Beginning Oscilloscope Question

Just taking a guess here, is there a knob that is set to "ground" or "gnd" instead of DC or AC?

Regards,

Mark

I've tried both channels on AC and DC.

You put in in WHERE? On the images I've been able to find of the 2336, there doesn't seem to be any such input.

Bob M.

** Groper Alert !

** What ** ARE ** you seeing on the screen??

Nothing at all ?

....... Phil

Forget the probes. Just touch the input pin with a small screwdriver while you are holding the metal shaft. You should get a ragged wave.

Poor wording on my part. I was (am) just using a little PIC program to generate a flashing LED so I know the circuit is working. I put the PIC16F88 into the INTRC+ClkOut mode. Which, if my understanding is correct, outputs the internal oscillator clock signal on a I/O pin. PIC program:

org 0 goto main org 0x100 main bsf STATUS, RP0 movlw 0x0 movwf 0x5 bcf STATUS, RP0 loop_3 movlw 0x2 movwf 0x5 loop decfsz 0x20, f goto loop movlw 0x0 movwf 0x5 loop_2 decfsz 0x20, f goto loop_2 goto loop_3

When I turn the circuit on the LED flashes as expected. And, if I use the frequency counter on my multimeter between the clock output pin (on the PIC) and ground I get about a 60khz reading. However, if I attempt to sample the same signal with the scope I get nothing but the horizontal sweep. I've tried different combinations of V/div and Time/ Div.

The only things I've been able to make the scope do is slow the h.sweep down enough to see the scrolling dot. I've even tried to see if I could get a DC offset with a battery, nothing.

He's referring to the way he set up the PIC. He is using the internal oscillator block and having it simultaneously present the instruction clock on an output pin. He is trying to see that clock signal.

Ok, it's triggering then. Have you made sure that the probe is switched to the X1 or X10 positions? Do like Homer said to make sure it's not the probe. Outside of something basic like that, it doesn't sound too good, but I would think it kinda odd that both channels would be dead.

I've tried both 1x and 10x on two different probes (although I purchased them from the same person on ebay at the same time). Messing with various settings I've gotten it to the point of having the screen blank unless I touch something metal, and then it will do a horizontal sweep. But I've still not been able to get it to show any vertical deflection.

The first time I powered it on, both channels were displayed on the screen and I was able to use the V.Position knobs to move the individual traces around, ever since first turning it on I haven't even been able to get that much, and the V.position knobs do nothing now. I'm wondering if something is wrong with the vertical circuit.

You've set both channels to max sensitivity?

Do you get any deflection when you probe the +5V ?

Graham

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Michael A. Terrell
Central Florida

Yes, same thing.

No.

You must be better than I am at it. I've spent a lot of time searching through their Manual Finder section and have not found a manual for the 2336. I found a service manual for a 2236, but on a different site.

You do realize taht ebay isn't the best source of quality(i.e. working) equipment? Its probably the largest source of con arists and scammers that exist.

I couldn't find it there either, but you can get it at

The site is very slow and hard to get in, but I did finally get the manual. You might try here also

Mike

"As we survey all the evidence, the thought insistently arises that some supernatural agency - or, rather, Agency - must be involved. Is it possible that suddenly, without intending to, we have stumbled upon scientific proof of the existence of a Supreme Being? Was it God who stepped in and so providentially crafted the cosmos for our benefit?" George Greenstein - Astrophysicist

at

Yes, I found the manual for the 2236, unfortunately I have the 2336. I tried the baseline test procedures from the 2236 manual as much as I could. I don't seem to get the 1khz square wave when I test the calibration output on the device.

Ok Jon, no need to rub salt in the wound. :-) E-bay is what it is, a cross section of society; the good and the bad. I've gotten some great deals on E-bay, but I've been rooked a time or two as well. Could be that the scope worked perfectly and that it was damaged in shipping, or any of a number of other possibilities. Before passing judgment, maybe we should wait to see how the seller treats the OP.

Just a guess, since it seems I was having a similar problem with my scope (Tek 2235 - 100Mhz). Are you grounding the probe? There should be a clip that comes off the probe to ground it. Sorry if my answer seems obvious, just thought I'd throw my 2 cents in. Good luck.

Scott

I haven't passed judgement. I'm just pointing out a fact about ebay. The real issue is that ebay doesn't really care about it. If it any fault then it would be ebays.