Logic probe and Williams CPU board

dahnz

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Where do people hook their logic probe power leads to on a Williams CPU board? I need to do some checks on my Robotron and nothing seems to leap out to me as an easily accessible place.
 
Where do people hook their logic probe power leads to on a Williams CPU board? I need to do some checks on my Robotron and nothing seems to leap out to me as an easily accessible place.

Any TTL chip will do. They all have power (+5v) and ground.
If you're looking at one with the notch in the top the power pin is the upper right. The ground is the lower left.

For example:
iphone_ipod_TTL_Pinouts958.jpg
 
Thanks. So how do you easily attach the leads to the chip? The alligator clips on the ends of mine are not exactly small.
 
I generally attach it to the wire harness connectors or, if I can't connect it there then I connect it to some ceramic cap lead.

RJ
 
Any TTL chip will do. They all have power (+5v) and ground.
If you're looking at one with the notch in the top the power pin is the upper right. The ground is the lower left.

For example:
iphone_ipod_TTL_Pinouts958.jpg

Not for all TTLs...
Code:
7483
4-bit binary full adder with fast carry.

    +----------+
 A4 |1  +--+ 16| B4          S=A+B+CIN
 S3 |2       15| S4
 A3 |3       14| COUT
 B3 |4       13| CIN
VCC |5  7483 12| GND
 S2 |6       11| B1
 B2 |7       10| A1
 A2 |8        9| S1
    +----------+
 
I normally clip on to one of the decoupling capacaitors... +5 to the cap... gnd to the metal plate or one of the screws.

That's where I attach mine, so much easier and less risky. You can get GND at pretty much any screw hole and the leads on the large caps are much easier to clip on to.
 
Not for all TTLs...
Code:
7483
4-bit binary full adder with fast carry.

    +----------+
 A4 |1  +--+ 16| B4          S=A+B+CIN
 S3 |2       15| S4
 A3 |3       14| COUT
 B3 |4       13| CIN
VCC |5  7483 12| GND
 S2 |6       11| B1
 B2 |7       10| A1
 A2 |8        9| S1
    +----------+

Okay... maybe not all. But 95+% of them. :)
 
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