EXPIRED: Avo Valve Characteristic Meter Mk lV

[QT Audiophile]

Item Condition: good for it age ( see picture)

Shipping Options: Pickup available but audition is not available.,Shipping is available at agreed cost.

Suburb or Town: Balwyn

State: Victoria

Payment Method: Cash or Bank transfer

Reason for selling: too complicate machine

Hi Stereonet member.

 I listing for sale Tube tester, This tester just bought not long ago. It turn on, I try to insert 12at7 test, it work but look like machine need service or i did wrong thing I am not sure The Machine so complicate Highly recommendation for professionals. If you know what is this, and how to used may be you are interesting. The machine will sale as is condition. They come with 160 page valve Data book, manual and working instruction book. 

Please Don’t Buy this machine if you are only test the valve.  Because this machine very complicate

Thank you for looking  
Photos:

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[Guest palexsia]

Some of the tubes you need to test fast or smoke come out of the tester . Incompetence peoples who not familiar with this tester need to aware .  I did a test with John of hifi exchange and that what’s happened because we are too slow , but we learned after that . 

Edited September 11, 2020 by palexsia

[McCvinyl]

Newton McLaren have their phone number on there. Maybe call them and see if they have an instruction manual.

It would look cool on display as well. GLWTS

[t_mike]

This may help.

 

https://frank.pocnet.net/instruments/AVO/index.html

 

https://www.kevinchant.com/avo.html

 

Available here on cd rom.

 

https://armyradio.com/Military-Test-Instrument-Manuals/

[Bisguittin]

34 minutes ago, McCvinyl said:

Newton McLaren have their phone number on there. Maybe call them and see if they have an instruction manual.

It would look cool on display as well. GLWTS

That company was apparently bought out by Lawrence and Hanson Ltd in 1974.

[Guest]

Used AVO gear previously (AVO stands for Amps Volts Ohms) - bullet proof gear if used properly.

[xlr8or]

One of the best valve testers if not the best on the planet and dead set easy to use if you understand the difference between mA and mA/V readings - totally agree with @Pigpen.

 

The former is all that is needed for a simple plate current measurement of a valve. There are a few youtube videos illustrating how to use this tester and other AVO valve testers, which operate on the same principle. The operating manual is written as an educational tool and easy to understand.

 

The only thing that goes in these is the galvanometer coil wire if bounced back and forth abruptly - yes -  it is sensitive and if bounced vigorously it burns out - not sure if smoke comes out though.

 

There is a mod online that protects this part of the circuit.

 

David Crittle at Retrovox is your man for servicing these beauties.

 

GLWTS.

Edited September 11, 2020 by xlr8or

[tchye nguyen]

Hi Ken, I can show You how to use the machine. Come to my place after the restriction is over. I have two of them and had been use it for many years. It is complicated to set up and use. It take time to set up and test each tube. Any thing wrong inside this machine can be fix but do not damage the VU meter, if the meter damage, the machine is in the bin. You can not get the right VU meter to replace it. It is specially made for AVO. The machine might need to calibrate to be accurate. To calibrate it use digital multimeter to check voltage on top of each pin for cathode, Heater, Heater plus, ground, A1 and A2 and D1 and D2 voltage. 

[QT Audiophile]

38 minutes ago, tchye nguyen said:

Hi Ken, I can show You how to use the machine. Come to my place after the restriction is over. I have two of them and had been use it for many years. It is complicated to set up and use. It take time to set up and test each tube. Any thing wrong inside this machine can be fix but do not damage the VU meter, if the meter damage, the machine is in the bin. You can not get the right VU meter to replace it. It is specially made for AVO. The machine might need to calibrate to be accurate. To calibrate it use digital multimeter to check voltage on top of each pin for cathode, Heater, Heater plus, ground, A1 and A2 and D1 and D2 voltage. 

Can you show example for 6ca7 setting

[tchye nguyen]

The selector switch 126 540 310.

Heater voltage 6.3v

Negative grid voltage 14.5v

Anode voltage 250v

Screen voltage 250v

mA/V 8.5

Factory requirement for a new 6CA7 tube is 57. If the test shown Your 6CA7 is 57 it is a pass if it is higher then 57 it is very strong and if it is under 57 it is low. You then have other test for gas, Cathode/ heater insulation test. short circuit test, test hot test cold. 

Note: D1 and D2 is for testing rectifier tube.

 

[QT Audiophile]

1 hour ago, tchye nguyen said:

The selector switch 126 540 310.

Heater voltage 6.3v

Negative grid voltage 14.5v

Anode voltage 250v

Screen voltage 250v

mA/V 8.5

Factory requirement for a new 6CA7 tube is 57. If the test shown Your 6CA7 is 57 it is a pass if it is higher then 57 it is very strong and if it is under 57 it is low. You then have other test for gas, Cathode/ heater insulation test. short circuit test, test hot test cold. 

Note: D1 and D2 is for testing rectifier tube.

 

Edited September 12, 2020 by QT- kWang

[QT Audiophile]

That is Reading first set up follow your number value instructions, look in pictures is this right?

[xlr8or]

11 minutes ago, QT- kWang said:

70mA versus 57mA new. Very strong EL34/6CA7 valve.

[xlr8or]

2 minutes ago, QT- kWang said:

That is Reading first set up follow your number value instructions, look in pictures is this right?

All settings look right.

[QT Audiophile]

1 hour ago, tchye nguyen said:

The selector switch 126 540 310.

Heater voltage 6.3v

Negative grid voltage 14.5v

Anode voltage 250v

Screen voltage 250v

mA/V 8.5

Factory requirement for a new 6CA7 tube is 57. If the test shown Your 6CA7 is 57 it is a pass if it is higher then 57 it is very strong and if it is under 57 it is low. You then have other test for gas, Cathode/ heater insulation test. short circuit test, test hot test cold. 

Note: D1 and D2 is for testing rectifier tube.

 

Which column is  "Anode voltage"

[Graywulf]

On 11/09/2020 at 3:43 PM, palexsia said:

Some of the tubes you need to test fast or smoke come out of the tester . Incompetence peoples who not familiar with this tester need to aware .  I did a test with John of hifi exchange and that what’s happened because we are too slow , but we learned after that . 

Mate if you made smoke come out of the tester? You've done something seriously wrong. They have an Anode overload protection circuit. If it's smoked, something is damaged and it will need a full check over. In perfect working condition it may be worth 1800 bucks, but from the look and your description of what happened???

[xlr8or]

2 minutes ago, QT- kWang said:

Which column is  "Anode voltage"

The Va column.

[QT Audiophile]

8 minutes ago, Graywulf said:

Mate if you made smoke come out of the tester? You've done something seriously wrong. They have an Anode overload protection circuit. If it's smoked, something is damaged and it will need a full check over. In perfect working condition it may be worth 1800 bucks, but from the look and your description of what happened???

Don't mistake this one smoke not come out!!!!!!!!

Edited September 12, 2020 by QT- kWang

[QT Audiophile]

2 minutes ago, xlr8or said:

The Va column.

Thanks Mate!

[QT Audiophile]

8 minutes ago, xlr8or said:

70mA versus 57mA new. Very strong EL34/6CA7 valve.

If it too strong !

What can i do next step??????

[Graywulf]

1 minute ago, QT- kWang said:

Don't mistake this one smoke is come out!!!!!!!!

" I did a test with John of hifi exchange and that what’s happened because we are too slow , but we learned after that . "

They were your words.... smoke came out of it.   Avo's (apart from that meter) are usually pretty bullet proof, I love my VCM 163

[QT Audiophile]

5 minutes ago, Graywulf said:

" I did a test with John of hifi exchange and that what’s happened because we are too slow , but we learned after that . "

They were your words.... smoke came out of it.   Avo's (apart from that meter) are usually pretty bullet proof, I love my VCM 163

That was comment from "palexsia" what he did before.

 

VCM163 the same family with this tester?

Edited September 12, 2020 by QT- kWang

[xlr8or]

Just now, Graywulf said:

" I did a test with John of hifi exchange and that what’s happened because we are too slow , but we learned after that . "

They were your words.... smoke came out of it.   Avo's (apart from that meter) are usually pretty bullet proof, I love my VCM 163

I think the issue here is definitely with the galvanometer and it sounds like it's overheating. As @tchye nguyen mentioned if you burn out the coil there is no replacement meter. It will need to be sent to Jacmusic to be reconditioned and the price is not cheap. I'm pretty sure this is happening when the mA/V readings are being taken.

[xlr8or]

7 minutes ago, QT- kWang said:

If it too strong !

What can i do next step??????

Nothing further needs to be done. Write down the value and test the next valve. If you want to also take the mA/V reading you need to use the dial on the right to get a full deflection value of 1mA/V. I would suggest only doing this measurement after you have measured several mA values and you feel comfortable using the unit.

[Graywulf]

2 minutes ago, QT- kWang said:

That was comment from "palexsia" what he did before.

 

VCM163 the same family with this tester?

the 163 was Avo's last tester. some would say the 'ultimate Avo'? There are other better 'laboratory testers' but extremely expensive. The real advantage of the 163 over the mk4, is it does not require the 'backing off' and Mu/milliamps are displayed simultaneously on two different meters. Otherwise really, the Mk4 is probably as good.