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Re: Any chance of a schematic for this?

PostPosted: Wed Apr 04, 2012 4:14 pm
by BillGriffiths100
Sigh.....
Avuncular (Means like an uncle)
Nempe vos a Eubonia (Surely you must come from the isle of Man)( Carn stumble is old Manx Language)
magna verba confundentes (large words are confusing)
Were none of you flogged to within an inch of your life at public school! I despair.....
Stop wasting your time on this forum with your folksy reposts and fix those TX's!!

Re: Any chance of a schematic for this?

PostPosted: Wed Apr 04, 2012 5:39 pm
by AltechMYOB
BillGriffiths100 wrote:Were none of you flogged to within an inch of your life at public school!


Nah... put your finger right on it. But the Headmaster, a 6' 6" brute, did spear another waif-like boy into the corner of a metal filing cabinet, ripping his head open as a consequence of performing one of his "touchy-toes" maneuvers. I chose to fake-it after that... my ed ja ma kation that is.

BillGriffiths100 wrote:Stop wasting your time on this forum with your folksy reposts and fix those TX's!!


I concur. To hard ATM, hence the request for a schematic. Life's priority's are keeping them on the shelf.

Re: Any chance of a schematic for this?

PostPosted: Wed Apr 04, 2012 8:56 pm
by cynr100
Thats what I like about this forum, you learn something new everyday.
I now have "Old Manx language" which I can store away never to be used again and thanks to Altech the meaning of "aliphatic glue" with a possible useage.
Thanks fellas, this makes my day :D
I'm killing time till China Post release my Tx from captivity.

Re: Any chance of a schematic for this?

PostPosted: Thu Apr 05, 2012 10:12 am
by BillGriffiths100
I concur. To hard ATM, hence the request for a schematic. Life's priority's are keeping them on the shelf

Seriously your chance of getting a hens tooth ( http://beeradvocate.com/beer/profile/203/878 ) is more likely than a schematic, get the tx's apart and trace the wires to the circuit board give them a wiggle and a pull. Your problem is not likely to be on the board and a circuit diagram would only show the pot central wire going more or less directly to the single encoder chip NE5044 or equivalent found on these tx's so you wouldn't really be any the wiser. Failure of this type is nearly always a wire fracture, a faulty pot would give an intermittent jerky failure.
You can find information on the chip from:
http://www.datasheetarchive.com/NE5044-datasheet.html

Re: Any chance of a schematic for this?

PostPosted: Fri Apr 06, 2012 4:50 pm
by AltechMYOB
BillGriffiths100 wrote:
I concur. To hard ATM, hence the request for a schematic. Life's priority's are keeping them on the shelf

Seriously your chance of getting a hens tooth ( http://beeradvocate.com/beer/profile/203/878 ) is more likely than a schematic, get the tx's apart and trace the wires to the circuit board give them a wiggle and a pull. Your problem is not likely to be on the board and a circuit diagram would only show the pot central wire going more or less directly to the single encoder chip NE5044 or equivalent found on these tx's so you wouldn't really be any the wiser. Failure of this type is nearly always a wire fracture, a faulty pot would give an intermittent jerky failure.
You can find information on the chip from:
http://www.datasheetarchive.com/NE5044-datasheet.html


I originally purchased 2 of these models, 1 to learn how to fly a larger coaxial model, the 2nd for parts when (not if) I trashed the 1st. Both out-of-the-box gave odd differing intermittent problems. I should have sent them back but unfortunately at the time I had put them on a shelf due to not having any time (or a location really) for play, let alone fault finding.

Eventually I MADE some time to play. By the time I worked out it wasn't me causing the problems there was no warranty left... 90 days if memory serves. So they became my white elephants. I disassembled both transmitters to look for 'the usual suspects' that normally cause these types of faults. broken wires from cold joints, connector miss alignments etc. I found nothing obvious and yet again, out of spare time, they went back on the shelf. Now that I was out of pocket for these 2 originals, I thought it best to make a few phone calls to the local electronics shops that had sold them and get a few more returned faulty models for a few bucks, cash in hand. These items for more spares in the hope they'd see me thru.

Sooooooo now it's time to fish, or cut bait.

I dissembled all of the transmitters, as after a process of elimination by changing crystals, it appeared that all the receivers were working, at least on the bench. I found that ALL of the transmitters were in the same condition... nothing obvious, no loose or cold joints. Eventually I came to the conclusion that (most likely) there had been a dump of factory-rejects of this item into the country, due to the large number of returned items with nothing obviously wrong or easy to fix.

So that's where I am now. I'd not gone to the trouble of serious fault finding to date. Now I have some time (well soon :oops: ).

Thanks for the tips Bill and the link to the "Programmable seven-channel RC encoder". I've downloaded the specs and tho the RCs are only 4ch, a quick glance at page 1 shows it will 'do' "3 to 7 channels" so it's a good place to start... if they're very common they may well be the one used, if not thanks to your direction I should be able to track down similar. I'll drag my old CRO out of storage and hopefully (if it's still working) I'll be able to make something work out of the pile of spares.

Also thanks for mentioning the pots, I wouldn't have thought to meter them, as I've never had one fail on me touch wood... the vast majority of my electronics experience has been on Mil-spec or high-end commercial equipment.

cheers...

PS: Thanks for the link to the Hens Tooth... I'll try to get one to contrast my Round-Tuit, and display with my resin-mounted Rocking-Horse Poo.

Re: Any chance of a schematic for this?

PostPosted: Sat Apr 07, 2012 8:28 am
by BillGriffiths100
Another thought has it got reversing switches?
These could cause a problem as they reverse the connections to the pots on some tx's, and you know that a cheap switch sitting still tends to get dirty and intermittent.

Re: Any chance of a schematic for this?

PostPosted: Sat Apr 07, 2012 4:07 pm
by AltechMYOB
BillGriffiths100 wrote:Another thought has it got reversing switches?
These could cause a problem as they reverse the connections to the pots on some tx's, and you know that a cheap switch sitting still tends to get dirty and intermittent.


No... but thanks for the prompting. There may be a related 'contact' problem...

Looking at the pic I posted, (I'm 522 km from their location ATM) it looks like it has mechanical trim controls. I don't remember what they look like from the inside... both of the models were so out-of-control trims never entered my mind. They may just be dummy, there for use for whatever manufacturer 'X' wants.
But then if they are used in this tx, it's potentially another large area for dysfunctional contacts (pot, trim pot or voltage divider network) for me to look into before I drag out the CRO...

tnx Bill.

Re: Any chance of a schematic for this?

PostPosted: Mon Apr 30, 2012 2:51 pm
by AltechMYOB
BillGriffiths100 wrote:Seriously your chance of getting a hens tooth ( http://beeradvocate.com/beer/profile/203/878 ) is more likely than a schematic, get the tx's apart and trace the wires to the circuit board give them a wiggle and a pull. Your problem is not likely to be on the board and a circuit diagram would only show the pot central wire going more or less directly to the single encoder chip NE5044 or equivalent found on these tx's so you wouldn't really be any the wiser. Failure of this type is nearly always a wire fracture, a faulty pot would give an intermittent jerky failure.
You can find information on the chip from:
http://www.datasheetarchive.com/NE5044-datasheet.html


Dragged out my old CRO and found an hour to spend on this project.

hmmm... the encoder chip in use isn't an NE5044. The one I have doesn't have any markings on it other than identifying pin 1 (nice of them!) and is a plastic DIL 14 pin device... the NE5044 is a DIL 16 pin device. I'd hopped there would be a similar pin usage but no dice. Pins 1-3 (or 8-10... can't remember ATM) of my ASIC are common for 3 of the 4 inputs (it's a 4ch Tx) but pin 4 input is on the other side of the DIL package... makes no sense until I can turn up a pin-out for the unnamed device OR spend enough time on it to compare to my other faulty Tx's in the hope I can eventually work it out. If my IC is only a 4ch encoder and not one that has additional channels disabled, these Tx's really are only good for practice with a low-end model like the AXN, sans FPV. A DIY FrSky mod is still only going to provide only 4ch's, if I properly understand how those modules work. Even the DHT-U all-in-one (my preference) is still only going to provide 4ch's.

I had a quick look on the net for 14 pin DIL RC encoders without success... not really surprising as they would be pretty old by now, given the relentless march of ASIC design.

If anybody knows of any part numbers for this vintage, please throw 'em @ me!

Tnx... :)