EEVblog #986 - Mailbag

[SeanB]

That microcontroller is a mask ROM Hitachi device, which was very common, a small microcontroller with integrated VFD drivers, and which was very common in VCR use as the system controller, doing everything in there from display, keyboard scanning ( using a resistive divider for the wired remote), IR receiver and driving the system all in the same small package. Runs off a 5V supply for the actual micro and a -26V supply for the VFD interface, and handled the scanning for the display all in one chip. Assorted ones all in almost the same package, with enough ROM to run quite a complex system, were all made by Hitachi.

[Paul Moir]

No UL on the Testo?

For European manufacturers UL is nothing but a royal PITA. So if you don't plan to sell to USA, you skip it. Criteria on product safety according to European standards and UL are quite similar, reaching similar levels of safety, but different in many annoying details, so eventually you have the double amount of cost and effort to fulfil both. Some would call this protectionism ...

It's got the CSA (C US) label.  That means that the Canadian Standards Association tested it for certification in the US and in Canada.  If you look at Fluke, they seem to use CSA most of the time.  UL and CSA agreed to cross certify many years ago.  And of course you can also use whatever accredited lab you wish, such as Intertek.

[Fungus]

I found Dave's approach quite unprofessional; he was potentially damaging the reputation of a quality brand for no good reason.

They sent it to him and Dave's motto/methods are well known. 

Having said that, he pointed out several times that he liked the overall design and that it appears to be a very well built, safety-oriented meter. It wasn't a negative review by any means, things like always starting up in AC mode is a plus for electricians.

[ebastler]

I found Dave's approach quite unprofessional; he was potentially damaging the reputation of a quality brand for no good reason.

They sent it to him and Dave's motto/methods are well known. 

Having said that, he pointed out several times that he liked the overall design and that it appears to be a very well built, safety-oriented meter. It wasn't a negative review by any means, things like always starting up in AC mode is a plus for electricians.

C'mon -- take it apart, put it back together (potentially not quite right), and then complain for minutes on end about some flaky behavior?!  Dave suspected that he might have messed with the meter during his teardown. So he should have tried the other meter they had sent, and if that works alright, should have scrapped the test footage from the one he messed up.

[Muttley Snickers]

I'm very interested to see how Testo responds to this mailbag video considering how they recently responded to another video which displayed that the relays incorporated in these meters may be prone to magnetic fields, in my opinion a company or manufacturer who makes a claim that their products are never at fault probably has their head stuck in a dark place and it does nothing more than show sign of a companies arrogance and ignorance, sorry but this attitude lost me as a potential customer.

Dave, If you happen to do a full review I would like to see this magnetic vulnerability further examined on these meters particularly when used in close proximity to coils, motors and other equipment that in normal operation would generate magnetic fields, also if internal shielding were added to these meters would it make any difference to their susceptibility.

Video Comment.




Testo Multimeter Fault.

[alho]

...then kept ranting...
I found Dave's approach quite unprofessional; he was potentially damaging the reputation of a quality brand for no good reason.

Yep. Thats what eevblog videos are these days. Zero Standby Power TV, Worlds shittiest tablet, Batterizer, Solar roadways  seems to be where Dave's channel is heading.  Long rants mocking something.

should have scrapped the test footage from the one he messed up.

Pushing out material that what makes the money, never mind the content. 


Touch Test 20 Multiemter. What a perfect item for it's own video. Multimetter thats not the standard single chip job nor an analog meter with resistor dividers, schematics and all.
But just look at this awful mess of bodge wires, obviously done by some moron.

[Fungus]

Solar roadways  seems to be where Dave's channel is heading.  Long rants mocking something.

...
EEVblog #978 - Keysight 1000X Hacking
EEVblog #980 - RoboMaid Automated Vacuum Cleaner Teardown
EEVblog #981 - Introduction To Digital Logic
EEVblog #982 - HP54616B 500MHz Oscilloscope REPAIR
EEVblog #983 - A Shocking Oscilloscope Problem ! aka Whack Triggering
EEVblog #984 - World's Best Dumpster Find!
EEVblog #985 - Siglent SDS1202X-E Oscilloscope Teardown

Yep, definitely looks that way.

NOT!

[Brumby]

It seems counting red lights is easier than counting green ones.

[McBryce]

It seems counting red lights is easier than counting green ones.

Well since Madagascar 2 we all know how to deal with red lights:



McBryce.

[joeqsmith]

I'm very interested to see how Testo responds to this mailbag video considering how they recently responded to another video which displayed that the relays incorporated in these meters may be prone to magnetic fields, in my opinion a company or manufacturer who makes a claim that their products are never at fault probably has their head stuck in a dark place and it does nothing more than show sign of a companies arrogance and ignorance, sorry but this attitude lost me as a potential customer.

Dave, If you happen to do a full review I would like to see this magnetic vulnerability further examined on these meters particularly when used in close proximity to coils, motors and other equipment that in normal operation would generate magnetic fields, also if internal shielding were added to these meters would it make any difference to their susceptibility.

Video Comment.

That's an interesting problem.  I didn't understand your comments as it appears they are saying the hanger could cause a problem.  I wonder if they mean they removed the strap, shortened it or did something else to solve it.   

I would be more concerned about how that meter was acting after it was taken apart.  For the time spent on the rant, would have rather opened a second meter, not take it apart and run it.  I am still waiting to find out if the $1100 Gossen Energy was a prototype with the tacked on axial resistor.   I wonder if the Gossen's relays will trip the same way.... 

[Fungus]

Really?

What was all that Fluke 12 nonsense about then?

[ebastler]

Those Fluke multimeters are not so "multi", since they can't measure current at all I believe?

[HKJ]

Those Fluke multimeters are not so "multi", since they can't measure current at all I believe?

But "Chauvin Arnoux" have a couple of DMM's without rotary switch in the MTX329x series

[rrinker]

 The Fluke 8060 doesn't have a rotary switch either... just sayin' 

[Cerebus]

I'm very interested to see how Testo responds to this mailbag video considering how they recently responded to another video which displayed that the relays incorporated in these meters may be prone to magnetic fields, in my opinion a company or manufacturer who makes a claim that their products are never at fault probably has their head stuck in a dark place and it does nothing more than show sign of a companies arrogance and ignorance, sorry but this attitude lost me as a potential customer.

I don't believe that you can have actually read the whole comment made by Testo. They acknowledge the problem and then go on to say:

The weak point has been identified and will be eliminated.

That sounds exactly the opposite to

[a] manufacturer who makes a claim that their products are never at fault

[Muttley Snickers]

First up Cerebus, congratulations on almost 1000 posts, just two more needed and you should have open access to the forbidden zone where all the special secret stuff is hidden away from those silly normal people.   

I don't believe that you can have actually read the whole comment made by Testo. They acknowledge the problem and then go on to say:

The weak point has been identified and will be eliminated.

I did in fact read their reply in it's entirety prior to posting, how Testo intend to rectify the issue shown in the video is anybody's guess as I found their reply rather vague and somewhat open to interpretation. As Joe pointed out earlier, they could simply shorten the hanging strap or do away with it altogether, my question related to whether other magnetic sources in close proximity affected the meter and how one would go about resolving such an issue.

In relation to other meters that do not have rotary dial selectors we did touch upon the subject once before in this thread linked below but I wouldn't know which meters have the specific ability to automatically change selection modes dependent or based on the applied input. I had also posted to link to the same Testo fault video in that thread as well but at the time it didn't receive as much attention as this time around. 

https://www.eevblog.com/forum/reviews/wanted-the-ultimate-multimeter-for-electricians-and-technicians/

[Cerebus]

First up Cerebus, congratulations on almost 1000 posts, just two more needed and you should have open access to the forbidden zone where all the special secret stuff is hidden away from those silly normal people.   

Seeing as it's you pointing this out Muttley, I have to ask:
Do I get a redalmedal?

[Muttley Snickers]

I never got a medal  ,  just a silly certificate.   

[rrinker]

 All I got was some silly t-shirt about negative feedback or something

But I paid for that 

[EEngo]

but the problem with relays and (neodym) magnets is quite interesting.
It's obvious of course but I am wondering which devices we will see failing next ... 

[Clear as mud]

I just saw this video recently, and noticed there's not much discussion here about the Nonlinear Systems Touch Test 20 DMM.  It was quite interesting (about 1/4 of the mailbag video was about it, from about 33 through 45 minutes).

Dave talks about its microcontroller brains at 40:04 through 40:35.  There are three rows of characters marked on the DIP-40 package.  Top line: 51-126.   Middle line: B8647-11.  Bottom line:8052, and some sort of logo, maybe Motorola.  Dave's first thought in the video was that the middle line of text was the model number of the chip.  My first thought was that it was the bottom line, an 8052 processor.  But, on the schematic at 44:32 through 44:42 in the video, the chip is labeled as 51-126 (the top line of text on the actual chip).

I'm thinking the 8052 printed on it is probably a date code.  Most of the components on the board lack date codes, but there are two other similar ones I saw - 8032 on the big blue resistor and something else similar on one of the logic chips after Dave pulls one of the boards out.  A web search does not initially reveal any microcontroller known as 51-126.  It might be part of the 8051 family of microcontrollers.

The logo on the chip is most visible at 40:09 to 40:11, but I still can't make it out,  It's very faded, and I'm not familiar enough with it to know for sure what it is.

At 43:25, "You'd get so excited if you had this back in 1981, let me tell you!  As long as you didn't open it."     Yeah, the PCB layout is pretty wacky.  It's like the company had one designer who had everyone else convinced he was the only one who could do it, but he had a lot of logical faults behind his decisions.