rewiring Avo two panel tester

[Bushbaby]

I need some help and guidance please.

I've decided to rewire the 10 plug to the valve base following the CAD drawing that was produced by Chris Colebrook. I started from the selector switch tag - yellow wire (pin 5 of the plug). This was followed by the heater - selector switch pin 10, black wire (pin 4 of the plug) and then heater 2 - selector switch pin 9 & 8, brown wire (pin 6 of the plug). I then went to add the wire to the screen - selector switch 3 which should go to pin 7 of the plug......but it doesn't. It goes to pin 8 of the plug! Have I missed something; wired it incorrectly so far or was it originally wired wrong.

Please note that yellow wire goes to the pin at the 12o'clock position in the second picture; the black wire is the next wire clockwise and the brown wire is the first wire anti clockwise to the yellow wire.

Thanks

Rob
           

[pwdrive]

See post #12 and 13#.

I would check it with the switches set for a pentode valve, one you already know which pin on the valve the screen connection is then see if you get continuity to the slider of the screen grid voltage selector switch from the appropriate socket number on the valve holder being used for that valve.

Lawrence.

[Bushbaby]

Hi All,
I'm back in the garage working on this pesky 2 panel valve tester and I am not about to give up on it. I have now rewired the rollers in order to wire the 9 pin plug from the valve base section to the meter unit. I'm trying to test each connection to determine whether the roller configuration is correct. However, I cannot ascertain the relationship between the various valve base wirings to the rollers and the valve base pin connections. If I set all of the rollers to position 1 (cathode) then I should be able to check the continuity between the cathode connection at the 9 pin plug and the same position on each valve base and so on. However, in checking the English octal base, this does not appear to be the case. I've included a liitle text from the Avo manual below. Can some kind soul point give any helpful guidance here please?

Many thanks

Rob

When the symbol * appears in the selector switch figures, it indicates that the unknown electrode may be connected to a pin internally. To obtain the complete selector switch coding, test with an ohmmeter between the pin marked and all the others (the ohmmeter should be on a sufficiently low range to discriminate between a dead short and the filament resistance). Dependent upon the electrode to which this pin is connected, the correct selector switch code can be set up and the valve tested in the normal manner.
When the pin marked * is open circuit to all the others, set roller to 0.

When the pin marked * is connected to:

Cathode set roller to 1.
Heater - ,, 2.
Heater + ,, 3.
Grid ,, 4.
Screen ,, 5.
Anode 1 ,, 6.
Anode 2 ,, 7.
Diode 1 ,, 8.
Diode 2 ,, 9.

[pwdrive]

So far as I know all the valve base sockets are wired pin for pin in parallel, the selector switch just routes the supply voltages to the respective valve pins as per the settings given for a particular valve in the settings info.

Lawrence.

[pwdrive]

For anyone following, here's a link that contains the extraction that Rob posted:

http://www.kevinchant.com/uploads/7/1/0/...ester..pdf

Lawrence.

[AlanBeckett]

Rob,

Are you fitting a new Cable?
That was what I've been thinking of doing as every time I touch one of the wires at the Roller end it falls off

Alan

[pwdrive]

""When the symbol * appears in the selector switch figures, it indicates that the unknown electrode may be connected to a pin internally. To obtain the complete selector switch coding, test with an ohmmeter between the pin marked and all the others (the ohmmeter should be on a sufficiently low range to discriminate between a dead short and the filament resistance). Dependent upon the electrode to which this pin is connected, the correct selector switch code can be set up and the valve tested in the normal manner.
When the pin marked * is open circuit to all the others, set roller to 0.

When the pin marked * is connected to:

Cathode set roller to 1.
Heater - ,, 2.
Heater + ,, 3.
Grid ,, 4.
Screen ,, 5.
Anode 1 ,, 6.
Anode 2 ,, 7.
Diode 1 ,, 8.
Diode 2 ,, 9. ""

Some valves have more than one pin connecting to an electrode eg: some RF valves have two lead outs for the cathode in order to reduce the effect of internal wire/pin inductance at high frequencies.

Lawrence.

[Bushbaby]

Hi Alan,
I've fitted a new cables using small tags to the ends of each roller connector and it was a very fiddly job indeed. I tried testing each valve pin connection using the set up for an Octal frequency changer valve as suggested in the http://www.kevinchant.com/uploads/7/1/0/...ester..pdf Avo tester manual and it appears that I have indeed wired correctly (fingers crossed). I shall take some pics of the work done so far but I'm process of reassembly.
I'm in two minds whether to replace the old resistors in the panel section as I would think that their restistance values will be very high by now. However, they are not in accessible positions to replace easily.

Regards

Rob

[AlanBeckett]

Rob,

Where did you get the Cable from?
There's a few different 9-Core ones on ebay which look suitable if not very 'Authentic', eg http://www.ebay.co.uk/itm/CABLE-9539-9CO...upplies_ET&hash=item3f3a7addd0
Ignore the Picture.

Alan

[pwdrive]

How's about some of this stuff, you could double up some of the conductors to minimize heavy heater current losses...maybe.

Not sure how flexible it is.

http://www.ebay.co.uk/itm/Heavy-Duty-12-...ccessories&hash=item4ac91a70be

Lawrence.