Electronics > Metrology
Repair worklog : Old rusty HP 3458A
TiN:
Received final item for volt-nut freaks - 3458A. It's old unit with chassis corrosion from seller in Philippines, which we already discussed in Buy/Sell section here..
So far initial inspection:
* U100 processor MC68HC000P8 had paper sticker BAD (A5 board manufactured 1990)
* Missing button cap on power switch, guard switch and front/rear switch.
* Missing fuse binding post for amps on front panel
* Rust on steel chassis
* Mark "X" on mains power transformer
* Mark "X" on analog board 66501 (manufactured 1996)
* Error message RAM 1 LOW
* Missing voltage reference board (so calibration is meaningless, even if it's still intact in 1990 year DS1220)..
* Missing fuse holder for mains
* Damaged plastic rear panel
* No legs
Smell like lots of work, lots of debug folks.
krivx:
What's the plan? DIY or OEM voltage reference assembly? Will you get this functioning and then refinish/repair the enclosure?
Vgkid:
This will be interesting...
Following.
Macbeth:
Looking forward to this :popcorn:
TiN:
Ok, back home with unit now. Let's see what we are dealing with..
Steel chassis is rusty on rear side. Not nice treatment for such an instrument. :(
Removing covers...
All analog stuff is contained in aluminum box, isolated from steel frame by plastic inserts. HP calls those boards inside as "inguard", rest boards are "outguard".
View on both sides without covers. As we can see, no A9 voltage reference present |O
Inguard PSU. Some PCB damage around CR12 visible.
Outguard primary PSU. All seems ok.
68000 CPU, RAM, ROM and digital logic, board A5. Dated 1990, while rest of analog PCBs dated 1996.
Probably seller changed digital PCB afterwards?
Removing inguard PSU for now, adding jumpwire instead of fuse (don't have suitable cap), turning on...
Aha. Nice and bright VFD, which is cool. Now will remove Dallas NVRAMs , and solder sockets instead, so we can troubleshoot this RAM 1 LOW.
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