|
The game was 100% dead upon arrival. Upon close
inspection the
LED lights for the +12vdc and -5vdc on the power board were out
which indicated zero output. I cleaned the very dirty fuse holder
but that didn't solve the problem.
I also repaired many cracked solder joints on the board but the LED's
remained out. Both voltage
regulator LM723's were checked with a logic probe and it was confirmed
that heir outputs were dead. As indicated by the red arrows in
the
picture, both
voltage regulators were replaced and the +12vdc and -5vdc were
now present!
|
|
With the power supply board up and running the game
still did
nothing. I discovered the bank of 4116 RAM on the main CPU board
was missing the +12vdc. The power board and harness were
checked and found to be good. After an extensive search a 0.1uf
capacitor at C22 was found to be dead shorted to ground. The
capacitor, indicated by the red arrow, was replaced
and the bank of
4116 RAM was now buzzing along.
|
|
The game still was not booting and the interconnect
cable from the ROM
board was dropping out multiple signals including the PSO signal.
A replacement cable repair kit is available so I ordered one and
installed
it. There are many pins and solder pads to deal with during this
repair so I recommend if you attempt it...be sure to have patience
as you go. The first picture shows the old brittle cable removed
and the 1000 solder pads (Mom told me a million times never to
exagerate!) cleaned up. The second picture shows the new cable
soldered in and ready to go!
|
|
At this point everything seemed to be working but I
still had a blank sceen and no sound to indicate that the game was
at
least playing blind. On to the WG4600 monitor. There were
the typical cracked solder joints everywhere but even after the
repair...no picture. It turns out my 'black adjust' pot was bad
and once replaced I finally had a picture! The game was booting
up but going straight to the bookkeeping screen. As it turns
out, the original battery holder was corroded so it was replaced with a
lithium ion battery kit. The pictures show the original crusty
battery holder and the new clean lithium ion battery holder.
|
|
With
the battery kit installed I was able to play the game but there was no
sound. The game was found to have a bad 6808 CPU on the sound
board. Once that was replaced - I FINALLY HAD DEFENDER RUNNING! I
was never
so happy to finally see the screen shown in the picture to
the left. After a long series of tough repairs...this game
is still just as TOUGH to play as I remember!
|
Defender Repair Log
