Electronics > Repair
Teardown : HP 4263B LCR Bridge meter (and repair)
TiN:
Ok, time to start new restoration thread, this time HP/Agilent 4263B LCR meter. Yes, it's not Keithley, as some people already wondering
about Keithley graveyard in here, and reliability of their products >:D
Any owners of 4263B, which don't care warranty and can open up their meter (just 4 screws on sides and cover off) and take photo to give me a hand
in repairs?
I'd like to know value or photo of four thru-hole resistors near J101 (A output). They are burnt on 4263B i received today badly, so cannot read value.
Attached photo of them. Also one burnt SMD resistor from pin 2 of U182, D5210G IC.
Also photo of SMD side on two mosfet/transistor module U107 would be helpful (some parts blown there too) but that need removal of front panel (uncrew 6 screws and disconnect front
terminals)
4263B Service manual does not contain parts list, nor schematics to help on this matter.
Units still power on, and gives PASS on self-test, but i doubt it works fine with these damages....
Teardown coming... ;D
So far total visible damages:
4 x 1/2W resistors (need value for them)
Broken in half tranzorb Z6010
Burnt 1206 on main pcb (100 ohm?)
And on secondary module with pair of PNP/NPN bulged SOT23 with code Y23 (second module have same layout and same Y23) and bunch of 1206 resistors..
As usual - handle tasks via my redmine tracker.
Thanks!
TiN:
Noone have 4263B ? :o ::)
TiN:
Seem it's way to go good old way, if want something done - do it by youself :D
Will try some usual "try put some parts and see what happens" way later.
For now teardown, as whole internet don't have a single hi-res photo of 4263B internals...
So here we goes, all photos click-able for hi-res.
Front panel
Back I/O
Unit is not deep, but wider than usual Keithley/HP bench meters, so it will not match in rack as for size :(
Remove cover by two screws from rear:
Bird's view
Disassembly pretty simple and user friendly. All can be done in few minutes. Well thought design layout.
Input BNC connectors.
LCD is standard 40x2 char type, with very well known 44780 controller. Maybe later I'll change LCD to something with better contrast, if repair will be successful.
Protection on inputs?
Mains protection and filters.
Unit low voltage power supply in it's cage. Two 22000uF 25V KMH capacitors and lot of small 22uF 50V electrolytes.
Here goes digital board, mounted on standoffs above signal acquisition bottom board. MC68HC000FN10 CPU, two Sony branded CXK581000AM 70ns SRAMs, Xicor X28C64 ROM, AM27C2048 UV ROM with firmware (04263-85041 on my unit) and some big National Semi S9652AB SCX6B65AHI ASIC, and bunch of 7400 series logic and AMD-branded PALs around.
No batteries to store cal/configuration constants or NVRAM, only supercap there. So this unit pretty safe from dying from dead batteries, like some other gear :)
Some sections done with PCB-PCB modules, one of which near standoff had burnt resistors and SOT-23 resistor.
It's similar to other presumably alive module, so should be not very hard to find out what it does.
Good module:
It have PNP and NPN with small heatsinks on another side.
Input terminals protection and switching. Probably some stuff is borked here...
I already put some resistors to check basic functions, but it's not working right, readings sometimes, all over the joint often, sometimes seem ok.. Need debugging
Analog/switching/measurement components
TiN:
Got back to 4263B repair project...
Made a schematics for little modules on 4263B front end board.
Some kind of half-bridge with pair of PNP/NPN.
SOT-23 probably BJTs, need to find out what part are they to replace on faulty module.
Faulty module had burnt 51 ohm resistors, 2.2ohm between power BJT's and "Y23" SOT23.
ve7xen:
I think the transistors are 2SC3734 / 2SC1461. Might be hard to find these days, and mind the gain binning.
Nice looking instrument, I look forward to seeing it in operation :D
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