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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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31st Oct 2025, 3:40 am
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#1 |
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Tetrode
Join Date: Sep 2024
Location: Lincoln, Lincolnshire, UK.
Posts: 74
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Avo model 8 mk9 odd behaviour on ohms
My meter needle moves to the left when shorting the probes in res x100,its as if the battery is in backwards but its not, any idea?, cheers Tony.
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31st Oct 2025, 7:34 am
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#2 |
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Pentode
Join Date: May 2019
Location: Ipswich, Suffolk, UK.
Posts: 202
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Re: Avo model 8 mk9 odd behaviour on ohms
Did it function fine until recently, or always done that since you’ve had it?
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31st Oct 2025, 10:25 am
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#3 | |
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Heptode
Join Date: Jul 2010
Location: Wellington, New Zealand.
Posts: 674
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Re: Avo model 8 mk9 odd behaviour on ohms
Quote:
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31st Oct 2025, 4:04 pm
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#4 |
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Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,888
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Re: Avo model 8 mk9 odd behaviour on ohms
MC reverse button?
Ed |
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31st Oct 2025, 7:32 pm
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#5 |
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Nonode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 2,319
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Re: Avo model 8 mk9 odd behaviour on ohms
The model number or variant has an error, correct me if I'm wrong, but the last version of the Model 8 was the MK7.
David |
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31st Oct 2025, 8:06 pm
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#6 |
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Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,430
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Re: Avo model 8 mk9 odd behaviour on ohms
Yes.
Model 8, Mark one to seven. Model 9, Mark two or four. (I still don't know what the fault is, but Ed may have nailed it) Dave |
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31st Oct 2025, 9:15 pm
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#7 |
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Heptode
Join Date: Mar 2020
Location: Rochdale, Greater Manchester, UK.
Posts: 766
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Re: Avo model 8 mk9 odd behaviour on ohms
The MC Rev button is on a pretty strong spring on earlier Model 8s which seems an unlikely scenario. The later mode 8s have a latching switch, but the OP was strangely specific about the x100 range and it would behave identically on the x1 range if that were the case. DC voltage ranges would also be affected and surely noticed during a cursory check before seeking advice?
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1st Nov 2025, 11:27 am
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#8 |
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Pentode
Join Date: Mar 2007
Location: Croydon, London, UK.
Posts: 137
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Re: Avo model 8 mk9 odd behaviour on ohms
What happens if you reverse the 15 volt battery in its holder?
Mike. |
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1st Nov 2025, 5:00 pm
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#9 |
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Nonode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 2,319
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Re: Avo model 8 mk9 odd behaviour on ohms
Could there be a possibly of the battery being incorrectly labelled? I seem to remember this happened with some capacitors a few years ago, sleeving with polarity marking was the incorrect way round.
David |
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1st Nov 2025, 7:48 pm
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#10 |
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Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,430
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Re: Avo model 8 mk9 odd behaviour on ohms
Well as the 15v battery is probably composed of buttons, i guess its feasible.
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