Micronta 22-167 schematic needed - Page 1
Forum section: electronics / testgear

author: Flump
author_rank: Frequent Contributor
timestamp: May 27, 2014, 08:49:25 pm
content: Hi AllI have an old Micronta 22-167 DMM but it needs to be realignedto bring it within specs on Resistance and DCV.There are 3 VR's on the board but I cant find a schematic for itso dont know what Mode they are for.Can anyone point me in the right direction for a drawing for it please ?

author: Lightages
author_rank: Unknown
timestamp: May 27, 2014, 09:56:09 pm
content: Three trim pots? Just started tweaking and see which one does what. There are only three!

author: Flump
author_rank: Frequent Contributor
timestamp: May 27, 2014, 09:59:25 pm
content: well i don't have a precision ACV or amps referenceso didnt want to take a chance incase one of the VR'sis for that.

author: Unknown
author_rank: Unknown
timestamp: May 27, 2014, 11:06:45 pm
content: Switch meter to a resistance (or DCV) range, and connect a resistor (or DCV) so that it's reading about 1/2 scale.Take another resistor of 200ohms or so and, on each trimpot, touch it between the wiper and each of the end pins in turn.Whichever one affects the reading is probably the adjustment pot for that range.

author: Lightages
author_rank: Unknown
timestamp: May 28, 2014, 04:22:09 am
content: That is a simply brilliant idea! Why didn't I think of that.

author: Flump
author_rank: Frequent Contributor
timestamp: May 28, 2014, 05:05:40 am
content: Thanks Tac , I tried your idea and 2 of the VR's effect the DCV readingso I jumped in and had a twiddle with all 3 as its a bit old and crusty anywayand was going to give it away to a friend as it's better than the POS he has.But before I go any further with it the resistance range is a little bit out and none of themVR's adjust this, A %0.01 620R reads 614R on the Micronta, all the other DVM's I haveand thats a fewread very close around 620R.So is 6 ohm out within spec ?I don't know as I cant find any info on the meter on the web

author: Unknown
author_rank: Unknown
timestamp: May 28, 2014, 05:26:29 am
content: Quote from: Flump on May 28, 2014, 05:05:40 amAh well, that's why I said "probably"Quote from: Flump on May 28, 2014, 05:05:40 amSo you haven't seenthis listthen? Specs are there under the entry for 22-167...(That was on the first page of results when I googled "micronta 22-167 multimeter manual". Admittedly I knew that Micronta = RatShack, and that they have surprisingly good lists like that tucked away since I've seen them before...)

author: Flump
author_rank: Frequent Contributor
timestamp: May 28, 2014, 05:44:44 am
content: wow nice find, ty300 ohms -3-30-300 kOhms: ... +/-1.0% of reading and +/-0.2% of full scale, +/-1 in last digitgoing by the above it would seem in spec on resistance then

author: subdude17349
author_rank: Newbie
timestamp: December 18, 2017, 08:22:18 pm
content: I realize that this is thread necrophilia, but the thread title is appropriate.I have a 22-167 that has burned out R21 (beside the fuse). Is there anyone on here who still has one that could possibly open it up and tell me what resistance R21 is?Many thanks!

author: Porcine Porcupine
author_rank: Contributor
timestamp: February 16, 2018, 12:37:46 am
content: Quote from: subdude17349 on December 18, 2017, 08:22:18 pmHere's a picture of mine. If I'm reading it right, it's 4.99 ohms ±0.5%.