Electronics > Repair
Repair : HP 3245A precision DC/AC source
Samogon:
OK, it has been fixed.
1. As i said Q901 was dead short, replaced both Q900 and Q901 (BUZ71A) as they make pair so to be sure that i have close parameters i used IRFZ20PBF
2. Blown linear regulator U906 (LM7915) replaced with same
3. Charred C900 470uF 25V changed
4. And fuse which blown after all components listed above went kaboom. Well at least it prevented more catastrophic consequences.
So need to order to replace Puffner filter and calibrate this nice peace of equipment.
But 10V is too low i will be locking for unit with option #2 or amplifier board itself. If some one has a lead i would appreciate.
Samogon:
About K3 relay, stupid me, it did stuck in wrong position, but what i have expected from latching relay :-DD. Once power rails were restored, firmware run initialization sequence and it K3 into proper position. Well, now i have spare relay for $20
rastro:
Has anyone found a replacement source/part for C900 on the source boards. This is the 470uF/25V radial electrolytic with an additional ground lead (screen?) at the top?
JesseLackey:
If you're going to dig in, why not do 3? :)
(see attached pic... not sure it shows up inline in the post, I'm a newbie here)
Been scouring this thread and the excellent writeup at <https://xdevs.com/fix/hp3245a/>
Hopefully somebody out there is still interested in these beasts, I'd enjoy any commentary and help. For sure I'll need to replace the NVRAMs.
I don't have an HP 3458A, but I do have a calibrated Advantest R6581T for DC V/I. And USB->GPIB coming soon.
Cheers all!
J
JesseLackey:
...and first questions, if anyone has some general tips...
1. the Schaffner is riveted (?) to the frame, at two points. I don't need to rivet in the Delta 06geeg3e replacement (or maybe just a new Schaffner), but ... how should I remove it? Is this a drill-out-the-rivet job? I've never had to deal with this before.
2. opening up the 1st of the three, everything looks really pretty good, a little dust is all. The only date codes I can find are on the EPROMs, 8849 and 8850, meaning the 49th and 50th week of 1988, one assumes. Is there a date code anywhere else? I wonder if the date code is not necessarily when the EPROM was programmed but the revision of the firmware. Seems unlikely tho. Thoughts?
3. The electrolytics all look just fine. I'm going to spot check ESR on 2-3 largest ones, if the ESR looks ok, should I replace anyway? Opinions?
From the date code, and somebody's post here about list price in 1988, the one I'm working on (it has option 1, two channel output) cost nearly $7000, which is nearly half the tuition for my sophomore year at Cornell!
Thanks all!
J
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