years latter. Also the rf output was on the back so re routed it to the front with semi rigid coax
Good idea! I've already bought a replacement membrane and might have a follow on video properly fixing these issues, but the conductive paint is definitely a way to go if you can't get the replacements.
The Feedback Loop repaired a fluke scopemeter's membrane keyboard by making a thin FR4 PCB to replace the membrane which I thought was quite clever, as they're extremely cheap from pcbway/jlcpcb provided you don't mind the CAD time.
Fantastic repair. I just wanted to ask if you still had a copy of the schematic as I have the single chanel model on my bench for repair? Karl
Thanks! Just email me at youtube@bansci.com. I haven't used the email much yet so ping me here too and I'll check the spam folder. Good luck with the repair, maybe comment what you found failed for future fixers like yourself to find.
@@bansci Email sent. Thank you and I certainly will share my findings
@@karlfell3768 I've replied, good luck!
Nice video and a nice channel. I got a 4418B (single channel version). After the video i checked the battery voltage but it is still 3.2V. What memory is supplied from that voltage? The cal memory or just the user settings?
Found the answer in the service manual:
"It is advisable to replace the RAM battery A2BT1 every three years. If the
battery fails or drops below 3 V the RAM will lose the following information when power is disconnected from the meter:
Unit Serial Number
Revision letter of Processor Card
Unit Option
User defined setups
User defined sensor calibration tables"
Thanks! You've got it right, its only an inconvenience to not have the battery working. The cal tables are nice for older sensors, and I think preserving the serial number is probably for when you have several of the meters on the same GPIB bus so you can tell them apart.
As an interesting side note, the motherboard actually indicates what SRAM chips are actually backed up by the battery with a white box and text in the silkscreen. Not sure why though, perhaps to warn repair techs that there may be 3.3v on them so don't start shorting pins?
Excuse me, could you tell me how you removed the front panel of the power meter?
I can't remember exactly how but it was a very painful process, I think the plastic clips over something meaning you have to flex it out, very nerve wracking when you have aged and brittle plastic!
The battery could have been easily unsoldered from the underside of the board in under a minute. You can replace the exact same battery with mounting by searching on digikey. You have brown outs because that's the original 20W supply which they stopped using in later productions. You can find 40W or higher for them on eBay. Hope this helps.
I tried desoldering the battery from below but I had issues getting enough heat in, so clipping the battery out first was the easy option. I'd also already ordered the replacement battery (with the wrong connectors) before taking delivery of the meter, so I went with what I had.
About the power supply, interesting to note they have different versions, I'll take a look at the 40W version and maybe measure the existing units peak draw. My issue was definitely the broken hex inverter though, the power controller was giving the all clear signal but it was not being correctly inverted. I even ran the system from my lab supplies to be sure. Might do a follow up on this when I finally get back into the lab after COVID lockdown and replace the hex inverter!
Would it be possible for you to send me the PDF containing the schematics?
Sure, please email me at youtube@bansci.com. Alternatively, join the agilent/keysight group and ask on there and someone will help you
Thanks for this vedio.i have agilent e4416a power meter.when i press the power button nothing happens can you help me
Sure, can you describe anything else? Does the power light come on at all? If the light is not on, you need to check the PSU. It is always on, so you should be able to measure it's voltages on its connector. If the light is on, then it might be in your reset circuit like mine. Also check the very top of the display for an error code like The Signal Path saw.
@@bansci thanks for your reply. voltages 12 v,-12 v , 5 v , battery 2,9v are ok . The stand by light is ok .when I press the power button notting happened.
@@radiotvrepair1059 OK it sounds like my issue, you need to check the voltages on the reset pins on the MCU (to see if you have an issue with brownout control like me), and verify the clock in and out is working on the MCU (to see if its the clock), finally, you need to see if there's memory bus activity and the voltages of that, to see if its bad memory like The Signal Paths' one.
@@bansci I didn't work with my power meter a month ago. before yesterday when I turned on my meter it does not want to start knowing that it works well before. can humility do that because I'm in a place where the percentage of humidity is very high.
@@radiotvrepair1059 it could be, there's lots of ways you can degrade electronics. Humidity, temperature, vibration can ask expose weaknesses.
Nice repair. I would very much appreciate it if you could send me the clip also, will send you an email. Thanks
Best of luck with the repair!
Would it be possible for you to send me the PDF containing the schematics?
Sure I can point you at it, just mail me at youtube@bansci.com. I haven't used the email much yet so ping me here too and I'll check the spam folder
You've got mail!
@@bansci Thanks to the schematics I got from you I was able to get my meter working again in no time. My channel B sampling board failed during the self test. Turns out the 2.5 volt reference voltage was shorted by a 100nF decoupling capacitor (C30). Thanks again for your help!
@@legomindstormsfan1 awesome, that was very fast! Glad to hear I helped in some small way.
Hi, can you please share with me the schematcs file too? Just got a unit with a weird symptom, if a plug the AC cable while pressing the power button it turns on and works as expected, after that I can press the power button to turn it off, but it then won't turn on if I press the power button again, I have to unplug the AC cable and repeat... Regards.