scotty4Him

a few years ago I bought a toygrade jeep rubicon by a compony called sector 7 from radioshack, it went relativly fast but it wasnt fast enough so I hooked up an 18v battery and a 12v motor... didnt work so well I blew all for heat sinks and a few other things so I got fed up and locked it away, recently I got the idea to try and fix it up I repaired the heatsinks and soldered everything back up I cant remeber why but i also took the remote apart, I put it back together as well, but no matter what I do it wont work the reciever chips arent the originals but I dont think that matters, if anyone knows whats im doing wrong or if the curcuit bord is shot let me know, all help isapreciated


this is the underside of circuit boardon the RC itself

kaiser01

i can tell by the pics of the backsides of the boards that it's fried. done, kaput...unless you are a slodering genius. meaning that you can solder circut boards under a magnafier.

i can see where solder has melted and now contacts other contact points. not to mention you probably have some fried micro chips and capacitors.

if you like the body try to fit it on a better rc.

scotty4Him

on the backside of the board on the rc I sprayed this water repelent spray which might be wha makes it look fried, but I used my multimeter and theres power going throughout the whole board same with the remote, im not that great at soldering on the circuit board so that why there spots the are a melted brown colour but the contacts are solered to the copper conections on the bottem of the board, and none of the connections on the bottem are touching

im stumped as to why it wont work but like you said it probably just fried

dust75

hi scott

i also think its fried
couldnt you just rip out all the old workings
and add a esc and a servo and rciever then that way
you could hook up the old motor or a faster one
just a thought

scotty4Him

if it was fried (which it probably is, I blew all four heat sinks at one time!) how would tell? it looks fine just by looking at it but I cant tell

ElectricGuy007

I think he did cook that board. looks like the solder melted and went into the other components.

scotty4Him

I can assure you the solder didnt melt into other components each component is seperate I just melted the board a bit while soldering

t9dragon

My Feedback: (11)

I will just say this maybe it is time to just by a newer RC and throw that one in the garbage.... Just a thought...

scotty4Him

I have an ax10 with $450 worth of upgrades I just want to see if I can make this one work again

sloppyG

oh yeah, well I've got an ax10 with $500 worth of upgrades, beat that!

scotty4Him

wait till I get a 55t motor and a novak rooster

t9dragon

My Feedback: (11)

LMAO................... I have 2 SCX10 loaded and a AX10 Warthog the chassis alone was $200..

scotty4Him

nice, all ive got is an ax10

ElectricGuy007

LOL

scotty4Him

ok were getting a little off topic here,

sloppyG

wait, you're telling me all these people and nobody can look at fuzzy pictures of a ckt board and tell what's wrong with it....

jeez, the local knowledge is really failing here today!

BigTb17

Are you saying the resistor you installed in place of the melted component is getting hot? Do you know what the component was? Was it a resistor before, and if so, do you know what the resistance value was? Without knowing for sure your replacement resistor is just a guess and may be doing more harm than good.

Those "heatsinks" you blew are likely the main power transistors for the speed control aspect of that board. They are screwed onto the heatsinks to dissapate heat during normal use. If you melted the connections off the bottom of the board under all four, you very likely cooked the transistors too. What voltage was the car originally supposed to run on?

Unfortunately it isn't likely to be worth trying to fix that board. You would probably have to start testing individual circuits and components to figure out what exactly isn't working properly.

scotty4Him

yes the resistor i replaced is getting warm , the componant was sort of like a cross between a fuse a resistor the value wasnt very high as the moment I pluged the battery in the fuse thing glowed bright orange as it melted, the heatsinks conections didnt melt on the board they all just cracked so I replaced them, the car is supposed to run on a 7.2 stick pack im using the same one it came with, but its also suposed to have a 9v wired in there as well I remeber before that without the 9v the car wouldnt work so I wired the 9v back in, I took my multimeter and test the continuity and the multimeter says there continuity everywhere throughout the whole board, theres no sign of overheating anywhere on the board so I dont know what could be wrong with it

ElectricGuy007

So let me get this straight, you replaced some components that were fried or shot
or whatever with another spare one you had. You powered it on and it still didnt work,
are you sure the part you replaced was the same kind of component you replaced it with?
Im sorry I dont usually mess with toy grade RC's so this is something new to me as well.
Those circuit boards are a pain to mess with.[&o]

scotty4Him

the only component that wasnt the same as the original was the wierd fuse resistor thing becuase I dont have another one so I dont know what could be the problem

sloppyG

you put 18v through a toy grade RC,

there's a lot more than a single problem in that ckt board...........

scotty4Him

lol I know but I think i fixed all the things that might be a problem all the resistors look fine no visual problems it simply refuses to work, i wonder if its the reciever chips

sloppyG

why not replace the reciever chips then and see if that fixes it, I'd start by replacing every component on that board

scotty4Him

the reason the original chips arent in there is I cant find them anywhere, I found one but have know Idea where the othere one went but I have an idea of where it could be

SyCo_VeNoM

my god this post hurt to read as an electric engineer [:@]

1st off you cannot and I mean CANNOT blow a heatsink. You fried the mosfets/rectifiers/transistors hooked up to the heatsinks.
Grabbing random parts that look similar will NOT work honestly you have a better chance of winning the lottery a few hundred times in a row, and becoming a multi-billionaire than it working right by just randomly replacing things with other parts that look similar.

That resistor looking thing could be an inductor, or a diode your pic is too bad to tell, and even if it was better it looks charred so it still would probably be impossible.

Honestly without a schematic of that board it is toast, even with a schematic finding the chips, and parts you fried would be a incredibly hard task seeing alot of those parts are not sold to the public(or if they are they are ludicrously expensive). I've blown parts out and even a partial number is not good enough you need the whole IC number to proceed with repairs. Hell just for reference to how monumental of a task this would be I got a Texas Instruments 7400 series chip reference book that is over 1200 pages with only the specs, and pinouts of that series of chips that they made(yes one series out of hundreds)

If you REALLY want the thing to move again you got 2 options. One is find a broken toy grade RC, and cram its guts into it. The other is buy a cheap hobby grade radio, a cheap brushed ESC, and figure out how to mount a servo in it for steering.