Hitachi V-1065A Scope Problems...

[Spork Schivago]

Hey guys, I got the broken part fixed on my first scope, as some of you might know. I am having some issues compensating the probes. I've done some reading and watched some videos on it. It's a X100 probe I'm trying to compensate and I can get a square wave on the screen but it is extremely small. It's very hard to see. The squares don't go very high. Even if I hit the X10 Mag, which, I don't think is supposed to magnify the wave. I might of misunderstood what I read. Is there any way to make it bigger?

Spork Schivao

[tom66]

Re: Hitachi V-1065A Scope Problems...

It's an X100 so has 1/100th normal amplitude. Try setting amplitude to 100x higher gain. e.g., if it suggests 1V/div use 10mV/div.

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

Okay, how to I tell what the probe suggests? Sorry for all the questions, real new at this. I received a paper with my probes. For the X100, it says When used with another instrument (meaning not the scope it was designed for), the scope must have an input impedance of 1 MΩ. The Imput Capacitance is between 14.5pF and 17.5pF roughly. Maximum working input voltage <2000VDC+Peak AC....that's all I see that might be of interest.

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

Also, these are the two controls I don't fully understand yet. This is what the manual says about them. One is called the VARS control, the other is called the VOLTS/DIV control.

9) VOLTS / DIV (smaller inside knob):
This is a step attenuator which selects the sensitivity. Set to appropriate range according to incoming signal level.

10) VAR controls (larger outside knob):
*Provide a continuous variable deflection factor. Attenuation of up to 2.5X is obtained by turning in a counterclockwise direction.

*These controls are useful when comparing two wave-forms or when measuring the rise time of a pulse.

*Normally turned fully clockwise to the CAL position.

[tom66]

Re: Hitachi V-1065A Scope Problems...

VARS = leave in cal almost always, you rarely need to change it,

"Probe suggests" did you get a manual with your probe? That is what I meant.

VOLTS/DIV = this controls the scale in the vertical axis. Each square approx 1cm^2. Each cm in vertical axis one div. Each div represents what VOLTS/DIV control is set to.

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

I only got a small, maybe two page, book. It doesn't mention anything about VOLTS/DIV. It has nothing like that on there either...One probe is a X100 100MHz and the other is a X10 100MHz probe. Both probes came with the same booklet, just different specifications for the probes. I believe the probe I'm currently trying to compensate is a T3100. If I just start messing with the VOLTS/DIV setting, could it damage anything? Or could I just start changing it until I get a good amplitude?

[tom66]

Re: Hitachi V-1065A Scope Problems...

No risk of damage from changing volts/div.
Set scope to 10mV/div, then connect 100X probe to compensation point, you should see a (possibly distorted) square wave occupying one or two divisions. If your scope has 5mV/div or 2mV/div options, try those too.

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

Thank you, one last question. I do not understand the purpose of the DC / AC button. Is that for me to switch if I'm working with AC current or DC current? And the GND button....I should have that enabled (pushed down), right? That means it's using the ground in the scope instead of the ground on the circuit, correct? Thanks again.

[tom66]

Re: Hitachi V-1065A Scope Problems...

AC option applies a highpass filter set at approx 3Hz which rejects the DC component... in a nutshell it strips the DC but leaves most of the AC present (all signals are equivalent to one or more sine waves at distinct frequencies (Fourier theorem), and DC is considered a 0Hz frequency.) This is useful for example trying to measure noise on a DC power rail which is only a few millivolts. You couldn't set the scope to DC and 10mV/div because the DC would overwhelm the display and you'd see nothing. Getting rid of the DC component allows you to see the important part, the noise.

The ground option essentially connects the input to ground. You don't use it in normal operation. It's only used as a quick way to get a ground reference in case you've moved the vertical offset from the baseline.

For most cases leave the scope in the DC mode, GND off.

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

Thank you so much Tom66. I cannot wait to actually use this to fix this TV I have. The OSD doesn't work. You can turn the channel, volume, hit menu, nothing shows up...no black boxes, nothing. Do you know if there's anything I should not do? Something that would or even could possibly damage my scope? Thanks again.

[tom66]

Re: Hitachi V-1065A Scope Problems...

Do not even think of bringing the scope near the HOT side of the circuit, the FBT (flyback) @~30kV or the focus voltages @~3kV. Other than that, you should be good.

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

I don't know what the focus voltages are. I can put it on any IC though, right? Also, for the 1x / 10x probe, I had to change the VARS control (it said I'd almost never take it off CAL) it around 20mV in order to see the top and bottom of the edges on the same screen. When it was on CAL, the top and bottom were off screen. Is that normal? Did I misunderstand the VARS control? Thanks again for the help! I got them calibrated pretty well now!!!! Still need to figure out what the Source or X knob, Trigger knob and the Mode knob does...I think I can google that. The manual seems to be in Japanese. I mean it's English but it might as well be Japanese. I think the Source knob has something to do with maybe what hookup I have it hooked too? The Mode one confuses me. TV-V TV-H, Auto, Normal, etc...

[tom66]

Re: Hitachi V-1065A Scope Problems...

ICs are usually fine, as long as they are on the secondary side. Just don't bring it near the CRT connections, which you don't need to probe anyway.

VARS: Leave it in CAL for -almost every application-.
Set your scope to AC couple for the probe comp.
First press GND. Center trace with V offset.
Then release GND. Set to 10mV/div. Connect to probe comp. What do you see?

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

What does V offset mean? Does that just mean center it to the center of the screen? For the 10mV/div, I change the VOLTS/DIV pot...the inner one, the one that changes the spread, how far apart the lowest part of the wave is to the highest part. I have to let it warm up for 20 minutes before I can do this, according to what I've read. In twenty minutes or so, I'll post back.

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

I typed that earlier but didn't realize I wasn't signed in. I have ran the tests and these are the results. When VOLTS/DIV set to 10mV and the line centered in the screen with GND pushed in and AC/DC set to AC, I release the GND and hook up the probe.

The screen is all jacked up. I cannot see anything, just very faint lines going vertically up the screen. When I adjust H-POS all the way up, I can see the bottom lines. If I just it all the way down, I can see the top lines. If I change the VARS to 20mV, I can see the squares perfectly. I'm wondering if in the manual they got the two mixed up. It seems to me like the one called VARS changes the distances between the very bottom line and the distance between the very top line. The higher I go, the smaller the distance. Here are some pictures...

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

The user and service manual must be messed up. On the second input, it shows that the smaller "inside" pot is for VAR and that the larger "outside" pot is for VOLTS/DIV. The opposite of what it says for the first input (channel 1). And when I change the one that is supposed to be VAR for the first channel, it works right. It has to be a typo. That's all that I can think of.

[tom66]

Re: Hitachi V-1065A Scope Problems...

Volts/div is the COURSE control, it moves in discrete individual increments, VARS is the variable control which is fully variable. If set on AC coupling, neither should significantly move the trace in the vertical axis.

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

Volts/div is the COURSE control, it moves in discrete individual increments, VARS is the variable control which is fully variable. If set on AC coupling, neither should significantly move the trace in the vertical axis.

5mV is off the screen, 10mV is about 5 squares from bottom to top, 20mV = 2 1/2, 50mV = 1 square...

The controls are definitely mislabeled in the manual for probe 1. When I push a button in, it's set to DC, when the button is out, it's AC. When it's AC, that means that AC coupling is set, correct?

[Spork Schivago]

Re: Hitachi V-1065A Scope Problems...

Sorry for the delay, I've been watching that long video someone (I think you) gave me a link to on how to use this thing.

[tom66]

Re: Hitachi V-1065A Scope Problems...

Yes, you want to have it set to AC.