While on the subject of Amplifones, has anyone tried using TO3 versions of
78 and 7924s in place of the TO220 ones? They source .5A more and might
perform better under heavy 'death star explosions'. Also, Mouser sells a
7824/7924 from NJR which sources more current? Would these help the
Amplifone more/ make it more reliable.
I was over Mike's last night with him tinkering with the Amplifone...it
really wasn't making a hissing sound...it actually sounded more like you
were pissing in a bucket (for lack of better terms)...it was kind of loud!
The absolute highest the HV rose to was 9 KV. I checked out pin 3 on the
555 and there was a square wave (initially), but my scope sucks and I
cannot really read the frequency very well (I got it for $15 at a thrift
store, and it works in XY mode so I cannot complain). Now, there is no
square wave which leads me to believe the 24V sources are dead. There is
no LED comming on anymore on the HV board. John, we did exactly what you
explained last night. However, I think shotgun replacing parts on this board
isn't necessary (i.e. replacing all transistors). If the 555 isn't
producing the square wave, then it is a
safe bet that the board isn't producing 24V (or getting voltage from the
deflection board), or the overvoltage circuitry SCR is stuck on somehow,
right? If it is producing a square wave, then every time Q1s base gets a
high pulse, Q2 should be shut off...etc.
The basic building blocks of the HV booard are real easy to understand
now that I have a good set of schematics. I'm just curious to hear
other people's experience with these monitors after upgrading them with
Wintron flybacks. Oh, and one more thing, does anyone know what the hell
that big, red MC1 thing is?
Sorry to ramble ...
Ed
Received on Fri Sep 4 13:55:35 1998
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