Hardware GBA SP turns on but won't charge

greenteagrasshopper · Jan 25, 2023

Hi,

Long time lurker. I've been tinkering with GBA SPs for a few months now, and I've purchased a few for-parts boards. One in particular has an issue where it won't charge but will turn on with a battery and a green battery indicator.

I've probed the charging port and it has roughly 4.8v. EM8 also appears to be fine as well as it's a well-known problem that I went to second immediately after the port.

Started probing around some more, and found there's a dead short on R53. Following the short, I kept probing more components and found a short on C32 as well. Removing R53 and testing again show it's definitely defective. C32 is a working component though, and the short only appears when soldered to the board. By my understanding, it's apart of the charging circuit so it would make sense that it's not charging.

Then there's this component that's not clearly marked on the silk screen which is also showing a short to ground:

Ignore the cracked coil. The core is intact and it's still functional, thought I have no easy way to test inductance.

Seems like I'm on a bit of a wild goose chase. Anyone else have a known working AGT/101 board that can help with probing that particular component, and the other mentioned above so I don't go crazy chasing a short that may or may not exist?

Oh, and the weird thing about this is it'll turn on just fine the first time, but won't turn back on if you flick it off and on again. Take the battery out, give it a few minutes, put the battery in and it'll turn on without any problems.

Any help would be greatly appreciated.

master801 · Jan 25, 2023

If I had to guess, that fuse you shorted (F2) probably blew a few components. But I haven't dealt with the GBA SP, so I have no idea.

According to: https://gameboy.github.io/consoles/advancesp
The F2 fuse may actually have blew the charge line?

If the charge light does not come on at all and you’ve ruled out the power adapter, the issue may be with the component F2. F2 is a small surface mount fuse located near the link port on the back of the PCB. With your multimeter, check and see if you have continuity across the component. If not, you’ll need to replace this fuse.

You can also take a look at the schematics (linked by that GitHub page) showing everything: https://github.com/Gekkio/gb-schematics/blob/main/AGS-CPU-11/schematic/AGS-CPU-11.pdf

greenteagrasshopper · Jan 25, 2023

I have been referring to Gekkio's schematics for a while now. For the large part, they've been very helpful but it's for an AGS-001, and not a 101 so there are a number of differences with the PCB layout and charge/power circuity (updated integrated power IC).

So, the charging circuit wasn't working at all even before I shorted the F2 fuse. It would also not turn on until I shorted it.

Also, that unidentified component is just a solder bridge, so it has to show a short. It would be more of an issue if it didn't show any continuity.

Still doesn't explain why the unit boots, but won't boot again once turned off and on again. Might have to explore other ways to locate the short, like voltage injection and finding hotspots using my Fluke thermal imager.

RipperSquid · Jan 26, 2023

greenteagrasshopper said:
Still doesn't explain why the unit boots, but won't boot again once turned off and on again.

This could be the r48 resistor causing this if I'm understanding correctly. This resistor drains the capacitors so you are able to turn it on and off quickly. I can't remember exactly the work around without the resistor, I think it was turning it on for a few seconds then off and leave it for the capacitors to drain.

The charge port might be beyond my level of diagnosing. You mentioned that there's voltage on the port so that's good, you probably won't have to replace that. Is the any corrosion near the port that could cause trace breaks?

I have an ags 101 myself but haven't taken it apart yet, I'd be willing to if you reckon poking around one could help.

greenteagrasshopper · Jan 26, 2023

RipperSquid said:
This could be the r48 resistor causing this if I'm understanding correctly. This resistor drains the capacitors so you are able to turn it on and off quickly. I can't remember exactly the work around without the resistor, I think it was turning it on for a few seconds then off and leave it for the capacitors to drain.

The charge port might be beyond my level of diagnosing. You mentioned that there's voltage on the port so that's good, you probably won't have to replace that. Is the any corrosion near the port that could cause trace breaks?

I have an ags 101 myself but haven't taken it apart yet, I'd be willing to if you reckon poking around one could help.

Hiya RipperSquid,

That's a really good place to start. I'll take a look at R48 and see if there are any issues with that or down/upline components.

I can't see any corrosion around the traces for the power port, but there is around the casing. However I did test continuity to EM8 and there seems to be power flowing through it at roughly 5V. There is also power to the downline components and charge circuit diode (D2), as well as the buck converter (3.3V) and caps.

Really appreciate your help, but I won't trouble you to open up a perfectly working SP haha! I'll keep poking around though and see what I can find out. Right now, I'm starting to think it's the Mitsumi 727A power IC that's gone bad. I've emailed Mitsumi to ask for a datasheet for it so I can start diagnosing that. Seems there aren't any datasheets for it anywhere to be found, so I'll have to go to the source.

I'll add that the 727A also contains the circuit for supply/control AND charge, whereas it used to exist on two separate chips (the other was to the far left of the board which is now unpopulated on AGS-101s).

Here's a photo of the difference:

Post automatically merged: Jan 26, 2023

Sure enough, R48 was missing. Looks like it'd been ripped off, but the pads were left undamaged. Just corroded. Cleaned them up a bit, fluxed and soldered a 1k resistor from a donor board. Sure enough, that's fixed the issue!

Cartridge slot is also kaput and full of corrosion. I'll keep working on that and the charging issue.

RipperSquid · Jan 27, 2023

greenteagrasshopper said:
Sure enough, R48 was missing. Looks like it'd been ripped off, but the pads were left undamaged. Just corroded. Cleaned them up a bit, fluxed and soldered a 1k resistor from a donor board. Sure enough, that's fixed the issue!

Cartridge slot is also kaput and full of corrosion. I'll keep working on that and the charging issue.

Glad to hear the resistor problem is fixed!

I honestly have no problem taking my 101 apart, I got mine with the shell in awful condition, seeing the differences between boards in interesting too, so the offer is there if you think you need it.
I'm quite new to fixing electronics in general and you seem much more knowledgeable than I am but I'm definitely willing to help where I may be able, especially since you don't see much about fixing 101s too often.
----
EDIT
As luck has it, I actually have a torn down 101 that turns on and charges at the ready, so let me know if you'd like me to check some things out.

greenteagrasshopper · Jan 27, 2023

Much appreciated @RipperSquid !

I'll keep that in mind. I'll have to give it a pause for the time being. Becoming cross-eyed from looking at these boards for so long.

I only repeat what I see and read on those schematics and whilst probing haha But thank you for the compliment. And you're right about the 101s being a little less talked about re: repairs.

Will keep that in mind though. Having a working 101 board is highly advantageous haha

DrunkenMonk · Jan 29, 2023

Does that L4 check out okay? it looks like it could've broken down with the plastic being cracked.

If I recall Q2 at the bottom of the board there is also a semi-common point of failure for the charging

greenteagrasshopper · Jan 30, 2023

DrunkenMonk said:
Does that L4 check out okay? it looks like it could've broken down with the plastic being cracked.

If I recall Q2 at the bottom of the board there is also a semi-common point of failure for the charging

Hiya @DrunkenMonk, without an LCR meter I've no way of confirming if the inductor is working correctly or not, unfortunately. However there is continuity and no resistance, which points to a good inductor. But, I suppose if the inductance is off, then it will have issues splitting the voltage variances between the 3.3 and 5v circuits. Not sure if this would affect it's ability to charge though.

I've take a look at Q2. See if that gives me anything to go by. Thanks for the heads up

Update: Okie doke, so I probed the emitter and base points of the transistor in diode mode and had a 1.65v drop, so that checks out as it's apart of the 3.3v circuit. It seems to be okay. I'll keep looking haha

Jayro · Jan 30, 2023

I dunno what happened here, but replace it. Looks like a lawn mower ran it over. :rofl2:

greenteagrasshopper · Jan 30, 2023

Jayro said:
I dunno what happened here, but replace it. Looks like a lawn mower ran it over.

View attachment 350155

Haha yeah, that's the L4 inductor we were talking about. I'd love to replace it but I'll have to find the value and the exact size first. It's still showing continuity, but again not sre if it's alright. I'll get around to sorting it eventually. Next month most likely with shipping from China being excruciatingly slow/bad.

greenteagrasshopper · Feb 21, 2023

Well bad news. The board is a complete flop. Turns out there was a internal short on the board which had killed the RAM and/or CPU. Without more spares to swap, I had to put an end to it.

No matter what I did, there was always a persistent short on C42. Good news is I was able to procure a working AGS-101 along with a spare board for a decent price. The board I might use on an IPS mod.

AGS-101 LCDs seem to be rarer than hen's teeth, and expensive to boot.

Eathen · Aug 27, 2023

Did you ever get the data sheet from Mitsumi for that power management IC?

Hardware GBA SP turns on but won't charge

Member

Well-Known Member

Member

Member

Member

Member

Member

Well-Known Member

Member

MediCat USB Dev

Member

Member

New Member

Similar threads

Popular threads in this forum