On Mon, 1 Jul 2013 21:18:05 -0700 (PDT), Peter Easthope
wrote:

I have a Sanwa BX-505 analogue multimeter where the needle wavers and can not be zeroed on the x1, x10 and x1k scales. Zeroing is possible on the x10k scale. The ohmeter is really an electromagnetic voltmeter connected in a circuit with dry cell, resistor, zeroing potentiometer, leads and a subject resistance.

Scans of the relevant pages from the manual are here.
http://carnot.yi.org/SanwaBX505Manual.jpg

What is the cause of this behavior?

In order of probability:

1. Dirty battery contacts. Clean the contacts and possibly replace
the battery.

2. Dirty test probe contacts, broken test probe wires, corroded test
probe tip. Clean or replace.

3. Dirty rotary switch. Spray with a small amount of contact
cleaner.

4. Dirty fuse contacts or bad fuse. Clean and/or replace fuse.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558