EEVblog #689 - Back To The Future Time Circuits Troubleshooting

Dave troubleshoots the Back To The Future Time Circuits in 'real-time", warts and all.
A journey of red herrings, garden paths, the bleeding obvious, and the inevitability of Murphy's Law.
Can you discover the fault before Dave does?

Discussion and comparison of the Tagarno microscope vs the Mantis 3D stereo microscope.

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[DasOrakelspricht]

Absolute stunning.
Errors are always instructive, Hardware repairs are not "peeking here, poking there". It's demanding duty. That was "real life"!
Big thumbs up!

[mrosenblatt]

You know what I like? I really dig that you're able to admit when you make a mistake. I know all too many people that simply won't do that, especially when it comes to troubleshooting things. The first step to troubleshooting: Being open to the idea that you can make a mistake while doing so.

[GadgetUK]

What we've learnt is a) Don't plug power connectors in the wrong way around, and b) Solder properly - Sorry, I am trying to be funny here ;) - I totally love your channel and you are one of the smartest people in this field on YT.  Brilliant stuff and if anything I am pleased you broke it, just so you could fix it and show us some interesting things along the way =)  Great stuff!

[Murphistic]

I've just started watching the video and the problem is obvious: No flux capacitor... :)

[davecc]

Always good to watch you troubleshoot. Learn much.
That was your intuition kicking in that kept you from going down the garden path with the analyzer.
Good vid. More!

[jonka]

If connecting the power wrongly damages one chip it rather makes sense to assume the others are at least likely to be worthy of inspection. What this teaches me is: stand back and take a few moments to see the whole situation instead of focusing in to a single known fault.
Dave thanks for all the time and effort you put into your videos.

[DaveCurran]

The chips are getting up to 88! (well 88°C), maybe you should go back to the day of the mailbag and turn the connector around when past-you isn't looking.

[bain]

This is one of the most informative trouble shooting videos you have done. It illustrates a very important trouble shooting point. 90% of the time when I've encountered trouble from a repair, it turns out to be something so utterly stupid that I fail to even consider it in my analysis. Only after performing numerous other test, as you did here, do I run into the brick wall of logic that causes me to look much closer at the obvious. Really good example of trouble shooting pitfalls!       

[sebrassino]

the fact you have blown it has made this video so damn good. I learned really alot of this. Was actually looking some time for a good explenation of how those led displays are driven. Couldnt have got it explained better! Thanks!

[dwDragon]

Dave, your method of filming the soldering at about 34:00 was excellent. Much more effective than a single tight camera angle, and probably a lot easier for you doing the soldering. I don't think I've seen any soldering tutorials filmed like that on YT. You could probably make some great videos with that setup.

[spiros]

Videos like this equal to many hours of troubleshooting. You dont need to know what gone wrong and what he did to fix it but how his thoughs in the process. Where to start and how to go deeper and deeper in the fault

[ThisDoesNotCompute]

As for the pin pitch: It also looks like the chip got soldered down slightly rotated. Notice that the pins at 30:25 that are off are on the lower right and upper left. If the chip wasn't rotated, they'd be off evenly. It does look like there's a slight pin pitch problem with that board, but it's not as severe as it seems.

[MrHolozip]

fantastic - great follow up Dave. Glowing comments all round too - isn't just me! We all love to see this kind of stuff. Big thumbs up.

[STUNRICK]

All these repair and troubleshooting videos of Yours, Dave, are incredibly educational! I'm really glad I've discovered Your channel and love all of Your videos. Keep up the great work!

[TheDocChannel]

+Kudos for holding your hands up and not deleting parts of the video and bullshitting your way out of it... nice one.

[TheOldmankk]

Common sense, patience and fundamental always find its path to a solution. Love this troubleshooting video. Thanks Dave.

[cogsinister]

Dont apologise for the video being too long dave, we love long videos, it was a very interesting watch.

[zzzsnorlaxzzz]

I've been down a few rabbit holes. You just proved the value of not only experience, but the value of questioning and verifying your own results while maintaining an objective eye to your process. With electronics, you simply can't be too observant. Hubris is the bane of science; You can wear it as a badge of highly salted honor but when you get cut it really burns.

[alexmihai]

Very nice, I worked as Debug in the production and this was one of the many defects that I meet. It was a very nice and entertaining job.

[CooperDuper]

This Episode was absolutely mindblowing, thank you!