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    Equipment Display Types

    Most Displays I have worked with are of course LCD Or Blueish Fluorescent Types. I Have a Marantz PMD800 tuner with sort of a white display. The display area is a sealed rectangular shape in a Glass Case. Looks like some sort L.E.D. display only not your typical section number type. I picked up this Tuner cheap as the display is very Dim. In front of the circuit is a dull red Plastic lens.

    The display is very week and hard to see. I've got my DC 5 Volts allover and also a DC 32 Volt that runs some other section. Power supply looks good front to back. Not familiar with this type of display. Don't know if the Chemical Element of the display itself has burnt down or exactly how this display works.

    Their is a Large Postage stamp chip that runs this display. Their is 5 Volts on the Operating input pin. The display works in all functions. But it is hard to see.

    No Clue? Any thoughts?
    sigpichttps://www.badcaps.net/forum/image....ine=1697924519

    #2
    probably a VFD, so you need to look for a schematic and it will probably be a bad cap causing the dim output

    Comment


      #3
      Originally posted by stj View Post
      probably a VFD, so you need to look for a schematic and it will probably be a bad cap causing the dim output
      Thanks Great Sage,

      So it is a vacuum fluorescent display. It's made up of many small dots that form the Letters and numbers. As far as a Schematic goes , Its hard to find.
      I'll have to search for one again. I assume that Bad Cap.. Should be on the main Display Board behind the front panel with the Postage Stamp Driver IC Chip.

      Did a quick look at the caps and nothing bulging up. Got My Sencore LC 103 Cap checker so it'll be pull and check if I can narrow the location down of the cap. Wonder what kind of voltage is used to drive the VFD??

      Any Ideas? Also... Cool Name...."MONKEY KING" L.O.L.
      sigpichttps://www.badcaps.net/forum/image....ine=1697924519

      Comment


        #4
        so,
        look at the display pins, the outermost ones are the heater and have about 3v AC on them - they often feed through a cap.
        also check the soldering - it often cracks on VFD panels - no idea why unless it's because they are heavy.

        Comment


          #5
          Originally posted by stj View Post
          so,
          look at the display pins, the outermost ones are the heater and have about 3v AC on them - they often feed through a cap.
          also check the soldering - it often cracks on VFD panels - no idea why unless it's because they are heavy.
          Thanks 齊天大聖,

          Thank you for the starting place. I have had my share of cold joints. Wave soldering does it every time. I have a PACE MBT 250 Solder-De Solder Station and a Hot Air Unit for SMD Devices. So I should be able to locate the problem.

          Interesting that they use a heater in the VFD. Now I can see why. If I locate a 3 Volt AC rail in the chassis plug feeding the Main front panel display board I should be able to run it down to a Cap as you say.

          I didn't notice an AC feed after the ac to dc conversion in the back end. I'll check the back end PS again. I'll rip the unit apart tomorrow or the next day.

          Thanks Again:
          Regards: Mark R
          sigpichttps://www.badcaps.net/forum/image....ine=1697924519

          Comment


            #6
            https://www.noritake-elec.com/techno.../vfd-operation

            Comment


              #7
              Great ..Got it... Will review and Operate on the Patience...
              sigpichttps://www.badcaps.net/forum/image....ine=1697924519

              Comment


                #8
                Just replace all of the capacitors around the display and around the display ic chip as well especially the low uf values ones under 100uf
                Also very carefully redo and display pins that look dull or are have rings around the soldering joints or cracked soldering joints because there have been a lot of issues with these displays after many years of use and service

                One note be extremely careful with ribbon cables between circuit boards do not be tempted to remove them if you do not need to because some of them are not remove-able even if they appear to be able to be removed this is the type that needs to be desoldered instead and to remove this type is not easily removed either I have been there and done it before and should have left it alone I would have been better off in the long run

                One other note about ribbon cable there is a flat type that has a locking tab mechanism that is a nightmare to get into the connector and to get the device to work properly again this type is another one that if you do not have to remove it do not do it make your life easier if you can
                Last edited by sam_sam_sam; 06-10-2024, 06:51 PM.
                9 PC LCD Monitor
                6 LCD Flat Screen TV
                30 Desk Top Switching Power Supply
                10 Battery Charger Switching Power Supply for Power Tool
                6 18v Lithium Battery Power Boards for Tool Battery Packs
                1 XBox 360 Switching Power Supply and M Board
                25 Servo Drives 220/460 3 Phase
                6 De-soldering Station Switching Power Supply 1 Power Supply
                1 Dell Mother Board
                15 Computer Power Supply
                1 HP Printer Supply & Control Board * lighting finished it *


                These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                2 Hem Saw Computer Stack Board

                All of these had CAPs POOF
                All of the mosfet that are taken out by bad caps

                Comment


                  #9
                  Originally posted by sam_sam_sam View Post
                  Just replace all of the capacitors around the display and around the display ic chip as well especially the low uf values ones under 100uf
                  Also very carefully redo and display pins that look dull or are have rings around the soldering joints or cracked soldering joints because there have been a lot of issues with these displays after many years of use and service

                  One note be extremely careful with ribbon cables between circuit boards do not be tempted to remove them if you do not need to because some of them are not remove-able even if they appear to be able to be removed this is the type that needs to be desoldered instead and to remove this type is not easily removed either I have been there and done it before and should have left it alone I would have been better off in the long run

                  One other note about ribbon cable there is a flat type that has a locking tab mechanism that is a nightmare to get into the connector and to get the device to work properly again this type is another one that if you do not have to remove it do not do it make your life easier if you can
                  Thanks For the reply Sam Sam Sam

                  As you say Been there done that..L.O.L. The ribbon cable is the removable type or plug in with a release tab on the main board. So no problem there.
                  I am able to remove the entire front panel complete. It's held in place by about 10 screws. Luckily I have a good Small power Screw driver...
                  ( Panasonic) which works great.

                  Also...Yep... the dreaded cold cracked solder joints. I also have a 10" screen LCD Microscope for working on SMD's. So I can see a small SMD Resistor which the scope makes it look like the size of a Foot Ball. L.O.L.


                  Iv'e had my share of cracked cold joints. This unit is a Japanese Marantz PMD800. It's well made and super easy to service. All the components are marked as well as voltages on the boards. Thanks for your tips, and I have run into those pesky ribbon cables that are soldered into the board!
                  That's called cheeping out because the plastic connector cost to much $.02....LMAO.

                  Regards: Mark R
                  sigpichttps://www.badcaps.net/forum/image....ine=1697924519

                  Comment


                    #10
                    Let us know if you are able to fix the issue with the display
                    9 PC LCD Monitor
                    6 LCD Flat Screen TV
                    30 Desk Top Switching Power Supply
                    10 Battery Charger Switching Power Supply for Power Tool
                    6 18v Lithium Battery Power Boards for Tool Battery Packs
                    1 XBox 360 Switching Power Supply and M Board
                    25 Servo Drives 220/460 3 Phase
                    6 De-soldering Station Switching Power Supply 1 Power Supply
                    1 Dell Mother Board
                    15 Computer Power Supply
                    1 HP Printer Supply & Control Board * lighting finished it *


                    These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                    1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                    2 Hem Saw Computer Stack Board

                    All of these had CAPs POOF
                    All of the mosfet that are taken out by bad caps

                    Comment


                      #11
                      Originally posted by sam_sam_sam View Post
                      Let us know if you are able to fix the issue with the display
                      Will do Sam Sam Sam ,, Been busy running around. Haven't been at the bench. I'll try and rip into it tomorrow. I hate when guys help you out and then that person who needed the help never answers back. That's Not me. I appreciate you guys and I will keep you posted. I'll take a few pic's when I find the problem. Thanks Guys..

                      Regards: Mark R
                      sigpichttps://www.badcaps.net/forum/image....ine=1697924519

                      Comment


                        #12
                        Originally posted by sam_sam_sam View Post
                        Let us know if you are able to fix the issue with the display
                        Ok Sam Sam Sam.. Here are some Pic's showing the unit broken down. There are a bunch of caps on one side of the board. Also I don't see any indication of 3 Volts A C on the board . Just 5 Volts and I think 31Volts. But it does read as DC Voltage.
                        So Next step is to get out the LC103 Cap Checker and Fire up The MBT-250 De solder station.

                        I'll check back after I check these caps.

                        Regards: Mark R Click image for larger version

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                        sigpichttps://www.badcaps.net/forum/image....ine=1697924519

                        Comment


                          #13
                          you need to clean up that potential solder-bridge you created on the display pcb

                          Comment


                            #14
                            Originally posted by stj View Post
                            you need to clean up that potential solder-bridge you created on the display pcb
                            At the time of the pictures I had not touched or soldered anything. Where are you indicating?

                            As of this time 12:05 AM EST I located the problem. It was a 6.3 Volt 1000 MFD cap on the display board. The LC103 showed Leakage and also showed high Dielectric Absorption. I replaced the cap and the display now is much brighter. I used a 1000 MFD @10 Volt cap. Seems to be working ok.

                            Now what is really ticking me off is one button fell out of the front panel which I have been looking for over 1 hour. Can't reassemble the unit until I find the button!!!!!!!!!!!

                            I'll report back with Pic's if I can find the dam thing!!

                            Thanks for the help to All. I'm not done here. I will tare my shop apart till I find it. LMAO Back soon.

                            sigpichttps://www.badcaps.net/forum/image....ine=1697924519

                            Comment


                              #15
                              look at the right side of the display controller in your pictures - there are 2 joints manually soldered - the lower one has some "splash" effect

                              Comment


                                #16
                                Originally posted by stj View Post
                                you need to clean up that potential solder-bridge you created on the display pcb
                                Are you speaking about the Main Multi pin IC? Between Pin 51 and 50? Post a picture from mine so I know which photo your speaking about.

                                Also: The unit seems to be working now since I changed out two caps... Thanks for leading me to that area and the link to The VFD display site and every one here who helped me.

                                Here is a pic of the now brighter display. Why they shove a Hunk of Red filter in front doesn't make sense to me. I guess they want to hide the circuitry in and around the VFD. It looks better in it's Natural color.

                                Click image for larger version

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                                sigpichttps://www.badcaps.net/forum/image....ine=1697924519

                                Comment


                                  #17
                                  Probably still a good idea very closely look at the soldering joints on the VFD display and any of them that look questionable redo them so you do not to revisit this issue again I would also recommend that you replace the capacitors around the VFD display and the display ic chip for good measure especially if the this device has a lot of use and age because both are hard on capacitors for this type of use

                                  I am not suggesting that you recap the tuner section or anything like that because then you would have to have special equipment to be realigned tuner

                                  The reason for the red filters is so it is easier to read in the dark and very low light settings I would recommend reinstalling them so it be like it originally was when new
                                  Last edited by sam_sam_sam; 06-13-2024, 06:06 PM.
                                  9 PC LCD Monitor
                                  6 LCD Flat Screen TV
                                  30 Desk Top Switching Power Supply
                                  10 Battery Charger Switching Power Supply for Power Tool
                                  6 18v Lithium Battery Power Boards for Tool Battery Packs
                                  1 XBox 360 Switching Power Supply and M Board
                                  25 Servo Drives 220/460 3 Phase
                                  6 De-soldering Station Switching Power Supply 1 Power Supply
                                  1 Dell Mother Board
                                  15 Computer Power Supply
                                  1 HP Printer Supply & Control Board * lighting finished it *


                                  These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                                  1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                                  2 Hem Saw Computer Stack Board

                                  All of these had CAPs POOF
                                  All of the mosfet that are taken out by bad caps

                                  Comment


                                    #18
                                    Originally posted by stj View Post
                                    look at the right side of the display controller in your pictures - there are 2 joints manually soldered - the lower one has some "splash" effect
                                    You call it the display Controller???? Are you speaking about the large Postage stamp IC Chip? Can you post a pic from mine that indicate what you are talking about?

                                    Also All solder joints on the VFD are perfect. They were looked at with a Jewelers Loop. All caps were changed out after testing. Two were bad. All solder joints are perfect on the front panel control board.
                                    sigpichttps://www.badcaps.net/forum/image....ine=1697924519

                                    Comment


                                      #19
                                      this - or is it flux?
                                      Click image for larger version

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                                        #20
                                        Originally posted by stj View Post
                                        this - or is it flux?
                                        Click image for larger version

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                                        Ok..Now Ise what your talking about. Ok I'll pop the cover since it's back together and take a Look. Thanks for the Photo and location. Get back to you soon
                                        sigpichttps://www.badcaps.net/forum/image....ine=1697924519

                                        Comment

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