Hi Richard,
I noticed some pictures you posted, the VP7722 is working on MANUAL mode.
Do you know how to change the range when VP7722 working on manual mode?
Sometimes VP7722 working on MANUAL MODE would be more stable. Press the MANUAL Key near by NO. 3 key twice, then "meas" LED will turn on. I try most the key but no response.
🙁
The 7722 goes into manual mode as soon as you push the freq or amplitude button. You do not have to do anything else.
THx-RNMarsh
THx-RNMarsh
With a few minor modes and updates it's as good or better than anything from AP for distortion measurement.
Thanks, David. It's tempting, although I have to take into account that I'm out of a job after new year.
Cheers,
Mogens
Cheers,
Mogens
Yes, you are right. Shouldn't be a problem. I will say that to the my wife, if she ask 😀.
Also, I just noticed bow that you have described some modifications in this thread. I will have a closer look.
Cheers,
Mogens
Also, I just noticed bow that you have described some modifications in this thread. I will have a closer look.
Cheers,
Mogens
On the day you posted this, yes the price was very good.
It has about doubled since then. Based on the recent bidding history, that is the way of the world.
I had found my 725C have bit high 3rd order distortion at <160Hz.(0.00025% at 10Hz, below 0.0001% at 100Hz)
Finally I found the cause which is A3 board "bridge" capacitor of bridge T.
I had thought it never be the cause why it is soshin's polystylene or something cap!surprise!
I tried replacing parts to parts, trimmer R, metalized cap, jumpering reed relay, fixed resistor, opamps...and finally I found it.
still have other problem, high dist at -5dBV to 0dBV input at low freq, it seems A1 board's beta circuit is the cause.
Finally I found the cause which is A3 board "bridge" capacitor of bridge T.
I had thought it never be the cause why it is soshin's polystylene or something cap!surprise!
I tried replacing parts to parts, trimmer R, metalized cap, jumpering reed relay, fixed resistor, opamps...and finally I found it.
still have other problem, high dist at -5dBV to 0dBV input at low freq, it seems A1 board's beta circuit is the cause.
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replaced with 0.22uF polypropylene cap(not metalized) and 1000pF C0G MLCC paralleled , selected by actual measurement.
And another probrem solved replacing A1 C33 75pF cap. correction, the problematic range is -2.5dBV to 0dBV not -5dBV to 0dBV.
And another probrem solved replacing A1 C33 75pF cap. correction, the problematic range is -2.5dBV to 0dBV not -5dBV to 0dBV.
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Very nice measurements!
Pretty awesome!
I have been trying to find some doc on teh VP-7722 but it is not easy. Schematics I did not find.
I have an AMBER 5500 looking for something that can measure only harmonics, and to lower ditorsion levels. I use "A"-weighting a lot.
Is the VP-7722´s PhosoA the same as a standard A-weighting filter?
/S
Pretty awesome!
I have been trying to find some doc on teh VP-7722 but it is not easy. Schematics I did not find.
I have an AMBER 5500 looking for something that can measure only harmonics, and to lower ditorsion levels. I use "A"-weighting a lot.
Is the VP-7722´s PhosoA the same as a standard A-weighting filter?
/S
The VP7722A is a great machine. I bought 2 of them from eBay over time .... one for California and one for Thailand. Not sure about that filter though. Guess you would have to measure it and compare with A weighted filter response.
Thx-Richard
Just a small teaser on the ShibaSoku AM51B, I'll do a full teardown when I get the chance.
Interestingly, my old 725B beats it in terms of THD+N by a bit, the residual of the AM51 is ~0.00020% (-114dB) THD+N @ 2Vrms, 1kHz/30kHz BW. Oh well, it specs -105dB, it just shows you how great the 725's really are.
On first impressions, it is a nice unit, maybe too nice to mod....nahhhhh. 😀
ASACA corporation does the servicing of the ShibaSoku audio gear now (they got eaten up I think?), I managed to get the AM51B user manual from them, very friendly bunch.
Unfortunately, they said the 725B is too old and they don't have the service manual any more. 🙁
Interestingly, my old 725B beats it in terms of THD+N by a bit, the residual of the AM51 is ~0.00020% (-114dB) THD+N @ 2Vrms, 1kHz/30kHz BW. Oh well, it specs -105dB, it just shows you how great the 725's really are.
On first impressions, it is a nice unit, maybe too nice to mod....nahhhhh. 😀
ASACA corporation does the servicing of the ShibaSoku audio gear now (they got eaten up I think?), I managed to get the AM51B user manual from them, very friendly bunch.
Unfortunately, they said the 725B is too old and they don't have the service manual any more. 🙁
Attachments
Nothing that fancy. Anything too new and it's hard to get stuff
from Shibasoku. Go figure...
If anyone has or isn't using their GPIB board on their ShibaSoku
It wouldn't hurt me to buy one. Mine was damaged from
the leaky battery.
If anyone need a copy of the calibration of the 725C manual
I have and old version that I could share, PM me your email addresses.
Be warned it's written in Japanese.
Cheers,
Sync
from Shibasoku. Go figure...
If anyone has or isn't using their GPIB board on their ShibaSoku
It wouldn't hurt me to buy one. Mine was damaged from
the leaky battery.
If anyone need a copy of the calibration of the 725C manual
I have and old version that I could share, PM me your email addresses.
Be warned it's written in Japanese.
Cheers,
Sync
Sync-
Can you send me a scan of your manual? I have passed around scans of by 725B manual. I'm sure they are very similar.
Can you send me a scan of your manual? I have passed around scans of by 725B manual. I'm sure they are very similar.