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1. polprog68k (gorplop@pleroma.m68k.church)'s status on Saturday, 04-Jan-2025 07:02:59 JST polprog68k
   I bought and am fixing an Agilent 66311B "Mobile Communications DC Source". You can use it as a lab PSU with cool measurement features. (they don't check that). There's a pretty DSP system inside. My unit turns on but there is no output voltage. I traced it to a blown fuse, surprisingly not the one directly on the output, but the one before the rectifier. There could be something else blown.
   
   Measuring around this unit is quite difficult because everything is in the way, it's quite packed. The service manual is better than nothing, but leaves some things to wish for. The circuit board seems to be made haphazardly, some parts cover their own designators, for example.
   
   This unit is dated 2003.
   
   #electronics #repair
   • polprog68k (gorplop@pleroma.m68k.church)'s status on Saturday, 04-Jan-2025 08:19:08 JST polprog68k

     in reply to

     • miek
     @miek I will check that, thank you! there is a pair of thin traces on the bottom layer, leading from the analog control part to a different rectifier that discolored, likely because of overcurrent. I was wondering what they were.
   • miek (miek@mastodon.social)'s status on Saturday, 04-Jan-2025 08:19:10 JST miek

     in reply to

     @gorplop nice bit of kit! I've got a pair of the similar 66312A's that I also bought broken & fixed. One of them actually had a bad rectifier that had failed short & had blown one of the traces leading up to it, might be similar on yours?

   • miek (miek@mastodon.social)'s status on Saturday, 04-Jan-2025 08:25:41 JST miek

     in reply to

     @gorplop ah yeah, sounds like the ones that went on mine

   • polprog68k (gorplop@pleroma.m68k.church)'s status on Saturday, 04-Jan-2025 08:25:41 JST polprog68k

     in reply to

     • miek
     @miek hmm, mine had a different trace, but only discolored to yellow/gold and not blown through. Ill check the rectifiers though.
   • polprog68k (gorplop@pleroma.m68k.church)'s status on Sunday, 05-Jan-2025 01:25:36 JST polprog68k

     in reply to
     It looks like there was no short inside the +Rail supply and the only fault was the fuse. I temporarily injected current limited 20V and the power supply works fine. Keysight sells these new for $3000 :)
     
     Gonna order new fuses and fan and finish this when they come!
   • Ret (ret@furry.engineer)'s status on Sunday, 05-Jan-2025 01:35:29 JST Ret

     in reply to

     @gorplop ooh it arrived - looks nice, a surprising amount of stuff in there!

     polprog68k likes this.
   • polprog68k (gorplop@pleroma.m68k.church)'s status on Sunday, 05-Jan-2025 06:49:19 JST polprog68k

     in reply to
     I ordered new fuses and a new fan
   • polprog68k (gorplop@pleroma.m68k.church)'s status on Sunday, 05-Jan-2025 06:51:12 JST polprog68k

     in reply to

     • F4GRX Sébastien
     @f4grx there is no short ;)
   • F4GRX Sébastien (f4grx@chaos.social)'s status on Sunday, 05-Jan-2025 06:51:13 JST F4GRX Sébastien

     in reply to

     @gorplop that wont solve your short circuit. You cant blow on the fuse to keep it cool.

     polprog68k likes this.
   • polprog68k (gorplop@pleroma.m68k.church)'s status on Sunday, 05-Jan-2025 06:52:10 JST polprog68k

     in reply to

     • F4GRX Sébastien
     @f4grx it's a controlled short so to speak. The power supply was unhappy and took itself out with a crowbar
   • F4GRX Sébastien (f4grx@chaos.social)'s status on Sunday, 05-Jan-2025 06:52:11 JST F4GRX Sébastien

     in reply to

     @gorplop the short is a lie.

     polprog68k likes this.
   • F4GRX Sébastien (f4grx@chaos.social)'s status on Sunday, 05-Jan-2025 07:03:46 JST F4GRX Sébastien

     in reply to

     @gorplop I see that, pretty hardware.

     polprog68k likes this.
   • polprog68k (gorplop@pleroma.m68k.church)'s status on Friday, 10-Jan-2025 03:12:18 JST polprog68k

     in reply to
     The fuse is replaced and the power supply works :) the on-screen min/max/high/low/RMS measurements are very nice. I replaced the fan as well, it's now much more quiet.
   • Wolf480pl (wolf480pl@mstdn.io)'s status on Friday, 10-Jan-2025 03:25:38 JST Wolf480pl

     in reply to

     @gorplop i love this supply's display. What kinda disolay is it?

     polprog68k likes this.
   • polprog68k (gorplop@pleroma.m68k.church)'s status on Friday, 10-Jan-2025 03:25:58 JST polprog68k

     in reply to

     • Wolf480pl
     @wolf480pl It's a 16 segment VFD! It's pretty, IRL it's more green than on the photo
   • Wolf480pl (wolf480pl@mstdn.io)'s status on Friday, 10-Jan-2025 04:03:16 JST Wolf480pl

     in reply to

     @gorplop that's so cool!

     polprog68k likes this.
   • polprog68k (gorplop@pleroma.m68k.church)'s status on Saturday, 11-Jan-2025 03:54:23 JST polprog68k

     in reply to
     Bought some sillicone wire and made a pair of EZ-hooks with sense wires. Now i can use it like a normal lab power supply :)
     Gonna clean the front panel a bit later.
   • polprog68k (gorplop@pleroma.m68k.church)'s status on Saturday, 11-Jan-2025 04:02:43 JST polprog68k

     in reply to

     • Ret
     @ret there are molded holes and there is space to install a front output. They are just covered by the front panel sticker, I'm thinking which solution I like more. I can install banana jacks any time
   • Ret (ret@furry.engineer)'s status on Saturday, 11-Jan-2025 04:02:44 JST Ret

     in reply to

     @gorplop are there any holes in the hard plastic front on the right-hand side for binding posts? I wonder if some models had front-panel connectors? Could be moddable?

     polprog68k likes this.