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| HP 400F Power Supply Troubleshooting Help Needed! |
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| Technical Ted:
If you like YouTube videos you might enjoy watching this one on his HP 400F. Ted |
| factory:
--- Quote from: Technical Ted on August 20, 2023, 04:20:25 pm ---In my unit, the transistors in question are actually marked with EBC for the leads. Don't know about the earlier versions of the A2 board... Ted --- End quote --- Here is the 00400-66504 Rev B board in mine (617 prefix), picture was taken a few years ago, I can't tell you what part the small dome style transistors are ATM. It has a few signs of older repairs, one of the Sprague 150D tubular solid tants is now a crappy bead tant. David |
| Technical Ted:
This seems like a good time to share, so here's mine. Sorry, I removed the -26V jumper and soldered in leads for shorting and connecting a 560 ohm resistor to load the supply during troubleshooting so you might have trouble reading the part number. My 400F is a 0950- (no A designation) series serial number. I have a scanned copy of what I believe is the correct version of the manual for this unit which is a huge file but much better quality. The newest manual from Keysight's site does have a little more information than this version though... i.e. using the 560 ohm resister to load the power supply... The nerd that I am I actually read both. :) Ted |
| David D:
--- Quote from: factory on August 20, 2023, 08:47:46 pm --- --- Quote from: Technical Ted on August 20, 2023, 04:20:25 pm ---In my unit, the transistors in question are actually marked with EBC for the leads. Don't know about the earlier versions of the A2 board... Ted --- End quote --- Here is the 00400-66504 Rev B board in mine (617 prefix), picture was taken a few years ago, I can't tell you what part the small dome style transistors are ATM. It has a few signs of older repairs, one of the Sprague 150D tubular solid tants is now a crappy bead tant. David --- End quote --- Better a crappy bead tant than a shorted tubular one! ;D Luckily, the Sprague tubulars are still available on Mouser and Digikey. I just gotta figure out what else to order since I hate spending that much money on shipping for one capacitor... :palm: |
| David D:
--- Quote from: Technical Ted on August 20, 2023, 10:08:42 pm ---This seems like a good time to share, so here's mine. Sorry, I removed the -26V jumper and soldered in leads for shorting and connecting a 560 ohm resistor to load the supply during troubleshooting so you might have trouble reading the part number. My 400F is a 0950- (no A designation) series serial number. I have a scanned copy of what I believe is the correct version of the manual for this unit which is a huge file but much better quality. The newest manual from Keysight's site does have a little more information than this version though... i.e. using the 560 ohm resister to load the power supply... The nerd that I am I actually read both. :) Ted --- End quote --- I wish I had the patience to read all the manuals cover to cover, but my attention span is only getting worse the older I get :( My doctor says that's normal for someone with ADHD. It might be "normal" in my case, but as my grandfather used to say, "Getting old isn't embarassing, it's just damned inconvenient". :( I didn't load my power supply output after I removed the jumper since it was evident that loading wasn't the issue with mine. Here's my board mid-troubleshooting: |
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