EEVblog #430 - Fluke 91 Scopemeter Teardown - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: February 26, 2013, 09:41:19 pm
content: Teardown Tuesday.Inside a 1994 vintage Fluke 91 Series II Scopemeter.Extended commentary on PCB Wave Soldering:http://youtu.be/ntxIdJTygIETDA8703http://www.datasheetcatalog.org/datasheet/philips/TDA8703T.pdf74HC4316http://www.fairchildsemi.com/ds/MM/MM74HC4316.pdfTLC27M2Ahttp://www.ti.com/lit/gpn/tlc27m2aLF453http://noel.feld.cvut.cz/hw/ns/LF453.pdfS83C196KBhttp://pdf1.alldatasheet.com/datasheet-pdf/view/66148/INTEL/S83C196KB.htmlPhotos:http://www.flickr.com/photos/eevblog/sets/72157632863100548/Dave.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: February 26, 2013, 11:16:13 pm
content: Actually, I believe a male BNC connector should always have an internal ground sheath as well. So that connector should work just fine with regular BNC connectors.

author: Unknown
author_rank: Unknown
timestamp: February 26, 2013, 11:27:36 pm
content: Except that using standard metal BNC connectors on them will cause much more wear and tear on the female connectors. And that they form a safety hazard unless you restrict the signals to SELV (40 V or so).

author: Bored@Work
author_rank: Super Contributor
timestamp: February 27, 2013, 12:40:05 am
content: The ScopeMeters where developed by Philips for Fluke, until Fluke finally bought the T&M part of Philips in 1993. That's why it says Made in Holland on the ScopeMeter 91, and why you have some Philips parts in it.

author: c4757p
author_rank: Super Contributor
timestamp: February 27, 2013, 02:05:25 am
content: Interesting - both HEF4093 and 74HC132 are quad Schmitt-input NAND gates. Why would they use both?

author: EEVblog
author_rank: Unknown
timestamp: February 27, 2013, 02:10:04 am
content: Quote from: c4757p on February 27, 2013, 02:05:25 amDifferent schmitt threshold levels perhaps.Dave.

author: justanothercanuck
author_rank: Frequent Contributor
timestamp: February 27, 2013, 02:30:12 am
content: Quick question about the wave soldering... If the solder thieves are meant to keep the trailing edge of a chip from getting too much solder, then how come the leading edge of the chip doesn't get too much solder from having a solder thief on the opposite side?

author: BravoV
author_rank: Super Contributor
timestamp: February 27, 2013, 02:35:30 am
content: Btw, for those who wonder about the strength, that plastic cover at the BNC female connector, although looks soft, it is a very durable and strong material. Have few of the bnc to banana adapter made by Phillips Fluke, they're really good stuff.Made a thread about this adapters while agoHERE

author: EEVblog
author_rank: Unknown
timestamp: February 27, 2013, 02:40:25 am
content: Quote from: justanothercanuck on February 27, 2013, 02:30:12 amSolder thieves are meant to keep the last two trailing edge pins from shorting. The result is that the last pin gets more solder than the pin next to it. This does not affect the trailing edge pin.Dave.

author: dewhite2485
author_rank: Newbie
timestamp: February 27, 2013, 03:10:43 am
content: Would you be interested in tearing down a Tektronix 213 portable scope/dmm? I have one that I got off Ebay many years ago and dont really use it anymore.

author: MadScientist
author_rank: Frequent Contributor
timestamp: February 27, 2013, 11:11:57 am
content: I have a Fluke Scopemeter 105B Series 2 , dual 100Mhz, on the bench , I still use it every day.

author: andersm
author_rank: Super Contributor
timestamp: February 27, 2013, 01:18:15 pm
content: I remember seeing a board (probably an old videogame console mainboard) that had "direction of wave soldering ->" silkscreened in two orthogonal directions. Does it mean the board made two passes through the wave soldering machine? I assume this would be to allow for parts being oriented along either axis.Anyway, it was interesting comparing this teardown to Shahriar's teardown of the Fluke 196B.

author: Flávio V
author_rank: Regular Contributor
timestamp: February 27, 2013, 05:02:50 pm
content: I guess that the fluke 97(which i own) is the 2 channel version of the 91...

author: Fraser
author_rank: Super Contributor
timestamp: February 27, 2013, 06:36:50 pm
content: I have a 'new in the box' Fluke 97 ScopeMeter complete with all the accessories etcIt was a backup to one that I have since sold. They still command pretty high priced on eb*y.The service manual is definitely available for free download as I have it on my PC. Its >20MB though. I will see if I can track down the source.Update: here is the MkI 93-97 service manual:http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Philips/pm93_95_97_fluke_93_95_97.pdfThese were state of the art in their day but the more modern units with colour displays make them look kind of boring and the user interface is the most unfriendly that I have used on an oscilloscope.Ahhh, memories of the 1990'sFraser

author: chicken
author_rank: Frequent Contributor
timestamp: February 27, 2013, 07:23:11 pm
content: How are the SMD pots managed with wave soldering? I'd imagine they'd get clogged up with solder if run through the process as is. Do they come with a cap that's removed after soldering?

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 27, 2013, 08:08:46 pm
content: Quote from: chicken on February 27, 2013, 07:23:11 pmIt certainly looks like they could have been capped, otherwise I don't know why they are constructed as they are, seehttp://www.flickr.com/photos/eevblog/8509778996/#in/set-72157632863100548Otherwise they had to be hand soldered after the wave soldering, and it certainly doesn't look like that.

author: RoelA
author_rank: Contributor
timestamp: February 27, 2013, 08:22:34 pm
content: I still have a fluke 99 scopemeter series 2, and the screen is as bad as this one.Fun thing, except one of the marker-move buttons is broken, the go left on the most left marker. Have to use the right marker to push the left one more to the left.. :-)

author: Cones
author_rank: Regular Contributor
timestamp: February 27, 2013, 11:09:37 pm
content: Excellent tear down as usual.I've just bought a Fluke 123 20Mhz scopemeter from ebay for a VERY good price.It needed a new battery (£15 which was also wired incorrectly from an Amazon seller. Good job Fluke do a nice service manual!).A bit of a clean and I have my very first oscilloscope, that I am pretty pleased with. For less than the cost of a set of Fluke scope probes!It does have three or four horizontal lines on the display due to a know fault with the heat bonded ribbon cable. I may investigate this further and see if I can repair it. I've seen an article where someone used a travel to to gently iron the cable down. The fact it trend logs and acts as a DMM as well is a bonus. It may be useful for looking at some Profibus communication wiring at work later this year as well.ThanksMark

author: Spawn
author_rank: Frequent Contributor
timestamp: February 28, 2013, 03:13:33 am
content: You ask in the video about the contrast Dave, I have seen couple of these back in early nineties and those where Philips / Fluke branded, can’t remember the model number since it was 20 years ago, my electronics engineer colleagues where using these, since I am electrics engineer I didn’t "play" with these but the contras was still bad on a new unit from what I remember, and my colleagues where handling like it was their child and where very proud to own one at work

author: grenert
author_rank: Frequent Contributor
timestamp: February 28, 2013, 05:53:25 am
content: Quote from: Aurora on February 27, 2013, 08:51:32 pmI believe the 123 Scopemeter uses Sub-C cells. Not sure about the 9X series.

author: free_electron
author_rank: Super Contributor
timestamp: March 01, 2013, 06:00:46 pm
content: the D-asic is indeed the display controlle.r the lottle tssop above is the frame buffer for the display.the Masic is a memeory controller.the 196 cpu interfaces with 1 ram ( the mitsubishi part in the middle. the two flashes ( 010 and 020 hold the firmware.the 83c193 means it is a mask ROM version so not an OTP or eprom or flash80 is romless 83 is mask rom 87 is eprom (otp if windowless package)the 196 only has 8 k of rom so it probabjy only holds a bootloader that can reflash the real firmware in the external flash memories.the masic switches the 196 form internal rom to external rom. when the thing comes out of reset the rom code in the 196 is run. if there is no reflash requested the 196 writes a register in the masic that pulls the EA pin low of the 196 and invokes a reset of the 196.at this point the 196 cannot execute itsinternal rom because the EA pin is forced so it executes from flash.simple but effective mechanism. this is some hardware trick because it makes writing code easier. you don't need to take overlays or offsets into account. the entire memory space is swapped out.the masic serves another purpose : DMA. when sample data is coming in the masic streams that straight into the frame buffer without passing through the 196 space. essentially the 196 write 'one plane' " grid, text , cursors while the incoming data is catapulted directly into trace memory. it's a kind of bus arbiter.

author: fleuroman
author_rank: Contributor
timestamp: December 07, 2015, 07:49:37 pm
content: a few pics from the 91 Service Manualpic 1 description of the display operation

author: fleuroman
author_rank: Contributor
timestamp: December 07, 2015, 07:50:50 pm
content: digital board layout

author: fleuroman
author_rank: Contributor
timestamp: December 07, 2015, 07:54:19 pm
content: it wont let me upload schematic pictures.. too big

author: justanothercanuck
author_rank: Frequent Contributor
timestamp: December 08, 2015, 12:05:48 pm
content: Quote from: fleuroman on December 07, 2015, 07:54:19 pmyou could always try throwing them up on imgur.

author: MostlyHarmless
author_rank: Newbie
timestamp: August 29, 2023, 12:59:50 am
content: Quote from: fleuroman on December 07, 2015, 07:54:19 pmI have a fluke 93 50 MHz scopemeter which does not power up, i am trying to find the correct version of the manual as my unit has an A1 Digital board with the six LCD driver chips as in your picture and not the 5 chip board as seen in the only versions of the service manual i've found online so far.i need the correct version to allow me to troubleshoot the On/Off circuit, i have high hopes as when probing with my oscilloscope i must have pulled something low that turned the unit on (just once and i cant replicate whatever i didDoes anyone have the full service manual and the layout diagrams for the fluke 93 with a1 board with the 6 LCD driver chips

author: dobsonr741
author_rank: Frequent Contributor
timestamp: August 29, 2023, 01:41:31 am
content: Puzzled... Where is 50MHz AFE bandwidth? LF453 only goes 4MHz.