Re: [DIYbio] Help Fix an Invitrogen Blue Light Transilluminator

It doesn't appear to me that those resistors had ever been
placed/soldered in. This is quite common, for selling variable
products with the same circuit board... or for test/calibration
points, or for backup in case there is a hiccup in parts supply and an
alternative circuit needs to be enabled so products can keep shipping
regardless of supply fluctuations. These are usually called
'BOM_IGNORE' or 'DNI' (do not inventory). We do this a lot with
capacitors, because the parts we test are so new the exact
requirements aren't know (though simulations/modelling gets us close).

I'd check all the solder joints with a jewelers loupe or a microscope
if you can fit the board under it... or a magnifying glass. Definitely
check that IC near the resistors you mentioned... and the transistor
with the heatsink. Mechanically stressed components (metal leads were
not in a relaxed state when soldered) can lift off of solder pads or
cause cracks, heat gets things close to the melting point, so one bad
hot day with heavy use could have lifted a single pin or cracked some
joint because of thermal cycling and dissimilar temperature
coefficiencts.

Second easy thing to check would be the response of the capacitors...
a simple signal generator (just a square wave of half a volt will
often do for in-circuit testing) and oscilloscope can diagnose bad
caps in a second or two.
https://en.wikipedia.org/wiki/ESR_meter#Methods_of_ESR_measurement

pic of electrical setup
http://meettechniek.info/passive/cap-images/circuit-c-squarewave.gif

write-up
http://fullnet.com/~tomg/esrscope.htm

some folks get away using a multimeter instead of an oscilloscope...
but I like 'seeing' the 'truth'.




I picked this up for testing bad lab equipment power supplies,
specifically because it was battery-powered and thus would minimize
risk of damaging through some weird short-circuit with
high-voltage/high-power:
https://www.amazon.com/Seeedstudio-DSO-Nano-v3/dp/B00UJOA10G/

it did need some modification to work well (desoldered the internal
flash chip, soldered in a micro SD card, then re-programmed with the
BenF firmware which upgrades the signal trigger SIGNIFICANTLY), pics
here of hardware mods:
http://seeedstudio.com/forum/viewtopic.php?f=22&t=4678&sid=49b9dc37e79d270e93051a041406c271


On Thu, Jul 28, 2016 at 5:18 PM, Cory Tobin <cory.tobin@gmail.com> wrote:
> Hi everyone,
>
> A non-functional blue light transilluminator was donated to my lab. It's an
> Invitrogen Safe Imager Blue Light Transilluminator 2.0. I cracked it open
> and found it was missing 3 surface mount resistors. Otherwise the device
> seems to be in great shape.
>
> See the images here:
> http://imgur.com/a/kfkmU
>
> If anyone has one of these transilluminators and wouldn't mind opening it
> up, I could use the values of the 3 missing resistors shown in the first
> picture. It's really easy to open. There's 9 screws on the back. Once
> those are out it comes apart in two pieces and the top of the board is
> visible.
>
> Thanks in advance if you can help me out.
>
> -Cory
>
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--
-Nathan

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