victor 885 parts

[Cirrussport]

I know they arent used in first but does anyone have a victor 885 that they could pull a part number off for me if its possibly visible?
I need the part number for the fets used.(these are the parts under the fan)
Thanks so much

[Cirrussport]

http://www.chiefdelphi.com/forums/at...tid=4638&stc=1
I know this isnt a picture of the blown up parts. this picture only shows where I removed one Mosfet.
Im still having camera problems so this is a pic from a few weeks ago.
Sorry for the delay. Im workin on more pics

[Al Skierkiewicz]

Originally Posted by Cirrussport

http://www.chiefdelphi.com/forums/at...tid=4638&stc=1
I know this isnt a picture of the blown up parts. this picture only shows where I removed one Mosfet.
Im still having camera problems so this is a pic from a few weeks ago.
Sorry for the delay. Im workin on more pics

This is actually a good picture showing the debris carried in by the fan. I have often found metal grit on the board at this point when opening suspect controllers. Teams are shocked by the amount of stuff once I open one of their controllers.

[Richard Wallace]

Very good photo. I have suspected this condition on many occasions; as Al says it is very likely the leading cause of Victor failure.

The moral of this story is: don't make chips and metal dust around the electrical system. You may think you've cleaned it up afterwards, but that's actually somewhere between extremely difficult and totally impossible.

[Mark McLeod]

Victor 885's use International Rectifier IRF3703 FETs.

[Cirrussport]

awesome, thank you so much.
Do you know if they use the same Pic micro controller?
Ive tried to find the microcontroller with some success. Just trying to replace blown parts on one. The microcontroller isnt blown but i wouldnt mind getting a backup to copy the program too.(you never know what could happen)

[Mark McLeod]

I don't know which microprocessor is used in the Victors. I remember locating it on an 883 or 884, but I don't think I went so far as to figure out which model it was. The program is not in the microprocessor, but on a nearby firmware chip. If any of that blows you've got bigger problems than replacing the microprocessor.

[Al Skierkiewicz]

It seems that I remember reading a statement somewhere that the 885 is a different beast than the 884. Besides the fact that it uses the higher voltage FET.

[Cirrussport]

i didnt notice any firmware chip. The microprocessor has all the built in memory and space to store the program.I see a few voltage regulators, 12 mosfets. A Capacitor. A few small other chips(i dont have one on me right now but i didnt think i saw a firmware chip. Theres also a few little pieces like the frequency chip which i believe runs the mosfets. Altho there are tons of little resistors.

I just have like 6 victors sitting around that are blown and want to fix them. There mostly 883's but thought i may be able to replace the mosfets with higher voltage mosfets to stop them from igniting and burning out. I dont know how well it will work but i think its worth a try. Unless someone else has tried it

Thanks

Craig

[Mark McLeod]

Forget what I said about the firmware chip. I was thinking of another system and confused myself.

There is more to blowing up FETs than their individual ratings. Put too powerful a FET in as a replacement and the rest of the Victor won't be able to handle it.
I agree with Al's comment that the 885's are a different beast. They handle higher power because they are designed for it with features other than "bigger" FETs.

Usually, the FETs short when metal shavings or particles fall into them. Bigger FETs might just release more magic smoke.

[Richard Wallace]

Originally Posted by Mark McLeod

... There is more to blowing up FETs than their individual ratings. Put too powerful a FET in as a replacement and the rest of the Victor won't be able to handle it. ...

FET's that are rated for higher breakdown voltage and/or for lower on-state resistance will also have higher gate capacitance. A driver circuit that is correctly sized for a lower-rated FET may not provide sufficient gate current to fully saturate a larger FET within the same switching interval; this would result in higher switching losses, so the larger FET might actually run hotter, depending on the chopping frequency. As Mark says, you should not try to soup-up a Victor by simply changing out FETs -- you have to consider the whole circuit.

[edit]666 posts![/edit]

[Al Skierkiewicz]

Not to pile on here,
As Mark has pointed out, FET death is frequently metal shavings related but all too often, teams are running inefficient designs that have extreme current demands (i.e. constant or near constant stall on a Chalupa will draw 129 amps). It is these extreme currents that raise the internal temperature that explodes the case of the FET. (Note that the FETs are not mounted to heatsinks.) Going to a higher breakdown voltage FET will do nothing for that type of failure. In general, a single FET failure is shavings related and will usually be accompanied by smoke damage near the base of the FET. A failure of six at a time is temperature related and will usually result in damage to the circuit board.

[Joe Johnson]

Originally Posted by Al Skierkiewicz

Not to pile on here,
... ... A failure of six at a time is temperature related and will usually result in damage to the circuit board.

Many competing products to Victors protect themselves from thermal destruction by having the micro onboard the Electronic Speed Controller (ESC) monitor current and/or temp flowing through the ESC.

Back when I was a rabid robot warrior, I thought that I wanted every ounce of performance from the ESC. I reasoned that I would rather replace any dead ESC between matches than loose a pushing match because the ESC was protecting itself.

I have since moderated my views. If everyone has the same constraints, it doesn't really hurt the competition to have everyone with a little less current capability in the ESC -- it's just one more constraint everyone has to live with. The main result of an ESC that protects itself would really just be lower sales of ESCs because fewer die and teams don't have to buy replacement/extra ESCs.

Bottom line, I think it is a good idea for ESC's used in FIRST to have internal thermal protection.

Joe J.

[Cirrussport]

i fully agree with the thermal protection idea. i have so many dead victors sitting around just because of over current. I wouldve much rather had the victor limit the current or cut out because of heat then had to replace them. Thermal protection should definately be considered.

I like the overall victor design. but thermal protection would be great.
I know it wouldnt work in first competitions. but i think it would be nice to have a full 2 victor system with mixing capabilitys available for r/c equipment. I like the victors much more than the double esc mixing systems out there