Need help with OLED. BSOD. RAM gets hot

Hello Guys.

The OLED turn on with Bluescreen. When I plug in the battery 1 of the RAM Chip get very hot in 1sek.

How to start the diagnostic?

Thanks for helping.

plug in charger only or plug in controlled bench DC supply to battery connector and check for current draws

Think in this scenario it’s not neccessary, sounds like somebody has reflown (or poorly reballed) Ram IC, caused a short (hence the heat) - So, just remove the ram IC in question.

I mean if you wanna verify it prior, measure the two Ram rails resistance to gorund (see that it is indeed shorted) then pull the IC and verify it’s cleared.

It draws 0.49 A without accu

You shouldn’t be plugging it in / connecting battery. If the Ram is shorted, as mentioned earlier, disconnect battery, measure rame rail/s resistance to ground, verify there is a short, pull the IC in question, then verify short is cleared :slight_smile:

USB current is going to tell you absolutely nothing.

Ok. I will test it later. Can I put a ram from a switch lite on the OLED?

Yeah, provided the ram manufacturer is the same, so if it’s originally Micron brand Ram on you OLED then it has to stay Micron, if it’s Samsung, then it has to stay Samsung brand etc. And of course provided you have the correct reballing equipment for the job too.

Just ensure you measure the Ram rails resistance to ground prior if you want to be sure that removing the IC/s in question clears the short after

Thanks for the great news. Yes I am waiting for my Pcb stencil. Then I do the job.

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Just to note, If your a beginner, then reballing the Ram with solder paste might be quite tricky, this is at the upper limit of what I’d personally consider possible (When I say “possible”, I really mean consistent and clean) with solder paste, in terms of package size, the bigger they get the harder it gets with stencil and paste.

These days, I wick the chip, I use a DH stencil and float pre-formed balls into the stencil with IPA (Stolen technique from Paul Daniels) and this works great and is super consistent, but this requires that your direct heat stencil for ram is thick enough as some are too thin and the balls won’t stay in the stencil. This also has the side advantage that the ball size is going to be slightly bigger (closer to stock solder ball size) , whereas, solder paste always results in slightly smaller ball size (which can be problematic in some cases) - Just telling you all this as if you attempt solder paste and fail over and over, you can cook the IC in question and potentially kill or curl it up.

Hi, thanks for response.

What size of balls do you use?

Can you send me the link to the balls?

Best regards

You are the switch god.

The short is fixed.

I use 0.35mm, 63/37 BST (best) brand (you could use chip quik brand but they cost a fortune in comparison)

I guess this is with ram removed? :slight_smile:

Yes I remove the ram. You my man.