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Author Topic: "Common Sense" ACDC-6 Charger - output transistor  (Read 4834 times)

Offline Keith Miller

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"Common Sense" ACDC-6 Charger - output transistor
« on: January 27, 2015, 07:37:32 PM »
Greetings all -
I have a "Common Sense" ACDC-6 Charger which smoked the output transistor (found inside connected directly to the output (+) and (-) PCB pads.
I have access to some skilled 2M repair techs, but we can't read the p/n on the transistor.
Might one of you who have one of these chargers be willing to post a photo of the PCB and transistor right at the output connections?

Yes, I'm well aware of all of the other chargers on the market and which ones are of which quality.  Please don't go down that path.  I have several and I'm good with them all.  But if I can buy a $1.20 transistor, I can resurrect this one and make it useful.

Thanks!

Offline Tim Wescott

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #1 on: January 27, 2015, 10:01:39 PM »
Keith:

Too smoked to read, or you can't make out the number that's there?  Part numbers are getting hard to read these days -- semiconductor manufacturers are constantly trying to make it harder to counterfeit parts, and parts counterfeiters are getting better and better.  I can share some techniques if the problem isn't that there's a huge crack through the middle &c.

Make sure you know what smoked the transistor -- if you didn't do anything and it suddenly popped, chances are high that whatever is driving the transistor died and took the output transistor with it.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #2 on: January 28, 2015, 08:13:41 PM »
Tim - Too smoked to read.
I can read the adjacent transistor.  Just hoping someone still has one of these working and can read the numbers on the one that I show as fried.

I have no way of knowing what smoked the transistor.  We use this charger primarily for 3-4 cell packs.  It started giving a "BREAK DOWN" fault which, per the manual, is useless => "There happens the malfunction at the charger circuit by any reason."
We moved it from our deep-cycle battery which was at 12.0V, and put it on our solar-system which was at 12.6 v.  It worked there for a while at 3A, then failed with "BREAK DOWN".
It will occasionally charge up to about 0.3A then bombs out with the same code.  All other functions, menus, etc work fine.

I'm willing to give it one shot - replace the transistor once; if it works - great.  If there's some other failure that causes it to pop again, it goes in the trash.

Offline Tim Wescott

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #3 on: January 28, 2015, 08:30:22 PM »
I want to believe that I'm looking at a N-channel MOSFET, but that's not where I would have expected to see the final transistor in the circuit.  If those two leaded components in the foreground are resistors that go to ground over on the right, then it almost certainly is an N-channel, and you can find just about any N-channel MOSFET in a SO-8 package that'll work.

Of course, there's two different widths of SO-8 packages (the thingie marked "2901" in the center of the photo is the bigger size), and I could be wrong about the polarity of the FET.

If you're going to throw it away anyway, and if no one else comes forward with a better idea, then amaze yourself by the selection of 40V N-channel, SO-8 FETs on Digikey (there's probably over 10000 different part numbers to choose from).  Pick one at random, solder it on, and see if the whole thing bursts into flame.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #4 on: January 28, 2015, 08:41:54 PM »
Awesome response, Tim - thanks!!  I enjoy folks who can answer a question rather than starting off on tangents about other vaguely related topics.  Nicely done sir #^!
I have a DigiKey account, so I think I'll go shopping.
Thanks!

ps - attached a zoom of the burnt unit.  Can you make out any recognizable numbers?  Best I can do with a smart-phone camera...

Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #5 on: January 28, 2015, 08:41:54 PM »
Awesome response, Tim - thanks!!  I enjoy folks who can answer a question rather than starting off on tangents about other vaguely related topics.  Nicely done sir #^!
I have a DigiKey account, so I think I'll go shopping.
Thanks!

ps - attached a zoom of the burnt unit.  Can you make out any recognizable numbers?  Best I can do with a smart-phone camera...

Offline Tim Wescott

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #6 on: January 28, 2015, 09:52:39 PM »
I really can't make out any numbers.  Given the number of cells it'll charge you want a 40V transistor.  The real mystery is if it's a logic-level gate or ordinary, N- or P- channel, and whether it needs some super-zoot low gate charge or something.

Probably if you just choose one that's specified for a logic level gate, you'll be OK.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Crist Rigotti

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #7 on: January 28, 2015, 10:13:41 PM »
This might be the same charger as a Imax.  Search RCGroups Chargers and Batteries.  I thought I saw a recent post on the very same component.
Crist
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Offline Fredvon4

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #8 on: January 29, 2015, 08:20:11 AM »
My version of that charger is labeled Thunder but looks exactly the same

My chip has a logo that looks like a P with a 4 in it followed by 4468
second line of script is BA 1N3E

hope this helps
"A good scare teaches more than good advice"

Fred von Gortler IV

Offline Tim Wescott

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #9 on: January 29, 2015, 09:04:36 AM »
That sounds like an Alpha & Omega AO4468.  http://aosmd.com/res/data_sheets/AO4486.pdf.

It's a 100V part (!) -- I wonder if they needed that, or if it was just cheap at the time*?  At any rate, DigiKey has them in stock: http://www.digikey.com/product-detail/en/AO4486/785-1552-1-ND/3621496.

* Or if a lower-voltage part was designed in, but some circuit error causes the need for the higher-voltage part.  Hmm.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Jim Carter

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #10 on: January 29, 2015, 09:12:56 AM »
Please don't get upset with me but why not just contact the "Common Sense" folks and ask them??  Or at worse, ship it back with a repair request, regardless of warranty??

Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #11 on: January 29, 2015, 07:06:17 PM »
My version of that charger is labeled Thunder but looks exactly the same

My chip has a logo that looks like a P with a 4 in it followed by 4468
second line of script is BA 1N3E

hope this helps

Absolutely  Fred - thanks!!!

Offline Tim Wescott

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #12 on: January 29, 2015, 07:17:25 PM »
Please don't get upset with me but why not just contact the "Common Sense" folks and ask them??  Or at worse, ship it back with a repair request, regardless of warranty??

Where's the fun in that?
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Carl Cisneros

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #13 on: January 29, 2015, 10:52:20 PM »
I checked my Thunder charger this evening and my part has the same numbers as Fredvon4's has.
Carl R Cisneros, Dist IV
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Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #14 on: January 29, 2015, 10:56:03 PM »
Please don't get upset with me but why not just contact the "Common Sense" folks and ask them??  Or at worse, ship it back with a repair request, regardless of warranty??

Hi Jim -
Yeah - tried that - no response.  Sure, I could ship it in for repair, but I'm fortunate to have access to some techs to do a repair, and the smart guys on these boards to provide some recommendations.  I'd rather have a go at it than send it in blindly.  Good ideas though.  Thanks! y1

Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #15 on: January 29, 2015, 10:56:55 PM »
Hi Jim -
Yeah - tried that - no response.  Sure, I could ship it in for repair, but I'm fortunate to have access to some techs to do a repair, and the smart guys on these boards to provide some recommendations.  I'd rather have a go at it than send it in blindly.  Good ideas though.  Thanks! y1
Thanks for the double-check.  Those numbers get tiny.

Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #16 on: January 31, 2015, 02:46:52 PM »
That sounds like an Alpha & Omega AO4468.  http://aosmd.com/res/data_sheets/AO4486.pdf.

It's a 100V part (!) -- I wonder if they needed that, or if it was just cheap at the time*?  At any rate, DigiKey has them in stock: http://www.digikey.com/product-detail/en/AO4486/785-1552-1-ND/3621496.

* Or if a lower-voltage part was designed in, but some circuit error causes the need for the higher-voltage part.  Hmm.

After looking at that spec sheet, the max continuous current the 4468 mosfets can handle looks like 4.2A.  The charger is rated for (and occasionally hits) up to 5A.  It's no wonder this thing burned through!


Offline Tim Wescott

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #17 on: January 31, 2015, 02:59:54 PM »
After looking at that spec sheet, the max continuous current the 4468 mosfets can handle looks like 4.2A.  The charger is rated for (and occasionally hits) up to 5A.  It's no wonder this thing burned through!

Sorry I missed that -- I was just making sure that the voltage rating looks good.

If you can find one that has the same voltage rating and gate charge, but with a better current rating, it may work.  Unfortunately, the current ratings aren't always honest -- you'll get ones that give you the current rating for the device that's held to a huge heat sink that's held at 25 degrees C, which certainly doesn't happen in practice if the thing has been sitting out in full sunlight on a hot day.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #18 on: January 31, 2015, 05:31:29 PM »
Well, I bought a couple of the AO4468 units (http://www.digikey.com/product-detail/en/AO4468/785-1038-1-ND/1855980) since it sounds like that was the original part.  The charger does sit in the sun quite often when we're charging.
I also picked up a IRF7490TRPBF (http://www.digikey.com/product-detail/en/IRF7490TRPBF/IRF7490TRPBFCT-ND/2441006) which appears to have similar ratings but can handle a bit more current - 5.4A.  Can't say if the footprints exactly correct - only the datasheet for the IRF7490TRPBF showed the mechanical dimensions.

We'll see when they come in.
Thanks all for the help!

Offline Fredvon4

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #19 on: February 01, 2015, 09:00:39 AM »
Hey Keith, not meaning to insult your intelligence but years ago when I started electric RC I went in search of chargers for Nimh and Lipo batteries. Many of the name brand AC/DC chargers were in the $150~$225 range.

Hobby King had this Thunder version for the low low price of $38. Got one, works well, but I just assumed it was a Chinese clone and used low spec parts and questionable assembly.

I use it weekly to keep a constant rotation of 17 batteries (PB/NiMh/LiFe/Lipo) topped up or storage charge. (pain in the ass having many various battery chemistry)

Occasionally it went to the field but mostly it stays in the shop where I never need to FAST charge at high current (wink)

Many of my club buddies got one or similar like your Common Sense version....They all let out the smoke trying to pump 5+A through the 4.2A part (what we know know from your post and the spec sheet)

I may ask if any of them still have the box and see if I can resurrect a few as you are planning. So please keep us posted here on your repair and testing.
"A good scare teaches more than good advice"

Fred von Gortler IV

Offline Howard Rush

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #20 on: February 01, 2015, 01:10:00 PM »
Let's exercise some caution here.  55 years ago, we got McCoy .35s cheap and "hopped them up" for combat.  People who merely put those McCoys in the back of a drawer are sitting pretty now, while the McCoys we hacked on are of no use to collectors.  Half a century on, stock Common Sense chargers will bring top dollar.  One can imagine a charger expert on Antiques Roadshow pointing out the valuable original transistors in dusty Common Senses. 
The Jive Combat Team
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Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #21 on: February 01, 2015, 03:36:46 PM »
Let's exercise some caution here.  55 years ago, we got McCoy .35s cheap and "hopped them up" for combat.  People who merely put those McCoys in the back of a drawer are sitting pretty now, while the McCoys we hacked on are of no use to collectors.  Half a century on, stock Common Sense chargers will bring top dollar.  One can imagine a charger expert on Antiques Roadshow pointing out the valuable original transistors in dusty Common Senses. 

I'm sure there's a message in there somewhere, Howard...  Just nothing to do with the original post... ???

Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #22 on: February 05, 2015, 08:40:46 PM »
So.... I had a tech at work put in the IRF7490TRPBF.  Gave it a shot - "CONNECTION BREAK" alarm, meaning the charger can't see the battery plugged into the output.  I verified the pin arrangement, but I can't see close enough into the gate pin to be sure the solder joint is clean.  Or we cooked it with too much solder heat...
I'll have to give it another go, probably with the AO4468 that we think is supposed to go in there.


Offline Keith Miller

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Re: "Common Sense" ACDC-6 Charger - output transistor
« Reply #23 on: February 17, 2015, 06:31:17 PM »
So, plopped in the AO4468 N-channel MOSFET, also get a connection break (open circuit at the battery).
A fellow on another forum thinks it may be an IRF4905 p-channel MOSFET, so I'll look that one up and give it a try.



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