VC8145 thread ... It's here, finally

[TunerSandwich]

they really should have considered better thermal management.....with that case packed so tightly, a fan would have been smart.....   Maybe you could "hack it" and add a full water cooling loop and some peltier.....be safe

[TunerSandwich]

. Now you have the perfect multimeter that you can easily modify.

 

[Dave92F1]

Does anybody know if the VC8145 is the same as the Unisource DM1105B?

See http://www.testequipmentdepot.com/unisource/multimeter/dm1150b.htm

I can only find two or three places online that sell the DM1105B, and they all charge about double what the Vichy (now "Vici" VC8145) goes for.

The two units look pretty much identical, and seem to have identical specs.  Either it's the same unit rebranded, or one is a pretty exact clone of the other.

I suspect the former (rebranded Vici).

[nctnico]

That DM1105B looks exactly like the VC8145 and the specs are also identical. I think the DM1105B is an expensive rebadge.

[Dave92F1]

I couldn't decide between the Rigol DM3058E and the Siglent SDM3055.  I wanted the sexy color screen of the Siglent, but the quality and reputation that goes with the Rigol.

So, after much indecision, I decided to save $300 and ordered a Vici VC8145. 

I'm not expecting it to match a $450 meter in terms of build quality or features (in fact, it looks a bit junky), but it will stack on my bench, has serial output for data logging, and a nice big readable display. If it basically works to spec, I'll be happy.

I'll post a review once I've had time to play with it (ordered from China, so it'll be a few weeks until it gets here).

[Macbeth]

I couldn't decide between the Rigol DM3058E and the Siglent SDM3055.  I wanted the sexy color screen of the Siglent, but the quality and reputation that goes with the Rigol.

So, after much indecision, I decided to save $300 and ordered a Vici VC8145. 

I'm sure it will be fine. In fact I am warming to it as I would modify it by adding a re-chargeable lithium battery, a $4 HC06 transceiver, and finally cut the case down to size for portability and saving bench space.

A nice portable 4 _7/8 digit bench DMM with bluetooth datalogging to my phone, laptop, PC... for only £110 ish, hmm... 

[gfiber]

I have owned a VC 8145 for some 5 or 6 years now. It is not labeled Vici however. It seems to be accurate though I have not tried every function on it. You will want some nice rubber feet on the bottom as it slides all over when pressing the buttons to change settings. I do not like the 'stand" or handle as it makes the face set up to high if on the top shelf of the bench riser. The beeps well they will wake you up. Otherwise for everything I measured it agreed with my old Fluke 77. I need to try the RS-232 output on the thing.

I am replacing the VC8145 with a Rigol 3058E and a recently acquired a Keithley 175A, though I need to replace the lighting strip in the Keithley as it s pretty dim.

[Dave92F1]

I'm sure it will be fine. In fact I am warming to it as I would modify it by adding a re-chargeable lithium battery, a $4 HC06 transceiver, and finally cut the case down to size for portability and saving bench space.

A nice portable 4 _7/8 digit bench DMM with bluetooth datalogging to my phone, laptop, PC... for only £110 ish, hmm... 

I was thinking much the same. Somehow I never have enough DMMs around, so someday I'll upgrade to a better one (probably the successor to the Rigol DM3058E, whenever they get around to that...) and the VC8145 will be a nice spare meter for various uses then.

[Dave92F1]

I have owned a VC 8145 for some 5 or 6 years now. It is not labeled Vici however.

According to http://www.vicimeter.com/en/newshow.asp?sendid=117 they changed their name from "VICHY" to "Vici" in April 2014. Probably somebody told them they'd spelled the Latin "vici" ("I see") wrong... Chinese can be amazingly casual about spelling of Western words. I suspect "Rigol" was meant to be "Rigel" (the star).

Do you know how to calibrate it?  From the photos there seem to be 4 trimpots (or trimcaps) in the VC8145.  I was thinking of contacting the Vici company in China and asking directly.

(Still waiting for mine to show up.)

[gfiber]

No I don't know how to calibrate it. The manual is small both in size and print. I need to blow it up a bit though it is in PDF format.

I just looked at my VC8145, no manufacturer name imprinted on it at all, not sure if it is a Vichy though I think it is as I bought it from Ebay. Never had any trouble with it, never even opened it up. I see the bottom has 8 screws two on each foot can't imagine it takes that many to hold the case together. The power connection and RS-232 ports are all screw mounted not snap on.
 
Once I get done with with my bench revamp I will play with this meter a bit to see what it does. Just used it for voltage readings in the past, though I liked it having a db capability.

[Dave92F1]

FWIW, mine has arrived and I unpacked it today and played with it a bit.

For $150, it's a very good meter.  It's not a $450 meter, tho (of course), let alone a $1100 Agilent.

Big, bright, easily readable display.

It does beep a lot needlessly, but I don't find it too annoying. The continuity check is not latching, but it's fast and loud - good enough for me.

I checked accuracy against a Doug Malone DMMCheck, a Fluke 876B, and a 40 year old 5.5 digit Systron Donner 7205 meter (in reasonably good calibration).

It's accurate - clearly within the stated specs (but not perfect of course). Not as accurate as the Systron Donner, but a digit more than the Fluke and always in agreement +/- 1 count (of the Fluke). In particular in most modes I notice it doesn't read zero even if you short the leads (it reads up to 5 counts away from zero). Not a big deal, and probably normal for a 80,000 count meter in this price range.

But it would be nice to figure out which trimpot adjusts the zero reading.      (But it has the relative measurement function, so you can do it manually if you really want.)

The backlight doesn't come on by default (for no reason, considering it's AC powered), and it doesn't remember that it was turned on the next time you power it up.

On the other hand, if I hold down the backlight button on power up, and keep it held down, it boots OK, backlight goes on, and everything works. So I could just short the button closed if I really wanted - not sure if it bothers me enough to do it yet.

I haven't tried the RS-232 output yet; tomorrow, probably.

Anybody who wants to know anything about it, just ask.

[Dave92F1]

Oh - another small annoyance. The LCD contrast is setup so that it's clear when looking at the meter from ABOVE - it's kind of washed out when viewing from the same height or below.

Which makes little sense for a bench meter, usually they go on the top shelf.

[Lightages]

I was looking for a bench meter just for the convenience. I considered the VC8145 but decided that a used Keithley 197 was much better value. I have one on the way. Why?

I have a a counter made by Victor and I am not impressed with the build quality. It works but I would rather have something used with a very good reputation even if I lose the data connection. The VC8145 is not going to match the build of the 197.

[Dave92F1]

The VC8145 we're talking about is made by Vici (used to be "Vichy"), not Victor.  Altho Victor does make a model 8145 - that's a totally different unit.

[Lightages]

Yes, I realize the difference in the manufacturer, but Victor seems to be better built than Vici!

[Dave92F1]

From the photos and manuals I've seen, I agree - the Victor build quality is better than the Vici.

But I wanted RS-232 output in a bench meter with good accuracy & resolution, and the Vici delivers that at a good price.  But I'll agree the build quality is lousy and this meter probably won't be around 20 years from now.

FWIW, I emailed the Vici company today asking about the contrast adjustment and calibration. If I get any reply at all (I don't really expect one), I'll post here.

I just finished hacking the backlight on the Vici make it come on at power up.  Just one jumper:

[Dave92F1]

I've had a chance to play with the RS-232 output a little.

The software supplied with the unit is beyond horrible. It doesn't run on x64 versions of Windows at all - 32 bit only. And it's really, really clunky.

It's 9600 baud; I haven't puzzled out the protocol yet. I'm looking to see if one of the (many) open-source DMM reading programs will work...

The RS-232 optocoupler is powered by the RTS line from the terminal (PC).  If your USB-RS-232 hardware/software doesn't raise RTS, it won't work.  It's working with RTS at +12 volts (per the RS-232 spec), but some USB/serial adapters only supply +5 or so; I don't know (yet) if that'll work.

[nctnico]

Which software included with a test instrument isn't horrible? They all are whether they come from an A-brand or a small Chinese brand! The software is there to show the communication works; it's up to you to tie it into your automated test environment.

[Dave92F1]

Which software included with a test instrument isn't horrible?

I've only seen software from Chinese suppliers - V&A (DMM), Uni-T (DMM), Rigol (oscilloscopes). And yes, they are all horrible. (I'd like to think that somebody out there offers software that isn't horrible, but maybe not.)

That's not a huge problem if the protocol is documented so you can write your own software. As far as I can tell, the VC8145 protocol isn't documented anywhere.

Poking around a little, it seems that if I interrupt the data stream from the PC to the VC8145, the DMM often crashes in some semi-spectacular way (beeps, crazy stuff on the display).  Not good, but a full power cycle does fix it OK.

On the plus side, I discovered that way that in principle it should be possible to adjust the display contrast - once when it crashed I got crazy random illuminated segments - but with excellent contrast from below...  :-)

I still think that it's a good value for the price. But some of these things would be trivial to fix at basically no cost. (Like releasing the protocol, calibration, and contrast adjustment details...even in Chinese would be fine - Google offers good-enough translation.)

[Dave92F1]

Today I did a little accuracy check comparing the VC8145 to my other DMMs and a recently calibrated (< 1 month ago) DMMCheck.

Here is error in the range +2%/-1% of reading:



and, zooming in on +/- 0.3% of reading:



This should be taken with a few grains of salt:

• This is one test on one date of one sample of each instrument.
• I haven't checked all modes or ranges - just these few.
• The SD7805 and UT61E were calibrated in the last year. The others are at the original factory calibration.
• The VA18B shows 3 1/2 digits, the Fluke and Uni-T show 4 1/2 digits. So the "dead-on" results in some cases just means it's correct to the LSD; a meter with more resolution may show a bigger error while actually being more accurate.

The VC8145 seems to be out of spec on the 1 mA test - it's off by about 0.7% (spec is 0.5% + 10 counts). Other than that it's within spec.

Of these 5 meters, the VC8145 has by far the best user interface - it's fast and convenient to use.  The SD7205 is the only other bench meter here - it's really accurate but otherwise outclassed in every way, it has very little in the way of features - not even autoranging.

[Mayor C]

It seemed to fit the  bill for what I wanted out of a meter and I must say I am very happy with it. I was using handhelds and was getting very POed with them falling over and turning as I was using them. I am not building space shuttles so I don't need anything super accurate and I won't be wearing anything out. Generally as I am working I use a magnifying glass to look through, the meters were always a look around, I put the Vici on a shelf and the large display is easy to see as I glance up. The other comments of it needing rubber feet are right on the money and I added them to mine. I may buy another and try to get all the handhelds off my bench, the dual display gets rid of two at a time.

I must admit, this is just a hobby to me, I usually build stupid little circuits, solder them together and throw them in the trash after I get them working. Other than the odd Arduino project I don't keep anything I make.

[k2teknik]

The chip (set) used is FS9704b http://www.ic-fortune.com/upload/Download/FS970X-DS-44_EN.pdf
This chip is not listed on http://sigrok.org/wiki/Multimeter_ICs
My instrument use 9600,8,N,1, have to use HW handshake to make communication work (ref voltage to signal, no communication on handshake signals)
It looks to me that the RS232 communication is done by the FSuP01 chip, I can't find info on that beast.

I had attach two files with loggin af communication, one Rx and one Tx, I may have tell that these file in byte format, so no sence to try to "read" them with Notepad etc.

Just added two more pictures, one of the UP board, remark the mode selector option, the second pic is the FS9704b chip, remark the apperently 8k/80k "thing".

Added 21-04-2015: This link http://xuewen.cnki.net/ArticleCatalog.aspx?filename=1012380427.nh&dbtype=CMFD&dbname=CMFD2012 maybe hold interisting info on the chipset (FS9704 + FS?P01), but I can't read Chinese or even make an acount to download the thing 
The SW for UNI-T UT70C works with the VC8145, except that the decimal point is in wrong position (Uni-t UT70C is 8000 counts, VC8145 is 80000 count).

Added 26-04-2015: Link to the Holtek HT48R30A data http://www.holtek.com/english/literature/IO_hb_3rd.pdf

[dev26]

Here are results of my reverse engineering attempt of the RS232 protocol: http://www.26th.net/blog/vichy-vici-vc8145-digital-multimeter-rs232-protocol/

[Lightages]

One thing I noticed in the manual is that the ACV accuracy is beyond terrible for values > 75% of each range: 8% of reading + 50 digits. Also note that ACV is only specified for frequencies >= 50 Hz.

As alm pointed out a long time ago, the AC measurement accuracy is horrible, worse than a joke. How do you guys reconcile that. Any handheld multimeter in this price range has much better specs.

[nctnico]

Utter nonsense. The ACV range is limited. If you stay within 75% of the range and between 50Hz and 20kHz it's accuracy is 0.8% of the reading +/-50digits. This is better than my (4.5 digit) Agilent U1241B handheld DMM which already is at 2% at 2kHz. At least Vici took the effort to characterise their meter properly so you have some clue what the readings outside the specs are worth.

You try to write bad things about the VC8145 every time. This time about a post from 2012. Why did you dig that up, quoted the wrong specs and say it is a joke without any technical merit? I know you import multimeters into South America. Why don't you start selling the VC8145 over there as well? Or is your competitor killing you with it?