Fluke 77 service

[jam]

Hi Chris,

Oddly enough the eraser trick was told to me by a tech at Fluke years ago, it worked on my co-workers Fluke though you had to be very careful and ran the risk of damaging the pads.
I prefer the alcohol method myself and you are right as I should have qualified it by saying Isopropyl alcohol.

Jam

[anatech]

Hi Jam,
I can't fault you for not specifying the type of alcohol used. This is the first time in this thread that I have as well.

The eraser on an elastomer idea makes me grit my teeth just thinking about it! The possibility of damaging the elastomer is very high.

Erasers used on PCB contacts is also a very bad practice. Try that in Agilent's service center and watch what happens! They have proved this technique will probably cause damage as well. You need high magnification to see the damage start, but that fact is undeniable.

Best, Chris

[dangus]

I saved an 87 display by simply flipping the conductive elastomer strip end for end. That put fresh conductive areas in contact with the board and LCD, and all the segments lit up like they should.

[figge77]

according to the servicemanual:

if ohms reads low or won´t read ol----> shorted Q1 and Q2 or leaky E1 or E2

the E1 and E2 are 1500V surge protectors. can i test them if they are ok somehow? or what can i use as replacement? a wire bridge hehe?

just kidding

will check the transistors aswell but aint gonna be inte workshop in a couple of days.

[troystg]

Thanks all, I will try it this week.

Again sorry for hi-jacking the thread.

There should be a "sticky" thread in a test instruments group for things like this...

Hmmm, Will have to write the moderators..

[anatech]

Hi Troy,

Hmmm, Will have to write the moderators..

I R 1

Now I feel completely forgotten, ignored. Just another old, forgotten tech from yesteryear.

Hi figge77,
Well yes, check the input circuit. This is the time when a good bench meter comes in handy. You can simply remove them for testing. I have seen a number that were either zapped or had some conductive residue in there.

They should test as an open, however, if you remove them and start getting better readings - guess what?

-Chris

[troystg]

Originally posted by anatech
Hi Troy,



I R 1

Now I feel completely forgotten, ignored. Just another old, forgotten tech from yesteryear.

........
-Chris

Oh stop acting like a melodramatic teenager...

I was just thinking out loud when I wrote that.

[figge77]

i removed the protectors E1 and E2 but to no good. i checked the Q1 and Q2 as mentioned in the sm and they are ok.

well well. life goes on.

[jackinnj]

Uuuuuuuuuuuuuhhhh, did you check the battery first?

[anatech]

Hi Troy,

What can I say?

Hi Jack,
Now, if you just nailed the fault, I'll be laughing pretty hard. Still, there is a "low batt" indicator on the display.

Now that you mention it, I do recall having to replace battery clips often enough on these meters. My memory needed a jog too - thank you!

It's generally the simplest faults that mess us all up.

Hi figge77,
Do you have the manual or schematic for that meter? This fault shouldn't really be a terrible thing to troubleshoot.

-Chris