WTF-Roadster 66

[Thunderdome]

well 2 months into use and I was happy as sh_t with it, then yesterday it goes into protection so being to close to miller time I decided to put it off till today so I ripped it out/apart this morning and then I found it but I,m not to sure what would have caused it all my outputs cracked and broken anyone have any ideas???

pics belowVVVV

[ttocs]

alot of heat really fast. Now what caused the heat, dunno? Any chance there could have been condensation built up on it somewhere?

[Eric D]

I don't want to jump to any conclusions here, not knowing all the details, but 95% of the time, abuse from working the amp too hard causes that.

On occasion the cause is a speaker which fails and takes the amp out with it, but this does not happen all that often.

On the positive side of things, that will probably be an easy fix. New transistors, new gate resistors and a bias adjustment is probably all it needs.

[Eric D]

Now that I look at the photo a bit more, it looks like that might be the power supply side. If it is the fix is even easier (no bias involved). I am not up to speed on the Rsd amps, so I don't know if that is the power supply side or not.

[kg1961]

fuck TIm Im so sorry about your luck and pg amp you might have to stick to orion..lol
Mike

[The Golden One]

that is pretty strange things like that didn't happen that much in the m ms or mps amps i guess the protection circuits where better in those amps. its like you could have a speaker wire stand touch the other or even a power wire strand touch and it would go into protection. it seems like the other amps are more sensitive to certain types of failure for example i have a zx450 that the outer case just touched the frame and it sparked and no more tunes. im not saying the other amps dont fail it just seems like they can have some crazy things happen and they still work.

[Thunderdome]

alot of heat really fast. Now what caused the heat, dunno? Any chance there could have been condensation built up on it somewhere?

never found any moisture thought it was pretty freaking cold that day and I was running it moderately but not anywhere near what it has run could the extreme cold -15 celsius and then a little workout on the way home have heated it enough? it was only about 60 percent volume when I was cruising so it wasn,t maxed out at all? fortunatly the safeties did kick in and shut it down before it was much worse, this happened pretty quick as well

[Thunderdome]

fuck TIm Im so sorry about your luck and pg amp you might have to stick to orion..lol
Mike

thanks, just have to re-capp my 100 and 200 and their going in

[Shinju]

If you want to part with that blown roadster cheap I might be interested.

[Thunderdome]

thanks but she,s part of my personal amps collection that I won,t part with anytime soon and should be relatively easy to fix once I track down some parts

: you are correct Eric it is the power supply side so should be good to go everything else seem ok so far so 8- Irfz44v and it should be good to go

also when I unbuttoned the heat sinks off the mosfets they all sprung up about 3/16 of an inch I wonder if this might have had something to do with the failure being under stress all the time?

[Eric D]

You need to at the very least measure all the gate resistors and make certain they are close to each other in value. If they are not, they should be replaced as well. If one of the resistors was damaged (which usually they are from the overload), the amp will do this exact same failure as soon as you power it on.

[Thunderdome]

You need to at the very least measure all the gate resistors and make certain they are close to each other in value. If they are not, they should be replaced as well. If one of the resistors was damaged (which usually they are from the overload), the amp will do this exact same failure as soon as you power it on.

thanks for info will add to list of things to do, anything else you would suggest? I found the fets at digikey they seem to have been replaced with the lead free ones now 1.87 each not to bad

[Eric D]

Take your time, and don't damage the board when you remove the old ones. The best thing to do is just clip all the leads at the base of the FET (the plastic part), and then using tweezers in one hand and the soldering iron in the other, remove them one at a time with as little heating of the board as you can. Clean up the holes with some solder wick, and you will be ready to install the new FETs. Also, be sure to bend the new FETs leads in the right spots so the clamps on them will apply pressure where it is supposed to be. If you install the FETs a bit too short or too long you may put pressure on them at an angle and they may fry under load.

[Thunderdome]

sounds good Eric, makes sense dealing with only 1 leg at a time, I,m still not sure if this amp didn,t have something funny going on allready , if you check out the fets in this close-up all I did was take the clamp bar off and they just popped up on there own a few popped up almost 3/16 when released its just that I allways fit mine to the sink before I solder to ensure as good of conductivity of heat as I can, I would never just push them down and hope they lay flat under screw pessure wish I would have looked more closely while taking the bars off

[Thunderdome]

fuck TIm Im so sorry about your luck and pg amp you might have to stick to orion..lol
Mike

Done

not PG but it has a really nice sound

[Eric D]

Having the FETs pop back up does not mean anything. Keep in mind these boards are populated with parts before being near a heatsink. Since they don't ever sit exactly the same in each heatsink having them be high or low is normal. The clamp bar will hold them down, and the small amount of tension is not a problem. Like you I also make sure they sit flat when I work on amps, but we have the luxury of working on the same board which is already mated to a heatsink.

[Thunderdome]

understood thanks

[Jacampb2]

I'm a little late to this party, and I didn't see this mentioned, but, the PS fet's don't typically just decide to explode for no reason. I have seen it happen on amps that had no other issues, but, my guess is the root cause in those cases has been current starvation-- someone running the amp far to hard with too small of a power/ground wire, or poor power and ground connections. I'm not saying that that is what you had happen to yours, but, there will be some reason. The number one cause I have seen is shorted output transistors that take out the PS, but there are dozens of other things that could cause the same damage.

Good Luck,
Jason

[The Golden One]

yea really man i would at the very least have the alternator tested before you drive that orion amp to hard because it could have a bad diode in it. a bad diode in an alternator can cause that same damage as what happened to your roadster or an amp that goes out like that can mess up the alternator and it will start dumping ac at high output.

[Thunderdome]

thanks for help guys I,ll definately check that stuff out

[marko]

agreed, the easy part is fixing the amp up and doing a nice job, but i'd be worried why it happened in the 1st place. would be very frustrating if it did the same again after a short period.

check the outputs with a multimeter too just to check one isn't shorted, this could give your PS a hard time..

Mark.

[Thunderdome]

noted thanks

[stipud]

I think this is the first RSD failure we've seen on the Phorum so far.

I wonder if the cracks had to do with them cycling temperature too fast? I've seen several speakers "blown" from the cold weather (torn surrounds, frozen VC gaps) but no amps yet.

[Thunderdome]

this is kinda what I had thought something like this coulda happened as I run 0 gauge front to back and have a 10 farad cap in line my lights never have dimmed at all with this amp even when I,m really giving it thats why I didn,t think it could have been the car but I am going to check everything over this week, even with my hcca 2100,s in the car it was good, thought they could make the lights pulse if I really cranked them up and no probs but things change sometimes

[Jacampb2]

I wonder if the cracks had to do with them cycling temperature too fast? I've seen several speakers "blown" from the cold weather (torn surrounds, frozen VC gaps) but no amps yet.

Nah, I've seen numerous Fets fail like that. It is because the solder inside the package boils rapidly from the intense heat. If it happens slowly, solder will force it's way out between the case and the tab and possibly the leads (though you'd never likely notice that), if it happens quickly, like above, the case fails catastrophically while the vaporized solder and semiconductor tries to find a place to vent.

From what I have seen, this happens when they are carrying a bunch of current, and something abruptly shorts.

Later,
Jason