Actions
Forum Thread Details
  • State Verified Answer
  • Replies 60 replies
  • Subscribers 291 subscribers
  • Views 1534 views
  • Users 0 members are here
Related
See a helpful answer?

Be sure to click 'more' and select 'suggest as answer'!

If you're the thread creator, be sure to click 'more' then 'Verify as Answer'!

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.

  • 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?