I tested the two 7404 chips with a dmm. They all check out at .5-.6 except the two top right pins on both. those check at 0.293. The same on both normal? How would i check a U5 chip? if thats the case ill buy it.
Taking measurements on a 7404 like this is meaningless. How do you know the 0.5v is because of bad outputs or because of an oscillating output?
As a minimum, you need to check these with a logic probe. An O'Scope or Logic Analyzer is the best way but not many people own them.
However, you said the two top right pins are at 0.293V? Tough to know which pins these are without knowing how board is turned...but does this mean the two top right pins near the IC's pin 1 end identification? If so, have you checked your +5V to this board?
Top left of IC (with indent of IC oriented up) = pin 1, top right of IC is pin 14:
pin 1 = input 1 pin 14 = +5V
pin 2 = output 1 pin 13 = input 6
pin 3 = input 2 pin 12 = output 6
pin 4 = output 2 pin 11 = input 5
pin 5 = input 3 pin 10 = output 5
pin 6 = output 3 pin 9 = input 4
pin 7 = ground pin 8 = output 4
Outputs are always inverse of what is on inputs. So, if input is low, output is high and if input is high than output is low.
A valid low on the input is considered 0 to about 0.8 volts
A valid low on the output is considered 0 to 0.4 volts
A valid high on the input is a minimum of 2 volts
A valid high on the output is a minimum of 2.4 volts
When measured with a DMM - the readings can be all over the place as you are often measuring high speed signals. Only true way to see the levels is with the oscope or analyzer.
Dragon is a System 1 machine. If you lost a spider IC, you are talking about a lot of work replacing it (for a novice) and quite a bit of money.
Ed