JR XP7202 Rf Vcc shorted. Please help!

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JR XP7202 Rf Vcc shorted. Please help!

Postby gyroguru » Sun Jun 27, 2010 4:55 pm

I was installing a new DIY 2.4Ghz module in my JR XP7202 when I accidently shorted the Vcc (pin 1) to Ground (pin 3) on the connector CN9. Now the Vcc reads only 0.872 volts. The radio seems to still work fine as long as I use other source for Vcc to power the DIY 2.4Ghz module.

From what I can tell, the pin 1 on CN9 is connected to pin 3 on CN7. On this trace, there is a resistor R46, but there is no value listed and I don’t see this resistor on the board.

Is Vcc the battery voltage ?

I would appreciate any help fixing pin 1 on CN9. I have attached pics of the schematic.

XP7202c.png (128.59 KiB) Viewed 957 times
XP7202b.png (47.42 KiB) Viewed 957 times
XP7202.png (43.04 KiB) Viewed 957 times
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Re: JR XP7202 Rf Vcc shorted. Please help!

Postby RCModelReviews » Sun Jun 27, 2010 11:03 pm

Transistor Q5 will almost certainly be blown.

It looks like a conventional PNP transistor in the schematic but the only references I've been able to find for a type A1204 suggest it's a hall-effect switch (which it clearly isn't).

If you can't find a replacement (or can't be bothered replacing it) just connect the +ve line from your DIY module to pin 3 of CN7 and you'll effectively be bypassing it altogether.
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