Iwatsu VOAC 7602

[radhaz]

http://www.iti.iwatsu.co.jp/en/products/voac/voac7602_top_e.html

Some pics of the internals.







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[mairo]

Nice pics!
So they are using TI's ADS1256 as a main ADC?

[radhaz]

Nice pics!
So they are using TI's ADS1256 as a main ADC?

I don't know much about instrument design. When I bought this DMM, I promised I would post pics of the inside. It hurt me cutting the tamper seal.

[lukier]

Strange design. ADS1256 INL is up to 10 ppm, 34401A for example is 2 ppm reading + 1 ppm range. Also, while LM399 is a great reference it has to be divided down to 2.5V and a divider that doesn't drift (especially with temperature) is gonna to be expensive. LTC6655 in a hermetic package could be better. Not as stable as LM399, but less noisy and 2.5V already.

[chickenHeadKnob]

Nice pics!
So they are using TI's ADS1256 as a main ADC?

I don't know much about instrument design. When I bought this DMM, I promised I would post pics of the inside. It hurt me cutting the tamper seal.

Your pain, our joy. You took a hit for the team,   thanks

[radhaz]

What I find interesting is the clean build of this meter. There are no flying wires across the unit, the operational sections seem to be well isolated and physically separated from each other. Looks like a good design. I will be interested in the critiques of the EEVblog community of this DMM.

[fanOfeeDIY]

What I find interesting is the clean build of this meter. There are no flying wires across the unit, the operational sections seem to be well isolated and physically separated from each other. Looks like a good design. I will be interested in the critiques of the EEVblog community of this DMM.

Would be nice if you have time to post front and back pictures with some powered on and measuring something.

[BloodyCactus]

thanks for the pics, i still want to get one of these! very clean looking layout!

[radhaz]

What I find interesting is the clean build of this meter. There are no flying wires across the unit, the operational sections seem to be well isolated and physically separated from each other. Looks like a good design. I will be interested in the critiques of the EEVblog community of this DMM.

Would be nice if you have time to post front and back pictures with some powered on and measuring something.

Well, to see the front and the back, you only have to go to Iwatsu's site.
For measuring something, I was looking at the bias of a Sony 4650 V-Fet integrated amp that I was restoring:
https://flic.kr/p/G9PAF6
The analog meter mode, with min max, very useful.

[fanOfeeDIY]

Well, to see the front and the back, you only have to go to Iwatsu's site.
For measuring something, I was looking at the bias of a Sony 4650 V-Fet integrated amp that I was restoring:
https://flic.kr/p/G9PAF6
The analog meter mode, with min max, very useful.

Your tear down pictures of Iwatsu VOAC 7602 are fantastic.
The pictures of front panel with powered-on at the Iwatsu site looks a bit animated and they are small.
I just thought we could have a better pictures here from the real product.

 

[robert_]

Nice someone finally figured out the battery belongs to the bottom side of the PCB!
Its always a shame to scrap some instrument that was killed by battery leakage. just because the designers always seem to place batteries where they can cause maximum damage when leaking.

That internal mains voltage selection jumper is strange. Why would they not go with the regular rear-mounted switch?

Also, why is the LM399 marked with its old HP part number?

Nice pics!
So they are using TI's ADS1256 as a main ADC?

Certainly not as its main ADC. Probably for some lower-resolution fast-update mode, bargraph or so. Pretty sure it still uses an multi-slope integrating adc built from discrete components, as im not aware of any integrated ADC that could meet the necessary accuracy.

[radhaz]

The display is very good. The selections of what to display is easy to get to with the interface. White and Black backgrounds look very good, I think you will choose these based on your lab lighting situation.
There is no fan, so the unit only makes relay clicking sounds when ranges change.
I would like to know what robert_ thinks about the absolute accuracy of this DMM, given the way it is designed.

Well, to see the front and the back, you only have to go to Iwatsu's site.
For measuring something, I was looking at the bias of a Sony 4650 V-Fet integrated amp that I was restoring:
https://flic.kr/p/G9PAF6
The analog meter mode, with min max, very useful.

Your tear down pictures of Iwatsu VOAC 7602 are fantastic.
The pictures of front panel with powered-on at the Iwatsu site looks a bit animated and they are small.
I just thought we could have a better pictures here from the real product.

[alfishe]

Display is ok, but seems it's TN with strong light bleeding. I know it's not an iphone but still expect top class display from device for such price. Besides that - looks and feels great and modern. Don't have other impressions - just finished unboxing and turned power on for the first time =)

[scopeman]

I realize that this post is rather old but the reason the LM399 has an HP part number is the Yokogawa actually built these DMM's as well as a lot of HP gear. I would bet that they had an arrangement for Iwatsu to sell them under their own name. You can find this exact same meter with the Yokogawa brand on it. IIRC it is the Yokogawa DM7560.

I bought my Iwatsu one when tequipment.net was blowing them out on clearance a couple of years back. I ran a comparison between it and a HP 6.5 digit TrueVolt DMM when it came back from Keysight cal and they both matched digit for digit. It's really a nice meter. I really liked it better operationally better than the HP. I'd call it an HP in disguise as I am sure that they share a common lineage.

Sam
W3OHM

[ResistorRob]

One of my favorite desktop multimeters of all time. I used to drool over them on tequipment.net all the time, then when they put them on clearance I could have bought one but it would have meant eating bread and water for a couple months, lol... so it was my dream meter that got away. It's pretty rare, so I find this thread amazing to see the internals of it.

Luckily my budget is now doing a little better and there are some other color LCD bench multimeters with datalogging. One of my goals for 2021 is to own a meter like that and get a Siglent SDS2000+

Thanks for sharing the photos, and thanks for letting me know about the Yokogawa equivalent. I'm a huge fan of them and Iwatsu.