EXFO FTB-200 WinCE - doesn't start fans and modules - power supplies (?) - Page 1
Forum section: electronics / repair

author: cozidinho
author_rank: Contributor
timestamp: April 10, 2025, 11:35:30 pm
content: Hi,I recently acquired an EXFO FTB-200 with an OTDR module. It starts up the Windows CE just fine and it's supposed to start the fans on boot and detect it's installed modules. But it just refuses to do that. I've disassembled it and found that there's three boards.1) BMS and power build-up for the second board, to which it supplies 24V (and it supplies).2) This board is an interposer between the 1st and 3rd board. Has 2 or more power supplies. One for 5V and another for 12V. Interfaces with the external modules, has fans connected and a magnetic reed switch for the battery cover (which is working)This board refuses to turn on the power supplies for the fans and external modules, making this handheld device a paperweight.3) The computer board part, working fine, just updated to the latest versions of software and reset.No visible signs of anything wrong, except the exploded Ni-Mh battery on the 1st board.Something either doesn't control the power supplies or they just don't power on (measured 0V at the test points). And i can't find any spare parts. Maybe the more trained eye can have a clue about what to check next. It would be very much appreciated.

author: joel16
author_rank: Contributor
timestamp: April 11, 2025, 05:27:08 pm
content: Can you measure the tantalum capacitors to see if they're shorted or otherwise defective? I would think that if one was shorted then the 24V supply would be low, but maybe not.You could try contacting EXFO to see about a service manual or technical help.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 11, 2025, 06:28:25 pm
content: Exfo mm i worked there in the past not sure they will help, normally they decommission the machines by removing their technology, ftb modules etc ...normally ending up with the pc side only ...you're lucky if you find an otdr with them, as you did, they may ask where you got it ...but do ask ... Exfo home base in in my town, Quebec city Canada

author: cozidinho
author_rank: Contributor
timestamp: April 12, 2025, 12:30:29 pm
content: Thanks for the feedback.Exfo does not provide service manuals and they also do not give paid support to an EoL model. This OTDR came from company liquidationNo tantalum capacitors shorted in this case.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: April 12, 2025, 08:31:40 pm
content: Is there any readable reference on the square IC ?

author: cozidinho
author_rank: Contributor
timestamp: April 12, 2025, 10:58:00 pm
content: On the board #1, it's the bq24703.On the board #2, the big one is a M430F155, two Si7884DP near the smaller connector.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: April 13, 2025, 04:56:06 pm
content: Not obivious to understand how this board works. What is the input voltage ? Mains ?Why is there a battery charger IC (bq24703) ?Check power supply and also the two PGood signals on the LTC3728 (synchronous dual output buck switcher)

author: cozidinho
author_rank: Contributor
timestamp: April 13, 2025, 10:42:24 pm
content: Hi, the input power source is the battery or the 24V transformer. I will check that signal, however, I'm more inclined to thinking it is related with the second board, because:1) System will boot just fine2) Has a CompactFlash reader that uses 3.3V and 5V and it reads a 1GB card3) Has an embedded ethernet port that works fine4) Has a CCFL backlight that works fine5) Battery charges just fine and has good runtimeAfter measuring some voltages around the test points of this second board what i see is:V5 BUS = 0.6VV+12 = 0.93VV+12_BUS = 0,98VV-12V = -0.01VVSUP = 15.97V (goes up to 23.96V when the charger is connected, other voltages remain the same)VFANS = 0.93VNow I know the issue is not on the turning on the power supplies. I see this board is supplied VSUP, with what it produces both -12V, 12V and 5V thru the DC-DC conversion.