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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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18th Mar 2023, 3:43 pm | #1 |
Triode
Join Date: Jun 2017
Location: Northampton, Northamptonshire, UK.
Posts: 28
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Avo Mk IV Valve Tester
Hi, My trusty Avo MK IV has given up. As soon as I rotate the leakage control (on any setting) the meter shows about 5 Meg leakage, this happens even without any valve inserted. If you continue to test with a valve inserted, when you select "Test" for anode current the meter goes negative. Does anybody have a service manual or any ideas? Cheers, Pete.
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18th Mar 2023, 6:33 pm | #2 |
Octode
Join Date: Nov 2010
Location: Ross-on-Wye, Herefordshire, UK.
Posts: 1,652
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Re: Avo Mk IV Valve Tester
The working instructions are available at https://frank.pocnet.net/instruments..._Mk-IVuser.pdf
There are several experts on valve testers on this forum. I expect someone will have seen your fault before. Richard |
18th Mar 2023, 6:42 pm | #3 |
Octode
Join Date: Nov 2010
Location: Ross-on-Wye, Herefordshire, UK.
Posts: 1,652
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Re: Avo Mk IV Valve Tester
SOrry- just noticed you want the service instructions - not the working instructions. I do have the service manual, but at 15MB its four times too big to post on here.
What I can do is to provide a link to my copy so you can download it: https://e.pcloud.link/publink/show?c...DmJcg6x8T09QuV Richard |
18th Mar 2023, 6:53 pm | #4 |
Octode
Join Date: Nov 2010
Location: Ross-on-Wye, Herefordshire, UK.
Posts: 1,652
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Re: Avo Mk IV Valve Tester
Incidentally, my guess about the leakage you are measuring is that it is caused by a leaky capacitor. I would make a start by replacing all the paper caps.
Richard |
18th Mar 2023, 8:07 pm | #5 |
Heptode
Join Date: May 2017
Location: Konongo, Ghana
Posts: 513
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Re: Avo Mk IV Valve Tester
The link to the service manual provided by Richard doesn't seem to work for me. This is a link to what I gathered on the AVO Mk IV valve tester, including the service manual:
https://drive.google.com/drive/folde...ycoeVwAJHgNMSj
__________________
Robert |
19th Mar 2023, 1:59 pm | #6 | |
Octode
Join Date: Nov 2010
Location: Ross-on-Wye, Herefordshire, UK.
Posts: 1,652
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Re: Avo Mk IV Valve Tester
Quote:
Sorry to provide a non-functioning link. I have just found the service manual with a file size within the forum's limits, so have attached it here in case its useful. Richard |
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20th Mar 2023, 12:53 pm | #7 |
Triode
Join Date: Jun 2017
Location: Northampton, Northamptonshire, UK.
Posts: 28
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Re: Avo Mk IV Valve Tester
Thanks everybody for your replies. I shall replace the caps first, then go from there.
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