I just received an oscilloscope I bought off eBay. I'm trying to test
it but can't seem to get any vertical deflection. I setup a little LED
flasher with a 16F88 and put it in INTRC+ClkOut. When I measure the
clock frequency with my multimeter I get 62kHz. But I can't get the
scope to show any deflection. I was expecting to get a square wave
with a peak voltage of 5v.

I don't have the manual. It's a Tektronix 2336 100mhz. Any ideas?

On May 4, 8:30 pm, "rpsomm...@gmail.com" <rpsomm...@gmail.com> wrote:
> I just received an oscilloscope I bought off eBay. I'm trying to test
> it but can't seem to get any vertical deflection. I setup a little LED
> flasher with a 16F88 and put it in INTRC+ClkOut. When I measure the
> clock frequency with my multimeter I get 62kHz. But I can't get the
> scope to show any deflection. I was expecting to get a square wave
> with a peak voltage of 5v.
>
> I don't have the manual. It's a Tektronix 2336 100mhz. Any ideas?

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

Regards,

Mark

On May 4, 8:51 pm, redbelly <redbell...@yahoo.com> wrote:
> On May 4, 8:30 pm, "rpsomm...@gmail.com" <rpsomm...@gmail.com> wrote:
>
> > I just received an oscilloscope I bought off eBay. I'm trying to test
> > it but can't seem to get any vertical deflection. I setup a little LED
> > flasher with a 16F88 and put it in INTRC+ClkOut. When I measure the
> > clock frequency with my multimeter I get 62kHz. But I can't get the
> > scope to show any deflection. I was expecting to get a square wave
> > with a peak voltage of 5v.
>
> > I don't have the manual. It's a Tektronix 2336 100mhz. Any ideas?
>
> 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.

<r...@gmail.com> wrote in message 
news:1...@q75g2000hsh.googlegroups.com...
>I just received an oscilloscope I bought off eBay. I'm trying to test
> it but can't seem to get any vertical deflection. I setup a little LED
> flasher with a 16F88 and put it in INTRC+ClkOut.

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.

<r...@gmail.com>

** Groper Alert !

> I've tried both channels on AC and DC.



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

    Nothing at all ?



.......  Phil 

<r...@gmail.com> wrote in message 
news:1...@q75g2000hsh.googlegroups.com...

> I just received an oscilloscope I bought off eBay. I'm trying to test
> it but can't seem to get any vertical deflection. I setup a little LED
> flasher with a 16F88 and put it in INTRC+ClkOut. When I measure the
> clock frequency with my multimeter I get 62kHz. But I can't get the
> scope to show any deflection. I was expecting to get a square wave
> with a peak voltage of 5v.
>
> I don't have the manual. It's a Tektronix 2336 100mhz. Any ideas?

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.

On May 4, 9:21 pm, "Bob Myers" <nospample...@address.invalid> wrote:
> <rpsomm...@gmail.com> wrote in message
>
> news:1...@q75g2000hsh.googlegroups.com...
>
> >I just received an oscilloscope I bought off eBay. I'm trying to test
> > it but can't seem to get any vertical deflection. I setup a little LED
> > flasher with a 16F88 and put it in INTRC+ClkOut.
>
> 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.


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.

Bob Myers wrote:
> <r...@gmail.com> wrote in message
> news:1...@q75g2000hsh.googlegroups.com...
>> I just received an oscilloscope I bought off eBay. I'm trying to test
>> it but can't seem to get any vertical deflection. I setup a little
>> LED flasher with a 16F88 and put it in INTRC+ClkOut.
>
> 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.

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. 

r...@gmail.com wrote:

> 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.

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.