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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sat 01, 2014 10:05 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3402
Location: Monterey California USA
I could be wrong but I think the blue thing is a polyester capacitor.

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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sat 01, 2014 11:25 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9533
Location: Powell River BC Canada
The Micronta model 22-164 Voice Meter used four AA cells for a total of 6 Volts.

The cells are in series. However, the midpoint, 3 volts, is also brought out to the power
switch.

It the meter is switched on, and the mid point contact of the power switch does not close,
the meter will work, however, the low battery will show on the LCD, and the meter will say
Replace Battery, and fail to report the scale and value. Another clue is when the contact
is failing, the voice is slightly distorted, and low in volume.

I simulated this effect by using a Heathkit IP 2718, dual voltage tracking power supply on
my bench, whilst investigating this fault, which was occuring intermittently on both of my
22-164 meters.

The solution is to clean the contacts, and if the switch is too badly worm, retro fit another.
It would be an easy task.

As to a proper retrofit of these meters, since they are getting scarce, all seven of
the low voltage electrolytics might be replaced as they are about 30 years old.

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MICRONTA 22 164 VOICE METERS ON THE BENCH.jpg
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Attachment:
HEATH IP2718 DUAL VOLTAGE TRACKING  TEST OF MICRONTA 22 164 VOICE METERS.jpg
HEATH IP2718 DUAL VOLTAGE TRACKING TEST OF MICRONTA 22 164 VOICE METERS.jpg [ 106.78 KiB | Viewed 1683 times ]

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sun 02, 2014 4:59 am 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 485
Location: Lagrangeville New York 12540
I made sure the batteries were in correctly. The sound is clear when it says replace batteries. It says that when I put the switch in the middle position and when I put the switch forward more to the last position the meter sounds short beeps continually and it still says low battery when I press the button.


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sun 02, 2014 8:27 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9533
Location: Powell River BC Canada
What you find is consistent with tests here on my two meters. The beeping is because the CONT
function is on when the power switch is on full-right. The clarity of the speech depends on capacitors,and
need not concern us now.

Change tack here. Plug in only the negative meter lead to your voice meter.
Take the batteries out.

Measure continuity of this meter test lead from the tip to the center joiner bar
in the battery compartment. Turn the meter over to do this .

The joiner is between the second and third battery terminals, closest to edge of the case at the rear top.


That joiner must connect to the meter negative input jack. It should be essentially zero ohms.

Without your talking meter, do you have another method of determining continuity?


On a test on both my meters, I simulated an open circuit between the mid point of the battery
circuit, and the meter electronics by connecting( the black probe tip) to that point on the dual
tracking power supply.


Why might it be open in one of these meters? The printed circuit trace passes from side to side of
the circuit board through several vias. Part of the trace is in a corrosion plane under the batteries.

Joining the circuit externally with a wire under that joiner bar, connected back to the negative jack.
might be a way of doing it. The route is otherwise tricky.


The more I look at this meter, the more complex it appears. It looks like it was made in China in
a small factory, decades before the large scale industrialization. Also both my meters are not identical.

I seem to get the feeling that an old auto ranging DMM chip was married to an external voicing chip.
The speaker is a low profile voice coil unit.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sun 02, 2014 3:48 pm 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 485
Location: Lagrangeville New York 12540
I used a continuity tester and toward the back of the case when I went between the second and third battery contack no continuity but when I touched the second and the third battery contack and hooked the tester to the negative probe I got continuity.


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sun 02, 2014 7:39 pm 
Member

Joined: Sep Thu 23, 2010 6:37 am
Posts: 9533
Location: Powell River BC Canada
The second and third battery contacts are one piece of metal.

The piece of metal is connected to the negative meter jack.

It is also connected to the one of the fuse clips.

There are two fuses, one is a spare which is connected to nothing.

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sun 02, 2014 7:57 pm 
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Joined: Aug Sun 10, 2008 10:19 am
Posts: 485
Location: Lagrangeville New York 12540
okay so that part is grounded right because I got continuity from the terminals to the negative lead wire


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Mon 03, 2014 12:22 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5889
Location: Black Hills, SD 57745
Thanks to Steve for the important bit of info and all your tests. I've sent a PM to Timmy with my address in case he wants me to take a shot at it. He asked in a PM if I had any knowledge of his talking meter, so that's why I'm here. Frankly, I don't have experience with this model, but I'm willing to investigate it since I happen to be very near-sighted. Without my glasses, I can "microscope" a board for typical problems. Good backlighting works wonders for inspecting multi-layer boards. I can bring it to this thread if I encounter problems. Just an offer I made Timmy to try to help and I'm here if needed.

I'm thinking the split supply is to accommodate the old-style op-amps. You'd have +3v/-3V voltages with a common neutral. This meter probably dates back to that age. Any minor break in that battery chain will have a big effect on operation.
-Ed


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Tue 04, 2014 2:10 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1570
Location: St. Paul, Minnesota
Apparently these aren't made anymore, but they work great. Ebay will have them.

http://www.omega.com/pptst/HHM2A-IR.html

In general, a talking meter has very limited application, one being when you're working on something you can't look away from, either due to tight quarters, or dangerous voltages where your hands are.

Erik


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Tue 11, 2014 6:47 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5889
Location: Black Hills, SD 57745
Tim's meter arrived here and I checked it out last night. First thing, I noticed a burnt smell, so looking for the culprit, I quickly spotted these four glass diodes with heavily scorched circuit around them.

Surprisingly, all four diodes tested good, as well as the adjacent caps and transistor (wired as a diode). The heat was enough to lift the traces, but I managed to get the diodes reinserted and soldered in. At that point I hoped I'd renewed a bad solder joint.

T'was not to be, it behaved the same way as before, so next I will check out the battery supply. The chip to the right of the pic looks a little less than pristine, I began to wonder if it took a hit or caused the diodes to overheat.

Darn! I hoped replacing the diodes would do it nice and simple!
-Ed


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sun 16, 2014 12:08 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5889
Location: Black Hills, SD 57745
I'm stumped. The suspect diodes all tested good, yet the board and traces around them are very darkened, besides the burnt smell. I've replaced a couple of the caps, but the replacements tested the same as the old parts and nothing changed in the meter. All other caps, diodes and rectifiers test good as well as any other parts I've tested.

All of Steve's suggestions were tried and the switch and battery supply all checks out. I'm down to baleful glares it seems. I'm open to any suggestions of where to try next. Otherwise, back to Tim it goes, unrepaired.

There was a listing on ebay with no bidders for an untested unit with battery corrosion. $16+ $10 shipping. He might accept less since there were no bidders and it might at least be more easily fixable, unless it ends up with the same problem as this one. A gamble for sure, but not a hugely expensive one if he'd accept less for it.

My next suggestion would be to add a switch the probe on Tim's other talking meter that works except for lacking that feature. Or perhaps the probe from this Micronta unit could be adapted to work.

Thanks!
-Ed


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sun 16, 2014 1:18 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9533
Location: Powell River BC Canada
Ed, I've got some time now. I'm going to work back from what caused that bridge to over heat.
as per your tests.

The fuse seems only to protect the AC and DC current range.

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Sun 16, 2014 1:37 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 5889
Location: Black Hills, SD 57745
Thanks Steve! I'm sure Tim appreciates it as well. I sent him the link to that ebay auction of the one with battery corrosion, so maybe a backup plan is in the works.
-Ed


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Jan Fri 30, 2015 5:02 pm 
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Joined: Mar Fri 21, 2014 9:17 pm
Posts: 146
Location: Portland, Oregon
Hello Gentleman:
I am working on one of these meters now.
My meter is flaky and is not consistent on its readings.
I also fiddled with VR1 and VR2 to no avail.
Anybody know what those control?
Anybody have any documentation whatsoever?
I have a youtube video on it
https://www.youtube.com/watch?v=x_4_iMVAJdU

Thanks Buzz


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Mon 05, 2018 8:36 pm 
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Joined: Jan Thu 25, 2018 3:32 am
Posts: 2
Mine is still going strong. Great multimeter


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Tue 06, 2018 3:18 pm 
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Joined: Mar Sat 03, 2007 12:53 am
Posts: 622
It was mentioned that the PC board of the meter was burnt (blackened). DMMs involve high impedance circuitry and I was wondering if the burnt areas have carbon that are acting as resistances that are affecting the operation of the meter and if cleaning the board in these areas would help.


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Tue 06, 2018 8:12 pm 
Member

Joined: Sep Thu 23, 2010 6:37 am
Posts: 9533
Location: Powell River BC Canada
I found this today. I just might order one because the Microntas
are getting very old.

https://www.ebay.com/itm/NKTECH-NK-51F- ... 2892272980

Attachment:
NKTECH.JPG
NKTECH.JPG [ 24.1 KiB | Viewed 95 times ]

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Tue 06, 2018 8:43 pm 
Member

Joined: Aug Sun 10, 2008 10:19 am
Posts: 485
Location: Lagrangeville New York 12540
does it have speech output


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Wed 07, 2018 3:14 am 
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Joined: Mar Sat 03, 2007 12:53 am
Posts: 622
I don't know anything about this meter, but I looked at the ad and the second photo on the left had the text "voice value standard english pronunciation" and the third photo on the left indicates that one of the push buttons controls true rms/average/voice.


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 Post subject: Re: Looking for a talking volt meter
PostPosted: Feb Wed 07, 2018 5:00 am 
Member

Joined: Aug Sun 10, 2008 10:19 am
Posts: 485
Location: Lagrangeville New York 12540
Hi is the radio shack talking meter analog or digital.


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