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Posts posted by fv1609

  1. Looks like you have Generator No.1 which is rated at 12A 28.5v there were two types of Generator Panel looks like you have No.1 Mk 1 a later rather different panel was No.1 Mk 2/1.

    Both of these panels are  very hard to find, but the good news is that I have seen people fit the Generator Panel No.2 Mk 1 which is the 25A panel intended for the Generator No.2

    Unlike the Generator No.2 which has a gearbox, the No.1 can be tested by running it as a DC motor. Via say 15A fuse energise the field winding (C & E) & via another fuse energise the output winding (A & B) & the dynamo should rotate as a motor would.



  2. 4 hours ago, Alan said:

    I have seen suggestions in some face book groups about having online shows with people posting pictures and info about their vehicles to enable visitors to virtually wander around a show.

    Would this virtual show be truly authentic & display pictures of overflowing toilets?

  3. Chris thank you. Yes gloss DBG & brown was most curious in NI, although it didn't seem to last long which is one reason I suppose is that there are so few pictures of it in use. It always struck me as odd that the Commers, Triton 1 & 2 were so painted, as a water canon is very much an urban vehicle, trying to look like a shrubbery in a built up area seems incongruous.

    I have only a few pics of Mk 1 Pigs in that scheme & apart from the Commers nothing else. I would be interested if you have pics of any other vehicles using it.

    Yes I can imagine that deniers get quite upset seeing this scheme reproduced. Here is one Pig courtesy of Victor Patterson.




  4. Yes it is curious how even mechanically minded people have an (ir)rational fear of electrical issues. What I like about electrical equipment is that when you apply appropriate test equipment you can measure what is happening in a give circuit. There is nothing discretionary in the diagnosis, apply logic to what the circuit should be doing & you can measure what is or is not happening, unlike some other automotive skills such as judging that an engine is pinking say, I'm at a complete loss on how to make such an observation with any certainty.

  5. Ferg inside looks quite reassuring. The various types of harness look nice, I suspect they have been painted as their connectors look less dazzling. But at least it shows someone has taken some interest & care to conserve the wiring in the back that so often is the first victim of bodgery.

    When you go to see it, do check that it is charging along the lines of the basic tests I suggested. If you get stuck on anything here is bit more light reading for you : )



  6. Ferg it is some years since I owned at LtWt but apart from air filter it does look pretty unmolested.

    I notice the two relays look newish as they easily rust out given their position & the king lead (ie HT) from the coil to distributor looks newish which all suggest that there has been sympathetic electrical maintenance going on.

    I notice the filter box (contains filter & ballast resistors) no longer has any of the original countersunk screw heads. In order to lose those, suggests the cover may have been off for a while. So it would important to ask if any modifications have been done inside. One of the ballast resistors has quite thin wire & can easily break, I have never seen a satisfactory owner repair with a substitute resistor.

    I'm pleased to see that the ignition coil is mounted correctly as military replacement coils fitted with a bracket generally are 180 degrees round from where they should be for mounting on the rocker cover. Due to the SW lead being quite short it then gets incorrectly wired up resulting in a positive rather than negative spark. I can tell yours is ok as I cannot see the two tiny drain holes as these are underneath & not visible.

    If the charging system has two ammeters on the dash, it would be important to observe the vehicle ammeter at switch on, start up & revving to see that it does in fact charge & that the ignition warning light goes out. If you have a single ammeter in a box (shunt box) between the two front seats, this ammeter only reads the rate of charge just to the radio batteries (if fitted) It does not measure discharge from the the radio batteries.

    If radio batteries are not fitted it is important that the two battery leads are isolated from earth & each other as these become live when charging as a relay in the Generator Panel No.9 joins the radio & vehicle batteries in parallel.

  7. As far as British military vehicles go, although a 24v ignition system through a ballast resistor reduces the voltage to the ignition coil to 12v (or 10v in series Land Rovers) it has an advantage over a purely 12v system.

    The rate at which the ignition coil can magnetise (when the CB closes) & demagnetise (when the CB open) determines the effectiveness of HT output, most importantly at high revs.

    This is because the time constant of the primary circuit in a 24v system is determined the ratio of inductance of the primary winding to the resistance of the primary circuit (ie resistance of coil primary + resistance of ballast resistor).

    Whereas the time constant in a purely 12v system will have a similar inductance but the resistance of the primary circuit will just be the resistance of the primary winding.

    So the time constant of will be lower in a 24v ballasted system than a 12v unballasted system.

    • Like 2
  8. 2 minutes ago, sirhc said:

     and lose originality?

    and lose value, people don't realise that chopping around the electrics might seem an expedient to them & may all be changed in what they believe is a logical fashion may turn out to be a nightmare for the next owner or anyone asked to sort out the bodgery!

    • Like 2
  9. I'm sorry I know nothing about a M38A1.

    I expect many people on here are using coils built 20 years earlier than 1963 without any issues. The vehicles I have owned from 1950s-60s have all run on their original coils, coils probably of better build quality than nowadays.

    To me it seems very strange to design a vehicle to run with a coil supplied with 24v rather than use a lower voltage coil + ballast resistor. The problem with a proper 24v coil is that it will have a primary inductance of about twice that of a comparable 12v coil.

    As the time constant (time taken for coil to fully magnetise) is related to the ratio of inductance to resistance, it seems better to reduce the inductance & increase the resistance of the primary circuit. Thereby ensure a more sustained voltage output at high revs.

    So a work around could be to choose a suitable 12v coil (suitable ie one designed for the polarity of earth your vehicle uses) measure its resistance & choose a ballast resistor of the same resistance. Your coil will then be supplied with 12v as it was designed for.

    Do not use the ballast resistor from a 12v system as often the coil will be designed for about 6v & the ballast resistor to match.

  10. Peter is your Bosch coil actually rated at 24v or is it rated to operate in the 24v system of your M201  ie it operates in series with a ballast resistor?

    The Land Rover "24v" coil is actually a 10v coil in series with two ballast resistors in series contained in the RF filter unit.

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