Quark regenesis!
 

Hey guys.

Now I know lot's of you won't care, or some of you don't even know what a Quark is, or just forgot... but I thought I would post this anyways.

My Quark has been pretty good up until now, started glitching and cogging, and shutting down with my new 35C lipos when on the brakes for the first 5 minutes of running. I have a race weekend this weekend, so I thought I would do an overhaul of the Revo to make it 'race ready'. Opened up the Quark, and damn, the two caps inside the thing, the leads were simply melted off, so they were useless... only the outer two caps soldered to the batt leads were still good. Not good. Anyways, I thought I would do a few other things to make it race worthy. Enjoy. :yes:

some more pics

and an arse end pic

Wires are all 10awg... kinda ran into trouble with the input leads as it was pushing against the case, so I had to grind away a section so it would sit properly. Cap bank is made up of 6 35v/330uF low esr caps, the same cap bank from the "FrankenQuark". I also used thermal adhesive on the heat spreader as you can see.

lol, some of us "old timers" love our Quarks! :P

Yup, I like the Quark... I will buy a MMM when it dies, although it may never die now. :whistle:

Also Brian, I meant to put this in 'Brushless' board, you can move it if you want, no big deal though.

Do you just plug the battery in then unplug it and go race?

haha, not quite, I only get 2 minutes of runtime off the cap bank, so not enough to finish a race... :lol:

Thats sweet. It really gets 2 min of runtime from the caps?

If those caps don't do the trick, then sadly nothing will :rules:

hehe, well let's hope, I don't want to be racing the nitro guys (and they are all nitro heads) and have the Quark do it's stupid shutdown thing... :whip:

It happens for the first 5 minutes of the pack roughly... when going at a decent speed, use even a bit of brakes, teh Quark just shuts down control, no brakes, no throttle, no nothing, at least for about 10 seconds of fiddling with the throttle/brakes trigger. I'll have to test it out, if it still does it, I will have to use partially charged packs, 4.0v/cell charge?

I am currently running around finding parts like angle the make a mounting bracket for the RC-monster heatsink it will be thermal adhesived to (is that a word?) I'll have more pics in a bit.

cheers

What you describe sounds EXACTLY like what was happening to me with my Quark for a little while. Turned out the UBEC I was using (a cheapie $5 Chinese one) was the culprit; it was cutting out causing the ESC to "reboot" because of receiver signal loss. Replaced with a DimensionEngineering BEC and has been fine ever since. And this was all with 4s lipo.

I'm using a PRO-BEC that S&T sent me the last time they replaced my Quark. Has worked perfect for 2 years now... I'll see what happens, I have an unknown BEC, and a Ultimate BEC I could try as well.

Okay, as I was typing this, I checked the BEC, one of the wires is brocken off... but it's the orange lead, which is not a power lead, and doesn't matter does it Brian?

No, the orange lead won't matter as it is the signal wire, which is not used.

hi,

good idea to add some more caps than usual. I have modded some chinese-plane-esc which I have used for my buggy conversion (the last two died because of water, but performed well...). I have at least doubled the capacaty of the caps, I changed the original ones by more and bigger caps. Size DOES matter :yes:

I just can say that the throttle is very smooth, and the esc doesn't get hot. Not even once it cogged. sure, brake's crap.

I have read a couple of times that more caps can help to keep the esc cool and prevent cogging; Schulze recommend for their esc to add caps in some cases.

Do you feel a difference now?

florian

Florianz, yes, caps make a difference, but it's not the size that counts, it's the low esr (equivalent series resistance) values that help the esc. That's why I have the cap bank right inside the case, soldered directly onto the board with a heavy buss bar. I would love to have some solid polymer caps to use on it, very low esr and small, and very durable.

My last Quark I modified, HERE, worked wonderfully, rarely cogged even geared to the moon, and ran super cold (most likely due to the heatsink it sat on, which actually increased to value of copper world wide when I put it in there, lol). It was too heavy, and was eventually killed because of physical damage from a hard crash.

Here is the Quark mounted... now I am trying to organize everything neatly and so nothing will get cought, or thrashed around. It's getting there.

very cool! THAT'S what I call a a modded esc.

i got some low esr caps, at least the best I could get here. here's a pic of the actual one:
http://s11.directupload.net/images/0...p/b7qyjgwr.jpg

it's a 125a esc, where you see the power cables there are the bigger caps. like that after hard bashing the temperatures are around 30-40 deg. c.

The funny point is: the two other (burned/shorted) esc and this one are super reliable, great throttle response. when I read about all the probs with MMM etc, I don't understand how these cheap esc's are so reliable and rugged. except the bl..dy breaks. I don't have mechanical breaks, but you get used to it...

florian

I've added a couple caps to my Quark. Just enough to make a difference, but not enough to be cumbersome:

http://scriptasylum.com/forumpics/quark_cap_5.jpg

looks good. but be careful that that the caps don't get "hurt". I had that a couple of times that - due to a crash - the caps cracked. suddenly the esc lost power after some minutes. later I found out that the reason were the caps.

I don't get it? What are the advantages of those Capacitors?

Caps help to shore up the battery for the high current draws during the PWM pulses.

The dreaded ripple....

But sadly even artur couldn't save my quark :`(

they help the esc to handle the peaks in current

Yes, it helps the 'micro peaks' in current, the esc needs very low resistance to operate properly, batteries are no match for low esr caps.

And GOOD NEWS, I just went out for a test run, and Viola! It works wonderfully now! Brakes don't cut out anymore when batts are fresh, and the brakes feel different now too, call me crazy, but they do. The motor sounds different too, especially when braking (that digital buzz noise). Only cogged once too, usually cogs quite a bit on fresh charge.

Now I just need to get this motor checked out, it's getting too warm too fast.

Yikes, is that a green eggs and ham sandwich?

yep, I like a little snack when I am bashing! :rofl:

I'm telling you guys, the truck is running different now with the modded Quark... I forgot how smooth it was before I killed my last one. I can't really explain it, but I am loving it... I think it's more proportional as well.

I was out earlier and had the eagletree plugged in, I had the thermal probe mounted inside the 1512 Neu for temps, and after 10 minutes running in 15C (60F), the motor was at 130F (using live mode in eagletree software.) So I guess it's not that hot, but it was cool out, so when running at the track, it might be 30C(86F) this weekend, so you can add 25*F to that. That's ~155F, now I remember when I had my IR temp gun, that after a full run on 7s2p, the motor was usually between 155F and 165F on a hot day.

I think I should be fine then for this weekend races. :smile:

Okay, about the LVC in the Quark, I have never acutally used it as I have been using A123's up until now. What does the Quark do when the packs hit LVC?

Does it just shutdown for a second? Reboot?

thanks

Hey zeropointbug... I'm having some issues with my quark... On start up it cogs a lot and after a 2-5 min run on full throttle it 'shots down' (currently running 5s)...
When it does this I can hear/see it applying the break... it sits for a few seconds before i can get any throttle responds again... Then it runs for a little on 1/3 throttle,
but when I squeeze harder it cuts again. I am not sure if the BEC has anything to do with it because I still have steering when it stops... Is this a thermal case or is it something
else entirely? I'll be doing a heatsink and cap mod soon to see if will help with the problem.

Alien

Not a bec issue as such, though running an external one always helps with older style escs. Sounds alot more like thermalling- the heat spreaders & thermal tape tend to let go after a while, then there FETs have no way of transfering their heat to the case which is also the heatsink. Cogging sounds more like either a gearing issue (too high maybe?), or just the software perhaps- not sure if its possible to update it without sending it back to Quark.. good luck that one... :/

I thought the bec was only good for up to 4s then you needed an external one above that voltage. Which might be causing the esc to thermal more often. I wouldn't say it is the only reason it's thermalling, just it's not helping.

Neil... I opened the esc today and found that the thermal tape was not sticking to the casing the way it should, 1/3 of the pad is covered with dirt, leading me to believe the FETs were overheating quite a bit... I am hoping this is the worst case... I am also thinking cogging is attributed to gearing... Mike shipped the new pinions for me this week, so I hope when I get everything back together the smaller pinions will help to reduce cogging... Is there an easy and safe way to remove the heat spreader from the FETs... and if it's really stock on there... should I bother to remove it?


Hey Pinkpanda... I'm actually using an external BEC... I clipped the red wire on the receiver lead to disable the internal BEC.

A few pics (I hope it's ok to post photos here):


http://lh5.ggpht.com/_4vPm5E8J5HA/Sv...0/DSC_0003.JPG




http://lh4.ggpht.com/_4vPm5E8J5HA/Sv...0/DSC_0004.JPG

Yep, that thermal tape is not the best stuff. It's kinda too bad that this ESC almost requires the internal mod, but once done, it works well even long-term. I still have two 125's that are fully operational as of today.

Panda: All the Quark xxB line ESCs use a linear BEC. And like all linear BECs, should be disabled in lieu of an external one on anything above 2s lipo or 7-8 cells NiMH.

Hmmm... Not the best design in the world I guess... should I remove the upper board to get to the other spreader? I notice they're some pins connecting the upper and lower boards... Or is it not that simple? It feels real uncomfortable trying to remove the lower spreader, it's really on there.

In all the mods I've done, I leave the middle one alone. It tends to stay put since it's not used to hold the ESC in place. The lower spreader can be tricky to remove. I usually heat the spreader a bit to make the thermal pad adhesive a little more pliable. Even then you have to be careful not to damage one of the FETs.

Cool BrianG... I'll see how it goes when I get some more time to work on it.

Ok... I got the slab off with ease after applying a some heat from a heat gun last night... I'll cut the new slab tomorrow and get some thermal grease for the reassemble.

If it comes off that easily with just a little heat, no wonder the pad doesn't hold during use since those FETs can get pretty hot. Don't know if you've seen this, but the pic below shows the proper dimensions for the new spreader plate when not using the thick thermal pads:

http://scriptasylum.com/forumpics/quark_mod.gif

Yep... It was quite disturbing to see how easy it it came off when I used the heat gun... I saw your diagram before when I started researching on this mod... nice illustration. I have a small sheet of 3/16 aluminum
(not much thicker than 1/8) That I think will work just fine after some light sanding and polishing. I am not sure if we have the popular 'ARCTIC ALUMINA' in the island... so I will have to settle with the generic brands.

Just be aware that you have to use thermal epoxy, not regular thermal compound. It has to hold the guts to the case.