Hello, I am totally new in this, but I am hoping someone here can give
me some tips.

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

All my electronic knowledge are only from my classes during college,
but I don't have any troubleshooting experience at all. The only test
tool I have is a multimeter, can only test resistance, diode, and AC/DC
voltage. So, I am hoping if anyone can tell me how I can go about to
find out what component has become culprit. And of course the next
question, would be where to buy replacement.

Many many many thanks!

wrote in message
ups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

Homer J Simpson wrote:
wrote in message
ups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

wrote in message
ups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

Homer J Simpson wrote:
wrote in message
ups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?

On 12/18/06 5:17 PM, in article
, "
wrote:


Homer J Simpson wrote:
wrote in message
ups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?




What type of receiver is it? Regen, single or dual conversion?

Don

wrote in message
ups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?

Without a service manual, I would need an oscilloscope with an RF probe for
starters.

Don Bowey wrote:
On 12/18/06 5:17 PM, in article
, "
wrote:


Homer J Simpson wrote:
wrote in message
ups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?




What type of receiver is it? Regen, single or dual conversion?

Don

Hi Don, I wish I can answer your question. All I know is this is a 27
Mhz AM receiver for R/C car. Do you think it will be too much for a
beginer to fix? I mean the circuit looks pretty simple, so I figured I
want to give it try.

On 12/18/06 6:44 PM, in article
, "
wrote:


Don Bowey wrote:
On 12/18/06 5:17 PM, in article
, "
wrote:


Homer J Simpson wrote:
wrote in message
ups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?




What type of receiver is it? Regen, single or dual conversion?

Don

Hi Don, I wish I can answer your question. All I know is this is a 27
Mhz AM receiver for R/C car. Do you think it will be too much for a
beginer to fix? I mean the circuit looks pretty simple, so I figured I
want to give it try.


If the receiver does NOT have a crystal, it is probably a regen receiver and
you might be able to retune it to the transmitter. If there is no crystal,
look over the receiver to see if it has small adjustable capacitors and/or
coils that have a slug inside that can be adjusted. You will need plastic
tools to make any adjustments. Let me know what you find.

If the receiver has a crystal, be sure it is seated in its holder.

If it is not a regen, then it needs tools such as a scope and signal
generator in the hands of someone who can trouble shoot without having a
schematic.

Post the name of the city where you live and maybe someone will volunteer to
help.

Don

Where are you located?

I repair radio systems for a large hobby shop in the MidWest, just north
of St. Louis, MO.

Have been doing R/C repairs since the 1960's

Will help if I can.

Make and model of car and radio?

Hugh




Don Bowey wrote:
On 12/18/06 6:44 PM, in article
, "
wrote:


Don Bowey wrote:

On 12/18/06 5:17 PM, in article
s.com, "
wrote:


Homer J Simpson wrote:

wrote in message
legroups.com...


What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?




What type of receiver is it? Regen, single or dual conversion?

Don

Hi Don, I wish I can answer your question. All I know is this is a 27
Mhz AM receiver for R/C car. Do you think it will be too much for a
beginer to fix? I mean the circuit looks pretty simple, so I figured I
want to give it try.



If the receiver does NOT have a crystal, it is probably a regen receiver and
you might be able to retune it to the transmitter. If there is no crystal,
look over the receiver to see if it has small adjustable capacitors and/or
coils that have a slug inside that can be adjusted. You will need plastic
tools to make any adjustments. Let me know what you find.

If the receiver has a crystal, be sure it is seated in its holder.

If it is not a regen, then it needs tools such as a scope and signal
generator in the hands of someone who can trouble shoot without having a
schematic.

Post the name of the city where you live and maybe someone will volunteer to
help.

Don

On 18 Dec 2006 14:32:50 -0800, put finger to
keyboard and composed:


Homer J Simpson wrote:
wrote in message
ups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

This makes no sense. AFAIK the transmitter should not transmit
anything until you move the joystick, otherwise its 9V (?) battery
would quickly go flat.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Franc Zabkar wrote:
On 18 Dec 2006 14:32:50 -0800, put finger to
keyboard and composed:


Homer J Simpson wrote:
wrote in message
ups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

This makes no sense. AFAIK the transmitter should not transmit
anything until you move the joystick, otherwise its 9V (?) battery
would quickly go flat.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Hugh, It is one of those ESC receiver combo for micro size R/C car.
May I ask you how much it would be to fix?

Franc, the transmitter for radio control car would start transmitting
immediately after you turned on, that's why it is a MUST for hobbist to
switch on transmitter before turning on the car.

On 19 Dec 2006 07:40:57 -0800, put finger to
keyboard and composed:


Franc Zabkar wrote:
On 18 Dec 2006 14:32:50 -0800, put finger to
keyboard and composed:


Homer J Simpson wrote:
wrote in message
ups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

This makes no sense. AFAIK the transmitter should not transmit
anything until you move the joystick, otherwise its 9V (?) battery
would quickly go flat.

- Franc Zabkar

Franc, the transmitter for radio control car would start transmitting
immediately after you turned on, that's why it is a MUST for hobbist to
switch on transmitter before turning on the car.

I've repaired quite a few toy R/C cars and don't recall ever
encountering one where the transmitter would transmit continuously
without user action. In fact some remotes had no on/off switch. Maybe
your hobbyist vehicles behave differently, but it still begs the
question, what is it that the transmitter is transmitting? I can
understand it signalling forward/reverse/left/right/turbo, but why
would it signal a "do nothing" command?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Franc Zabkar wrote:
On 19 Dec 2006 07:40:57 -0800, put finger to
keyboard and composed:


Franc Zabkar wrote:
On 18 Dec 2006 14:32:50 -0800, put finger to
keyboard and composed:


Homer J Simpson wrote:
wrote in message
ups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

This makes no sense. AFAIK the transmitter should not transmit
anything until you move the joystick, otherwise its 9V (?) battery
would quickly go flat.

- Franc Zabkar

Franc, the transmitter for radio control car would start transmitting
immediately after you turned on, that's why it is a MUST for hobbist to
switch on transmitter before turning on the car.

I've repaired quite a few toy R/C cars and don't recall ever
encountering one where the transmitter would transmit continuously
without user action. In fact some remotes had no on/off switch. Maybe
your hobbyist vehicles behave differently, but it still begs the
question, what is it that the transmitter is transmitting? I can
understand it signalling forward/reverse/left/right/turbo, but why
would it signal a "do nothing" command?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

I would think the hobby grade transmitter are quite different than the
toy grade RC. With the hobby grade transmitter, they are not only with
4 signal, but are propportional. So, there are steer trim and throttle
trim noob/button so that you adjust the car's alignment or throttle at
its neutral position. So, it is also dangerous for nitro or high power
electric car to switch on the power on the car first before the
transmitter is on. I don't exactly know how things work, but I think
the transmitter should be on to keep the car in neutral position before
applying throttle or steering.

But back to my very desperate question [I have no car to play for
almost two weeks now :-( ], I have heard from other hobbyists
mentioned when they have the powered on transmitter antenna
accidentally touch the antenna would fry the car's receiver; and I have
heard they fix the receiver by replace an inductor. I guess the
inductor on the circuit board usually begin with "L"? Do you think I
can check if the inductors are blown without investing with a probe or
occiloscope by using just a DMM?

On 12/20/06 5:55 PM, in article
, "
wrote:


Franc Zabkar wrote:
On 19 Dec 2006 07:40:57 -0800, put finger to
keyboard and composed:


Franc Zabkar wrote:
On 18 Dec 2006 14:32:50 -0800, put finger to
keyboard and composed:


Homer J Simpson wrote:
wrote in message
ups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

This makes no sense. AFAIK the transmitter should not transmit
anything until you move the joystick, otherwise its 9V (?) battery
would quickly go flat.

- Franc Zabkar

Franc, the transmitter for radio control car would start transmitting
immediately after you turned on, that's why it is a MUST for hobbist to
switch on transmitter before turning on the car.

I've repaired quite a few toy R/C cars and don't recall ever
encountering one where the transmitter would transmit continuously
without user action. In fact some remotes had no on/off switch. Maybe
your hobbyist vehicles behave differently, but it still begs the
question, what is it that the transmitter is transmitting? I can
understand it signalling forward/reverse/left/right/turbo, but why
would it signal a "do nothing" command?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

I would think the hobby grade transmitter are quite different than the
toy grade RC. With the hobby grade transmitter, they are not only with
4 signal, but are propportional. So, there are steer trim and throttle
trim noob/button so that you adjust the car's alignment or throttle at
its neutral position. So, it is also dangerous for nitro or high power
electric car to switch on the power on the car first before the
transmitter is on. I don't exactly know how things work, but I think
the transmitter should be on to keep the car in neutral position before
applying throttle or steering.

But back to my very desperate question [I have no car to play for
almost two weeks now :-( ], I have heard from other hobbyists
mentioned when they have the powered on transmitter antenna
accidentally touch the antenna would fry the car's receiver; and I have
heard they fix the receiver by replace an inductor. I guess the
inductor on the circuit board usually begin with "L"? Do you think I
can check if the inductors are blown without investing with a probe or
occiloscope by using just a DMM?



Are you certain the transmitter and receiver are on the same frequency?

On 20 Dec 2006 17:55:30 -0800 wrote in Message id:
.com:

So, it is also dangerous for nitro or high power
electric car to switch on the power on the car first before the
transmitter is on.

From what I remember when I was a boy flying R/C planes (back in the late
70's), switching on the transmitter first keeps the servos from getting
"jammed" at the far end of their travel, possibly damaging the gears.
Whether this was a myth or not, or whether the current crop of RC stuff is
subject to this...?

FWIW, I have seen them lurch suddenly in one direction when turning on the
transmitter after the receiver. (I just HAD to try it

On 20 Dec 2006 17:55:30 -0800, put finger to
keyboard and composed:

I have heard from other hobbyists
mentioned when they have the powered on transmitter antenna
accidentally touch the antenna would fry the car's receiver; and I have
heard they fix the receiver by replace an inductor. I guess the
inductor on the circuit board usually begin with "L"? Do you think I
can check if the inductors are blown without investing with a probe or
occiloscope by using just a DMM?

A simple DMM will only tell you if the inductor is open circuit. It
cannot distinguish between a good inductor and one with shorted turns.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.