Twin Acer 1916s

[smason]

My wife brought me 2 Acer 1916s to fix from a client. Isn't she great?

Cracked the first one open, wow some seriously bad caps.
One 470@25 measures toally open. Another is 1.46 uf, and 150ohms esr, that's right I read it several times.
Between that and the open one, I thought I had fried my ESR meter. Another 470 @ 10 reads 60uf and 7 ohms.

This time, my in stock 470 @ 25 FMs are about 2mm too tall. I knew one day I'd get bitten. FCs ordered... Will update on the outcome.

[smason]

Re: Twin Acer 1916s

Things that make you say "holy shit!"

I ordered 70 caps last night at about 7:00 from Digikey.ca
Here on my desk this morning at 9:45, are the 70 caps. Freakin' amazing.

[retiredcaps]

Re: Twin Acer 1916s

Things that make you say "holy shit!"

I ordered 70 caps last night at about 7:00 from Digikey.ca
Here on my desk this morning at 9:45, are the 70 caps. Freakin' amazing.

Wow, for cross border, that is really quick!

Mail within the same province via Canada Post takes longer than what you just experienced.

[smason]

Re: Twin Acer 1916s

Well the first monitor is done.
Did a full recap (minus the big one) and fired it up, works perfectly.

Second one, not so good.
Full recap (minus the big one) and it's still mostly dead.
Power supply outputs are fine 5v and 12v, and the regulator on the main board has 3.3v out, but only occasionally does the power light come on, and then only for a few seconds.
Photos tomorrow.
There are a few caps on the main board, but most of 'em measure ok capacitance-wise in-circuit, though they aren't exactly low esr, again in-circuit around 2 ohms. Hopefully the bad caps on the power supply didn't toast the main board chips.

[smason]

Re: Twin Acer 1916s

Second one, not so good.
Full recap (minus the big one) and it's still mostly dead.
Power supply outputs are fine 5v and 12v, and the regulator on the main board has 3.3v out, but only occasionally does the power light come on, and then only for a few seconds.
Photos tomorrow.
.

OK had some time to look at this in detail tonight.
It's not the same mainboard as the other threads with the reset controller, though the main chip is the same, so I used the schematic to find pinouts.

Here's what I know:
Power supply outputting clean 5v and 12v.
Microcontroller gets clean 3.3v
14.3 MHZ oscillation on the Xtal pins of the MCU.
The reset line does go high about a 1/2 second after power is applied.

When I plug the panel in to the main board the power supply starts to whine a bit, and the 12v goes up to about 13.2
Not sure if it's anything user-serviceable at this point. It may not be worth spending much more time on it.

Photos, sorry couldn't get decent light, will supply part numbers if anyone cares

[smason]

Re: Twin Acer 1916s

So, before I tell the owner that 1 out of 2 ain't bad, did I miss anything?

Or WWPBD? (what would PlainBill do?)

[PlainBill]

Re: Twin Acer 1916s

So, before I tell the owner that 1 out of 2 ain't bad, did I miss anything?

Or WWPBD? (what would PlainBill do?)

The power supply whining and the 12V rising indicates a heavier than usual load on the 5V supply. I would suggest trying to identify what is drawing the extra current. If it is a capacitor, diode, or transistor it should get unusually warm. If it is the main processor you probably won't be able to detect the increased temperature.

PlainBill

[smason]

Re: Twin Acer 1916s

Thanks Bill!
Left it running for a while, couldn't feel anything warm on the mainboard or on the panel circuitry. I'll probably park this one on the parts shelf and get on with things that I should be doing.

[PlainBill]

Re: Twin Acer 1916s

Thanks Bill!
Left it running for a while, couldn't feel anything warm on the mainboard or on the panel circuitry. I'll probably park this one on the parts shelf and get on with things that I should be doing.

I was just thinking of doing the same thing myself...

PlainBill