Defender repair log

Arcade Games & Cooking.

Moderators: AArdvark, Ice Cream Jonsey

User avatar
Ice Cream Jonsey
Posts: 28877
Joined: Sat Apr 27, 2002 2:44 pm
Location: Colorado
Contact:

Defender repair log

Post by Ice Cream Jonsey »

Just keeping track, as it was like a year for Tempest and Zoo Keeper and I am not doing that gain.

Started Defender today and got "Initial Tests Indicate RAM failure."

Figured out that I can't adjust the +5 on the Defender power supply. (It can be done with a mod.)

So first steps:

1) Ensure the right voltage is getting to the 4116 chips
2) See if I have any others
3) If so, identify the bad chip and replace it
4) If not, order some 4116 RAM chips
the dark and gritty...Ice Cream Jonsey!

User avatar
Ice Cream Jonsey
Posts: 28877
Joined: Sat Apr 27, 2002 2:44 pm
Location: Colorado
Contact:

Post by Ice Cream Jonsey »

Annnd fixed, it appears. (If this was a Taito game, it breaking again 25 minutes later would stop me from having any sort of confidence.)

So, to run the RAM test, you have to have the one "manual" test switch, which is black, depressed when you start the game up. Get into the RAM test.

RAM test said 12 was bad. This post from gamefixer (who also saved my Spy Hunter in person before he moved to Texas, great dude)

https://forums.arcade-museum.com/showpo ... stcount=10

Said that it's just bank 1 chip 2. Cool. As far as I can tell, the Defender boards aren't labeled anywhere, so the "4M" that the manual speaks of is not helpful information.

Swapped that chip out for a new 4116 that I had picked up somewhere along the way. Glad I had it. Defender started right up again.

Defender was produced in 1981 and the original chips were all there. So that's 36 years? I guess one chip failing after 36 years is OK. (And it is a dream to work on, big giant spaces, easy-to-get-to boards, exact opposite of Taito.)
the dark and gritty...Ice Cream Jonsey!

User avatar
Jizaboz
Posts: 4811
Joined: Tue Jan 31, 2012 2:00 pm
Location: USA
Contact:

Post by Jizaboz »

Nice! Good job dude.

Defender is one of my favorite games. Wish I owned the real thing like you do. My buddy Scott had his freak out on him last month. Booted to RAM error.

About a week before that I noticed the screen would sometimes do this quick glitchy flash on occasion.. especially when a lot of shit is blowing up in the game.

User avatar
Tdarcos
Posts: 9333
Joined: Fri May 16, 2008 9:25 am
Location: Arlington, Virginia
Contact:

Post by Tdarcos »

Ice Cream Jonsey wrote:(And it is a dream to work on, big giant spaces, easy-to-get-to boards, exact opposite of Taito.)
I've seen the same thing in the PC world. Hewlett Packard desktop PCs almost always use clips or thumbscrews, everything can be taken apart and parts replaced without tools. Sony Vaio desktop PCs, on the other hand...
Alan Francis wrote a book containing everything men understand about women. It consisted of 100 blank pages.

Post Reply