HP-8640B repair. It needs a broken lamp!

[@ch2o2]

Attention to detail, genius and perseverance ..admirable. Like some of us, I've sometimes also dealt with exotic, ancient components (such as archetypes of optocouplers with tiny incandescent bulbs and LDRs in encapsulated packages), but I've never met something like this ...and you solved it. Another achievement to be very proud of Frank..great, as usual

[@iz8dwf]

Thank you for the very nice comment! I just suspected the lamp was broken on purpose, but the fine people on the HP-Agilent group confirmed the theory. I wish I had realized the "filament" support thermal effect before completing the second repair.... But it works anyway, it's just a bit lazy when waking up... Greetings to Austria!

[@wadowicegwadowiceg8093]

Very professional. It was a pleasure watching it.

[@HeyBirt]

Imagine being the engineer who came up with the idea of using a broken lamp. He had to get some strange looks from the other engineers at first.

[@iz8dwf]

You know, in the (old) university years we would study some real instruments schematics. I always had the impression that -hp- was one of the best places an engineer could work.... And yes, it must have been fun when this particular "part" choice was made, I agree :)

[@marcopantanetti4053]

Incredible thing! :))) Nice work Frank, thanks to share.

[@mikefry9920]

Nice work and thanks for sharing

[@NarcissaHdrs]

It must feel so nice being able to repair everything you've got! I have an old CRT monitor that hasn't been working, I thought of replacing it, but I fear I will zap myself to death if I try. 😅

[@iz8dwf]

Well... Not everything maybe, but I do surely try :D CRTs aren't the most forgiving parts on earth, but it doesn't take too much to handle them properly. You need to understand how the various electrode work and how to properly discharge the anode capacitor before servicing. If you need advice, you can always drop me an email. Take care!

[@ecycleit]

I have a HP 8640B with no RF output. The Power meter light does not turn on. The unit turns on but no RF output and no counter output movement when the internal frequency dial is turned. The power supply LEDs are and no -5.2VDC. I removed the RF Divider Filter Assemble and the -5.2 VDC is correct. Can you please provide suggestions on what is drawing the voltage down to 0VDC? The rectifier boards and filter caps are good. Al

[@iz8dwf]

Hi, if your divider assembly has a short on the -5V line, it could be an ECL IC or a bypass capacitor. You should open the assembly and check the resistance to ground with a good multimeter having at least 4.5 digit resolution. You can pinpoint the shorted component with a bit of luck if you have a suitable instrument. The HP-8640B is one of the most complex instruments I've seen, so it's not usually an easy repair job for anyone.

[@danielepatane3841]

Ciao Francesco bravo come sempre 🙂saluti

[@iz8dwf]

Ciao Daniele, grazie per il commento e le prove effettuate insieme :) Un saluto