Now time is going by epoch resources are getting thin on the ground, so thought I would start a repair thread.
Recently turned up a small pile of boards from ebay for £10, In the pack was a epoch mk1 lamp board. Now i find Mk1 boards better than the later MK2 one stop boards because although the mk2 are supposed to be better, modified versions I have found the fet transistors that do blow have not been up-rated at all and STILL blow! also the mk2 drive the alpha display from a small surfacemount custom chip and if you are unlucky to unplug the alpha or plug it on with the power connected it tends to blow the alpha drive output of this chip! the Mk1 board the alpha is driven from a much more robust PIC chip which does withstand this. how do I know...... yes have done it!!
so what happens to the MK1 boards is the lamp transistors burn up! and this MK1 board was no different! I presume a bulb holder in the machine gets shorted out somehow which burns up the transistor driving it
the board!
no dispute here on the blown transistor!
all others tested with a meter and no other shorts found so a bit of hot air from a chip re-work station and chip was out! It had taken the pad off where it had burnt so soldered on a replacement wire!
New transistor chip fitted and the wire neatly soldered to the leg of the chip, metered to make sure it is connected as it should be
and so job is done and the board will live to fight another day instead of being scrap!
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