RG1 1.8v regulator

Just to expand on my original observations, the negative current I see on the output of RG1 seems to be due to it outputting 1.79v for a few seconds on initial powerup before stabilising at 1.804v. While the LAN9512 appears to power up at 1.805v and stay there.

My second order of Raspberry Pis arrived earlier in the week. A quick check shows one of them is running slightly warmer than the rest, not too much, I can still hold my finger on the LAN chip. I measure 1837mV at RG1 compared to 1793mV on one of the cooler ones (at idle, unmodified boards). Perhaps the LAN9512 core is running over voltage due to the external source and hence a bit hotter in this case. There may be multiple scenarios depending on components.

I don't expect it will reduce the life of the chip unless it gets really hot, so I'll leave the rest alone unless LAN chips start dying all over the place.

My IR thermometer arrived yesterday

I was looking at picking one up, but noticed that even rather expensive ones seem to have a minimum measurement 'spot' of something around 20mm which is rather larger than the lan9512. I was wondering just how that affects the readings..  Presumably they average the total emissions over whatever is in the sensors view somehow.

Like you I don't have a Pi that runs as hot as some reports, and without one it's difficult to form a theory on what the cause is.

selsinork wrote:

 

My IR thermometer arrived yesterday

I was looking at picking one up, but noticed that even rather expensive ones seem to have a minimum measurement 'spot' of something around 20mm which is rather larger than the lan9512. I was wondering just how that affects the readings..  Presumably they average the total emissions over whatever is in the sensors view somehow.

 

Like you I don't have a Pi that runs as hot as some reports, and without one it's difficult to form a theory on what the cause is.

yes the IR meter have there issues and you have to know it to get good readings and i have even an very good Fluke 568 there is on the high side of them and i dont use muchs because they crude in eletronics work and it is better to use an IR cam

The Fluke 568 IR meter i am having is having and IR spot of (the number is is IR spot size and the distance from the surface)

Spot 19mm @ 300mm distance

Spot 18mm @ 900mm distance

Spot 42mm @ 1500mm distance

you also has to hold it at an right angle

next time i will do some testing i will take both some IR images and use the IR meter and let you know what it is showing, but in the mean time try look at the images i have posted there is an graf showing the temparatura across the surface of the chip and you can clearly see the edges of the chip and that there is an very tinny hotsport at the center of the chip.

Tooms

it is better to use an IR cam

I'd love one.. I looked at prices. No way can I afford one

The Fluke 568 IR meter i am having

Yeah, that's the one I was looking at, it was the only one I could find that gave a good explanation of the D:S relationship and that was what decided me not to bother getting one - my dodgy sensor stuck to the top center of the IC is likely more accurate

Has anyone found the emissivity coefficients that we should use for the encapsulant on the chip (0.92 has been suggested)?

I've asked a few chip suppliers FAEs and been met with a blank stare!  I guess that's why I still use thermocouples, but they are messy as I always gunk them up with heatsink compound.

Cheers

Pete

Hi

I am using the 0.95e on my Fluke 568 as this is the default one and it is for black plastic

the 568 build in tabel has:

0.93 paint

0.95 plastic

0.93 water

an book i have about IR is having

0.85 Brick, common

0.94 Brick, refractory rough

0.95 electrical tape black plastic

0.92 Glass

0.93 lacquer, bakelite

0.94 paint average oil based

0.94 paper black

0.93 rubber

0.92 tar paper

(I have only listed the values there seems usagbol to this as the list is alot longer..)

So based on this i will say around 0.93-0.95 so a good point will be 0.94e but as other users here is having IR meters and they are very likly fixed at 0.95e so i think it is best to use 0.95 so it is easyer to compire the results there is posted.

Thomas

Seems like a good suggestion - as you say at least we can compare results with some confidence, I think the issue on resolution, spot size is also a complicating factor.  From what I understand you will get the average of the spot size so any real hot spots will be averaged away.

I've been trying to find a IR lens that will give 10mm x 15mm as the total field of view.  Interestingly it gets even more complicated when you look at effective touch temperature and we need a gizmo called a "thermesthesiometer probe" but these are not commercially available as far as I have found - if you find one let me know.

NASA (slightly old but the most recent I could find) have suggested that 45C is tolerable (indefinitely) for polished metal with an effective infinite heat capacity, and obviously a very high thermal conductivity, but this does not play well to our circumstances unless we measure less than that.

So I think there are three issue in this thread:

1) Touch temperature concern.

2) Die temperature and effect on performance.

3) Effect on functionality of USB? (Circumstances yet to be determined)**.

I have not seen any reports that making the suggested mod fixes anything, I'm sure you will let me know if I've missed it.

As always - comments welcome.

Cheers

Pete

Hey Morgaine,

As a somewhat related question. . . posible for you to suggest an affordable soldering iron with a small tip-to-grip ratio? Price range around $125 or so? Everything I come across is beaucoup bucks! I have a "hobbiest" iron from Adafruit but don't think it's going to work for me. Since I'm quite interested in this stuff I should invest in something I can use for eons..

Thanks as always

Peg

You are in the US right ?

This is one option -> https://www.sparkfun.com/products/10553

This is a better option -> http://www.newark.com/weller/wes51/analog-soldering-station-50w-120v/dp/92C1414?in_merch=Popular%20Soldering%20Stations&in_merch=Popular%20Products&MER=PPSO_N_C_SolderingStations_None

And if you want digital (more expensive) -> http://www.newark.com/weller/wesd51/digital-soldering-station-50w-120v/dp/94C3885?in_merch=Popular%20Soldering%20Stations&in_merch=Popular%20Products&MER=PPSO_N_C_SolderingStations_None

- J

Peg,

Check out Aoyue. http://www.aoyue.com/en/ArticleShow.asp?ArticleID=372

For a little over $125 you might be able to get a combination station that also does hot-air. I have the just-hot-air station from them. (and the weller)

I don't know of one yet, but I'm definitely in the market for one because under 14X binocular magnification it's really hard to control an iron with a long tip.  Currently looking through jamodio's links.

Addendum:

• The iron that comes with Adafruit's Hakko FX888 Soldering Station seems to be 190mm long without cord, and the tip looks kinda long.
• Newark's Tech Data Sheet link for the Weller WES51 is currently down for me, I'll check again later.  On Farnell UK, no such model, might be US-only.
• Weller have a "micro" range WHS-M,  http://uk.farnell.com/weller/whs-m-uk-eu/soldering-staion-40w-230v/dp/1729967 , which looks very small, but I can't see the actual tip length specified.

General comment about Weller pricing ... ouch.   It's clearly industrial pricing, hard to justify for very occasional use.

Morgaine.

I don't know of one yet, but I'm definitely in the market for one because under 14X binocular magnification it's really hard to control an iron with a long tip.  Currently looking through jamodio's links.

Addendum:

• The iron that comes with Adafruit's Hakko FX888 Soldering Station seems to be 190mm long without cord, and the tip looks kinda long.
• Newark's Tech Data Sheet link for the Weller WES51 is currently down for me, I'll check again later.  On Farnell UK, no such model, might be US-only.
• Weller have a "micro" range WHS-M,  http://uk.farnell.com/weller/whs-m-uk-eu/soldering-staion-40w-230v/dp/1729967 , which looks very small, but I can't see the actual tip length specified.

General comment about Weller pricing ... ouch.   It's clearly industrial pricing, hard to justify for very occasional use.

Morgaine.

I found other discussions regarding this question. Sorry to have jumped in to the wrong discission. . . I'm going to check into the chinese market. Thanks for the suggestions. I'll let you know what I come across for soldering irons. The "re-work" stations have me confused. . .like what would I ever need a hot air gun for??

Best,

Peg

Peg Wagner wrote:

 

The "re-work" stations have me confused. . .like what would I ever need a hot air gun for??

A soldering iron is great for soldering or desoldering a single terminal.  It doesn't work well if you want to heat up multiple terminals simultaneously, such as the two terminals of an SMT resistor.  And if you want to desolder the LAN9512 chip, forget it.  You have to heat up 64 tiny terminals plus a large ground pad under the chip which you can't even touch with the iron.

The right hot air tool makes it possible to desolder these kinds the packages, and resolder all pins at the same time.  But you do need to know what you're doing (which I don't).