USM-223 Multimeter


© Brooke Clarke 2017
Background
Description
Photos
Manuals
Patents
Related
References
Links

Background



Description

Fuse

After installing some batteries, there was no response to any switch position.  The fuse was blown.
1-1/4" (32mm) long x 1/4" (6.3mm) dia (3AG);   5 Amp @ 250 Volts on the blown fuse.
The manual says 2.5 Amp Fuse.
27 Oct 2017 - Installing the new fuse did NOT fix the problem.

Batteries

There are three batteries:

BT-1

This is a common "C" battery.

BT-2 & BT-3

This is a stack of three each BA-1312 batteries.
I ordered LR50 cells as replacements for the BA-1312 mercury battery(Wiki) .
The LR50 is the correct size and a stack of three of them fit correctly.  Note that the LR50 batteries on eBay don't have brand names.
My web page for the TS-183 Battery Test set lists the BA-1312 as follows:


Battery Type No.
Jack No.
Minimum
Permissible
Voltage
Load
Resistance
Ohms
Used On
Replacement
BA-1312/U
6135-00-269-5843
4
1.00
 19.7
 PAS-5, SU-43/PAS-6 IR viewer, PDR-10, PQS-1(XN-1), USM-223, VRC-53, VRC-64, KS-19B, GRC-9 Bias Battery  Duracell: PX1, RM1N, RM1R,
EverReady: 1, 1A, EVG PC1A,
Gold Peak: PC1A, I.E.C. LR50,
Mallory MR50,
Military BA1312/U,
NEDA 1100M,  1109M,  1110MP,
Panasonic MR50,
Radio Shack:23-9011
Rayovac RPX1,  T1N,
UCAR EPX1,
Varta V1PX,  VPX1
BT-70265, E1N

Photos

Fig 1
USM-223
                      Multimeter
Fig 2
USM-223
                      Multimeter
Fig 3
USM-223
                      Multimeter
Fig 4
USM-223
                      Multimeter
Fig 5
USM-223
                      Multimeter Battery Compartment
Fig 6 Inside
USM-223
                      Multimeter Inside


Manuals

TM 11-6625-654-14

Operator's, Organizationalo, Direct Support, and General Support Maintenance
Repair Parts and Special Tools List (Including Depot Maintenance Repair Parts and Spedial Tools List) for
Multimeter AN/USM-223
13 September 1974

TM 11-6625-654-24P

Organizational, Direct Support, and General Support Maintenance Repair Parts and Special Tools List for
Multimeter AN/USM-223
NSN 6625-00-999-7465

Patents


Related


References


Links

PRC68, Alphanumeric Index of Web pages, Contact, Products for Sale
Page Created