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Products => Test Equipment => Topic started by: chrisnotton on March 25, 2023, 10:39:03 pm

Title: Hitachi Oscilloscope V695 etc.
Post by: chrisnotton on March 25, 2023, 10:39:03 pm

Good evening all,

I have just acquired one of these on Ebay. I used to have one (that was stolen) in the 80's and found the auto-timebase feature particularly useful for audio applications, and lining up tape machines etc. I have been a Tek guy ever since but recently I find myself working on tape-machines again!  |O This bargain popped up so.............

The scope I bought has a few dirty switches but the only annoying thing is that the trace horizontal is off-centre by about 5mm. I have read all the posts i can find and downloaded the service manual but cannot see an obvious trimmer for this alignment.

Does anyone have the alignment procedure, or know where this adjustment is located? I will have to disassemble somewhat to access the dirty switches but I would imagine that the adjustment must be moderately accessible for calibration.

Thanks in anticipation

Chris

Title: Re: Hitachi Oscilloscope V695 etc.
Post by: grumpydoc on March 25, 2023, 10:47:49 pm

When you say "trace horizontal is off-centre by about 5mm" what do you mean exactly?

Photo would be good.

Title: Re: Hitachi Oscilloscope V695 etc.
Post by: chrisnotton on March 26, 2023, 08:38:26 am

The centering; the traces start 5mm. to the right of the graticule. No photo available at the moment. Sorry for the ambiguity! 😉

Title: Re: Hitachi Oscilloscope V695 etc.
Post by: grumpydoc on March 26, 2023, 02:17:07 pm

OK, so you've only got half a trace?

Can you use the h.pos control to move the trace (that's selected with the function toggle switch)

Double check you're not in a delayed sweep mode and x10mag is off.

Title: Re: Hitachi Oscilloscope V695 etc.
Post by: chrisnotton on March 26, 2023, 09:11:25 pm

I have tried but there is not enough adjustment. I have just found the alignment procedure in a different online manual.  ;)
I am going to study that.
Thanks

Title: Re: Hitachi Oscilloscope V695 etc.
Post by: grumpydoc on March 26, 2023, 10:00:42 pm

OK

Have you checked all the power supply voltages?

The first thing the procedure does is ask you to position a dot in the centre of the graticule in x-y mode so that you can adjust the CRT bias.

I presume you found some of my old posts on these 'scopes eg

https://www.eevblog.com/forum/testgear/teardown-hitachi-v1065 (https://www.eevblog.com/forum/testgear/teardown-hitachi-v1065)

There is a trimmer for H Pos Start - it's RV 807 on the schematics that I have and it's on the CPU/horizontal board - you can see the label for it on the silkscreen in my photos. The pots on that board can be accessed from the bottom of the 'scope as the Y board is a bit shorter (again, see the teardown photos for the CPU board - RV807 is readily visible).

PS: If you feed a signal in - the probe "calibration" square wave will do, is the trace basically OK, just too far to the right. or is it distorted at all?

Title: Re: Hitachi Oscilloscope V695 etc.
Post by: chrisnotton on March 27, 2023, 02:43:13 pm

Thanks,

I'll check the PSU voltages and start from there. The scope seems to function normally except all the traces on the display start after the graticule. I have read your teardown posts, Very helpful!

I'm away at the moment so will have a go when I'm back.

Thanks for your help

Chris