multi meter

Thread Starter

beatsal

Joined Jan 21, 2018
169
I have an old Bell and Howell Schools ( De vRy Institute) multimeter. 3 or 4 wires are disconnected, don't know where they connect. Please help - Thanks
 

spinnaker

Joined Oct 29, 2009
7,835
You are going to have to give a WHOLE lot more information that that. For starters what 3 or 4 wires are disconnected. Post a photo.

And is it 3 or 4 wires? You mean you are not sure??
 

JohnInTX

Joined Jun 26, 2012
4,280
You are going to have to give a WHOLE lot more information that that. For starters what 3 or 4 wires are disconnected. Post a photo.
..And be sure that photo includes the model number and the insides if possible. IIRC B&H schools and CIE, too, had students build a VTVM (vacuum tube volt meter) as one of their projects for use later in the course.
 

AlbertHall

Joined Jun 4, 2014
10,388
Is there a battery holder in the other half?
Could that be where the wires are from, someone disconnected the wires to separate the two parts of the meter?
 

Thread Starter

beatsal

Joined Jan 21, 2018
169
Could not see a battery holder; there is a 1.5V battery though which is soldered. The yellow wire seems to have been connected to the battery. The Red and black could also be from the battery
 

spinnaker

Joined Oct 29, 2009
7,835
The battery was to measure resistance from what I recall. Odd that it is soldered in place. I am sure it will need to be replaced.
 

Reloadron

Joined Jan 15, 2015
5,646
Below the trim pots and below the meter movement terminals I see what looks like two brown colored transistor sockets. Take a look at this old thread which will get you to a schematic. There is also this.

This should be a schematic of what you may have.

If I am correct about the transistor sockets I don't see the transistors? My read is that they were germanium transistors. I read 2N369 Germanium transistor which can be had for about $5 USD each.

The schematic I found reflects a 4.5 Volt battery which could have been 3 D Cells.

Ron
 

Reloadron

Joined Jan 15, 2015
5,646
I just did a random Google of the transistor part numbers. The prices ranged a little below $5 USD from a few vendors. Hopefully what you have is close to what I found.

Ron
 

Wolframore

Joined Jan 21, 2019
1,786
Be careful those old germanium ones vary quite a bit. sometimes have to go through a bunch to find a good one. The hfe varies a lot on them.
 
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