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Nintendo 64 PAL – No Signal After Reassembly

kiltro

Hello everyone!

I have a PAL Nintendo 64 with the following issue.

When I first received the console, I disassembled and cleaned it. It worked fine.

Video quality was not great, so I replaced all electrolytic capacitors. The console still worked and I could play games.

After final reassembly in it's case, it started showing “No Signal.”

What I did so far:

Disassembled again, this time also removing heatsinks.

Cleaned everything again: card slot, AV cable, jumper pack contacts (even with 800-grit sandpaper).

Reflowed electrolytic capacitors and main chips: CPU, RCP, PIF, DENC, and jumper pack connector pins.

Tested various points with oscilloscope (I can share waveforms if needed).

Swapped my Expansion Pak with a new Jumper Pak.

Replaced power supply.

AV cable is brand new, so I don't think this is the cause.

Tried inserting/removing cartridge and jumper pack while powered on (as suggested in some threads).

At this point the console still gives no video output at all.

I was hoping that someone can give me some advice or is available to make a comparison between the measurements made on a working console and mine


Here are measurements (in the Gsheet file) and other related stuff

drive.google.com/.../1_iCxMZg6JVUPDNlzgr-V5CmYrW0aUk71


Schematic of one of the NTSC versions. From what I see what differs from mine is from the video encoder to the output connector.

Parents
  • 0 in reply to kiltro

    Okay, a more substantial update for you.  I took the N64 apart today.  The encoder I have is the AVDC-NUS.  I did some probing with no cartridge and no jumper pack installed.  I will add a disclaimer here.  I have an old 50MHz analog scope so these pulse trains are at the limit of scope"s capability.  In fact instead of square waves I was seeing triangular peaks.  Anyway, the pins that correspond to D0 through D3 had the same type of signal... and in my judgment their duty cycle was less than 50%.  The pins that correspond to D4 through D7 were 0V flat line.  The pin that corresponds to the SYNC signal had an AC waveform.  It's duty cycle was greater than that overserved on D0 through D3.  The pin that is supposed to be the clock had a sine wave.  I suppose it's really a square wave but due to the limitations of my scope I observed it as a sine wave.  My observations are more or less consistent with yours... it's very possible that all your electronics are fine but a poor contact with the jumper pack or cartridge is messing things up.

  • 0 in reply to dang74

    You can see what I have measured so far here
    https://docs.google.com/spreadsheets/d/1GrGj95BcU5GfZvYtvYVBCxaKokOzlmxlZgRDTHP93-8

    DENC sheet in this case

    I see a sinewave on CLK too, it's a 50Hz wave (my digital oscope is 100Mhz)

    I've checked, cleaned again and again, also reflowed the two connectors (card and jumper pack), but I can check again.

    Maybe by opening a card and the jumper pack I can check resistance directly from the two boards and the destination of every signal?

  • 0 in reply to kiltro

    I like your idea for checking the resistance to the jumper pak to ensure continuity.  You could use the same approach with a cartridge as well. That is of course if you don't mind opening a cartridge up.  Before you do this, I was wondering if you tried using the original jumper pak.  I seem to recall at some point that you switched to a new one.

  • 0 in reply to dang74

    The console was sent to me with an original expansion pack (the one that has red plastic). It was working with that one. Then when the console stopped working, I've bought a jumper pack (not original, completely black) but that doesn't changed anything.

  • 0 in reply to kiltro

    in the spreadsheet you list d0 - d7 is there data moving on those pins. what ics does this use 

  • 0 in reply to acdc90

    Hi, yeah if you click on the pin name in the DENC sheet you should see an image of what I'm measuring there (activity on D0-D3, 0V on D4-D6).
    I'm measuring with game and jumper pack inserted

  • 0 in reply to dang74

      Unfortunately I dont see anything strange on the connectors.

    I've measured from solder pads of the card connector (removing the top connector) and the various arrival pads on the chips, every trace is 0,4-0,6ohm (connecting my probes directly I get 0,2ohm)

    For the jumper pack connector if measure from the spring pin inside to the solder joint (pins-pcb) of the same connector and I get 0,4 ohms

  • 0 in reply to kiltro

    I thought of an alternate way of testing that the jumper pak is making good contact.  I came across a site that shows which pins connect to the resistors and which pins connect to VTT.  (See link below.)

    Anyway general strategy is to:

    1) Install the jumper pak

    2) Position one multimeter probe at the pin 8 SMT pad on the N64 board (pin 8 directly connects to VTT)

    3)  Position the other multimeter probe on the pin 5 SMT pad on the N64 board (pin 5 is one of the pins that connect to a resistor)

    4) If you measure low impedance like 100 OHMs then you know you have good contact between 5 and 8.  On the other hand if its open load or high impedance then you have poor contact.

    5) Repeat general process for other pins that connect to a resistor (7,9,11 etc)

    There is one complication to this.  If the jumper pak is in its case it completely obscures the SMT pads that need to be probed... and I am not sure how easy the task will be even if the jumper pak is removed from the PCB.

    bitbuilt.net/.../

  • 0 in reply to dang74

      Actually it's quite easy once the jumper pack is remove from it's case

    I measure 51ohm for every resistor, using pin8 as common.

    The only one that I strangely measure as 40ohms is the one connected to pin15.

    I've also measured resistance from all ground pins to ground and they seem fine

    Caps on the board to gnd it's ok too

Reply Children
  • 0 in reply to kiltro

    Sorry I didn't see this update when I posted my last response.  It looks like you have good contact with the Jumper Pak... assuming that 40 ohms on pin 15 is normal.

  • 0 in reply to dang74

    They are 4x51ohm resitor packs so I dont know what I'm getting a lower resistance there...

  • 0 in reply to kiltro

    One possibility is that there is also a parallel resistor on the mother board.  Remove the jumper pak and measure from pin 15 to pin 8 on the mother board.

  • 0 in reply to dang74

    for reference, this is a scheme of the board with an expansion pack, not the jumper we are using. Not exactly mine, it's a ntsc one. That pin goes to RXCLK (on the two ram and rcp)

  • 0 in reply to kiltro

    Thanks, I found some silkscreen on my board that says Vterm.  With the jumper pack installed I measured 41 ohms between Vterm and pin 13 of U14 which I think is the RCLK signal you mentioned.  So we are more or less consistent.  You measured 40 and I measured 41.  I have some questions related to cartridges.

    Do you have access to multiple cartridges?

    I have not removed my cartridge connector so I am a little in the dark as to how it makes its contact with the PCB.  Is it a compress/pressure fit or are there little receptacle sockets on the PCB?

    Do you have the means to open a cartridge?  If so you can measure point to point continuity from some of the pins on U9 and their final destination on the cartridge PCB.

    Another thing you can do, not related to continuity or cartridges is measure the Vterm voltage.  On my PCB it's approximately +2.5V. 

  • 0 in reply to dang74

    Yes I have access to multiple cartridges. I've tried the two that was working, and another one to be sure that the issue wasn't that for some strange reason both of the working ones were suddenly dead.

    You can easily remove the card connector, on the top side of the pcb (where is the cpu etc), by pulling it and maybe shake it a bit. See here



    Vterm is ok. If you look at the gsheet there is a "Power Rails" sheet, with my measurements. Vterm is 2,56v like in the schematic.
    Five power rails are used 12v, 5v, 3v3, 2v56 (vterm) and 1v92 (vref).

  • 0 in reply to kiltro

    Did you verify each of the power rail voltages on your board?

  • 0 in reply to dang74

    Yeah those on the gsheet is what I've measured

  • 0 in reply to kiltro

    We're running out of easy things to check.  The only things I can think of off the top of my head are:

    1. Point to point continuity between the motherboard and cartridge PCB

    2. (Assuming you have a microscope or magnifying glass) Do a good and thorough visual inspection to make sure there are no shorts near the fine pitch components.

    3. Gently push on the cartridge while powering up.  Try asserting force in different directions each time you power up.

    4. If you are open to investing further you could buy another cartridge connector... of course there are no guarantees.

    5. You could try touching the fast data lines while you power up the board.. sometimes a finger adds enough capacitance to fix reflections.

    6. Feel around for abnormally hot components.

    7. Explore the possibility that one of the new caps you installed is defective.

  • 0 in reply to dang74

    I'll try what you suggest.

    In the meantime, might it make sense to order another video cable?

    As I said, mine is new, but it's not original, and I see some people on Amazon saying things like "poor quality" or "no signal" (actually, a fairly small percentage of reviews)...

    What I tried was testing the resistance between the connector pins and the cable's RCA connectors, and I got about 4 ohms for each signal, so it should be fine... but who knows?