RCA Master Voltohmyst WV-87B - Videokarma.org TV - Video

bandersen · #1 06-08-2012, 07:20 PM

I recently acquired this VTVM from a friend and spent some time today going over it.
It's very clean inside and out.

I suspect this had been used up until recently as the battery is still good and hasn't leaked all over

polyphase · #2 06-08-2012, 09:18 PM

A most attractive piece (especially the meter) but that D cell just doesn't look 'factory' to me.

bgadow · #3 06-08-2012, 10:08 PM

I think that is what they used; seems like the senior voltohmyst might use a 'C'? I guess the original would have been an RCA-branded carbon-zinc.

bandersen · #4 06-09-2012, 01:40 AM

I'm not sure what size the original cell was as I don't have the manual. This particular battery is fairly new for sure as it still has a charge.
Here's the heavy gauge shunt for the 15 Amp range.

I did a little recap plus calibration and it's working just fine

This just might be my new favorite VTVM

dieseljeep · #5 06-09-2012, 09:25 AM

Is that large meter movement damped real well? The larger meters usually swing a bit before they settle down.
I see you have the proper probe. Too many probes are MIA lately.

polyphase · #6 06-09-2012, 12:01 PM

To clarify my comment, I meant that soldering a battery into a product, especially a carbon type, didn't seem, well, 'factory' to me.

bandersen · #7 06-09-2012, 11:17 PM

Quote:

Originally Posted by dieseljeep

Is that large meter movement damped real well? The larger meters usually swing a bit before they settle down.
I see you have the proper probe. Too many probes are MIA lately.

Yes, it does seem to be damped fairly well. I only have the one probe and three RCA VTVMs so I'm on the hunt for more.

earlyfilm · #8 06-10-2012, 02:07 PM

Quote:

Originally Posted by polyphase

To clarify my comment, I meant that soldering a battery into a product, especially a carbon type, didn't seem, well, 'factory' to me.

Yup! I thought so too, when I changed my first failed battery in the Senior Voltohmyst back in 1950's, but it is the RCA way!

The WWII era versions, such as the 195A had to use two batteries, which were inside a metal cage. Two insulated slugs, with copper contacts, were inserted in there with the batteries and the whole mess was tightened with a screw held by a locking nut. As the metal case expanded with temperature and the unit got moved, the contacts would work loose and started giving erroneous resistance readings.

Some of the early post war Juniors had their batteries in a holder, but the later ones soldered them.

I've never used a Master, but both the Junior and Senior ones that I've owned have used C batteries. Most modern batteries do not have a breathing hole on the top connector, but instead vent by the fiber washer at its base. On the 1950-60's batteries, if one accidentally closed the breathing hole with solder, the battery would have a short -and usually messy- life.

Bandersen, I started to congratulate you on getting one of the older probes that can be opened and repaired, but just noticed that the writing on the probe was the wrong color. A closer look shows that is a VIZ WG-299E, and not an RCA. Did VIZ continue the horrid RCA practice of cementing the probes together so they would be unrepairable, or can they be opened to clean the switch and replace the resistor?

This is the reason why Voltohmyst probes often sell for more than the meter itself. The probe on my Senior that I've used since the 1960's finally gave up the ghost and I bought a Senior on ePray that had a cracked meter case and no other bids. It had an original WG-299C, which I think was the last probe that came apart. When I asked the seller to quote a price for just shipping the probe, he thought I was crazy. He sent me the probe and relisted the meter at a lower price without the probe and sold it to some unsuspecting sole.

The 195A came with Burgess (sp?) batteries and the Senoior came with an RCA battery.

James.

bandersen · #9 06-10-2012, 03:46 PM

I also have one of the old type RCA probes that does open up and was puzzled why I couldn't get the VIZ open. Mystery solved.

earlyfilm · #10 06-10-2012, 04:23 PM

Quote:

Originally Posted by bandersen

I also have one of the old type RCA probes that does open up and was puzzled why I couldn't get the VIZ open. Mystery solved.

RCA earned more selling the whole probe, than just the resistor and/or the switch.

Probes for the B&K Dynascan VTVM work on the RCA Senior, and the single-cable Junior Voltohmysts.

They are usually not as expensive.

ziggy7 · #11 01-27-2013, 11:13 AM

That's one of the nicest meters around for those of us over 50. Congrats on the fine example you found. I have taken to mounting a AA holder on top of each VTVM meter case so I can keep an eye on the battery. No more corroded messes for me. Modern AA batteries can produce plenty of current, they just don't last as long as the D.

davet753 · #12 03-02-2013, 09:26 PM

My first VTVM was one of these RCA units. It was a good meter, despite the fact the switches were so worn out they barely "clicked".

I always preferred the B&K models as they didn't require a battery. In fact, I have one now that was built in the 70's that I picked up NOS from a (now defunct) parts distributor in '95. He sold it to me for a song, because he said I was the only tech he knew who didn't use a digital VOM.

dieseljeep · #13 03-03-2013, 10:54 AM

Quote:

Originally Posted by polyphase

To clarify my comment, I meant that soldering a battery into a product, especially a carbon type, didn't seem, well, 'factory' to me.

The manufacture's claimed that it was better to solder the leads to the battery, as it minimized errors on the low ohms scale.
It sounded logical to me.

Don Lindsly · #14 03-03-2013, 02:20 PM

That instrument was built by Jetronic Industries of Philadelphia. The blue precision resistors are a giveaway.

Jet also built the later versions of the WV98 and WV77 VTVMs as well. All had soldered-in batteries, primarily for cost. The low contact resistance was a byproduct.

The WV87 is a decent instrument for the time period and cost. All three use the same basic circuit. Component quality and features improve with price.

Jetronics took over the RCA test equipment line, renaming it VIZ.

Don Lindsly · #15 03-03-2013, 02:23 PM

That instrument was built by Jetronic Industries of Philadelphia. The blue precision resistors are a giveaway.

Jet also built the later versions of the WV98 and WV77 VTVMs as well. All had soldered-in batteries, primarily for cost. The low contact resistance was a byproduct.

The WV87 is a decent instrument for the time period and cost. All three use the same basic circuit. Component quality and features improve with price. The WV87 measures current.

Jetronics took over the RCA test equipment line, renaming it VIZ.