Cisco DPC3939 router

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • frankiek3
    New Member
    • May 2013
    • 5
    • USA
    #1

    Cisco DPC3939 router

    A recent lightning storm took out a Cisco DPC3939 router (and a LG 50PJ350 TV), on to the Cisco DPC3939:

    Symptoms: Ethernet ports dead, one with faint green light. Wifi broadcasting but no longer connecting.

    Found this Ethernet IC that was getting very hot: Marvell 88e6172
    Found that it's VDD was shorted to ground (0.21Ohms)
    Started removing 5 capacitors that were shorted to ground connected to VDD.
    All capacitors were good.
    First attempt at removal used my small rework station, but didn't budge. Then removed with the Honton. Middle of the chip has a grounding plate soldered to the board. Chip tested bad. Board with no chip tested no short. Hopefully the only bad component.

    Now on to find a replacement chip. Not a very popular IC, the schematics I got for the router have the pin layout. Otherwise no datasheet for the IC. Two authorized dealers (only for quotes) and alibaba. I'm guess the chip will be about $10
    Tags: None
    • ben7
      Capaholic
      • Jan 2011
      • 4059
      • USA
      #2
      Re: Cisco DPC3939 router

      Good luck, my sense is that if a company doesn't give out datasheets without an NDA or something like that, then you aren't likely to be able to get those chips in small quantities. They only want to do business that brings in big $$$


      Hm, there is a dev board for it, "DB1-88E6176-1", but it seems that you have to contact them to get a quote. It probably won't be cheap xD

      -Ben
      Muh-soggy-knee

        Comment

        • frankiek3
          New Member
          • May 2013
          • 5
          • USA
          #3
          Re: Cisco DPC3939 router

          I had another DPC3939 that I was going to sell, now using that. I got them for $80,$85

          I'm 99% sure that the surge came from the ethernet connected to a shutdown mac mini (and out it's hdmi)

          I should say, I assume that the VDD_CORE should not be measuring close to ground. The one port with the green led faintly lit makes me think it is shorted on.
          I guess I'll sell it for parts. if I can't source the chip. Thanks.
          Last edited by frankiek3; 06-23-2015, 07:19 PM. Reason: 'm

            Comment

            Previous template Next

            Related Topics

            Collapse
            • acedogblast
              Guide to transplant MEC1503 EC chip and EEPROM reprogamming for T14s gen 2 and X13 gen 2
              by acedogblast
              This is a guide that I am writing for helping others to replace their MEC1503 EC chip if it breaks (or to get around an inconvenient prompt to the BIOS). This forum has been extremely helpful to me so I would like to contribute to help others. I will tell you right now that this task is very difficult to do. You MUST have experience and tools to do precision micro-soldering, BGA reballing, trace repair, and general laptop repair skills.

              There are some specialty tools needed to do this task. The replacement MEC1503 chips can be acquired from Aliexpress. Do not buy the bare chips as...
              11-02-2024, 05:13 PM
            • DynaxSC
              ASRock B650M PRO RS - BIOS CHIP 25Q256JW BLOCKED BY STATUS REGISTERS
              by DynaxSC
              Hi

              I have a very strange issue with the BIOS SPI chip of an ASRock B650M PRO RS motherboard.
              The SPI chip is an Winbond 25Q256JWEQ model (1V8).
              The motherbaord doas not POST - it lits only CPU and DRAM EZ Debug Leds, and stays that way forever.
              The Flashback function of the motherbaord is also not working, despite all instructions followed correctly - I'm 100% sure of this.

              I have then desoldered the chip, backupped the contents, and tried to earease the chip in order to program stock image, but the chip is locked by status registers SREG2 (TB) and SREG6...
              08-04-2025, 12:20 PM
            • barry101
              Apple 820-3662 VCore shorted to ground.
              by barry101
              Hi, Would appreciate some help.
              I have an Apple Late 2013 15" A1398 MacBook Pro with Logic Board 820-3662.
              Get charger light but no fan spin or chime. No liquid damage.
              Found PPBUS and VCORE both shorted to ground. Other rails were ok.
              Removed VCORE MOSFETS U7310, U7320 and U7330. Found U7330 was in fact shorted.
              With the 3 MOSFETS removed, get PPBUS and fan spin. VCORE is still hard shorted to ground (0 ohms).
              Attempted voltage insertion on VCORE to locate short using bench supply set at 1.0 VDC and 4.95 Amps (max current for my...
              06-24-2025, 07:34 AM
            • mkdj
              Acer TravelMate P214 - N19Q7 main power rail shorted to ground
              by mkdj
              Dear all,

              I have taken out the motherboard of a Acer TravelMate P214. There is a short to ground on the main power rail (19V). I don't have the schematics or boardview for this board (DAZ8IMB1AA0 REVA). But I have found 4 MOSFETS close to the main power rail : 2 N-Channel and 2 P-Channel.

              I have checked resistance across each of the 4 MOSFETS. I have the following readings:
              Both N-Channel Mosfets: nothing odd

              P-Channel MOSFET number 1:
              source - drain : 117 kOhm
              source - gate: 96 Ohm
              gate - drain: 117 kOhm

              P-Channel MOSFET...
              08-20-2025, 06:08 AM
            • mkdj
              Lenovo Thinkpad L480 : 3VALW rail shorted to ground, but I can't find the shorted component
              by mkdj
              Dear all,

              Laptop is Lenovo Thinkpad L480 (boardview can be found in this badcaps topic). When pressing the power button the LED power light turns on, but nothing else happens.

              I removed the motherboard, checked for shorts on the main inductors. I found that there is a short to ground on the +3VALW_P rail (@PL201). I soldered a wire on the PL201 inductor, and I injected up to 1.3V with my power supply. Current drawn is approximately 3.2A.

              I used a small thermal camera to locate the shorted component. But nothing on the board heats significantly, except the...
              08-11-2025, 04:55 AM
            • Loading...
            • No more items.
            Working...