RCMC Lansu 3 channel 2.4 radio problem

[sgl]

Hello;
My order from mouser came in the mail today, I'll make up a harness so I can swap with out soldiering each of the 6 pots that came. No point in not having results for each. Plus if I soldier each to the board, I am sure to make some sort of mistake. I'll post results as soon as I gather the results.
Sgl

RCMC 1/24 Sumo
Losi MRC-Pro

[Charlie-III]

Originally Posted by sgl

Hello;
My order from mouser came in the mail today, I'll make up a harness so I can swap with out soldiering each of the 6 pots that came. No point in not having results for each. Plus if I soldier each to the board, I am sure to make some sort of mistake. I'll post results as soon as I gather the results.
Sgl

RCMC 1/24 Sumo
Losi MRC-Pro

Thanks for the update.

I've been looking at a few sites for a pot with the design you have. Sorta thin right now, but I'm looking.

This is sounding like a good thread to review.

[sgl]

Hello:
I was able to wire in a three position Terminal Block (uses 3 set screws ), to solve the terminal connection issue. pots used were #1. A 5k linear (Bourns PT902-2015K-B502 ) unit ( traditional 2 gang with 6 terminals) worked although very jittery through out range metered 4.693 (upper) RT and 4.812 LT (lower). #2. A 1K audio (bourns PTV142B20AA102) no function at all didn't meter this unit. #3 5K Linear ( Bourns PDB12-H2201-502B) ( 3 pin) worked with severe jittering mettered 4.68. #4 A 2K linear (Bourns PDB12-H4251-202BF ) Unit worked well problem is nonthreaded 12mm shaft Metered at 1.024K ohm. There was a fifth but I damaged a leg while working out a method for a non soldier mount, so did not get readings. I am going to try and find the equivalent to # 4 with standard 12mil threaded mounting shaft if not will use # 4. Thanks braq and Charlie-III for all the help and suggetions, it made the task manageable!
sgl

[braq]

excellent, so 2K was the best fit

any way to rework the shaft, plastic is usually quite easy compared to metals "to make fit"? >save on shipping!

grind down to smaller dia > use file
loose > glue
lock > make pin and drill hole through shaft & dial

so in the end only the typical three pin setup was actually connected?

cheers

braq

[sgl]

Braq:
fortunately the shaft is long enough, the problem is the outer sheath along with having been designed as a surface mount ( two prongs into PCB board, actually the one pictured in your mouser reference ) . The outer sheath ( surrounding plastic shaft ) is only about 1 mm in height. I am pretty confident they will have a panel mount ( threaded 12 mm ) available. Seems the PDB12 prefix, series, family? works. The 2k better than 5k obviously if thy don't have one I'll a fix the threaded shaft from the original unit to it some how. The real surprise to me was that a 5k even worked at all. When I got the original 1.6 then 1.7 readings, I really thought it would turn out to be a one off spec'd (sp) and manufactured specifically for Lansu. I can understand the 2k working as it's close but 5k ? Seems just a little imprecise (sloppy) to me.
I will post the out come.
Thanks for all your help.
sgl

RCMC 1/24 Sumo
Losi MRC-Pro

[sgl]

Sorry, forgot to answer one of your questions yes it was a three pin , although the six pin ( traditional double gang center pins connected together using alternate outer pins ) worked as well but-was 5K. It was interesting that they all metered low for me, then they were very inexpensive.
sgl

[Charlie-III]

Thanks for the follow-up, glad you found something that will work.

As to the help/support, no problem, glad to add what I could. You're the one actually doing the work!!

Hope the basics of this thread help out others down the road.

[sgl]

looks as if I'll have to wait till after the holidays to complete this project. I am going to attempt to mount the surface mount unit. Going with adding the threaded portion of the failed unit. Two reasons 1. I don't want to modify the radio housing. 2. I would prefer not to modify PC board for surface mount .
Happy Holidays to all!
sgl

RCMC

MRC-Pro

[sgl]

After the holiday travel etc I have found time to complete my receiver fix. I unfortunately cheated and found an alternate source for the pot. Unfortunately one not readily available to everyone , unless they live in the San Francisco bay aria. There is a large electronics salvage store here called appropriate enough Weird Stuff, it's a huge warehouse filled with bins and shelves of new, used, reclaimed and salvaged electronics material. So I bought a few dollars worth at a quarter a piece and among the group found one that metered out near spec ( High ) but with a threaded shaft identical to the old unit. I however didn't soldier it through the board but used the short leads I had placed for my testing connector. My only reason for this was to minimize soldiering the board again and leaving things such that if I had a problem in the future it would be a simple quick fix.
I wish I were able to document a specific part with numbers and manufacturer and supplier, making it easier to fix this issue with this radio. Hopefully there is enough information in these post to find a solution.
I was fortunate to receive great input and encouragement from members of the forum, specifically Braq and Charlie III.
Thank you
SGL

[Charlie-III]

Cool, glad you found an "easy" fix. I've done similar trips to similar places.

No problem on the help, wish we could have been more specific, but you got it.

BTW, thanks for replying back on this thread, it may help someone else down the road.