Gallagher M800 cicuit
I repaired a Gallagher M800 a few years ago and took some notes on the circuit but did not generate a full diagram. The fault with the unit I had was that it had had an argument with a thuderstorm. The thunderstorm won, the copper strips on the output board were blown off and the diodes on the output board had been burst apart. The diodes (BYV96E, 1000V 1.5A) were replaced with BYM26E (1000V 2.3A) as I have some. The copper tracks were mended with wire and somewhat surprisingly it then worked.
The input (230V) is doubled using a pair of 2microF capacitors to charge a 40microF capacitor to 600V giving a stored energy of 7.2J (quite high). There is a 2N6027 programmable unijunction transistor, timed with a 22M resistor and 1microF capacitor to give a pulse about once a second. The pulse is fed to TAG9105 which I think is a triac used as an SCR to dump the charge into the output transformer (prim 0.6R, secondary 11.6R).
There are some unidentified white components on the oputput board, these may be MOV voltage limiters.
Output measured - half power 2.5kV, full power 6.1kV.
TIPS
1. Be warned that the cheap yellow digital voltmeters don't seem to like high voltages, mine went fizz with 600V on 1000V range.
2. If there is corrosion in the fencer it could be due to sparking generating ozone..A problem is with plug-in boards and if there are signs of corrosion I would solder a short link wire across the contacts.
I do not have access to the M800 at present as it is back in use and 100 miles away.
