Wavetek 288 VFD1 Trouble. - Page 1
Forum section: electronics / repair

author: youngwug
author_rank: Contributor
timestamp: March 20, 2021, 09:04:13 am
content: The Wavetek 288's VFD1 (ITRON FG1611A1 or NEC FIP16A11R), which worked fine yesterday, has no indication today.VFD is dead.I'm looking for the same part, but I can't find it.Please tell me where to get this part.Or replaceable parts and detailed data sheet are required.+22V, -22V, Display Controller +15V, Filament power AC 8.5V input to VFD are all checked normally.If there is anything I'm missing, let me know.

author: youngwug
author_rank: Contributor
timestamp: March 20, 2021, 10:24:40 am
content: Front Panel, display board, VFD1

author: TheMG
author_rank: Frequent Contributor
timestamp: March 20, 2021, 01:28:53 pm
content: I doubt the VFD is the problem. Those don't just suddenly stop working unless the vacuum seal goes or filaments broken.But from the pictures, filaments look intact, and the vacuum is good as the "getter" is still a nice dark/silver color. That's the stain in the upper left corner of the display, it's a substance that collects stray particles inside the vacuum, and if exposed to air it would turn kind of a milky color.More likely a controller problem, or something in the instrument (does the rest of the instrument function as normal?) Causing VFD controller not to get any data.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 20, 2021, 02:18:18 pm
content: service manual link:http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Wavetek/288.pdfpage 75 working schematiccheck the -22v, the display pcb 15v regulator, the filament voltage ..... be careful with the white flexible cablecheck all the psu voltages ...

author: youngwug
author_rank: Contributor
timestamp: March 20, 2021, 03:10:59 pm
content: Thank you.When the power is turned on, everything works except for the front VFD.The relay operation sound of the main board, the front LED, and when a button is pressed, the relay operation sound and the LED operation are shown.Q1, 2, 3 (Display Controller Driver) are normal. (2N3904, NPN)+15V is also good.However, even when the power is turned on, U1 does not become warm.If so, U1 is suspect.If U1 is OK, I need to zoom in and track DSPOR, DSPCLK, and DSPDATA.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 21, 2021, 01:40:36 am
content: maybe with a scope or an logic analyzer you could see if the data line, clock, dspor are working or receive something ??

author: youngwug
author_rank: Contributor
timestamp: March 21, 2021, 04:03:32 am
content: When power is ON, DSPOR, DSPCLK, and DSPDATA each measure +3.5V.After 10KΩ is applied, it goes down to 0.7V.There is no separate logic signal.The input voltage of VR1 is measured +21.9V.If you measure the output voltage of VR1 (+15V, ISO), it is +14.791V.The cause of the voltage drop is suspected to be C9 (22uF).So, I want to accurately measure VFD by opening a little gap with the circuit board, but the work is not easy.(The VFD and Circuit Board are attached with strong adhesive.)Please tell me how to work efficiently.

author: picburner
author_rank: Frequent Contributor
timestamp: March 22, 2021, 07:48:40 am
content: The output voltage of 14.791V is perfectly within the 78L15 tolerances: that's not the problem.Instead you need to check if there are signals on DSPOR, DSPCLK and DSPDATA with an oscilloscope not with a DMM.And then you have to verify that the same signals are present, inverted, on the collectors of Q1, Q2 and Q3.Attached is the U1 datasheet (MIC10937/10957).

author: youngwug
author_rank: Contributor
timestamp: March 22, 2021, 01:43:25 pm
content: Thank you.I also checked the allowable range in the spec of 78L15. (+14.4V(min), +15.6V(Max))I measured a 12pin white flexible cable to check DSPOR, DSPCLK and DSPDATA, but only DC voltage is checked as before (+3.5V).So, when I measured pin 6 of the previous 40pin connector(P12) of U3, 6 pulse periodic waves of +5V and 30us were measured as shown in the attached figure.The remaining two pins are odd and cannot be measured at the bottom.Measure by connecting a separate 40pin extension cable. (Female to Male)What I have is Female to Female, so I am worried about what to do.Now you are suspicious of U3.

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 22, 2021, 02:37:16 pm
content: page 110, put scope on U1 SCLK; DATA; POR (from datasheet is active high, normally he's low after start-up close to GND)you should have data traffic on CLK/DATA and steady POR (I expect you already verified FILA-FILB, +-22V, +15ISO and +5V voltages)you can scope of course the data lines between u1 and vfd1depending on your findings, we move on[first , I was going to propose you disconnect display driver and test display only (removing U1 and just activating some vfd1 input), but changed my mind (maybe it's complicated for you to remove u1 at this stage)]make your choice

author: youngwug
author_rank: Contributor
timestamp: March 23, 2021, 03:35:30 am
content: perieanuo, Thank you.Please tell me how to test VFD1 after removing VFD1.The removal process has not yet proceeded.

author: picburner
author_rank: Frequent Contributor
timestamp: March 23, 2021, 06:33:25 am
content: A vfd display won't break overnight unless:1 - it loses the vacuum.2 - burn the filament.Looking at the display (as others have already told you) it seems that it is not at all the culprit of the fault.Furthermore if, after you have left the instrument on for a few minutes, the display is slightly warm you will have the confirmation that it works perfectly.In my opinion you have to look for the fault elsewhere.

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 23, 2021, 04:32:15 pm
content: according to manualquick solution is to activate PNT or TAIL signals (pins 39, 40 of 10957P40) or a full drive with arduino (CLK/DATA... but that's some full project to implement)go with first one and light the decimal separator or the comma, I guess clk isn't necessary for those.for activate TAIL for example, you cut track from 10957P40<-->vfd1 on 10957P40 side (leaving RN1 connection wired with vfd1 pin 26, TAIL)and with 10kohm series resistor soldered to PCOM pin 26 (vfd1 connection end of TAIL signal from driver 10957P40) you apply +15ISO or GND (not sure if it's positive for 'on' but it should be like this, maybe someone knows better those vfd's)if TAIL works, vfd1 is finei know it sounds low-cost but it's someyhing that can't fail, if done properlybut imho I'd go with scope analysis on driver input/output pins, backwards, meaning from vfd1 to 10957P40 and so onas other user say, I doubt vfd1 is dead, I proposed TAIL/PNT quick test for you to be sure vfd1 comes out good and move on to find the defect IC