caiman

My Feedback: (1)

I have a Futaba 8UAPS that broke after connecting it with another transmitter using the training cord (due to the other radio having a problem I guess). It doesn´t work if I turn it on by itself (display dead) but it works ok if powered by another transmitter using the training cord.

It seems to me that the problem should be in the voltage regulator circuitry or maybe on a damage diode or fuse resistor. I am an electronics and communications engineer and I think I could easily repair it if I had an schematic.

Any one has an schematic for this radio or knows anything about its power supply circuit and parts placement on the PCB?

Please reply directly to my email: [email protected]

Note: I would preffer not to send it for repair, but do it by myself instead.

Thanks,

Alberto J. Elizondo.

Ladyflyer

My Feedback: (2)

Would you like to compare to a 6XA ? That is the last schematic we were able to obtain before Big Brother at the Huge Hobby Cartel took over the US rights and slammed the door shut on people who service their own. I can scan it and e mail. I can send the power suply circuit if you prefer a smaller file.

caiman

My Feedback: (1)

I would appreciate it very much if you could email me the complete schematic of the 6XA that you have, I think the power supply section should be similar to the 8UAPS.

Please email it to:
[email protected]

Thank you very much.

petros047

Please can you email the schematic of 6xa transmiter to me because I have one 6xa and the problem is that didnt transmit the signal to antenna.I test with osciloscope the signal and nothing no signal no power the rf unit is dead but the power supply is ok ( 12v line ) for this reason I need your schematic so I can fix it.
Anynone who knows what componet have problem please replay.


sorry for bad english
Please email it to me
My adress [email protected]

flatfour

My Feedback: (8)

The Edberg book suggests checking for an open coil L210 on the same board that has the pins that connect to the RF module.

petros047

Because I am electronic enginearing you can help me very much giving me electronic schematics or service manual thank you very much for your information about coil but do you know what mh is it?
Please note that all other fuctions of my transmiter work perfect (lcd buttons pc emulator etc)The only problem is that didnt transmit the signal no rf power.
If anyone have any idea to solve this problem replay


My email is [email protected]

Thank you flatfour

flatfour

My Feedback: (8)

My suggestion was for the 8U. The 6XA is comlpletely different.

caiman

My Feedback: (1)

Petros,

If you are talking about a coil (inductor), "mh" should stand for milli-Henry (the inductance of the coil.

I am also an electronics and communications engineer, however unfortunately I don´t have any schematics for these transmitters, if I can be of any help please let me know. Did you check the final RF power amp to see if it´s damaged?

petros047

I have check all transistors ,coil,and I have replace the amp 358 and multiplexer cd 4051 but nothing I am going crazy with this transmiter also I conect the oscilloscope to crystal legs and the crystal didnt have high frequency so I thing that the problem is that the crystal didnt oscillation for this reason I check twice the transistor near the crystal and the resistor and is ok but I canot check capacitors because I have no schematics so I dont know the value.Also the crystals work with other transmiter and the transmiter work fine with pc emulator and have all fuctions that means that cpu is ok.

Thanks all of you for helping me to solve my problem

sorry for bad english

Lynx

If it will not power up with batteries, but will with the training cord attached. First off, are the batteries good? If so a simple visual inspection tracing with the case off from the battery connectors will show you where the problem is. The diode is probably first on the chain, check to see if that's still alive. Use a 5 volt source and and LED if you need to to check for conductivity with a potential. All the parts for the voltage controller should be either component or surface mount and easily spotted. You may be used to schematics but if you can't spot the real thing by tracing the wires and PCB traces the schematics won't help. simple tracing from the battery up will eventually find the problem, even if it is on the RF side. Check for shorts, black marks etc.. etc.. Just avoid any IC's you run across if you don't know what they are, can fry some CMOS stuff pretty easy.

LesUyeda

Caiman:

If you take your radio appart to repair, cut the buddy cord pins where they extend beyond the circuit board. They are way too close to the antenna, and have a habit of shorting out. Just what happened to you.

Les

petros047

For one more time I check for short circuit on board and the parts and look fine.I am ready now to throw it to rubish.One more information I need if anyone knows the Ic with 8 legs is lm358? and the big one ic is cd45001?Finaly the crystal takes triger from futaba cpu (the ic down from lcd) because I found a pulse that going to transimitter board from cpu.
If I have free time I design by myself the pcb layout and give it free to internet and first of all to you in the forum Thanks again for helping me.

delvan

Dear Ladyflyer,

I have a 6XA transmitter with problem, i need the schematic diagram,

A.T.

Never use a Futaba Trainer Cord with Hitec TX, whilst it may work in some instances, there are many combinations which will let the magic smoke out of one or the other TX and also does not stop RF emitting from a Hitec TX when used as a Buddy box if the crystal or module not removed. Some of the very early Futaba 8UAP would let the smoke out of their trainer board when connected to Hitec. The Futaba 10µH coil next to the socket would burn out. The Futaba Buddy socket ceases to operate but no other damage is done to that 8UAP, all remaining functions usuallyoperating normally. A simple DIY fix with no more problems, refer .jpg attached.
Note from Hitec :Important Information Regarding Trainer cord compatibility
"To our valued customers,
While Hitec radios are known to be trainer compatible with other Hitec and Futaba systems, Hitec has determined that the two-way Futaba cord is not 100% compatible with our systems and strongly suggests it not be used at any time. Our tests show that when the Futaba trainer cord is used with a Hitec radio the slave transmitter will emit an RF signal, thus creating a potentially dangerous interference situation, and in some cases will burn up components in the slave and or master radio. Hitec suggests that only the one-way Hitec trainer cord (#58310) be used with Hitec radio systems for training. Failing to do so will void the customers warranty and could create a potentially dangerous situation. Hitec apologizes for any inconvenience this may cause, but the safety of our customers is our utmost concern."
NB:
Problems can also arise when 2 Hitec transmitters are connected with a Futaba buddy cord, where smoke comes out of one of the radios. This happens with some more recent Hitec radios, but not any problem exists when using a Hitec trainer cord.
Here the problem cases when a Futaba trainer cord is used :
Eclipse<>Prism, Eclipse<>Flash, Eclipse<>Focus, Laser<>Prism, Laser<>Flash, Laser<>Focus

See also sub Section "Trainer (Buddy box) cables - DIY " under
"Buddy Boxes. Servo Leads. Flight Simulator & Interface." at:
Alan's Hobby, Model & RC FAQ Web Links

Regards
Alan T.