Transistor Tester crash

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • manstoblame
    Senior Member
    • Jan 2011
    • 85
    #1

    Transistor Tester crash

    Howdy all at BdCaps purchased one of these transistor capacitor testers from you know where. Had it a few months and now the thing wont power on, the power on led just blinks and display don't light up. I've checked the voltage on the 9012/9014 NPN BJT Transistors and they measure within specs from pin 1 emitter and pin 2 the base and all the way to the pins of the digital display. Has anyone had
    Attached Files
    Last edited by manstoblame; 04-01-2019, 10:40 PM.
    Tags: None
    • redwire
      Badcaps Legend
      • Dec 2010
      • 3900
      • Canada
      #2
      Re: Transistor Tester crash

      Check if the HT7550 LDO is making 5V for the MCU and display. The 9012 PNP transistor switches on power to start the 5V regulator, and then the MCU is supposed to run and keep the 9014 /9012 on.

        Comment

        • stj
          Great Sage 齊天大聖
          • Dec 2009
          • 30950
          • Albion
          #3
          Re: Transistor Tester crash

          that's an ancient design, you only had it a few months??
          they got outdated several years ago!

            Comment

            • manstoblame
              Senior Member
              • Jan 2011
              • 85
              #4
              Re: Transistor Tester crash

              Originally posted by stj
              that's an ancient design, you only had it a few months??
              they got outdated several years ago!
              well that's probably why i got it so cheap and its a piece of it!

                Comment

                • manstoblame
                  Senior Member
                  • Jan 2011
                  • 85
                  #5
                  Re: Transistor Tester crash

                  Originally posted by redwire
                  Check if the HT7550 LDO is making 5V for the MCU and display. The 9012 PNP transistor switches on power to start the 5V regulator, and then the MCU is supposed to run and keep the 9014 /9012 on.
                  nope the 7550 only has 2.50 volts from Gnd to Vin and 2.98 from Gnd to V out
                  now to find a replacement or equivalent thanks bro, hope this fixes it!

                    Comment

                    • stj
                      Great Sage 齊天大聖
                      • Dec 2009
                      • 30950
                      • Albion
                      #6
                      Re: Transistor Tester crash

                      that's not logical - how do you get more output than input?

                        Comment

                        • R_J
                          Badcaps Legend
                          • Jun 2012
                          • 9531
                          • Canada
                          #7
                          Re: Transistor Tester crash

                          There is some info on this device here https://goughlui.com/2016/10/27/proj...or-tester-kit/
                          along with a hand drawn schematic if it helps.

                            Comment

                            • manstoblame
                              Senior Member
                              • Jan 2011
                              • 85
                              #8
                              Re: Transistor Tester crash

                              Originally posted by stj
                              that's not logical - how do you get more output than input?
                              True I got numbers crossed just know its not the 5 v needed. Would you know of a substitute I could use in place of the 7550

                                Comment

                                • manstoblame
                                  Senior Member
                                  • Jan 2011
                                  • 85
                                  #9
                                  Re: Transistor Tester crash

                                  Originally posted by R_J
                                  There is some info on this device here https://goughlui.com/2016/10/27/proj...or-tester-kit/
                                  along with a hand drawn schematic if it helps.
                                  Hey Thanks RJ, couldn't find this info on my own I love BadCaps

                                    Comment

                                    • redwire
                                      Badcaps Legend
                                      • Dec 2010
                                      • 3900
                                      • Canada
                                      #10
                                      Re: Transistor Tester crash

                                      Originally posted by manstoblame
                                      Would you know of a substitute I could use in place of the 7550
                                      I use LP2950CZ-5.0 or ACZ. But different pinout, have to bend output pin around.

                                        Comment

                                        • R_J
                                          Badcaps Legend
                                          • Jun 2012
                                          • 9531
                                          • Canada
                                          #11
                                          Re: Transistor Tester crash

                                          What are the voltages on Q9012, Is it getting hot? It could be bad and not supplying the 9 volts to the regulator. Is the 7550 regulator getting hot?

                                            Comment

                                            • stj
                                              Great Sage 齊天大聖
                                              • Dec 2009
                                              • 30950
                                              • Albion
                                              #12
                                              Re: Transistor Tester crash

                                              i would remove the regulator and see if you get 9v to the input pad.

                                                Comment

                                                Previous template Next

                                                Related Topics

                                                Collapse
                                                • magneh
                                                  Behringer Eurolive B205D repair - help identifying transistor
                                                  by magneh
                                                  Hello
                                                  Got this speaker from a friend , defective. Power led comes on and off , in a loop.
                                                  Disassembled, got the board out, and after a bit of measuring I found a low resistance on a 5v6 line. With a bit of current I found a transistor heating up on that line (labeled T1 and 113 as on pic).
                                                  After removing this guy, I got a value of 0.7 in diode mode on that 5v6 line, which before had 0.02 or something like that.

                                                  I tested powering it up without the IC, and the speaker turns on and stays on, and works fine

                                                  Still, I need to replace this transistor....
                                                  06-18-2025, 02:34 AM
                                                • Lifeisfun
                                                  Trying to troubleshoot DDR4 SODIMM slot with slot tester
                                                  by Lifeisfun
                                                  Hi folks!
                                                  I have some kind of memory problem on Lenovo laptop. I was initially able to install windows after several tries since the laptop did freeze in middle of those attempts.
                                                  Eventually I discovered that it was related to moving the laptop.
                                                  Later on it even stopped booting unless I pressed around the memory slot. (no keyboard LEDs only power button responds)
                                                  If I remove the RAM I get the beeps that RAM is missing. Inserting the RAM there is silence and it will not boot most of the time. No picture.

                                                  I removed the board got one of those memory slot testers...
                                                  06-04-2025, 02:26 PM
                                                • spleenharvester
                                                  Reverse engineering of 18650 4-channel tester
                                                  by spleenharvester
                                                  Hi friends

                                                  I have reverse engineered this tester, schematic is attached and is complete except for capacitor values. These testers annoyingly have no model number but they are the ones you find on the first page of just about any website if you type in "18650 4-channel tester". There is also a 2-channel variant and a newer 8-channel variant. They are very cheap (about £15) and can measure voltage, current, internal resistance and capacity. They have a multicolour display for all these statistics. They also have terminal blocks so that if you want to use a breakout board...
                                                  05-04-2025, 02:43 AM
                                                • sam_sam_sam
                                                  FNIRSI HRM-10 Internal Resistance Detector AC Lead Acid Lithium Battery Tester Review on some testing of device
                                                  by sam_sam_sam
                                                  https://www.ebay.com/itm/405035016711

                                                  I got this device yesterday and did some testing on some tabbing and some incandescent light bulbs and it seems to work very well from what I can tell but how do I know how accurate the m-ohms section is what can I use to verify it accurately I also tested some li-ion battery cells and this seems to be fairly accurate because I have another tester and they seem to agree with each other

                                                  I also checked some capacitors with it that were brand new and seem to show about what I expected to see with my blue capacitor tester so I think it...
                                                  04-13-2025, 08:17 PM
                                                • elsomer
                                                  help to identify transistor msi ms-15ck1
                                                  by elsomer
                                                  hi people, i need some help to identify a transistor(q14) that is missing on the board, so the gpu has no voltage i think that q14 activate the phases for gpu, but i dont have schematic or boardview, but i think its the same transistor than q15 and q16, thanks...
                                                  1 Photo
                                                  02-17-2025, 05:30 PM
                                                • Loading...
                                                • No more items.
                                                Working...