In search of really small voltmeters for my PSU - Page 1
Forum section: electronics / repair

author: jogri
author_rank: Frequent Contributor
timestamp: June 01, 2018, 10:08:12 pm
content: I am currently repairing two Oltronix B703DT and wanted to replace the analog voltmeters on those with digital ones (there is a variant of this psu with them), but i could not find voltmeters that are small enough to fit the 42x12mm holes of the analog ones (the original digitals have the same size, +/- 1mm). Next problem: Since there is literally no free space in this PSUs, i can't build a seperate power supply for those so they have to be driven from the same psu.Btw: Don't ever plan on buying one of this things broken as a "casual" repair job, they are among the most nasty designs i have ever encountered: Ridiculously short cables, unlabeled identical connectors, everything is soldered and there is no room at all. Oh, did i mention that the only thing holding it together is the aluminum top plate? So if you want to remove it (which you have in order to open it), the only thing holding it together is the pcb (which is getting twisted btw). So if you want a free demo of what becoming mentally insane looks like, go for it.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 02, 2018, 12:35:29 am
content: https://www.ebay.ca/itm/NEW-2-wire-Mini-DC-5-30V-Voltmeter-LED-Panel-3-Digital-Display-Voltage-Meter/292491065006?hash=item4419d376ae:m:m8T8X0y-WVrAmTjUPHWu4XQtoo big, but keep looking!

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 02, 2018, 12:41:05 am
content: ooo....https://www.ebay.ca/itm/Mini-OLED-USB-Charger-Capacity-power-Current-Voltage-Detector-Tester-Meter/261518647554?hash=item3ce3b9e102:g:xScAAOSwA3dYTgIp

author: LateLesley
author_rank: Frequent Contributor
timestamp: June 02, 2018, 07:50:20 am
content: https://www.ebay.co.uk/itm/0-28-LED-DC-0-100V-Voltmeter-Digital-Display-Voltage-VOLT-METER-12V-24V-Blue/272834926905?hash=item3f863a9939:g:CCEAAOSwX7pZrqU5Dimensions: 24mm * 11mm * 9mmI'm sure these could be modded onto a plate to fit.Look for 0.28" Voltmetershttps://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=0.28%22+voltmeter+&_sacat=0https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20180601234940&SearchText=0.28%22+voltmeterEDIT: ooooo!!!https://www.aliexpress.com/item/GWUNW-BY428V-0-28-inch-4-bit-Micro-voltmeter-DC-0-500V-500V/32843540086.html?spm=2114.search0104.3.86.5b27607ctAUQ0d&ws_ab_test=searchweb0_0,searchweb201602_2_10152_10151_10065_10344_10068_10342_10325_10343_10546_10340_10548_10341_10696_10084_5722520_10083_10618_10307_10135_10133_10059_5722620_5722920_5722720_5722820_100031_10103_10624_10623_10622_10621_10620,searchweb201603_19,ppcSwitch_3&algo_expid=8a7f38db-0972-43fd-b4f6-dc1017a5d6c8-11&algo_pvid=8a7f38db-0972-43fd-b4f6-dc1017a5d6c8&transAbTest=ae803_2&priceBeautifyAB=0Overall dimensions:39.6MM*10.6MM*9.6MM(L*W*H)

author: jogri
author_rank: Frequent Contributor
timestamp: June 02, 2018, 10:36:50 pm
content: Thanks for the links, i totally forgot to check for meters manufactured with imperial measurement in mind... I think i'll just connect the source input to one of the other outputs (should work if i just have every output on all the time since they all are galvanically isolated from each other), if anyone has a better idea let me know. Other option would be to tap into one of the secondary windings on the main transformer and use a small one for stepdown and isolation. But that means cramping another pcb into this thing...Oh, one last thing: What would be a good choice for internal wire connectors (diameter max 1mm) that can handle shocks and don't require a crimping tool? Should be as small (lengthwise) as possible as there is not much room. I thought if i had to repair it, i could just as well improve it to ease later repairs and service.

author: LateLesley
author_rank: Frequent Contributor
timestamp: June 04, 2018, 10:23:27 am
content: I don't really know what would be best for connectors, I was trying to think of the best non crimp connectors, and the best I can come up with is to use some 2.54mm IDC connectors, and some pin strip. You could get the header sockets and solder them if you have the kit, and just insulate with some heatshrink. I think it's about the smallest you could do without crimping pins.

author: CM800
author_rank: Frequent Contributor
timestamp: June 04, 2018, 11:07:29 am
content: Quote from: LateLesley on June 02, 2018, 07:50:20 amHow do you feel putting 500V on this:

author: LateLesley
author_rank: Frequent Contributor
timestamp: June 04, 2018, 11:22:38 am
content: Quote from: CM800 on June 04, 2018, 11:07:29 amFair point - but it's not going to have 500V on it, the PSU seems to be putting out up to 65V, so I think it would be fine in this case.I do see your point though, it's not exactly spaced/isolated for 500V, is it?