Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[scimitarjohn]

  I've just bought this Tx unseen (big mistake) in a bad state, I can fix the cosmetics but the circuit board is a tad corroded (again fixable) but a couple of wires are hanging off the board so want to be sure where to refit!  I love Digifleet gear, I've had an AM set from new (yes, I'm and old geezer) I use this with my steam launch[/size].  I[/size] bought this FM Tx to convert to 2.4GHz, it was cheap but I really don't want to throw it away and would like the project.

[HMS Invisible]

Here I'll expand on what I wrote weeks ago (link) by saying the one I have beside me and in the attached photo looks the same vintage as yours and is from mid 1984. There are so many variants and board versions.
 The basic Fleet circuit architecture was unitary gain inverting opamps (LM 324 with 33k resistors) handling servo reverse, span, mixing then feeding four of the encoder inputs. Three decades ago I drew a full circuit for my own reference but the basics are retained in my head.
I can't help you with a service manual but I'll give you a link to the encoder datasheet and reference to the 2.4 GHz module for connection. Fleet was return-to-base and working from his attic or kitchen table. Service agent?   
Just a decent photo or two from you is all the boat club electronic slaves need to say what the wires are for on the stopwatch.
NE5044 data is here https://www.alldatasheet.com/datasheet-pdf/pdf/17948/PHILIPS/NE5044.html
I likely don't know you John. If you were J.B. of Gravesend-Chantry I'd draw you a circuit from photo or do any repair or conversion or swap with this pristine 35MHz after rejuving the NiCd and putting in a 2.4G module.

[scimitarjohn]

  Hi, very much like mine but tad better nick. Have taken some photos and will send them just as soon as I find out where my grandsons put the cameras download cable!     Many thanks John

[HMS Invisible]

Your camera may have Bluetooth wireless even if it has mini USB and certain to do so if it has hdmi.
Beforehand, what I guess about the wires:
A photo of both sides of the printed circuit is what is of interest. If the loose cables are not battery, or added charge wires for battery or a connection a missing din style trainer/charge it may be one of the channel inputs or a switch to one of them like the switch that connects two throttles to one stick.
Four channel controls go to the LM324 via 33k resistors. Extra up to number seven go via resistor networks to the encoder as per datasheet.
A previous attempt to a 2.4G module will trace through components to the dil encoder chip output ppm.

[scimitarjohn]

    Hi, all OK, wife had put lead 'somewhere safe!'.  It's probably a lot simpler than you suspect.  The loose black wire is negative from the battery pack and the loose white wire is from the middle contact on the ON/OFF switch. I've attached photos, your PCB looks very similar, a tad newer and certainly in better condition than mine. Oh, and while I'm asking, if I get it powered up I can check around with a scope but it would save some trouble if you know where to pick off the pulse train for the 2.4 module.   Sorry photos not working, message come up -  'message field left blank' ??

[HMS Invisible]

    Hi, all OK, wife had put lead 'somewhere safe!'.  It's probably a lot simpler than you suspect.  The loose black wire is negative from the battery pack and the loose white wire is from the middle contact on the ON/OFF switch. I've attached photos, your PCB looks very similar, a tad newer and certainly in better condition than mine. Oh, and while I'm asking, if I get it powered up I can check around with a scope but it would save some trouble if you know where to pick off the pulse train for the 2.4 module.   Sorry photos not working, message come up -  'message field left blank' ??

The same photo server problem is affecting everyone including me. If you do one or two after a coffee break it'll work.
I tried to cover all possibilities. Switch at "off" should normally connect the battery to a charge port. In the "on" position the battery is fed to the board.
   It would be daft to make all +ve wires red to a switch & that confuses without a schematic unless you expect it.
 I'm just out the optician and shopping so won't see pics.
Serial output of NE5044 is pin 11. The 2.4G module will say if you want +ve or neg pulses.
Cycle NiCd cells to revive them. A 4-button multicharger, if you have not used before, makes the task to revive NiCd cells so easy.

[scimitarjohn]

  Many thanks for that but what I really wanted to know was which 'blob of solder' on the PCB to stick the errant white and red wires to. Also does  the output of the encoder goes straight to the modulation without any buffer?  Still unable to post photos here or DM don't suppose email OK?

[HMS Invisible]

I had a look inside my radio.
I'll convert mine so what I'll do is take my radio to bits to convert tomorrow after I get home from a jobsite.
I'll snap and mark up photos of where to solder a 3 pin connector. It is possibly done at the din socket but I put in a connector to match the Frsky module. I have not used Corona but if you can get them rather than Frsky, I'd pick Corona by choice so I could use multiswitch modules that early Frsky modules don't like.

Picture upload test of a 142kB jpeg worked.
After 21 posts you can do it on posts by attachment or ImgBB.
Mind the filesize limit. You can't send a photo by dm other than a link to a hosted photo.
My little test and battle last night and this afternoon shows filesize is very constricted.

[scimitarjohn]

This is crazy, reduced file size to 105kB and same message?

[Colin Bishop]

Never had any problems with attachments under 500k myself.

Colin

[HMS Invisible]

Don't worry about a photo, John. The extra details of today was a big help. It just remains for me to find the time tomorrow what I was going to do. A local dropped off a radio for repair on Tuesday.

Colin, I have rarely had a problem within the limit but yesterday around 4pm to 10.45 this morning it took many attempts to work. I mentioned it twice in the dual esc thread.
As I thought out loud at 1.27pm,  Brown, orange and white wires from ON, OFF & middle of the slide switch terminate on the copper lands etched ON, OFF, and SW.
Red and black wires to the right of the photo go to the 8.4 welded NiCd in mine.

John, I only know you have a voltage scope but not the extent of your electric knowhow. It's up to you if you use that era of charger. It is safe but crude but a pancake flat pack will blow it's non resettable thermal fuse.

[HMS Invisible]

I've highlighted the copper land connecting to pin 11 ( serial output) on my Heli version. The conversion module can directly connect with no buffer components.

The paper layout of my version is inside the cover.

 

[scimitarjohn]

  That's great thanks, I'll check out my PCB later today .  No idea what's up with photos, I've posted before and it's worked, hey ho.

[Circlip]

And don't forget, you're probably going to have to replace the Black battery wire.


 Regard  Ian.

[scimitarjohn]

Yes, anything like that likely to be flexed in any way I replace with silicone insulated wire.   John

[Circlip]

Flexing isn't the problem, "Black wire blues" is.


 Regards  Ian.

[scimitarjohn]

Don't worry about a photo, John. The extra details of today was a big help. It just remains for me to find the time tomorrow what I was going to do. A local dropped off a radio for repair on Tuesday.

Colin, I have rarely had a problem within the limit but yesterday around 4pm to 10.45 this morning it took many attempts to work. I mentioned it twice in the dual esc thread.
As I thought out loud at 1.27pm,  Brown, orange and white wires from ON, OFF & middle of the slide switch terminate on the copper lands etched ON, OFF, and SW.
Red and black wires to the right of the photo go to the 8.4 welded NiCd in mine.

John, I only know you have a voltage scope but not the extent of your electric knowhow. It's up to you if you use that era of charger. It is safe but crude but a pancake flat pack will blow it's non resettable thermal fuse.

  No, I'm afraid I'm not J.B. of Gravesend-Chantry. Up until retirement I was an industrial process control tech, in all that time there was the full gambit from thermionics to DCS computer control systems, and I loved it all.  After my message I cleaned the board a little and it was all pretty obvious but good to have it confirmed, many thanks for all the great info. I've got the board about as good as I can so now it's power it up and see!  Interesting about batts, however I've standardised on 18650 L ions nowadays and, if required, creating whatever with an appropriate L78xx.

[scimitarjohn]

Flexing isn't the problem, "Black wire blues" is.


 Regards  Ian.

  I'm probably being a bit 'Tom and Dick' but what's "Black wire blues"?
[/size]        Cheers

[HMS Invisible]

...Interesting about batts, however I've standardised on 18650 L ions nowadays and, if required, creating whatever with an appropriate L78xx.[/size][/font]

I kept off the battery migration subject for brevity but I agree that 2s Lipo is the perfect choice.
 If Lipo was available in 1984, the radio's year of manufacture, Fleet sets would use it and Sir Clive Sinclair's bacon would have been saved. The media darling revealed his next project, still very much under wraps, would be a battery powered car.

Black wire syndrome
  Battery gas oxidises nickel, copper and tin and you must have seen corrosion at NiCd and primary cell terminals and crystal growth.
   It migrated the full length of pack leads in my unused radio wires. Insulation stripping would snap the wire as it wouldnt glide off with unaffected wire. You can't resolder multistrand wire with rosin flux after it has happened.
 I will replace with a red JST bump connector supplied ready-crimped.

[scimitarjohn]

Black wire syndrome
  Battery gas oxidises nickel, copper and tin and you must have seen corrosion at NiCd and primary cell terminals and crystal growth.
   It migrated the full length of pack leads in my unused radio wires. Insulation stripping would snap the wire as it wouldnt glide off with unaffected wire. You can't resolder multistrand wire with rosin flux after it has happened.
 
  Ah, now I see the 'black wire' thing.  We had the same issue in the workplace, noxious fumes from the production process would enter I/O rooms causing all kinds of problems with corrosion on - well just about everywhere.  I wanted positive pressure venting from building exterior but installing AC units was cheaper and for some reason seemed to help (the filters?), also made a nice place to be away from the production environment .
 
  Right, powered it up and nothing, wires to an from power switch fused together?  Connected supply direct to board and hey, a pulse train at pin 11 of 3.5v, more of a sawtooth than square wave but responds to stick movement. Strange thing is the battery voltage meter sometimes goes off scale then, next time power on, it will go below zero or hard below zero?  Thinking I really need a circuit diagram, any ideas?

[Circlip]

Surprised you didn't recognize the term John. If your original 27moggies had a rechargeable pack - DEACs, the symptom  was widely known. On stripping the pvc coating, green dust (Copper Sulphate?) would be surrounding the wire. Strangely, it only seemed to happen on black wires.


   Regards  Ian.

[scimitarjohn]

Black wire syndrome
  Battery gas oxidises nickel, copper and tin and you must have seen corrosion at NiCd and primary cell terminals and crystal growth.
   It migrated the full length of pack leads in my unused radio wires. Insulation stripping would snap the wire as it wouldnt glide off with unaffected wire. You can't resolder multistrand wire with rosin flux after it has happened.
 
  Ah, now I see the 'black wire' thing.  We had the same issue in the workplace, noxious fumes from the production process would enter I/O rooms causing all kinds of problems with corrosion on - well just about everywhere.  I wanted positive pressure venting from building exterior but installing AC units was cheaper and for some reason seemed to help (the filters?), also made a nice place to be away from the production environment .
 
  Right, powered it up and nothing, wires to an from power switch fused together?  Connected supply direct to board and hey, a pulse train at pin 11 of 3.5v, more of a sawtooth than square wave but responds to stick movement. Strange thing is the battery voltage meter sometimes goes off scale then, next time power on, it will go below zero or hard below zero?  Thinking I really need a circuit diagram, any ideas?

[HMS Invisible]

A hard copy of the NE5044 datasheet should be all you need.
Pin 14 gives a sawtooth output and has a resistor pull up to 18 (Vcc) so maybe my numbers are wrong.
The chip notch is between pin 1 &18 then 2,3,4 are counterclockwise from the component side.
I double checked and I have the right numbering and highlighting for my board. Serial out would also go to a trainer port.
It's up to you how you want to progress but help is at hand and you have the toolset to make it easy. You could do an internet search to see what aero forums say about schematic but I think that's a wild goose chase. I've lost count of the NE5044 radios I've repaired or adapted so knew pin (ser. out) was pin 11. All I initially needed to draw a circuit for (c1990) was to find what the Fleet opamp gubbins was for.
Take the crystal out and ignore the meter. It'll be meaning rf power and the wire on mine goes to the rf section.

[scimitarjohn]

  Yes the OP amps baffled me a bit, the 5044 data sheet shows an internal supply feeding pots for the variable inputs of the chip, simples.  I've been testing with the crystal out so as to keep an eye on current consumption, I assumed meter was supply volts but if it's rf that explains it, assume nothing eh.  I'll have another go at cleaning the pcb and see but the 5044 looks an interesting thing to play with, would it be safe to 'assume' pulse positions and durations would be the same here as my Digifleet AM?

[HMS Invisible]

I have never seen a Fleet AM set and I can't remember if the NE5044 is a fixed frame time.
  There is no rule stating frame length. It can be ~15msec or less for old sets with few channels. Old sets could centre the channel pulses on 1.3ms then +/- whatever.
    If you had your old Tx to hand you can pick up its timing in a second by wrapping a few turns round the aerial and crank  up the scope gain.