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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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Thread Tools |
25th May 2020, 6:39 pm | #41 |
Pentode
Join Date: Mar 2020
Location: Bodmin, Cornwall, UK.
Posts: 212
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Re: AVO valve tester meter servicing
Martin I should have mentioned that the original MK3 meter (no swamp resistor)is dead (coil is shorted). The meter referred to in my more recent posts is a meter from a CT160 which is in need of a neg grid pot. I was determined to get the meter back to specification to enable correct calibration of the Mk3.
The original 10k shunt measured 43K so is about to be replaced with a new 10K resistor. I now have a new problem to sort out. When I switch on the MK3 the needle on the meter does not rise to the SET position in fact it does not rise at all. I checked the heater, anode volts which are good but when moving on to set the neg grid volts I do not get the expected volts so I tomorrow I will have to check out that part of the circuit. |
25th May 2020, 6:48 pm | #42 |
Octode
Join Date: May 2009
Location: Linkoping, Sweden
Posts: 1,465
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Re: AVO valve tester meter servicing
Thanks, that explains a lot. Had me confused for a while there!
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Martin, Sweden |
26th May 2020, 7:40 am | #43 | |||
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,288
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Re: AVO valve tester meter servicing
Quote:
Quote:
Quote:
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
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26th May 2020, 9:58 am | #44 |
Pentode
Join Date: Mar 2020
Location: Bodmin, Cornwall, UK.
Posts: 212
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Re: AVO valve tester meter servicing
Graham have done what you suggested and get FSD at 40uA, is that close enough? I will start a new thread about the fault which has turned up.
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26th May 2020, 10:01 am | #45 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,288
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Re: AVO valve tester meter servicing
Yes. 40uA is good enough to proceed with testing.
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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |