Hi there - I have a problem
I was just testing some EL34 when the meter stoped working
What am I going to do now. Does anny of you know where to get a "New" meter or where to get the old meter repaired?
Is there annything I can do myself to fix it again?
Thanks Peter Jensen
I was just testing some EL34 when the meter stoped working
What am I going to do now. Does anny of you know where to get a "New" meter or where to get the old meter repaired?
Is there annything I can do myself to fix it again?
Thanks Peter Jensen
Hi,
Quite possibly...
Have you already opened it/or looked for and checked for a popped fuse?
Have you tried it with a lower power valve? ECC83, EL84, something along those lines...
If the fuse(s) check out O.K. and the smaller valves aere fine it could be a faulty contact in the octal socket.
I'm not sure about the AVOs but alot of these meters used a rheostat to set/correct the line voltage. Maybe you incidentally turned it down too much.
Could be a dead rectifier valve inside as well....could be a number of things really but this is often stuff that just works and works, for ages.
Cheers,
Is there annything I can do myself to fix it again?
Quite possibly...
Have you already opened it/or looked for and checked for a popped fuse?
Have you tried it with a lower power valve? ECC83, EL84, something along those lines...
If the fuse(s) check out O.K. and the smaller valves aere fine it could be a faulty contact in the octal socket.
I'm not sure about the AVOs but alot of these meters used a rheostat to set/correct the line voltage. Maybe you incidentally turned it down too much.
Could be a dead rectifier valve inside as well....could be a number of things really but this is often stuff that just works and works, for ages.
Cheers,
I have a service manual for the 160 which i once used to own. Send me an email if you want it. You should really open it up and test the moving coil system before jumping to conclusions. If a coil is really burnt you only stand a chance if the open circuit point is visible and accessible.
AVO help
Hello ,
With the tester set to 'C/H' , does your valve under test light up ?Can you obtain a reading when set to mains calibration ? You should be able to obtain FSD on the meter . Inside the tester there is a pot which is the only adjustment , if you can't adjust FSD when calibrating the mains you will need to adjust this . If there is a red light on behind the meter scale , open the tester and reset the trip relay . If you can't get any meter movement , open the tester , check the fuses . Across the meter is a shunt resistor , desolder this and measure for continuity . If this is open , your meter is stuffed . If the meter obtains a measurement , solder the shunt back in and start to fault find .
The circuitry is very simple , there is only a single 6AL5 inside (I can send you one if you wish) , the grid pot can be a problem and is unreplaceable , also the thumbwheel switches may need a clean . Gerry at Crowthorne Tubes is the guru on these things . He can supply circuit diagrams and also has a replacement meter movement . Hope this helps
cheers
316a
webercarbmann said:Hi again
Thanks for replying.
The valve tester is still working. The tube in the tester keept running. I am Quite syre that it is only the meter that is not working.
Peter
Hello ,
With the tester set to 'C/H' , does your valve under test light up ?Can you obtain a reading when set to mains calibration ? You should be able to obtain FSD on the meter . Inside the tester there is a pot which is the only adjustment , if you can't adjust FSD when calibrating the mains you will need to adjust this . If there is a red light on behind the meter scale , open the tester and reset the trip relay . If you can't get any meter movement , open the tester , check the fuses . Across the meter is a shunt resistor , desolder this and measure for continuity . If this is open , your meter is stuffed . If the meter obtains a measurement , solder the shunt back in and start to fault find .
The circuitry is very simple , there is only a single 6AL5 inside (I can send you one if you wish) , the grid pot can be a problem and is unreplaceable , also the thumbwheel switches may need a clean . Gerry at Crowthorne Tubes is the guru on these things . He can supply circuit diagrams and also has a replacement meter movement . Hope this helps
cheers
316a
AVO
Hi again
Thanks a lot for the advide. I will open it up and check the things mentioned. It is nice to nav that a replacement meter it posible get get. About the grid pot - it sucks. I constantley have to ajust it to keep the negative grid voltage konstant. I always use a digital multimeter to check the actual voltage when testing.
I will let you know how the repair is comming up
Peter Jensen, Denamrk
Hi again
Thanks a lot for the advide. I will open it up and check the things mentioned. It is nice to nav that a replacement meter it posible get get. About the grid pot - it sucks. I constantley have to ajust it to keep the negative grid voltage konstant. I always use a digital multimeter to check the actual voltage when testing.
I will let you know how the repair is comming up
Peter Jensen, Denamrk
Avo
Hi again
Thanks a lot for the advice. I will open it up and check the things mentioned. It is nice to know that a replacement meter it posible get get. About the grid pot - it sucks. I constantley have to ajust it to keep the negative grid voltage konstant. I always use a digital multimeter to check the actual voltage when testing.
I will let you know how the repair is comming up
Peter Jensen, Denamrk
Hi again
Thanks a lot for the advice. I will open it up and check the things mentioned. It is nice to know that a replacement meter it posible get get. About the grid pot - it sucks. I constantley have to ajust it to keep the negative grid voltage konstant. I always use a digital multimeter to check the actual voltage when testing.
I will let you know how the repair is comming up
Peter Jensen, Denamrk
Re: Avo
Hello ,
Good idea , I do this also . The grid pot in mine has been changed . The pot that should be fitted is a weird log/lin/log but mine is a linear so I can't use the dial . Remember to remove the meter when taking cathode leakage tests , that is if you get the thing working . Wish you the best of luck with your faultfinding
cheers
316a
webercarbmann said:Hi again
Thanks a lot for the advice. I will open it up and check the things mentioned. It is nice to know that a replacement meter it posible get get. About the grid pot - it sucks. I constantley have to ajust it to keep the negative grid voltage konstant. I always use a digital multimeter to check the actual voltage when testing.
I will let you know how the repair is comming up
Peter Jensen, Denamrk
Hello ,
Good idea , I do this also . The grid pot in mine has been changed . The pot that should be fitted is a weird log/lin/log but mine is a linear so I can't use the dial . Remember to remove the meter when taking cathode leakage tests , that is if you get the thing working . Wish you the best of luck with your faultfinding
cheers
316a
More AVO
Hi again
Now I have tryed several things. Both the 2A fuses are ok. The meter powers up/read light in the bulb between the fuses. Are there anny fuses inside the meter? I tryed to lift the 10K resistor over the meter and mesure the resistance over the meter. It was 1.4 Mega Ohm. - So it is now open. The manual says somthing about setting the selector to 0 0 0 0 0 0 0 0 0. I tryed that also. Still no result. Anny ideas please??
Peter
Hi again
Now I have tryed several things. Both the 2A fuses are ok. The meter powers up/read light in the bulb between the fuses. Are there anny fuses inside the meter? I tryed to lift the 10K resistor over the meter and mesure the resistance over the meter. It was 1.4 Mega Ohm. - So it is now open. The manual says somthing about setting the selector to 0 0 0 0 0 0 0 0 0. I tryed that also. Still no result. Anny ideas please??
Peter
Meters for AVO testers
Have you tried Crowthorne Tubes???
ISTR that they have a stock of meters for AVO testers.
http://www.crowthornetubes.com/
Have you tried Crowthorne Tubes???
ISTR that they have a stock of meters for AVO testers.
http://www.crowthornetubes.com/
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Design & Build
- Equipment & Tools
- AVO CT-160 --- Help