T2M Swallow advance charger repair

[bruce_c]

Just had a bad/expensive day.

My ripmax Pro Peak constellation charger (that has been playing up for a while now) finally died, releasing its magic smoke - but in the process shot down my Swallow advance charger :censored:

How it happened:
Constellation was charging the Rx pack on my U can Do, while the swallow was charging the onboard glow cell. As i've done many times before.
Now my onboard glow is the 'Intelligent Glow Switch' from South Herts models, and it looks like it connects the -ve side of the glow cell to the -ve side of the rx supply.
It also looks like my rx switch is single pole (+ve side only) - and i have no switch on the glow (simply because the instructions said there was no need - tho im not too sure about that now)
Note - both chargers were running off the one supply.

Anyway the Constellation for some time has been reporting 'Output battery open circuit' after about a minute of charge on the Auto settings (but would usually work on on manual).
Anyway I had the plane on charge on the way to the field - when i got there i smelled the destictive aroma of crispy fried semiconductors & saw that the Constellation screen was totally blank (1 dead charger :( ). The Swallow was happily flashing away end of charge so i presumed it was ok. Untill I went to charge another batery - It now will not see any battery connected to its output and on closer sniffing, it also had the crispy fried semicanducor smell to it (2 dead chargers :mad: )


I presume that when the constellation died, it somehow has passed the input supply to its output terminals and this had via the common -ve cooked a power FET in the swallow (swallow basically saw one of its output terminals shorted to the supply battery?????) Does that sound like a feasable hypothesis?

Anyway - big question - how do I get my £140 of broken chargers working again?
Constellation looks to be totally dead so will be returned to ripmax for warrenty repair hopefully. But the swallow was bought abroad on holiday 2 months ago & sending off for warranty work would not be worth the trouble.

I have taken the swallow to bits (pics posted below) but i can not see any obviously fried complonents. No burst caps, or scorched power diodes etc on the front side of the board.
The only sizable semiconductors are on the back side of the board (stuck to the heatsink case) and are marked 'FET4' and 'U6' on the board.
'FET 4' seemed to have the most smell about it, but i cant see any damage to it or scorch marks.
'U6' heats up a bit when power is applied to the charger with the case (and thus heatsink) off.

Can anybody suggest which component is most likely to have fried? Or how to determine exactly which it is.

All help is really appreciated

[Gary Warner]

Can anybody suggest which component is most likely to have fried? Or how to determine exactly which it is.

All help is really appreciated

FET4 looks burned. Take a look at the other side of the FET and you'll see a split case at the leads, center or on top where the plastic meets the metal backplate.

Most likely, other parts are bad too but maybe it's just the FET. I hope you can read the numbers on the FET.

Gary
--

[bruce_c]

Managed to bend FET 4 upright and it is an IRFZ34N which according to the datasheet is a N-Channel HEXFET Power MOSFET in a TO-220AB package.

The casing on it is intact and does not look scorched - just has a small amount of solder flux /pcb laquer at one side of it (pic attached)

For once its a shame that there is nothing obviously fried.

I'll replace the FET and see what happens. It would seem the most likely candidate. Providing i can source one or similar

I was going to check what was being but out on the chargers output terminals and see if U6 (LM7805 - 5V 1A regulator) was operating correctly (it was getting warm when plugged in) but it would seem that when my dad borrowed my meter at the weekend, he managed to leave it out in the rain and now it doesnt work either :censored:

What the heck else electronic can break around here?

[Gary Warner]

The first photo 'looked' like FET4 metal back had gotten too hot. Most FET's fail with a dead short between the source and drain, unless in doing so, it internaly fused open from the excessive current. I agree with you, the second photo makes the FET look much better.

Gary
--

[Bruce Abbott]

My guess is that FET4 is OK, as it is probably part of the Discharge circuit which is not active during charging.

The most likely victims are the SO8 FET connected to the negative terminal, and the two low-value SMD power resistors which connect between the FET and Ground.

[Paul Telco]

[QUOTE=bruce_c]Just had a bad/expensive day.

"Now my onboard glow is the 'Intelligent Glow Switch' from South Herts models, and it looks like it connects the -ve side of the glow cell to the -ve side of the rx supply.
It also looks like my rx switch is single pole (+ve side only) - and i have no switch on the glow (simply because the instructions said there was no need - tho im not too sure about that now)
Note - both chargers were running off the one supply."

Regarding the above:
Fit the safety switch! SHM have never suggested otherwise, specially if using intelligent chargers. If charging Rx and IG batteries simultaneously it is always advisable to fully isolate the circuits to avoid strange feedback effects from one to the other. Go to our website www.southhertsmodels.com and look at page 6 of the 'Glowswitch Handbook'. In fact look at all the pages as it's full of useful information.

Paul Telco
South Herts Models

[badcockr]

Just had a bad/expensive day.
Constellation was charging the Rx pack on my U can Do, while the swallow was charging the onboard glow cell. As i've done many times before.
Now my onboard glow is the 'Intelligent Glow Switch' from South Herts models, and it looks like it connects the -ve side of the glow cell to the -ve side of the rx supply.
<SNIP>

Anyway - big question - how do I get my £140 of broken chargers working again?
Constellation looks to be totally dead so will be returned to ripmax for warrenty repair hopefully. But the swallow was bought abroad on holiday 2 months ago & sending off for warranty work would not be worth the trouble.
Do you think that both chargers were damaged by being effectively shorted across each other? Have you identified the fault on the Swallow yet, or have you decided to go down the warranty route for the Constellation and Swallow?

Rod

[bruce_c]

Paul:

Thanks for the link. I can't locate my printed instruction sheet but i don't recall seeing anything regarding the use of smart chargers (mine is one of the older units). I was sure they said the safety switch was only there to allow you to disable the unit so you could safely fiddle with the engine and thus optional.
But I agree that fitting it would make a lot more sense considering.
Great glowswitch unit btw. Really easy to setup and effective in use.

Rod:

The constellation had been playing up for a while so it fried itself properly (lot of burnt electronics smell) and i presume it internally shorted -ve output to supply input (FET died short circuit??). Consequently as the other chargers -ve output was interlinked via the common -ve of the batteries (and as it was bring run off the same supply as the constellation) it would have found its output shorted to input too and it would have got upset at that.
A flying buddy managed to toast another charger by similarly accidently shorting the charge output to the supply input - so it looks probable that that is how it killed it.

My plan is to have a look at Bruce Abbots suggestion but i have been too tied up with work and other project recently to have a proper go at fixing it (any the delay in replying to the previous posts - sorry)

I might just have to treat myself to a new charger at the Woodvale show in a couple of weeks time if i dont get it fixed by then.

Anyway it looks like the thing to learn from this is if you have a multiple battery setup - charge them individually ar make sure they are fully isolaed from each other.

[PLMS]

Better late than never. I just repaired a friends Swallow charger that suffered a similar death. The charger smoked after being momentarily shorted to another chargers output terminals. Both smoked actually.
Bruce's tip was good (of course), the SO-8 output FET near the negative terminal was the blown part, and the ONLY blown part in this case.

The original FET is an F7413 N-channel 30V 13A 0.011ohm MOSFET. You can replace it with any similar spec N-ch FET. I just found a good one on a dead Hextronic 30A ESC and transfered it over. Keep the orientation the same.
The ESC has higher spec Vishay Si4362 FET's, so the charger has been brought back to life AND been 'hotted up' . :-)

Martin

[mts247]

Anyone know what this component is under the capacitor and silicone, its fried big time, also anyone know of a circuit diagram of the swallow.
look forward to your reply

[PLMS]

Anyone know what this component is under the capacitor and silicone, its fried big time, also anyone know of a circuit diagram of the swallow.
look forward to your reply

Not me, but is there enough of the letters on the component for at least a partial ID ?
Maybe get a close-up picture of it.

[mts247]

This pic is just copyied from above, the chip has popcorned, that is turned insidout :)
so i cant see the number, i am looking for a circuit diagram but iv had no luck

[mts247]

Update i just investegated the problem a little more, with i little scraping i found the chip has burnt the surounding 4 or 5 resistors, the chip "was" i think "8 legged" allthough there is no sign of the other 4 legs. i think its gone unless i can get i circuit diagram, also the chip burnt clean through the circuit board!

[PLMS]

That's not good. It's going to be a labour of love job now, or just buy a new one...

[bruce_c]

sorry i can't help either - I recently binned the remains of mine (couldn't source a suitable replacement fet - that and i'd bought another charger {or 2})

Didn't bin all of it though - kept the lcd screen/board - and it is now connected to the parallel port on my pc (real easy to do) and displays a load of useful stuff like RSS feeds thanks to a little program that runs in the background called LCD smartie

Kind of made up for having to bin the charger - was either that or i could have transplanted the backlit scrren into one of my other chatrgers that doesnt have a backlit screen

[castaway_bill]

I have one of those chargers, which I have in bits for another reason (it cuts out too early on NimH charge - a common problem I believe)

The component to which you refer is another MOSFET. It is a IRF7424 P channel , data sheet is http://www.irf.com/product-info/datasheets/data/irf7424.pdf

The 6 surface mount resistors are 180R 0805 package types, and there are two capacitors, in 1206 packages whose value I don't know without removing from the CCT and measuring.

This mosfet looks like it forms part of the switching regular circuit, operating on the input voltage side. Its worth trying, it won't be dear to replace.

Good luck

Rob

[ZS4LR]

It is a hex powermosfet no. IRF7413Z, it basicly is used as a 13 amp switch,the Swallow has 5 of them. I am in the process of obtaining one for a friend

[goneXC]

Re. your burnt out device: it's a FET F7413 as indicated above. There are 2 others on the circuit board. I managed to get one off another charger which although it had a different brand name to the Swallow uses the identical circuit board. It took a bit of doing as the heat had destroyed the very fine track that switches the FET (the gate) but I managed to solder in a very fine piece of copper wire instead. For a guideline on desoldering and soldering SMDs check out the info at http://www.infidigm.net/articles/solder/#floodandsuck - it's not as difficult as you might think. Strongly suggest you put an in-line fuse on the positive wire to the power source - it's much easier to do than fix the mess! Check out http://pdf1.alldatasheet.com/datasheet-pdf/view/68233/IRF/IRF7413A.html for the data sheet and note that when soldering the source pins (1-3) are common as are the drain pins (5-8). No. 1 pine is marked by a small recessed reference dot.