JR MAX-44 radio repair help needed - RC Groups
Thread Tools
Aug 14, 2010, 07:49 AM
Martin - AKA mr.sneezy
PLMS's Avatar
Question

JR MAX-44 radio repair help needed


I have a JR MAX-44 transmitter that I'm repairing for a fellow club member.
He unfortunately reverse powered the TX when fitting up a brand new battery pack.

Two components have popped, IC2 & D2. I could guess that IC is a regulator, and guess again it's a 5V regulator (but there is a small but real chance it's lower than that). However, I'd rather not guess if somebody has the right information at hand.
So if somebody has or knows where I could find a MAX-44 schematic, or if they can measure the voltage on pin1 of IC2 on their own MAX-44 radio for me it would be a great help to us. Pin3 has 12V and pin2 is Ground.
See the images if you know about this radio (please, no wild guesses, I can do that myself).
Thanks all.
Martin
Sign up now
to remove ads between posts
Aug 14, 2010, 12:35 PM
Registered User
It is a 78L05F 5V reg, D2 is a 1SS352 diode.
Aug 14, 2010, 09:19 PM
Martin - AKA mr.sneezy
PLMS's Avatar
Quote:
Originally Posted by mac_man
It is a 78L05F 5V reg, D2 is a 1SS352 diode.
Thanks mac_man, just the concise info I need. Off to warm up the soldering station....
Many thanks,
Martin
Apr 29, 2011, 01:43 AM
Registered User
Quote:
Originally Posted by PLMS
Thanks mac_man, just the concise info I need. Off to warm up the soldering station....
Many thanks,
Martin
Were you able to repair your radio?

I have about the same issue with a XF421EX. I haven't used the radio for about 8 years and I've just fired it back up recently whenever I turned the radio on everything on the LCD was active. I took it apart and noticed that IC2 and D1 are blown. The IC is split in half and has the same markings (AE with a 041 in the circle).
Apr 29, 2011, 05:13 AM
Martin - AKA mr.sneezy
PLMS's Avatar
Quote:
Originally Posted by whatelse_is_new
Were you able to repair your radio?
No, I replaced the parts and tested it. No response from the radio. I think the MCU was destroyed by the reversal and excess current. The radio is scrapped now.

If you know how to do it, it would still be worth spending a few minutes fitting up a TO92 size 5V regulator and see if yours fairs better...

These radios are still useful when fitted up with a 2.4Ghz hack module like the one FrSky makes. I've done a few of them now.

Martin
Apr 29, 2011, 09:21 PM
Registered User
I just ordered the 5V regulator and a diode as well as a 3 volt battery today from mouser.com. We'll see if it fixes the problem.
May 01, 2011, 06:53 PM
Registered User
PLMS, you should have PM'd me... chances are the CPU needed a hard reset by shorting out the reset pins on the pcb. Or I could have given you further test data as another transistor in the supply chain may have blown.
May 02, 2011, 04:56 AM
Martin - AKA mr.sneezy
PLMS's Avatar
Quote:
Originally Posted by theaton56
PLMS, you should have PM'd me... chances are the CPU needed a hard reset by shorting out the reset pins on the pcb. Or I could have given you further test data as another transistor in the supply chain may have blown.
I can still get it back from the club member who owns it and do that, but I did check that 5V was on the MCU power pins, and looked for MCU clock with my scope. It had the 5V, but no clock or other digital activity.
Given that info do you think it's worth trying further ?
Martin
Aug 01, 2015, 03:10 AM
Registered User
I did a Max 7 conversion from 40 Mhz to 2.4GHz using a Flysky Rf board. https://www.rcgroups.com/forums/show...postcount=5279
Works well and Rx's are cheap.


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Help! JR max 66 Help needed Desert flier Radios 0 Aug 14, 2006 05:32 AM
JR radio, opinion and guidance greatly needed, please help...look @ me, im begging kryptoniteRxn Micro Helis 12 Oct 03, 2005 01:34 PM
Help needed with JR radio DrBill Radios 0 May 05, 2005 03:13 PM
JR Radio Setup (help needed) Pookee Electric Heli Talk 2 Nov 27, 2004 04:15 PM
Help needed please. Mixing on JR radio XF421FX Michael in Toronto Radios 1 Jan 03, 2003 08:39 PM