(Topic ID: 295193)

Think I botched an NVRAM install.

By hool10

5 months ago

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  • 18 posts
  • 11 Pinsiders participating
  • Latest reply 5 months ago by PinballManiac40
  • Topic is favorited by 1 Pinsider


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#1 5 months ago

I have a BSD and I decided to buy an NVRAM chip and install it on my own. I followed this video almost exactly and apparently it wasn't the best guide at all and I should have followed Vid1900 guide.

So I don't have a powered solder sucker and tried to do the best job I could sucking out the solder. I got the chip out with a tad bit of difficulty and noticed one of the traces lifted from the board. I did the best job I could putting the trace back onto the pad and put in my new NVRAM. If you notice in the video they don't mention a polarity whatsoever. Luckily I took pictures and noticed a notch on one side and put the chip in correctly. That being said I didn't get a socket and unfortunately soldered the NVRAM directly to the board. It shouldn't cause an issue but 30-40 years from now someone is going to ask why I didn't install a socket first. Soldered the NVRAM chip in without too much heat and it was fairly fast and booted the game up. All the LED's on the boards lit up red and there were dots scattered across my Color-DMD display.

1) Is the trace that came off from the board the culprit?
2) Did I fry anything by booting the game up (I don't believe so)?
3) Did I fry the NVRAM chip itself soldering it (I don't believe so)?
4) None of the contact points are bridged.

#5 5 months ago
Quoted from Roamin:

Are you 100% sure you installed a compatible NVRAM chip ? What part number is it ?
1) Yes , most likely
2) No
3) Unless you applied a crazy amount of heat for a long time, doubtful.
4) That's a must.
You may not be aware of this , but holes in PCB have what is called a "via", which connects both sides of the board together. It is common for people to rip off the vias when desoldering and not being careful enough (or unaware of those vias). Take your multimeter and set it to continuity. Make sure every pin on the NVRAM (U8) has continuity to the pins of U6. Follow the picture below, for which pins connect to each other. For example signal A0 is pin 10 on the NVRAM U8 , make sure there is continuity to pin 12 of U6 , which is also A0. Repeat this for every pin on U8. Pin 14 of U8 should be connected to Pin 16 of U6. Pin 28 of U8 should be connected to one side of the R93 resistor. Pin 22 of U8 should be connected to one side of the R12 resistor. The last 2 signals are connected to U9 and will be a bit more annoying to measure because of the socket of the ASIC. You could use a needle to touch that pin while it's in the socket or probe from the solder side of the board.
[quoted image]

Thank you. I will try this out on Sunday and get a REAL de-soldering pump. One that is powered. If it really is the trace can this be repaired?

#12 5 months ago

Yeah I just bought a HAKKO FR301. I could have went with the bulb/iron type but you really can't control the heat and it doesn't get the all the solder out. Big difference between $245 and $15 but the question is "do you want to F things up and start doing wire jumpers"? On top of this I will more than likely do a few more installs because I'm part of a pinball coop so I can get my money back potentially. Do it right the first time with the right tool for the job!

1 week later
#15 5 months ago

So I got some free time and spent literally 7 hours that ended in failure (the person I joked to hold the fire extinguisher isn't me but a friend of mine).

So what I did was use my new Hakko de-soldering tool in the first photo in an attempt to salvage the $15 NVRAM. I put a generous amount of Rosin flux on the PCB. Unfortunately the NVRAM had solder that wicked though the hole and up its leg's. I spent 3 hours trying to remove the solder before I gave up and unfortunately lost a few contact pads. Next photo I cut the trace, gently scraped away the PCB to reveal the copper trace, recreated a copper trace as best I could, and soldered it to the 2 points. Third photo I cut out very tiny copper square and used a razor blade to make a hole to fit over the pin to replace lost landing pads. Fourth, satisfied with my repairs I put in my 28-pin IC socket like I should have done. Pictures 5/6 just show the completed process with NVRAM socketed with polarities matching the silkscreen on the PCB.

So I fired it up with fire extinguisher in-hand and the GI lights up for a split second, fuse blows, and that is that. So now what I'm doing is having a guy I know locally professionally repair the board. I think the board is toast but my firefighter friend thinks the tech can because he can fix literally anything. Had I followed Vid1900 instead of that video, had the proper tools, I know this whole ordeal wouldn't have happened. Good news I know what CAN happen and what not to do.

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