Fluke PM97 Scopemeter EV replacement - Page 1
Forum section: electronics / testgear

author: lamello
author_rank: Contributor
timestamp: September 14, 2015, 01:27:24 pm
content: Hi,I have received a defect PM97 as a gift and have repaired it. It's function as it should be, but the backlight is dim, very dim.Has someone an idea to replace the EV with a foil illuminated by led's. Is this even possible or what are other possibilities to get more light.?Thanks in advance,lamello

author: BradC
author_rank: Super Contributor
timestamp: September 14, 2015, 01:44:34 pm
content: No, but I have the same unit in the same state. I bought some EL paper a while ago with the intent of replacing the existing backlight, but it ended up getting used elsewhere and I've not got around to buying another piece.It was a few years ago when I stripped the display down, but I don't think there will be anywhere enough room in there to put a LED backlight. I had intended to laminate the EL paper to protect it but measurements showed that might be a problem also using commonly available laminate.You might have kicked me into having another crack at it though. I'll be watching this thread closely.

author: mij59
author_rank: Frequent Contributor
timestamp: September 15, 2015, 07:07:25 am
content: I was disappointed with the backlight of the PM97 from the beginning, so what is very dim ?I have removed the display, and there is about 1.7mm space between the back of the display and the top of the zebra strip, I think there is not enough space to mount smd leds, and you need some kind of diffuser to light the display evenly.Also found some bad smd caps in the middle of the display pcb, the leakage has caused some damage on the copper traces.

author: lamello
author_rank: Contributor
timestamp: September 15, 2015, 03:27:38 pm
content: Thanks for the responses,I don't know how bright the back-light was when it was new, so i don't have a reference how bright it should be.Lets describe the following light-conditions:Bright: Display good readable.Dark: Acceptable. EV gives just enough to read display.Not so much light: Display hard to read. Very little reflective light from available light and EV back-light is to weak.Does someone know which type of back-light is used in the PM97?

author: radhaz
author_rank: Regular Contributor
timestamp: September 15, 2015, 11:52:05 pm
content: There's this:http://areciv.com/blog/2013/02/fluke-scopemeter-97-el-backlight-repair/

author: lamello
author_rank: Contributor
timestamp: September 16, 2015, 09:51:21 pm
content: Thanks for this great linkVerstuurd vanaf mijn SM-T800 met Tapatalk

author: lamello
author_rank: Contributor
timestamp: October 07, 2015, 10:19:32 pm
content: Changed the backlight yesterday.Works like a charm. I'm very pleased with the result.Thanks for the usefull hints.Lamello

author: mij59
author_rank: Frequent Contributor
timestamp: October 08, 2015, 04:50:19 am
content: Quote from: lamello on October 07, 2015, 10:19:32 pmPictures of the display with the backlight in action would be nice, what el-paper did you use ?

author: lamello
author_rank: Contributor
timestamp: October 08, 2015, 07:02:05 am
content: Hello,For a photo, look at the link mentioned by radhaz. Those photos display the eindresult well.For the brightness: It doesn't lite up your living room, but it's adequate to lite up the display.The reading of the display is now good. For example: I can now read the Volt/Div in scope mode ( top-left in the display) very well, which was very difficult before.The display used:http://nl.aliexpress.com/item/10x10cm-EL-Lamp-electroluminescent-panel-backlight-led-alternative-with-2-AA-battery-inverter/32306223444.htmlJust a tip: Desolder de wires from the EL-Display as quick as possible. There is not stress release and the wires are to stiff. As a result, the solder pads on the display break off. (mine within a half off an hour). Use for the el-display very flexible wires as possilble.

author: WindPowerGuy
author_rank: Newbie
timestamp: January 15, 2016, 05:42:29 pm
content: I replaced Capacitor C1302 and the original EL paper became bright. C1302 Is the 10uF 50V cap nearest to Flash memory chip.

author: Milmat1
author_rank: Contributor
timestamp: January 30, 2016, 02:06:55 am
content: My 97 is pretty dim as well, I tried using it this week to troubleshoot a machine in Oklahoma. Became very frustrated with it for sure. I personally think Fluke us insanely over rated, especially the DMM's. But when I need a portable scope its the only game in town. The new models are nice but wow, 5 grand for a portable is just out of my league.....Maybe I will give the repair a try.Anyone have any feedback about the model 123 ? I see them on ebay for reasonable prices.....

author: eTimesV
author_rank: Contributor
timestamp: March 07, 2016, 12:54:08 am
content: I tried to do the EL panel replacement based on the link posted by radhaz,http://areciv.com/blog/2013/02/fluke-scopemeter-97-el-backlight-repair,but for some reason, after all the effort to put it in, it did not work. Does anyone have a suggestion? Would replacing the capacitor C1302 mentioned by WindPowerGuy maybe help? I took the panel out and connected it to a small electroluminescent wire driver that I had lying around and the panel turned on fine when powered by that.Here are pictures showing what I did:http://somewhereinlimbo.com/vistas/public/scopemeterSorry for the large number of pictures. I was trying to capture all the steps.

author: mij59
author_rank: Frequent Contributor
timestamp: March 07, 2016, 04:34:02 am
content: At power up the EL- panel is switched off, when turned on the inverter makes a high pitch sound.

author: eTimesV
author_rank: Contributor
timestamp: March 07, 2016, 10:54:39 am
content: I'm not sure if mij59's comment is directed to me but if so--good point. I tried pushing the BACK LIGHT button again and listening for that sound (which I remember always hearing now that you mention it) and do not hear anything (but I had already desoldered/removed the new EL panel in case that's relevant). Is that something I can fix?

author: mij59
author_rank: Frequent Contributor
timestamp: March 07, 2016, 11:15:24 am
content: Quote from: eTimesV on March 07, 2016, 10:54:39 amIt seems the inverter is not working, you could check the electrolytic capacitors, in my unit all of them where leaking and starting to corrode the copper tracesEdit: Service manual availablehttp://www.opweb.de/nl/model.php?id=1177] http://www.opweb.de/nl/model.php?id=1177

author: eTimesV
author_rank: Contributor
timestamp: March 07, 2016, 01:51:10 pm
content: Thanks a lot for the tip. They look to be in perfect condition...would it still make sense to replace the C1302? I measured it in place at about 3.3µF. Not sure if measuring in place is valid, also I'm using a very old Fluke 79 meter, not calibrated for at least 16+ years (I tried just now to measure some brand new electrolytic caps I recently ordered and two separate 100µF ones measured 94.9µF and two separate 47µF ones measured 45.6µF, if maybe that gives any sense of how badly miscalibrated it might be).

author: mij59
author_rank: Frequent Contributor
timestamp: March 07, 2016, 02:03:52 pm
content: C1302 is 10 uF so about 3 uF is too low, I think it's best to replace the four capacitors.The back light circuit is on page 10-7 check the voltage of +VBAT and the LIGHT signal ( on the previous page )

author: mos6502
author_rank: Frequent Contributor
timestamp: March 07, 2016, 02:27:25 pm
content: Quote from: eTimesV on March 07, 2016, 01:51:10 pm"Measuring" caps with a multimeter is fairly pointless. Electrolytic caps are usually specced at +80/-20%. So 80uF for a 100uF would still be in spec even for a new cap. Also, even a defective/high ESR cap will most often still measure good on a multimeter. You really need an LCR meter to determine capacitor health, because you're not interested in capacity, but rather D and ESR.

author: eTimesV
author_rank: Contributor
timestamp: March 07, 2016, 04:56:12 pm
content: mij59 : I don't see C1302 in "replaceable parts list" in the service manual so am not sure exactly what the exact specs are and what to replace it with or where I can order that (Mouser? AliExpress?).Before ordering it, just to test if it's going to fix it, could I solder on/attach some other 10µF / 50V cap?Also, I'd rather not replace the other caps since the meter works besides the EL panel and I'm a little wary of breaking it.mos6502: interesting, thanks. I don't have an LCR meter and it's not worth it to me to get one for this single case but it's good to know that'd be the way to go.By the way, out of curiosity, I connected the very old original EL panel and the new EL panel from Sparkfun that I'm trying to put in, to some little EL driver boxes for EL wire. The old panel works ok although the new one is brighter (and I did swap the drivers between EL panels to rule out that one might be more powerful than the other--no change as far as I could see). In the last pic I included a piece of white paper on the bottom right and at the top an 18% gray reference from Lastolite to try to get the colors accurate but the AWB in the camera looked to me the most realistic (i.e. I did not set the white balance in the pic uploaded here). Original EL panel on the left, Sparkfun panel on the right.

author: mij59
author_rank: Frequent Contributor
timestamp: March 07, 2016, 07:05:01 pm
content: The part has a Philips number on page 191, but that won't get you very far.First check the voltages.The properties of C1302 are not that critical, a standard capacitor should work just fine.

author: eTimesV
author_rank: Contributor
timestamp: March 07, 2016, 10:31:01 pm
content: wow, I can't believe I missed that on page 191. Thanks.It looks like one of these might work:http://www.conrad.ch/ce/de/product/421573/Elektrolyt-Kondensator-SMD-10-F-50-V-20--x-H-6-mm-x-5-mm-Samwha-JC1H106M6L005VR-1-Sthttp://www.conrad.ch/ce/de/product/1280267/Elektrolyt-Kondensator-SMD-10-F-50-V-20--x-H-63-mm-x-55-mm-Wuerth-Elektronik-WCAP-ASLL-865060643005-1-Sthttp://www.conrad.ch/ce/de/product/1280474/Elektrolyt-Kondensator-SMD-10-F-50-V-20--x-H-5-mm-x-55-mm-Wuerth-Elektronik-WCAP-ASLI-865080642006-1-St(I measure ~6.2mm diameter for the current caps but I guess I will order a few of each to not be left stranded and anyway they're not a big expense)And miraculously this supplier is offering free shipping today.

author: eTimesV
author_rank: Contributor
timestamp: March 19, 2016, 06:57:31 pm
content: As a final followup to this repair: I think I could have gotten away with just replacing the capacitor and not the EL panel, however the new panel is a bit brighter and whiter. Also, I had a very hard time fitting the EL panel wires in and had no room to put the little silicone-like strip (to block dust/dirt?) back under the panel. After re-assembling, the display had one horizontal line going across it which (see pic) turned out to be a spec of dirt on the panel contacts inside. After reassembling, the display had all sorts of lines criss-crossing it and I was dismayed to think I might have blown it out somehow and bricked the meter. However, after taking apart and reassembling about five times I finally got it to seat well. Then I noticed the EL panel wire solder joint had broken with all the dis- and re-assembling.Finally after more rounds of dis- and reassembly I got it all back together, working. And they lived happily ever after (we hope).

author: mij59
author_rank: Frequent Contributor
timestamp: March 20, 2016, 04:51:47 am
content: The new EL looks really good !Now for the bad news, the cap to right of the replaced one is leaking.Take a close look at the solder joint !

author: eTimesV
author_rank: Contributor
timestamp: March 20, 2016, 12:43:15 pm
content: Thanks for you inputs/help.Do you now mean that because the capacitor leg solder part looks a bit rough it means it's leaking? I did look at the other cap's but thought they were ok (unfortunately I've no experience in what good vs. bad should look like so I expected a leak to look far more dramatic and obvious).Is it really necessary/worth it to replace it at this point when there's no apparent problem? It's a tiny, slow leak or?

author: SeanB
author_rank: Super Contributor
timestamp: March 20, 2016, 01:06:55 pm
content: Replace now, the grey is solder ( and the pad beneath as well) being corroded away. Left alone it only grows, eating away at the other components and traces in the area. When you remove it you will be "rewarded" with a fishy smell. Clean area with a water wash using a cotton bud Wwet bud in distilled water, use once to wipe then use the other side to dry, then use a new bud again at least 5 times to get the liquid away, then rinse the board in IPA and dry before soldering the new one in.

author: mij59
author_rank: Frequent Contributor
timestamp: March 20, 2016, 01:23:44 pm
content: As already mentioned, replace the 3 other capacitors also, they are / will become leaky and destroy the pcb.

author: Liteace
author_rank: Regular Contributor
timestamp: February 01, 2017, 10:50:45 pm
content: Quote from: lamello on September 14, 2015, 01:27:24 pmSorry to dig this one up, I would like to know please if possible what you found wrong with the unit, I also have a non working PM97 that I would like to get up and runningThanks

author: lamello
author_rank: Contributor
timestamp: February 03, 2017, 09:47:20 am
content: Hi,I had multiple faults.Well, to begin replace the 4 smd capacitors.In my case, a capacitor had leaked and made a shortcut on the board, so i had to replace the 74132 chip (located near the capacitors) and made 2 replacement wires from the 74132 to another chip.The film connector which connects the two boards had multiple broken wires.I have repaired last month another PM97. That one was easy, the (soft) power on switch didn't worked correctly.An other PM97 had an pre-production mainboard without an maskprint, this one is not repaired. But had all the probesSuccess with the repair.Lamello

author: Liteace
author_rank: Regular Contributor
timestamp: February 03, 2017, 10:43:30 pm
content: Thanks for the reply, at some stage I will open it up again and have a good good look inside and start doing some testing, I hope I can get it up and runningThanks

author: Pablitox
author_rank: Newbie
timestamp: January 28, 2019, 12:23:48 am
content: Quote from: mos6502 on March 07, 2016, 02:27:25 pmCuento mi experiencia:Cambie los capacitores electrolíticos (los 4). Cambie el panel El y todo funciono de maravilla un tiempo, despues dejo de funcionar. Desarme para ver que era y todas las conexiones estaban Ok. Verifique los electrolitos y la esr y capacidad estaba bien. El transistor V1307 levantaba temperatura (BCX54-16), desoldé y estaba ok, lo volví a colocar.Los transistores V1304 y V1306 Los retiré y estaban OK, los volví a colocar.Quite el transistor C1303 (smd 10nf) estaba en corto, coloque el remplazo y el transistor volvió a la normalidad al igual que la panel El.Espero que a alguien le sirva mi experiencia.Gracias mij59 por pasar la pagina exacta del manualTell my experience:Change the electrolytic capacitors (the 4). Change the panel and everything worked wonders for a while. It stopped working. I wanted to see what it was and all the connections were fine. Check the electrolytes and the ESR and the capacity was fine. The transistor V1307 raised the temperature (BCX54-16), unfolded and it was fine, we replaced it.The transistors V1304 and V1306 The withdrawals and they were OK, I replaced them.Enough transistor C1303 (smd 10nf) was short, place the replacement and the transistor returned to normal as the panel.I hope someone will serve my experience.Thanks mij59 for passing the exact page of the manualTranslated by Google

author: eKretz
author_rank: Frequent Contributor
timestamp: January 28, 2019, 12:36:10 am
content: Definitely replace. Might be a good idea to recap the whole board really.