Logic probe

JoeB1355

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What's a good logic probe to get.

Been a while since I used my scope and I think its broke now I can never get it to trigger and weighs 4000 pounds!

so I wanna get a logic probe

PS anyone out there got a 465B scope? maybe I got the settings wrong. I only have 1 probe its seems to measure voltages ok, but I can never get the things to sync -- once and a while I can get its to a slow roll where the pulse are visible but its takes a lot of tweaking and its never locks
 
What's a good logic probe to get.

Been a while since I used my scope and I think its broke now I can never get it to trigger and weighs 4000 pounds!

so I wanna get a logic probe

PS anyone out there got a 465B scope? maybe I got the settings wrong. I only have 1 probe its seems to measure voltages ok, but I can never get the things to sync -- once and a while I can get its to a slow roll where the pulse are visible but its takes a lot of tweaking and its never locks

First off, the manual can be found at http://bama.edebris.com/manuals/tek/465b

Secondly, look immediately below the center of the CRT - you should see a metal lug sticking out of the front of the scope. The manual calls this the 'calibrator' loop (page 2-5). If you probe it, you should find a 0.3v square wave at about 1 Khz. That should let you know if the scope is completely hosed or not. Put your probe tip on it (you don't have to attach the probe ground wire to anything).

You'll want trig mode to be 'norm', the ac/gnd/dc switch to be in the AC position, and the vert mode switch to be set to CH1 (assuming you've got your probe plugged into channel 1).

You'll probably want volts/div to be at .1 or so.
You'll then be able to play with the time/div control until you can see the signal.

If you can't see the signal no matter what you do, then either the probe or the scope is bad. You could try channel 2 instead of channel 1 (just change the vert mode switch to ch 2 and plug it in there.).

good luck!
 
So as it turns out I have a 466 not sure why I was thought it was a 465B (maybe because of the DMM on it)

Here is a video of me measuring the calibrate signal with is on the back of this scope

http://www.youtube.com/watch?v=aQUZHO4ohXo

I just can't get it to trigger and hold steady -- could I use something external? I tried using the calibrate as an external trigger hence the cable I was probing no help

So it kinda works -- just no sync or trigger....
 
So as it turns out I have a 466 not sure why I was thought it was a 465B (maybe because of the DMM on it)

Here is a video of me measuring the calibrate signal with is on the back of this scope

http://www.youtube.com/watch?v=aQUZHO4ohXo

I just can't get it to trigger and hold steady -- could I use something external? I tried using the calibrate as an external trigger hence the cable I was probing no help

So it kinda works -- just no sync or trigger....

OK, it looks to me like you've got trigger mode set to 'auto' (bank of 3 buttons below the time/div control). If I understand things correctly, then you should really set that to 'norm'. If I understand these scopes correctly 'auto' means that the scope ignores the signal as far as triggering, and just runs as fast as it can. 'normal' means that it tries to trigger on the signal.

I could be seeing it wrong, of course, but try that.
 
OK, it looks to me like you've got trigger mode set to 'auto' (bank of 3 buttons below the time/div control). If I understand things correctly, then you should really set that to 'norm'. If I understand these scopes correctly 'auto' means that the scope ignores the signal as far as triggering, and just runs as fast as it can. 'normal' means that it tries to trigger on the signal.

I could be seeing it wrong, of course, but try that.

After you put triggering to 'norm' you'll also need to play with the trigger level control. The trigger level is, if I'm reading the manual correctly, on the right hand side all the way rightwards of the auto/norm/sngl buttons. I think the inner portion is the slope control (rising or falling) and the outer is the level knob? Hard to see on the manual without having the scope in front of me.

Your manual is at http://bama.edebris.com/manuals/tek/466dm44
 
If I put on norm push button no trace -- if I keep messing with the trigger knob its flickers but I never can get it. I do think that knob (or pot behind it is bad). Anyone know or have replacements?

I did get it to trigger on chop which is kinda whack!

I got it working enough though(no trigger still) to track some signals on my asteroids board and found the bad chip!!

Wahoo!!

So --
Scope marginal
Asteroids now good!
 
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Looks fine but I've never been a fan of coiled cords on logic probes. They are a PITA.
 
Mine's labeled 610B and is a simple probe, but it has what counts... separate LEDs for high/low and the audio buzzer.

Agreed. I think our probes were made by the same OEM, too. The "Elenco LP900" is just a generic "625" which is, I think, a beeper-less 610 with an integrated pulser.
 
Is the Mhz speed of any concern for arcade pcbs? I see some probes rated at 20mhz and others at 50.
 
Most of the arcade boards I repair are 12MHz and below...
 
not to hijack but related... What reference books should I be picking up?

I've read the TTL Cookbook and Cmos Cookbook are good choices..

There is some Texas Instruments book?

I think I need a basic reference book showing how each chip functions.
 
Getting Started in Electronics by Forest M Mims III... he also has a couple of electronic cookbooks that are full of digital logic projects. I still have mine from the early 80s. :) It's very tattered.

Outside of that, just Google for some logic primers.

Oh, and learn to count in binary. That will come in VERY handy when dealing with microprocessor circuits.
 
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