You'd be surprised how much legacy (Cold War) technology is still in-use or are components of modern military equipment. Having retired gentlemen like that around and still willing to assist - is honestly like rediscovering lost knowledge as valuable as gold!
The military equipment is not actually that complicated, however the method of construction makes it it much more difficult to maintain, however it also makes it really reliable. The military connectors are a pain in the bum, you need the right tooling and practise helps a lot...
I am electrical engineer seeing this corrosion doesn't surprise me, I served time in the forces (70's-80's) we used to see this on radio equipment . Part of the problem was a mixture of metals in the relays, switches etc i.e aluminium and steel don't like each other. I am now working with 1930's - 1960's all electrical was brass & bakalite no corrosion. I think mr Hewes you get out your brass brushes & clean them up- slow job but cheap. You could always send them up to me I will do it for a cup of tea and a cake Maybe I am a bit sad but you do, I find fascinating
I'm one of those sad types that found this interesting, thanks for going into such detail. I mentioned on the last video of this series that their could be modification level issues. The plug with a wire 'missing' could be a symptom of it having been modified to accommodate the new computer control system, as they were heavily modified to take the system. They didn't originally have the computer or laser ranging. Might be something John could check for you, the data plates should be marked with the MOD level.
Sad types... Bro there are people out there who watch trannies talk about having periods by shoving topato sauce up the back end....there is nothing sad here
I, too, find this sadly interesting. To have so MANY components fail!!?? At one time? Dominoe affect? Faeries? With a single failure a unit would typically go into disuse and so I often wonder how 2 or more problems arise simultaneously as the domino thing can't occur , by design or by function. Nonetheless multiple failures can and do occur regardless of their proximity of function. Hard to foresee, and can alter the 'should be' readiness quite a lot. I love it when mindless management cries 'well YOU SAID it would be ready by' (some imagined and hopeful schedule) thus beginning to cast blame regarding a component failure that came about at an undetermined time prior to the techs involvement. I say- WAAAH WAAAAH!! to that. So sad.
The relays appear to be 4-pole Double Throw (4 x DPDT) per side, or 8 poles in all. RS Components (for example) have Power relays with multiple poles for around £10. You could stack 8 in a line perhaps or use 4 DPDTs. Their current handling (6A - 10A) should be sufficient and there are a variety of operating voltages. The only issue to watch is whether the relays need to default Off or On when unpowered to ensure correct start-up state. With regard to the socket I would get a new one, and wire every pin with a length of cable to be cut to length in situ, a connector then crimped on.Simple and cheap. Since there appear to be thermionic valves in the tank you do need to be careful on units like the PSU since after power-up electrolytic capacitors can carry 200V-400V or so even after switch-off (assuming no bleed resistors). And electrolytics degrade over time in any case so are best tested/replaced. Be very careful if you start repairing valve kit and be sure to measure HT voltages in the PSU before starting work. Another thought - where do high voltages for valves come from? The Auxiliary engine? The main engine generator? This all sounds a bit dangerous too! Have fun and keep safe.
Definitely my favourite vid so far Joe, as someone who has worked on control systems for 35 years (not tanks) and done the “replace it all with a modern logic controller / PLC / CAN system / whatever” many times for customers I’m 100% with you on rebuilding the original kit albeit with available parts 👍
As a 30yr Electrical Draughtsman I produced schematics and wiring diagrams. Every one of those boxes were probably wired up exactly the same so that the looms and routing were duplicate also. I bet sourcing new modern relays with the same number of change-over contacts would be not hard (and cheap). I learned on a drawing board with my trusty Rotrings and ended as a CAD user. Just that control box from design to build/test/commission will have taken a huge number of man-hours.
Those appear to be 4PDT, probably 20A or 30A contact rating, probably 24VDC coil. I just did a quick search a few minutes ago, and it is right hard to find that exact specification. You can get 4PDT off the shelf, but only with 15A contacts. That might or might not work. You could use pairs of DPDT 30A relays with the coils paralleled, and can get them for about $6.50 each. You would probably also want sockets with screw terminals, and those will be another few bucks. And won't match the current pin layout, so a lot of wire modifications would likely be required.
I'm a design engineer in aerospace. The average person has no idea what goes into designing, building and testing most things especially complex vehicles or systems
I spent many years working and re[airing such equipment (no tanks though) before you throw those old relays away check what the contacts are made of. In that era many relays used platenium contacts which are worth a lot of money today and may be why the price of a new relay is so high. When you are looking for new relays check that the contacts will take the current that goes through them. You should have no trouble getting replacement relays. If I were doing it I would make up a board and wire it as a stand alone then terminate the incoming cables on a connector to connect it to the board, which would make it easy to change again if you need to and you could make up several for spares A firm called Radio Spares are good for the bits. I hope this has been of use I love your videos as I always wanted to drive a tank, but I am too old and stiff now.
I was 12 years old when that relay was made and I feel really old right now. I am a former U.S. Army M1A1 Master Gunner and so happy I never had to deal with stuff like that.
Well diagnosed young man and John. One thing about 'electronics' of that era is that things were large and basically simple (ie mechanical). Complex but not complicated. I don't know about anyone else, and forgive my OCD, but I was mightily impressed with the quality of the build in that unit. Whoever built it had the attention to detail to have the cable ties lined up like little soldiers! And the loom stitching was just beautiful. Don't let anyone tell you we didn't and can't do quality! Depending on the power loadings there are many options to those failed relays and if it was me I would take out those extra pins and cables on the first (PSU?) replacement plug and use one of them where that cable is missing on the second (Trim?)plug . OCD again. Sorry!
Agreed! And the wires are all MIL Spec with what looks' like fiberglass jacket for strength and fire retardant. Debugging stuff like this tight up my street!
I just love the way everything is sealed against the elements, sand, wind ,rain, and sun modern tanks not so much but with their maintenance schedule those Abrams hold up to moisture, sand sun, trouble is their workshop is absolutely ginormous with many many soldiers and civilians overhauling them.
@@1chish Honestly I never said it was an Abram's tank, what I actually said was the old tanks can stand up to extreme conditions NOT LIKE THOSE ABRAM tanks, but with their fix it schedule they don't have to because they are completely overhauled.
Simply dismantle the lower part of the relays and shorten the springs by one turn, clean out, and rebuild, Job's a good un! There are screws longitudinal to the relay body folding the coil assembly on, you may be able to do this without disconnecting a single wire. I spent a working lifetime doing this with various relays and contactors, it is amazing what can come back to life with a little care, just try it on the bench with a 'spare' one first, so you can see what you need to do.
To be honest I did anticipate problems with Ted not being on hand to keep and eye on things. I guess he's off tinkling the ivories somewhere taking the occasional draw on a Cohiba Siglo.
Can hear the tiredness creeping in during last few minutes! I thought I had a wiring nightmare on a scooter t'other day but THIS IS A WIRING NIGHTMARE lol!
Grief how do these tanks ever run with so much that was high tech that when it went wrong then John and his fellow engineers are and were of huge value
I had exactly the same problem on our Mk10. I took the bad relays apart, replaced the rusted out springs, cleaned the contacts, rebuilt them, and they worked. Biggest problem I had was a lot of the terminal screws on top of the relays were so corroded, they just sheared off when I tried to remove them. I ended up dremelling the sheared stubs down to clean metal, soldering a wire pigtail on the screw stub, and soldering wire pigtail to original wire. Bit of a nightmare job actually. Another problem I found was a wire buried right in the middle of that thick harness that runs along the top at the back must have had a break in the insulation from new. Water had got in and corroded the wire. But at least that was to fix once I found it.
The spring screws onto the threads of screws at either end of relay. IIRC, one of the screws is used to adjust tension on the spring to get a nice snap but not so much tension coil can’t move armature. Pretty clever.
Nano technology major here . Could probably build that box with the same pinouts in a 6 sq inch footprint nowadays. The skill you guys have is surely a lost art . Thankyou for posting this .
When I was an apprentice in telephone exchange many years ago we used to repair relays. I don’t know about your ones but ours were easy to take apart fix or replace parts then reassemble. I don’t know about yours but it might be worth a try disassembling a broken one. Steve
I like how the professional pointed out the actual issue and you had him replace a simple connector instead of addressing the issue he identified immediately
My old man was REME and spent a while at 23 Base Workshop in Germany where all the Chieftans were stripped down to the last nut and bolt and rebuilt from the ground up. Chassis in A & B works All the electronic stuff in C works. I bet theres mod state labels attached to your stuff with a 23 Base Wksps stamp on somewhere.
A bit before his time. He got there in june 83. After being an instructor at Arborfield for 3 years. My childhood school holidays were great times, spent driving tanks and APC around the test track
I used to work for a company called Fisher controls making looms and panels for the MOD and it was always that pink wires with the numbers on which was a pain in the ass then wrapping with rhe cord normally all in one piece
That looks like a nightmare. An incredible number of connectors, which all stop working when they are affected by oxidation or corrosion. I remember in a factory where I worked, oxidized circuit boards were washed in the circuit board washing machine. The washing machine had a pool where the circuit board was when it was washed and it couldn't be water because it is the enemy of the circuit board. The substance in the tank immediately started to boil when the device started. The protective coating could come off the circuit board in that machine. The use of the device was banned because it was too dangerous or toxic. I have repaired thousands of circuit boards. That tank really needs a lot of work to make it work. Circuit diagram drawings of the circuit boards are needed and wiring diagram drawings are needed to check the wiring. That seems like a real nightmare to get working, but it's not impossible. What I learned from electronics is that if you make one wrong connection, the electronics will burn right away. Everything has to be checked and verified several times. Overloading can break circuit board components. There is nothing spiritual about electronics, everything is simple, but it can be very difficult to understand. All circuit boards intended for outdoor use should be protected with varnish intended for circuit boards. Varnish must not go on connectors, switches, relays or connecting surfaces where it should not be, or the varnish prevents the flow of electricity and jams all switches or relays, but it protects against oxidation. You have to be careful with varnish if you use it. Use specific varnish for circuit boards very crefully.
What a legend John is - but also your persistence and patience is unreal. That box of wires would have been smoking if I had it, from the gallon of petrol I'd have lobbed on it
All of our junk when it was rewired in the field and 40yrs old looked like that, when it was rewiring nobody gave a shit after it left the factory. Some genius even cut fuses onto the back terminals if they had shorting issues.
Only one way out as I see it. Recondition one with a new spring, fit it, fix the one you pulled out. And so on. If the coils are good that’s a winner, the rest will ‘fix’ (bodge) ^-^
@@markrainford1219 I did do well in Civvy street with what i learned and was taught. So there's that I guess! Fun times but it was so outdated, like most technology in the Army at the time. I certainly preferred working on a 353 on the bench than any part of the harness actually in a Chieftain, being tall didn't help. 🙂
Is it only the springs that have rusted away,perhaps tracking down the spring would be cheaper.The relay module looks like it can be completely disassembled to be rebuilt.
Ah yes.....those round connectors on that control console look like amphanol connectors Be careful when you connect plugs and sockets together Make sure the locating dowels are correctly aligned and the pin configurations are the same Apply a small amount of lube to the internal and external threads😅.....i have had loads of fun with these style of connectors lol......but keep at it you will crack it in the end🎉😊
Look at the plugs that match the defective sockets as they maybe damaged as well. Interesting to see the connectors and strip terminals plus cable forming same as my era as an apprentice at Marconi. It Was like knitting spaghetti on a pin board drawing. Any errors and it was cut and you started from scratch. Burnt insulation at the plug start again. No wonder the MOD contracts overrun in time and cost.
Might have to settle for several new relays to replicate the function of each old relay. Try not to disturb the nearby wire loom, that stuff is artwork and takes up less space than plastic tie wraps.
What connectors were they using in those panels? Are they standard 32 pin Amphenol? Have you not thought about getting a pin extractor kit and possibly some new blank panel sockets. The problem with brass nickel pins in alloy I galvanic corrosion
As an aviation tech in the Navy and into electronics for over 50 years, use your nose to smell for smoke. 80% of troubleshooting is something burned up and use your eyes. Unfortunately the fastest way is look up the connector number, replace the plug and swap out the wire one at a time. Many times the plugs are out there are used even on new boxes and they use standard wire release extractors.
As many other commenter's have suggested, if the contacts themselves look okay (not greatly pitted) or can be cleaned up without removing too much plating or material, as far as the mechanical bits within the relay, you could machine new ones and rebuild the relays. I think it is easier to rebuild the old relays and clean up the original wiring harness rather than trying to rewire a different type of relay because you would also have to rewire the connections or try to install inside of the original footprint. Also, you have a working relay that you can take apart, measure and accurately copy. The relay switched contacts look like 30ADC 48VDC type. However, I am unsure what the coil requirement is.
Its possible to take the pins out of some of those connectors with a tool that looks like a very thin walled tube, it compresses the barbs on the pins so they can come out, saves changing the wire loom. Great vid hopefully it will all work for you.
Just use an old telescopic antenna part of the tube antenna. That what I use. Works well.Slude it over yhe pins and rotate it around a fee times and then yoy can pull the individual pins out.
Buy a dmc crimp kit or chinese equivalent (they crop up in Ramco's tender) You can release pins, clean them and install new pins etc. You can buy the amphenol inserts. I am sure for future you could assemble a kit from an arduino or raspberry pie that would take inputs from tanks reference componentry and translate them into the correct outputs to control the gun. Someone would code it easily. It is a shame knowing there were probably pallets full of these systems that were no doubt smashed up for the wire and aluminium as is allways the case. Maybe being on youtube / social media an expert will come out of the woodwork or someone with a spare unit will appear.
Mmmmmmmmmm! Good old electrical problems. Time to get out the RS Components catalogue eh lol. I'm sure they sell those exact connectors too! About £30-40 IIRC.
Having pulled my hair out over bodged wiring looms on bikes this is incredibly humbling. Your perseverance is to be applauded. Can't believe some jokers asking £7000 for a relay. Who's going to care that it's not a period item. Sterling work as always.
there'd be nothing to stop you using commercially available relays although retrofitting them could be a bear, the only issue is that your frontmost relays are 8 pole, and it's uncommon to get anything over 4, granted it's easy enough to connect the coils in parallel. something like an OMRON G7J4AB24DC would probably do for the rear ones, the heavier cable suggests much higher load and I'm assuming it's a 24v system. I would imagine the end user isn't going to care what's inside the box so long as the box works. also, those connectors are still available, although I'll be buggered if I can remember what they're called (I could find out tho)
Ah, what you guys need is another Chieftan Tank you can use for spares LOL 😆 Local car wreckers should have at least 10 to 20. Seriously though, just looking at the internals of that box scares me. A valiant effort on your parts fellows.
...I've seen Server rooms in the late 90's, at DFW International Airport, that were far more disorganized than this panel. That is some clean wiring harnesses and layouts. They don't build stuff like that anymore, everything nowadays is Disposable, because of Built-In Obsolescence by manufacturers and engineers. Obviously a G.E. Engineer was never involved in the building of this electronic service panel, or else it'd be a nightmare to service. Former G.E. Computer Service technician, 1996
That was dead interesting. Back in the early 80s our electrical instructor at the coal board was an ex Chieftain tech. He was god-like to us spotty sixteen year olds.
