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 > Specific Vintage Equipment > Vintage Test Gear and Workshop Equipment

Notices

Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

Closed Thread
 
Thread Tools
Old 6th Jun 2017, 2:20 pm   #1
proton21
Triode
 
Join Date: Jun 2017
Location: Northampton, Northamptonshire, UK.
Posts: 28
Default Avo MkIV Valve tester problems

Hi, I have an Avo MKIV valve tester that works fine until I get to the "test" part of the checks. The meter then tries to swings hard left instead of showing a positive reading. Is this a common problem? Do the back off controls on this meter work the opposite way to the MKIII?

Thanks in advance.
proton21 is offline  
Old 6th Jun 2017, 3:13 pm   #2
trh01uk
Octode
 
trh01uk's Avatar
 
Join Date: Nov 2010
Location: Ross-on-Wye, Herefordshire, UK.
Posts: 1,648
Default Re: Avo MkIV Valve tester problems

On the Mk.IV you set the two backing off controls fully clockwise. I don't know what the Mk.III does - but the user manual for the Mk.IV is totally clear on the point (page 16), and I am pretty sure that's what my own Mk.IV does too.

That assumes, of course, that your Mk.IV isn't faulty and someone hasn't been messing with the wiring! But there's no point in worrying about that until a quick twiddle with the backing off controls sees if that clears your problem.

Richard
trh01uk is offline  
Old 6th Jun 2017, 3:20 pm   #3
Pamphonica
Nonode
 
Pamphonica's Avatar
 
Join Date: Mar 2008
Location: Virginia Water, Surrey, UK.
Posts: 2,872
Default Re: Avo MkIV Valve tester problems

Backing off control at fully clockwise should always give (positive) anode current display on the meter. Negative deflection means a bust control, damaged diode or similar, putting negative offset into anode load even when control is clockwise. Check if anode volts across load resistor make sense. Then track back down the offset circuitry.
Good luck

Jeremy
__________________
Jeremy, G8MLK, BVWTVM Friend, VMARS, BVWS Secretary.
www.pamphonic.co.uk www.bttt.org.uk
Pamphonica is offline  
Old 6th Jun 2017, 6:28 pm   #4
proton21
Triode
 
Join Date: Jun 2017
Location: Northampton, Northamptonshire, UK.
Posts: 28
Default Re: Avo MkIV Valve tester problems

Thanks for your quick reply. I had not used the tester for a number of years, and the manual I have is for a MKIII tester which states that the back-off controls should be fully anti-clockwise. so, it looks like the MKIV reversed these controls. I will have another try, and see if there are any other faults! Thanks again.
proton21 is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 9:23 am.


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.