Electronics > Repair

Fluke 289 not quite sorted.

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Yakuzza:
@saturation
Do you mean to desolder input protection and check it piece by piece?
Assuming the input protection is fine, what else can I check and how?
If the input protection is faulty, does that mean that the board might be fried as well, or should the input protection actually protect the further elements?

I will be updating this question list from now on.
Here is a summary of my questions (slightly rephrased) and with some answers:

Q1. Just to check if there is a warranty option, where can I find the production date, serial number, and other info needed to fill the online form for requesting repair by Fluke. I’ve read that it might have 10 years of warranty, right? Note - LCD doesn’t work.

Ans: Since I’m not the original owner and I don’t have any papers to even show when and where the meter was bought, the conclusion is that the warranty is off the table.
-Q1 closed-

Q2. Assuming the warranty is not an option, what else can I check?

Q3. Does the power light in an operational meter behaves in this way, that is lids up for couple of seconds and then turns off?

Ans: I’ve just found out that according to Calibration Manual, in the “Power LED test” section: “... power button [should] lights for approximately 4 seconds, and then extinguishes”, which is what I observe in my unit. That is okay than.
-Q3 closed-

Q4. The steady 25mA current draw might be a sign, that everything except the LCD is fine, right?

Q5. How can I check the LCD itself?
Can I assume that pin 1 is ground and pin 2 is VCC, and check if get readings on the board, after disconnecting the LCD?

Here are some data I found in the Calibration Manual:
dot matrix LCD, DS1,
LCD MODULE,289,320X240,FSTN,3.5 MONO GRAPHIC,TRANSFLCTV,WHITE LED,0.22MM PITCH, Part number 2734828.

Q6: Anybody have some readings on the test points, so I can compare them with my unit?

Q7: This might be a silly question, but how can I attache voltage to PCB? There are those two small copper areas in the middle of the board and small holes right next to it. Are there any special probes cable that you stick the board on them or what?

Ans: According to Calibration Manual: “TP8 and TP10 can also be used to apply power to the PCA.” And since these two points are on the side of the board I can use crocodile connectors or something similar.
-Q7 closed-

purpose:
Yakuzza,
I'll be borrowing a working 289, so I'll get some readings up soonish.
Trouble is knowing from where to where one measures.

I was onto Fluke UK, asking about their 'fixed price repair' and was told £271 plus this and that.
I'll not be sending it to them.

peter

Yakuzza:
@purpose
Hi. I’ve assumed you managed to repair your unit, but I see you still haven’t fix the issue. Well, about the readings in test points I thought to measure in respect to ground, but maybe that is not a correct approach. Anybody?

I actually just did some readings on the LCD connector and few test pins, and then I realized that it doesn’t make sense to compare it with other unit’s readings. There is no Service Manual available for this model (as far as I tried to find one), so even if we identify differences in readings there is no reference to say what does that mean and what is broken. Don’t you agree?

Tomorrow I will try to grab a friend which owns a CAT mobile phone with infrared camera, so maybe I can have a look at the board and see if there is something suspiciously warmer than other.

The fact is that I don’t want to spend hundreds of pounds for repair of an old unit (with unknown history of usage, without all the accessories and even test leads). I will do few attempts and check what I can, with some advices from you guys, and if it does not help I will just ditch it.

I can share my readings in test points if you like, maybe we can see a pattern anyway  8)

Cheers,
Mike

purpose:
Yep... it's back to NFG.
I'll measure all points on the working 289 relative to the common input for starters and post the results.
I invested in a cheap FLIR TG165, in the hope of seeing something the back of my finger is missing.

peter

purpose:
I've got most readings from a good one... enough to know that my -2.5v rail is kaput.
All measurements taken relative to COM input, switch at VDC and 9V to the battery pads.

TP    BAD    GOOD
1    -0.81   -2.49
2     2.26    0.61
3    -0.13    2.49
4     2.26    0.61
5     2.25    0.61
6     2.24    0.61
7    -0.81   -2.49
8     8.23    6.53
9     1.16    1.11
10  -0.81   -2.49
11   0.23    0.46
12   -0.81   -2.49
13   2.22   0.438
14   -0.81   -2.49
15   2.13   0.438
16   2.11   0.437
17   2.26   0.609
18   0.98   0.68
19   2.13   0.43
20   2.13   0.43
21   2.13   0.43
22   2.13   0.43
23   2.13   0.43

28   -0.81   -2.49

30   -0.81   -2.49
31   -0.81   -2.49
32    2.26    0.61
33    2.26    0.61
 
U20, which I assume to be some sort of pwm, is chuffing along on one side at 293kHz and other side at 143kHz. Both at 97/98% duty.  How pertinent that may be, only one of you can tell me.

BTW... My new TG found the 10mA hungry component, but removing it just brought the draw to the normal 19mA and did nothing for the rails.

peter


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