Scorpion xl fault??

[leorcc]

I have a message here from Chris Baron. For some reason his application for the forum (and of Simon Windich) were never approved.

Any way: the message:

quote:

Hi All,

Im the owner of Robot Power, the maker of the Scorpion XL and the Sidewinder.

Let me see if I can shed some light on this problem. From the description of the problem it sounds like it might indeed be heat related. There are a couple of ways the heat can affect the operation of the unit.

1) is obviously to overheat the power chips on the bottom of the PCB.
This is easy to tell because they wont cut out until the inside reaches about 125C and the outside is about 100C. Believe me if you feel them when they are in that state you can tell! The latest version of the software does not require a power cycle to rest after a power chip overheat. So they if they overheat they should come back in a few seconds.

2) Less obvious is that the CPU chip operating frequency is effected by heat. The unit does not have a crystal oscillator and uses the internal CPU clock. We have seen a warmed up chip shift frequency enough for it to think the (valid) radio signal is out of range and thus go into safety shutdown. Some chips seem to shift frequency more than others.
It may be that a batch of the more shifty ones were sent over to you all.

3) is that the 5V voltage regulator may overheat and go wonky if the HV jumper is not clipped when operating above 18V. At 24V the regulator and the largish diode near it should be warm as they are dissipating all of the 24V to 5V drop as heat. This 5V regulator also cuts out well over 100C so it should be easy to figure out if that is the problem.
Using an external RX battery and clipping the BEC jumper will help reduce the load on the internal regulator but this should not be necessary in normal operation.

In this case it sounds like #2. The solution to this is to do some experimentation with the calibration of the unit. a) run a calibration cycle when the unit is at normal operating temp. b) be sure to pull the jumper while the unit is powered on (the procedure mentioned by one poster was incorrect) it has to be powered to store the settings into the EEPROM of the CPU when the jumper is pulled. c) you might try calibrating at 100%-110% ATV in the radio and then reducing that slightly for operation. This can give a little margin and allow some temp variation before the signal hits the illegal zone.

Finally all units should be checked for a recalled voltage regulator
(IC1 chip near the HV jumper). The recalled chip has the identification
3940M3 the replacement chip has L358 or something similar along with some other numbers. You may have to use a magnifier to see the faint lettering on the top of the regulator chip package. If you find you have one of the 3940 regulators you can ship it back to us for upgrade.
Well work with James Baker to get a supply of replacement chips to him for local upgrades.

Regards,

Chris Baron
Robot Power

[jamesb]

I have just checked my current stock of scorpion XL controllers.

All but one are of the newer, L538/L358 type, which is reassuring, but there is one of the older type....

This means there is a good chance the older types may have sold to some customers in the UK and Europe recently.

Please could all customers look at your scorpion XL controllers, directly below the HV jumper is a small chip with 3 legs on the side of the HV jumper. This is the chip in question. If it is of the older type, do not send it back yet. I will speak with Chris Baron about the best way to solve the issue. Please email me on James@xbotz.com, but copy to jamz_b@hotmail.com as my email provider is messing about again. If a simple recall is required, I will accept all the returns as Robot Powers European agent and make sure they are returned to you with the modifications. This may not be neccessary, I will confirm what you need to do shortly.

No older type scorpions will be shipped from this date to UK/Euro customers, so rest assured you can be positive this issue will not continue past today. I do have several of the newer type in stock if you are placing an order in the near future.

It is important you make me aware if your controller has this problem before taking further action, so I know how wide spread the issue is, and can discuss the best course of action with Robot Power. Please Email both addresses above as soon as possible to identify your scorpion type.

Many Thanks
James
Xbotz

Hi
Just finished my fan upgrade!..Everything works ok,cant test it properly until tomorrow its to late and to noisy to start running the bot.Twin fans,larg heat sink,seperate battery,and lots of holes for ventalation.Cant do any thing els,so im having a beer.
In answer to your question Leo,no you dont have to always re calibrate,but it does seem that by recalibrating you stand less of a chance of failure,as Chris Baron says it helps if you have a shifty chip so i would recomend re calibrating before you go in to the final on sunday!!
As long as the fan does its job and my robot works I dont mind the extra work,im glad I found out now and not on saturday,I would not be so happy then.
I hope all your scorpions are ok

My scorpion is of the L538/L358 type!

I dunno what scorpion type I have, I bought it from James Baker but I havent tested it yet. Ill wire it in at the space centre

[leorcc]

just my luck, one is OK, other one has the wrong chip.

The third one i still need to check.

[graeme]

The scorpion in LS2 has the new chip but it overheats with a heatsink on it. battery voltage is 28v(on the limit) so i am using a seperate 150ma reciever battery and it stays cool.
Will find out tomorrow how it holds up under full combat conditions.

I have 2 with the right chip, one with the old one.

[andrewmahoney]

Hi,just to let you know!.... Had a great time at the space centre,lost count of the number of battles we hadand the scorpion xl never let me down once...infact it worked perfectly...So if you have a shify chiplike me,dont wory..... Fit a fan!