Electronics > Repair
Hioki 3532-50 LCR Repair (One major problem solved, SM still wanted)
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coromonadalix:
Check ic108 a 3 pin sot,  near one of the ram, try to find what it is

the SED lcd controller  has a ram chip for itself

seem pretty simple logic  loll   lots are hidden in the fpga ....

Unlees the flash chip has began to deteriorate,   but you say it eventually work  ???  I would still suspect the ram ic's  ??

With the datasheets,  you are able to measure many ic's vcc pins voltage(s)

Suprised to see somekind of a clock generator instead of a crystal ??

For the yellowish color,  there was some talk here   about whitening plastic / restoration  etc ... 
Martin72:
Hi,

Tomorrow I´ll turn my scope on and doing some measures.
First the reset signal from the battery controller chip, then looking further.
It must be something which last a while, maybe a voltage to come up on the right level.
When it´s something with the RAM...As long as they are avaible I don´t care.
At work I got access to a rework station so this would be a minor problem.


--- Quote ---Suprised to see somekind of a clock generator instead of a crystal ??
--- End quote ---

There´s a second oscillator on the main pcb.


--- Quote ---For the yellowish color,  there was some talk here   about whitening plastic / restoration  etc ...
--- End quote ---

Good to read, post tomorrow a pic of the front panel.
Martin72:
I´m coming closer to to the solution...
Not done scope measuring yet, but this will be the next, because:
The 5V voltage (I guess it is) from the supply starts with appx 4.2V (meter reading) and increase slowly, at appx 4.4V the system boots up because the battery control chip release the reset signal then.
This is not normal... ;)
Next is watching the 5V signal how its look like - Unfortunately at later afternoon, part of the sunday is reserved for family.
Stay tuned.
Martin
Martin72:
Short snip before I´m off:
Got it..
It´s the 5V supply..
Martin72:
Hi,
A Multimeter is never enough for failure analyzis... ;)
This I´ve learned over 20yrs ago in a "painful" way and it´s still valid.
Looking at the 5V for the Controlboard with scope, first setting the timebase to 10s because I wanted to see the signal rising.
But there´s no rising, there´s a huge noise on the dc-signal, reduce timebase to µs, aha...
Something is heavy oscillating and the signal remains even when you disconnect the plug from the controlboard, so it´s definetly on the supply board.
The board itself is "simple" as it can gets, several aux voltages from the transformer goes through rectifiers and then stabilizing with classical 78/79xx types, plus one 317.
And where every other voltage is clean, the 5V for the controller is oscillating.
So the 5V regulator must be replaced.
I got several ones here, but not in fully isolated housings.
Maybe for testing I´ll take one.
So or so, I think this was it... 8)
If I´m right, next step will follow, what to do with the touch panel and (perhaps) with the backlight.

Martin
(edit why are the pics "shuffled"...it´s not my order I´ve placed them)
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