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 16th Nov 2022, 12:25 pm   #1
waran2005
Tetrode
 
Join Date: Feb 2020
Location: Cardiff, Wales, UK.
Posts: 65
Default Mk3 VCM additional resistor

Hi all,

During my repair of my Mk3 VCM I have come accross a resistor that I'm unable to identify on the circuit diagram. It is a resistor fitted accross R28 and R29 of the meter switch and so will be in circuit for the 25, 10, 2.5 mA and (test) mA/V positions, not the 100 mA positiin? As far as I am aware it should not be there, it reads around 1k, colours are old / faded so difficult to exactly identify the original value. Is anyone aware if this is an AVO modification, it appears to have been there for some time and appears to be an identical type as used on R1, the 3.9 Ohm resistor, so looks original.

Any help appreciated, now would be the time to remove it if it's not meant to be there.

Thanks all.
Waran.
waran2005 is offline  
Old 17th Nov 2022, 9:17 am   #2
Dekatron
Octode
 
Dekatron's Avatar
 
Join Date: May 2009
Location: Linkoping, Sweden
Posts: 1,463
Default Re: Mk3 VCM additional resistor

There are a few errors in most AVO VCM schematic diagrams and in the Mk III there is an error with the Inner-Outer Slope switch, a resistor is missing in the circuit there, if you compare with the Mk IV you can see that resistor. That resistor is 750 Ohm in some testers and 1000 Ohm in some.
__________________
Martin, Sweden
Dekatron is offline  
Old 19th Nov 2022, 12:27 pm   #3
waran2005
Tetrode
 
Join Date: Feb 2020
Location: Cardiff, Wales, UK.
Posts: 65
Default Re: Mk3 VCM additional resistor

Hi Martin,

Brilliant, thank you, that makes a lot of sense. It didn't occur to me to check the schematic of the MK4.

Kind regards,
Waran.
waran2005 is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 1:01 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.