Any ideas what could have gone bad in this Ryobi Tek4 charger?

[gellfex]

I can't recall a charger simply crapping out like this, unresponsive. Opened it hoping to find a soldered fuse, nada. No obviously burnt caps or resistors, no smell. It seems pretty simple, doesn't even have a microchip! Any ideas? My next step is simply bypass it's circuitry and use it as a battery holder to charge the batteries from my ImaxB6 charger which has settings for 4v Li Ion.

[reggie_obe]

AC in the middle bottom, right side seems to be AC/DC conversion, is the brownish block a full wave rectifier bridge or? Or could the single diode above it have popped? Do you measure any voltage on the board tracing the path on the right side?

[PStechPaul]

Anything on the reverse side? It almost has to be a switching supply with the small transformer on the upper right, and in the upper left seems to be a regulator or transistor. The six position SIP connector looks similar to a programming header for a PIC or other microcontroller.

[reggie_obe]

Upside images, difficult to read any component marking on the board.

[woodenbird]

I wouldn't be surprised if the transformer has shorted turns therefore failing the unit. I have had several small switchers fail in this manner.
I would agree with Paul as there must be some chips on the reverse since it is listed as able to charge many different LI ion batteries

[mattthemuppet]

the "use it as an adapter with a different charger" play might not work - some tool battery pack boards need an electronic handshake between the battery and charger before the battery will accept a charge. Should be easy enough to test though, just clip the appropriate leads from your Imax onto the back of the prongs at the top.

[J Tiers]

It has a microchip" on the other side. Along with a number of other parts.

No big shorts, or it would blow its fuse.

Could be a diode that is unsoldered (from heat?) or just bad, and anything from a bad solder joint to a totally failed part. "unresponsive" as in no light even, means it probably is not even starting up, so the start circuit is a possibility. You need to know what chip it has to know how that works.

It's a battery charger, so it MAY not even try to turn on unless there is a proper voltage battery plugged in and giving it the required minimum start voltage. That's a great way to make a charger, power the controls from the battery you are charging. That way it has to have the battery, and will not sit there idling all day without one, plus it has to be a battery within the range of the charger for it to turn on. No bad batteries need apply.

[gellfex]

Well, the Imax charger does work, I've done it, but I didn't let it get full and see what happens. I figured the other 2 contacts on the battery were for a reason. Or are they just a thermistor? I didn't want to unsolder the power connections just yet to access the other side, but it didn't look like there was much there.

I wouldn't be surprised if the transformer has shorted turns therefore failing the unit. I have had several small switchers fail in this manner.
I would agree with Paul as there must be some chips on the reverse since it is listed as able to charge many different LI ion batteries

That's surprising it does multiple voltages, since this is dedicated to the 4v format the Tek4 system uses. So is it worth the effort to try and diagnose this sucker? I've already ordered one off Ebay with a battery and mini driver. I'm a big fan of that minidriver and liked the idea of having 2. It's got a clutch and is perfect for small assemblies and even changing household electric devices and plates. I think I can more than pay for it selling a NIB Tek4 flashlight, apparently people are willing to pay stupid money for them. Collectors!

[chipmaker4130]

If ryobi electronics are anything like their power tools I wouldn't waste any time or money on it.

[J Tiers]

Chargers do "current" not voltage, but for the LI, it may have preset "possible" voltages, OR it may just rely on the battery processor to tell it to stop charging.

[SLK001]

There undoubtedly is some circuitry on the reverse side (you can see the vias). Remove the board and take photos of the back side.

[Noitoen]

There undoubtedly is some circuitry on the reverse side (you can see the vias). Remove the board and take photos of the back side.

To remove the board you would have do dissolder the L N plug connection (I think)

[mattthemuppet]

Well, the Imax charger does work, I've done it, but I didn't let it get full and see what happens. I figured the other 2 contacts on the battery were for a reason. Or are they just a thermistor? I didn't want to unsolder the power connections just yet to access the other side, but it didn't look like there was much there.

that's good to know. I imagine that your imax would work just fine in that case, as it would for any other battery. Some tool battery/ charger set ups have a contact for the charger to read the thermistor in the battery, so that it won't charge if the battery is above or below a set temperature, some have more complicated circuitry where the charger queries the battery to see if it's within parameters (voltage, temperature, balance) and will only start charging if it receives the correct info. Some even work the other way, where the battery will only "unlock" if it receives the correct signal from the charger (Ryobi 40V packs). They can get pretty complicated.

[J Tiers]

The chargers and equipment know way too much about the battery. My phone was presented with a perfectly identical (electrically) battery. It even operated the phone.

But the phone only operated enough to say "Unsupported battery". Which totally proves the battery was the right voltage, of course. But it did not have the battery chip programmed with the code for the service that sold me the phone.

The correct battery would cost 6x the cost of the other one, for the same function. I "threw the phone at them".

[A.K. Boomer]

None of the caps looks puffed where they usually expand when they "shell out",,, it's a double board so can help to go over pathways while using magnification and holding it up to bright light,,, I just also look for toasty looking resistors and diodes and stuff and try to test what I can but admit don't really know what im doing that way...

lot's of good electronic guys on here but this path could take allot of different directions i fear....

oh yeah - look for halo's around soldered connections esp. resistors that see heat...