EEVblog #808 - Fluke 196 Scopemeter Repair

[AF6LJ]

There was a number of displays that used similar technology that had the same reliability problems. A piece of amateur radio gear I own is notorious for the displays developing horizontal lines just after warranty.

Let me guess, an Icom IC-756 transceiver

Indeed and now there is nobody making a replacment display module for the radio.
Thankfully in 2011 I bought a module and replaced it.
Not that great contrast is crap, it is the nature of the module.
One of these days I hope to find something that woks better.

https://forums.qrz.com/index.php?threads/ic-756-display-replacment.302777/

[wblock]

That "anisotropic" glue is amazing stuff.  Well, amazing that it works at all.  Conductive only in the Z axis... but how does that work?  Wikipedia says some of it is stuck together at room temperature, so at least those connectors do not rely on heat to make a chemical change.  Maybe it's something that happens as it cures?  Other web searching just pointed out that yes, it's only conductive in one dimension, but not really how it does that, or how it knows which dimension is which.  A chemical change that goes from edge to edge and so completes in the thinnest dimension first, blocking the others?

[steve30]

Well done Dave . I expected you'd at least make an improvement with the display cable. I attempted to repair one of those cables once, and whilst I didn't fix it completely, I did at least make the display readable.

[NiHaoMike]

There was a number of displays that used similar technology that had the same reliability problems. A piece of amateur radio gear I own is notorious for the displays developing horizontal lines just after warranty.

I once had a tablet with a "static LCD" that failed with lines twice under warranty. The second time, I had them trade it for the version with a conventional LCD.

[Rasz]

Yay another win 

5.7" 320*240 is typical industrial parameters = very expensive
but someone dedicated could do a conversion to this http://andybrown.me.uk/2013/10/19/vivaz-u5-lcd/

hitachi driver bus is slow and simple, pic32/stm32 could easily grab that and convert to another screen, or even stream directly over bt/wifi to a phone/tablet

[Smokey]

Just a little aside: I think below that bodge cap there is a resistor

That's what I was going to say.

[Monittosan]

Its the same deal with the fluke 120 series except the flat bar is even harder to access.
I had a go at repairing one nearly a year ago with a soldering iron and its still working fine. I did want a 196c - 199C but I guess thats not going to happen now Dave 

you can rework the LCD ribbon cable with a soldering iron on its lowest temp setting.
The challenge is getting to the vertical ribbon cable as its behind the glass

before



After


[/quote]

[PA4TIM]

Nice video, I'm glad to know these strips are more or less repairable.

I have a dead Fluke 192 from a customer here. But I'm stuck. I hoped to see/learn some troubleshoot techniques but the 192 differs a lot. Non the less it would be great to see a follow up video.

The 192 has three Fluke Asics and one of them is a huge bga. The firmware and SRAM is on a piggy back and one of those bga's reacted on pressure so I reballed it. Now it charges, beeps when powered on, the 3 clocks do what they should do according the tests in the manual. And following the manual trouble shoot part and my measurements the problem seems to be missing or corrupt firmware and/or defective memory.

The manual now wants software and an interface to check things.

But these scopes are a pain in the ass because those asics work together.  The psu ASIC fires some parts of the psu for charging and "booting" . That in turn starts the digital asic and that digital ASIC then starts the rest of the psu ASIC etc. (or something like that, it is resting for 2 months now, the owner try's to get the interface/software so I do this from memory)  A bit a chicken and egg situation. 

For the electronics scopemeter-porn aficionado's,  I repaired a Tektronix equivalent in the meantime. (pictures:  http://schneiderelectronicsrepair.nl/?p=212 )

 

[gordo51]

Two successful repairs in a row. Dave is on a roll.
I have an older 100MHz scopemeter that refuses to run on the battery even though I have two different fully charged batteries.
The internal connections appear to be fine and I cannot see anything like a fuse so nothing obvious.
Any ideas out there? 

[AF6LJ]

There was a number of displays that used similar technology that had the same reliability problems. A piece of amateur radio gear I own is notorious for the displays developing horizontal lines just after warranty.

I once had a tablet with a "static LCD" that failed with lines twice under warranty. The second time, I had them trade it for the version with a conventional LCD.

My IC-756 was my first encounter with those displays, When I read about their high failure rate and started seeing the same display in point of sale terminals failing I was rather unhappy. There were a few other issues I had with the radio and after spending 2.2 K$ on the radio I was not happy. I know they have become more reliable but the way they are put together doesn't give me a lot of confidence.

[mcleod]

Do the various chips that looked like they had a thin heatsink pad on them require heatsinks? Being at least one person has previously tried to fix it they may have removed the heatsinks. Or do the pads make contact with a metal shield when assembled?

Yes, they need heatsinks. There is a large sheet metal shield/heatsink that covers that section of the scope from the factory. It is not in the case, but a separate piece. Obviously, some clown lost it or was too lazy to replace it.

There are also shields/heatsinks that cover the scope input sections and the meter section.

[Assafl]

The heat sink is part of the shield cans. There should be an angled piece inside connected to the can that presses on the ASIC. Therefore the heat pad is required.

If you do get a battery remember to charge it and use the scope meter at least on a semi weekly basis or the batteries die rather quickly.

[memeruiz]

Hi Dave,

I don't know if you could finish fixing the Scope completely.

A couple of things:

1) Keyboard membrane fails a lot. Sometimes the scopes seem unresponsive, when in reality is the keyboard that is not working.
I fixed this by using a fixed PCB instead of a membrane one: 

https://www.ebay.com/itm/Fluke-192-196-199-Scopemeter-Keypad-Contact-Board-Replaces-Foil/231220134535?hash=item35d5cb4287:g:u~0AAOxyOalTYqZ8

2) The sticky tapes that you found on the ICs are actually for connecting to the metal back of the scope. They come into contact when you rescrew the scope. It happened to me that the scope freezes if some of these ICs overheat. Check that. Or reapply heat transfer paste there. Those tapes looked toasted and old.

What I want is to upgrade my old 196 scope with the newest firmware. Mine is so old that it can not be upgraded by the user according to fluke. Apparently the board must be modified. If you could take a detailed picture of the main board, both sides, that would be great to take a look into my scope and see if it is possible to upgrade at home.

All the best!