Botched PROM Job Lifted a PAD

[dcbarry]

ARRGGHH---

After three perfect attempts on useless boxes, I freaked screwed up and lifted pad #25 on my Tivo HD. It is pretty much is completely gone. Big white space where the pad was.

Is there anything I can do to salvage this? There is the tiniest little trace 1mm or so that leads to the former pad. Unfortunately from there it ends in a hole (via?) without copper around it, and then assume it goes under the board to elsewhere.

I've seen this post http://dealdatabase.com/forum/showthread.php?t=61297 by cartouchbea

indicating I assume it leads to resistor "B6" (his legend).

I'm assuming my only hope here is to redo the socket (minus the bad pin) and fold it up, and then run a wire to that resistor? Only, I don't even know which side, if that is even possible.

I saw some comments on another post here somewhere that talked about running a wire (from an old IDE cable -- very thin) into on those holes (via is the term, right).

I'm so mad and tired, I'm just going to end this post for now. ANyone who can give advice would be appreciated.


(of course, this is my lifetime box). Grrr...

[Omikron]

You could _very_ carefully use an x-acto knife to scrape away the green solder mask from the trace and via, solder the rest of the pads for the socket, then solder a thin copper wire from the socket to the trace, laying the last bit of wire right on top of the trace. Once soldered, you can cover the trace area with a bit of hot glue (not too much or the chip won't go into the socket) to help add some strength.

I've done these types of repairs for friends on screwed up console work or other SMD rework mishaps and it has worked well, but you only get one shot to do it. If you mess it up twice, you'll have made things quite difficult for yourself indeed.

[Omikron]

That said, if you want to fix it _right_, one could follow this method: http://www.circuitrework.com/guides/4-7-2.shtml

Although that method requires purchasing special pad repair stickers.

[dcbarry]

Ok, I'm still kicking myself today, but I'm a bit calmer. Frankly, I got too damn cocky after my initial sucesses, and should have taken it as slow on the real board. A real lesson learned here.

Anyway....

With the scraping method, the via leading to the (former) pad is about 1 mm away and is located under the chip, not outside of it. So, I'm a bit skeptical of my chances of success here. Also, the visible trace mask is so narrow..... is the actual copper a bit wider?

Is there a problem in scraping too large an area around the trace itelf? I'm guessing not, so long as it is covered after the connection is made. Also, any advice on what to use to scrape. Is a new razor blade or exacto knife sufficient? Sanding paper? Again, I'm going to practice on my junk tivos, but would appreciate the advice.


I observe that some vias have copper and others do not. The one that leads to the missing pad does not. Is this significant?


Dumb question --- is it possible to solder the wire into the via somehow? It is so damn narrow/fine, I can't imagine it can be done... but if it were, I'd guess it would mean pre-tinning the a superfine wire wire, inserting into the via, and the re-heating with a heat gun. Is this total folly?


I'm wondering if doing the fly wire to the next point is a detter option here. Of course, those resistors are packed darn tight. I'd also need guidance on which side of the resistor would "take" the wire. I'm assuming (and definitely need correcting here), that since they are oriented the same way, that I "should" be able to to use the continuity tester with the other pads and determine which side should be soldered to. Or will both sides show continuity, leaving me without a clue?


Again, I realize I am talking out of my butt here mostly, so again, advice is appreciated.


BTW, Omicron... thanks for being a gentleman about all this. ;-) As I mentioned, it was never about the cost, just the pride. My lesson comes straight from the words of St. Augustine...."Humility, Humility, Humility!"

[Omikron]

Ok, I'm still kicking myself today, but I'm a bit calmer. Frankly, I got too damn cocky after my initial sucesses, and should have taken it as slow on the real board. A real lesson learned here.

Anyway....

With the scraping method, the via leading to the (former) pad is about 1 mm away and is located under the chip, not outside of it. So, I'm a bit skeptical of my chances of success here. Also, the visible trace mask is so narrow..... is the actual copper a bit wider?

Nope, it really is that narrow.

Is there a problem in scraping too large an area around the trace itelf? I'm guessing not, so long as it is covered after the connection is made.

Scraping too large of an area isn't a problem, although scraping to deep will remove the trace completely.

Also, any advice on what to use to scrape. Is a new razor blade or exacto knife sufficient? Sanding paper? Again, I'm going to practice on my junk tivos, but would appreciate the advice.

The problem with normal razor blades and sanding paper is lack of control. Use an x-acto type hobby blade and use very, very light pressure. You can always take off more, but you can't put any back.

I observe that some vias have copper and others do not. The one that leads to the missing pad does not. Is this significant?

Nope, they all have copper. Some just have more of a mask covering it.

Dumb question --- is it possible to solder the wire into the via somehow?

Not dumb, and it indeed is possible. You need a VERY fine gauge single strand of wire, like magnet wire, and you need to use an x-acto knife to remove the mask off of the via first.

It is so damn narrow/fine, I can't imagine it can be done... but if it were, I'd guess it would mean pre-tinning the a superfine wire wire, inserting into the via, and the re-heating with a heat gun. Is this total folly?

Pre-tinning the wire will only add thickness to it, which will make it harder to seat in the via The secret is a good quality liquid flux, a very fine tip on your soldering iron, and not too much solder. If you use this method, resist the urge to yank on the wire to see if it's connected. You'll rip it right out, with the trace coming with it.

I'm wondering if doing the fly wire to the next point is a detter option here. Of course, those resistors are packed darn tight. I'd also need guidance on which side of the resistor would "take" the wire. I'm assuming (and definitely need correcting here), that since they are oriented the same way, that I "should" be able to to use the continuity tester with the other pads and determine which side should be soldered to. Or will both sides show continuity, leaving me without a clue?

Can't help you there. I never had to do that on the TiVo so I never looked into it.

Again, I realize I am talking out of my butt here mostly, so again, advice is appreciated.


BTW, Omicron... thanks for being a gentleman about all this. ;-) As I mentioned, it was never about the cost, just the pride. My lesson comes straight from the words of St. Augustine...."Humility, Humility, Humility!"

No worries. This isn't the first time I've seen someone lift a pad:



Note that neither the TiVo or photo are mine. It was from another DDB member on IRC, but I don't recall whom. If that member doesn't wish for this photo to be posted anymore, please let me know.

All that aside, ALWAYS REMEMBER TO USE FLUX. This repair will not succeed without it.

[dcbarry]

Great news ... I'll post more later, but my sopposedly lifted pad --- turned out not to be at all. Turns out that while I cleaned each of remaining pads, I realized the "white" I was seeing was really just bad solder. I was so tired and upset that night, and since the pin for that socket pulled out, I jumped the gun.


So, after a good cleaning of all the pads - I started over. Still did not boot. Damn! But this time, I simply went to bed. Next day, got out the continuity meter, and used cartouchbea's post to trace around. Came up with a few open circuits. A bit of touch up, and then I was still left with 3 open circuits. They really looked good, so after scratching my head a bit, I experimented a bit, and discovered 3 errors in cartouchbea's post. (No disrespect to him ---- he did caution it was a bit from memory -- and it helped me find several of the problem areas.) I'm going to IM him privately first to see if he wants to correct his original post with my notes, rather than me confuse with an additional posting.



Omicron and Cartouchbea --- I am in the debt of both of you. I haven't yet burned my new PROM -- but just having my lifetime box up and working again is excitement enough for one day.


Cheers,

d.

[warewolf]

The above image of pure prom chip horror is one of nine TiVos I've owned in my lifetime, and that one was a $800 Series 3 unit. I have since purcahsed a replacement, but I still have the unit. The first and only TiVo I've destroyed.

Take note: be very very gentle with a soldering iron, or do what I do now: snip the legs off the chip and then remove them with an iron. Or let Omikron take care of it for you.

(the above image is free to use as long as somebody doesn't try to claim it as theirs... although I'm not sure why they'd want the embarrassment)

[dcbarry]

You're a good man to take .... uh... credit for that pic! ;-)


I've gotta ask ... How did that happen? And was a rescue ever attempted?


Cheers,

d.

[warewolf]

I've gotta ask ... How did that happen? And was a rescue ever attempted?

Too much pressure from the soldering iron between the leg of the chip and the pad on the board.

No, a rescue wasn't attempted (I don't have the skill). The unit doesn't even have service, and right now the HD for it is a "spare" in case one of the other S3 unit hard drives go tits up.

[buckster]

I've been looking around, but finding nothing here. Is anyone still socketing for those of us who have no idea on how to handle an iron. I can't find anything saying another date or anything! Is anyone still doing it?

[unitron]

The above image of pure prom chip horror is one of nine TiVos I've owned in my lifetime, and that one was a $800 Series 3 unit. I have since purcahsed a replacement, but I still have the unit. The first and only TiVo I've destroyed.

Take note: be very very gentle with a soldering iron, or do what I do now: snip the legs off the chip and then remove them with an iron. Or let Omikron take care of it for you.

(the above image is free to use as long as somebody doesn't try to claim it as theirs... although I'm not sure why they'd want the embarrassment)

Was it a TCD648 original S3?

Was it lifetimed?