A Vintage Tamiya Mercedes CLK with old concept of electronics

[holyhope]

Hi to all!

I'm here to write for show you my last buy (ok, maybe it is not and affairs for you but for me it is enough for me). I suppose I'm in a correct section due the old age of my rc BUT I'm not sure if it very old as require this section and, in truth, I not know how it is old... I describe it and take photo, if it is too young for this section can you move another way? And I will be sorry for miss the correct section :-( Sorry...

So the RC it is Mercedes CLK DTM 2002 with the screw instead the bodypost and have a very old style circuit. Only rear traction, front wheel are only neutral. I have some problem (i buy only for collect without any racing purpose) and I need some info for know a piece of story like that.

I buy all togheder, remote, car, shell, servo, motor ecc... I suppose it is a complete kit sell as is by tamiya, 

I have (eheh many user maybe know my other RC and hate me!) a cc01 Pajero with Carson remote servo receiver and a 17.5T motor (and a new 27T motor with ESC of SkyRc that I'm not using), With this RC I have no problem for control that but with the Mercedes is impossible! Some time the car not reveive the command for go ahead or break (steering ALWAYS work fine) and it is impossible to set , by trim on remote, a correct "dead band" to leave car stop (if you move a bit this trim the car start to go ahead or backside...), Some time I kickdown the threolette on remote and car not response... I move steer keeping down throlette and start do go ... Boh! I not understand!

My first idea is to replace the ESC and motor with my 27T that is unused but when I open It I see a discrete circuite that I never see before!

Can sameone tell me how to solve the remote problem and if it is possible to change all elevtronic with a new one? (or maybe it is a very bad idea change internal vinitage circuite with a new one....)

thanks 

Massimiliano

[WillyChang]

Sounds like you've got the QuickDrive series https://www.rcjaz.com.au/tamiya-46021-110-quick-drive-clkdtm-2002-amgmercedes-p-6279.html

Did you remove anything off that brown circuitboard? Without knowing anything else... looks like the xtal is missing - 2-pin white socket.

Dont know much about these electronics but I'd assume it's just AM, very likely 27MHz so try a good 27band AM receiver xtal in that slot. 

These types of radiogear can be wornout or water damaged, causing erratic operation. Spareparts were never sold retail afaik.

They ran a 8xAA pack I think... like Tandy/JetHopper.

Its not impossible to rip out everything and replace with proper radio gear - ESC, RX & servo. That 5-wire servo in there only works with QuickDrive board. 

But more commonly ppl just take the shell and put it on a proper touring chassis. Could be less work, guarantees you a usable model. 

[holyhope]

willy, seriously, you're omniscent of the RC world! Exactly my model is that! maybe is not very old as I supposed!

Yes yes yes I tell you that the better thing is to keep all as it is and maybe in future buy a new chassis (maybe 4wd)

I try do disassembly the rear traction... the motor works fine because (i not desolder the wire) but I give it some voltage and it start running! So the problem is another way... I hope I not break anything putting directly voltage to the motor, without cutting wire... Now, after reassemble, the motor no work anymore... maybe I have damged the power output of the circuite board... ****!

But a strange thing occours: when I press throlette or the trim to throlette the steering move a bit... like receiver is missunderstanding info (or remote is sending wrong info...) it is very strange...

Your explanation it is very complete but it is hard to understand for me now and i'm in hurry.... this evening or tomorrow I will read with more attention and document on web... Sorry! wait some hours!

thanks Massimiliano 

[WillyChang]

I think it is possible that if you've put power to the motor without disconnecting from the control board, you may have reverse-biased the drive transistors & burnt them out  

same thing sometimes happens when small kids push RCs around on the floor (with vroom vroom noise), the moving motor can generate enough current to blow the ESC transistors. Or if you move a steering servo manually... it can blow it's control circuits and sometimes the receiver too.

 

[holyhope]

Oh ****! I supposed it will be protected from reverse current! If you put a car in down hill she generate current from motor, so it is logical that the engineers have protected the ESC... But I'm wrong.. If I was one of the developer i never permetted reverse current to burn it! So it is a very bad engineering ... This is my personal opinion.... 

thanks Massimiliano 

[holyhope]

Hi!

I made it! I repaired! The problem is on the resistor (or inductior maybe) between motor and negative pole that not work proprely... I bypass it and RC start to go very well! it is very slowly compared to my Pajero (with slow motor and LiPo 7.4v) but it works! I suppose the component I bypassed is a protection on breaking and maybe could damage in a long time the internal RC circuite but... I buy it only for use few time so I can  leave as is!

Only one info: I need to replace battery because it is the original NiMh 9.6v and it is very poor of power and I can use my rc only for less then 10 minute!!! When I recharge it (I use  iMax B6) its max charge was of only less then 400 mAh...  I want to replace with a LiPo 7.4 (2s) , in your opinion it is ok this battery for this old and entrlylevel circuite? LiPo 3s (11.1v) I nevet think on it but if LiPo 2s are optimal what you thing of LiFe 3s (are 9.9v).??? I play at softair game so I have many battery but I not want to damage my just repaired car!

thanks Massimiliano 

[WillyChang]

Are you sure it's NiMH not nicad?  afaik those JetHopper packs are just 8xAA cells... nicad cells back then were only ~500mAh when new anyway.

I would suggest keeping to 8xAAs... it's > 2s lipo anyway, if all 8 cells are alive. 

Going lipo will have low voltage cutoff headache.

You can make your own pack or I'd think they're still used by some RCs like Nikko or Tandy etc 

[holyhope]

Hi Willy

maybe you are right! Are NiCd, in true are 8x AA so it is better think that are NiCd and not NiMh.... 

I can buy (in true I already have) a LiFe battery 9.9V... can maybe use that? it is similar like power and it is very strong like discharge C! On my Pajero Tamiya I use LiPo 7.4

thanks 

Massimiliano

[WillyChang]

LiFe 9.9V = 3s afaik... so when it's fully charged it'll be 12.5-13V.

LiPO 2s 7.4V goes to 8.4V when fully charged.

Lithiums don't drop their voltage much when under load, the volts stay up there.

Healthy Nickel x8 9.6V would be max around 10-11V under load fully charged & falls away quite quickly.

There's probably enough tolerance in circuit design to survive 13V but do remember it's 15yo+ & the capacitors on the board have aged so they won't regulate as well, they were probably cheap ones too not very high quality to start with.

Your car! 

[holyhope]

Hi Willy!

I have performed a very little test! I attach a LiFe 9.9V fully charged (10.8V with my iMax B6) and compared to NiCd (Yes NiCd NOT NiMh.... I was wrong before...) fully charged to about 14v (With my iMax b6.... arrived to this voltage!!!) . I try to flip up and hear the sound of wheel with this two different battery... I can't do a test on road because LiFe battery is to high... is more short but it is too high ****! 

On my personal opnion the wheel are running faster with NiCd!!! Maybe is because fully charged it reash more voltage...

If I want to change motor for getting faster... what motor I must buy? a motor for Mini4WD is compatible? A softair motor could be compatibe (example: 

 )  ???

Or there is some cheap to buy? Solder and desolder is not a problem for me.

Maybe I can put a good battery and a new motor and improve durable (for hour plays without recharge battery) and speed... only if it is a cheap modify otherwise I preferre buy a very good and compatitive RC and keep that only for bodysheel and exposition eheh

thanks

Massimiiano

[WillyChang]

yeah keeping to 8xAAs would fit into original hole & solve problem of size/space 

mini4WD?  nah their motor is 130 size, much smaller 

no idea what's inside QuickDrive, here says its 380 https://tamiyabase.com/tamiya-models/46021-46021?position=52&total=981 I never got around to pulling them apart that far... only went as far as seeing their wheels aren't standard.

380 is size used by Grasshopper & some 1/16 cars

Tamiya TamTechGear uses 370 which is probably just a shorter version of 380

 

[holyhope]

Hi Willy

Ok thanks! Now I search something and I will think on it... maybe i will change maybe not... I need to know if there is a real big improve of performance...

Massimilkiano