UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Components and Circuits

Notices

Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

Reply
 
Thread Tools
Old 21st May 2024, 9:15 pm   #1
daveone23
Triode
 
Join Date: Jun 2023
Location: Tampa, Florida, USA.
Posts: 30
Default RCA WV-54A VTVM issues. (Actually a WV-65A)

When ever I turn this machine on the meter pegs. None of the controls do anything. Where should I start looking?
Attached Files
File Type: pdf RCA_WV-65A-2.pdf (22.5 KB, 49 views)
daveone23 is offline   Reply With Quote
Old 22nd May 2024, 12:12 am   #2
Silicon
Nonode
 
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 2,232
Default Re: RCA WV-54A VTVM issues.

Check the continuity of the tube heaters and replace any paper capacitors.

Do you have the original probe lead?

Last edited by Silicon; 22nd May 2024 at 12:16 am. Reason: more info
Silicon is online now   Reply With Quote
Old 22nd May 2024, 1:54 am   #3
daveone23
Triode
 
Join Date: Jun 2023
Location: Tampa, Florida, USA.
Posts: 30
Default Re: RCA WV-54A VTVM issues.

Probes are not original but it does it without probes. They are
Simple probes, nothing unusual. I will test the valves.
daveone23 is offline   Reply With Quote
Old 22nd May 2024, 7:13 pm   #4
Silicon
Nonode
 
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 2,232
Default Re: RCA WV-54A VTVM issues.

Some VTVM have a 1M Ohm resistor built into the probe lead.

It won't cause the swing to full scale but it will affect the calibration.

To avoid damage to the moving coil meter you could replace it with a matching resistance and then monitor the voltage across it.

When you start to fault-find the circuit set the selector switch to measure 1,000V.
Compare the voltages at the anode (plate) of each valve (tube).
Silicon is online now   Reply With Quote
Old 23rd May 2024, 8:03 am   #5
stuarth
Heptode
 
Join Date: Feb 2010
Location: Heysham, Lancashire, UK.
Posts: 693
Default Re: RCA WV-54A VTVM issues.

The schematic in post 1 shows a battery valve (tube) circuit with a seperate filament cell and power switch for each valve of the long tail pair.

A poor cell or a dirty contact to either valve filament would cause enough unbalance to peg the meter.

However, the schematic is for a WV-65A, the thread title is WV-54A.....

If the actual instrument uses 2 seperate valves for the long tail pair rather than the more usual double valve, then you can quite quickly see if the problem is a valve by swapping them round, if you have a faulty valve, then with them swapped sound, the meter should peg to the other end stop.

Stuart
stuarth is offline   Reply With Quote
Old 23rd May 2024, 2:46 pm   #6
daveone23
Triode
 
Join Date: Jun 2023
Location: Tampa, Florida, USA.
Posts: 30
Default Re: RCA WV-54A VTVM issues.

It's a WV-65A. Title is a typo. Is there a way to correct that? I found out the valves are bad so I am in the process of buying new ones.
daveone23 is offline   Reply With Quote
Old 23rd May 2024, 3:36 pm   #7
Craig Sawyers
Dekatron
 
Craig Sawyers's Avatar
 
Join Date: Nov 2010
Location: Oxford, UK.
Posts: 5,105
Default Re: RCA WV-54A VTVM issues.

Introduced in early 1948. What are you using for batteries? There are two 1.5V cells each supplying 0.1A to each heater. There are 2 x 45V ones in series to supply the anodes (plates). And another two 1.5V cells in series for the resistance measuring function.

Craig
__________________
Doomed for a certain term to walk the night

Last edited by Craig Sawyers; 23rd May 2024 at 3:41 pm.
Craig Sawyers is online now   Reply With Quote
Old 23rd May 2024, 3:52 pm   #8
daveone23
Triode
 
Join Date: Jun 2023
Location: Tampa, Florida, USA.
Posts: 30
Default Re:RCA WV-54A VTVM issues. (Actually a WV-65A)

I stacked 9v batteries for the 90v and used the stock holders for the 1.5 supplies
Attached Thumbnails
Click image for larger version

Name:	batteries.jpg
Views:	24
Size:	62.8 KB
ID:	297928  
daveone23 is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 6:36 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.