Golborne Vintage Radio

Best greetings to everyone. 

I am rarely stumped, but I am now.

Just rebuilt the AVO MkII, however the mains meter advanced only one division when circuit and leakage are on the proper settings for the tester to advance to the black calibration mark. Changing the leakage to (H) and the needle returns to zero. 

Reset is set.  All diodes (1n4007) are in proper polarity.  Continuity from the meter to R4 and beyond is right all the way to junction r10 and r9 and diode.  All bobbins are good or replaced, same with resistors.  Pots are also good.

Sometimes, after setting for a few minutes and plugging in, the meter will jump up and then fall again. Solder joints are refreshed.

Now here is my stupid question so I can continue tracing.  Looking at the schematic where to meter is shown to be connected to pole 6 and 7 ( in the Check © position, there is no wire indicated to be connected to number 6 (on the schematic).  What am I missing?

When I follow the calibration by Hein Ros, the first instruction to position the circuit selector to TEST, pins the meter into the negative.  There is no mention if this is expected.

Do the last two paragraphs help make sense of this problem?

bud

Greetings Bud,

You'll have to be a replacement for the late lamented Alan Douglas

There's another Thread on here about them - http://golbornevintageradio.co.uk/forum/...p?tid=5090&highlight=VCM
He's got 3, lucky sod, so he should be able to help, at least by comparing Voltages etc.

Alan

Well Hello Alan,

I sort of knew Alan Douglas via a common friend named Chris.  Chris passed and I withdrew from most sites, long story. 

bud

It seems the screen valve may be bad.

Does anyone have the original AVO schematic that is clear? The one in the third printing is condensed as new and the original is very blurred but has more detail.

Come in Ocean, your time is up.
Actually there are references to other Information in the Link above.

Alan

I can't see any links to service data in that other thread, Alan - they all seem to be concerned with pots on eBay.

Here are a couple I've found:

http://frank.pocnet.net/instruments/AVO/..._Mk-II.pdf

http://www.jacmusic.com/Tube-testers/AVO...Manual.pdf

You're right, clearly advanced memory failure.
Somewhere there were references to other Threads with comprehensive Service Data

Alan

!2 years ago I bought a MK 1 and a MK 11 for a knock down price.  One was only supposed to be for spares but in the event I repaired both of them and they still work and calibrate spot on with a "Standard Valve".  At that time I wrote two articles on them which have had wide circulation and you are welcome to copies of the original text (not copies of the articles).  This text was updated about 5 years ago because some of it wasn't as clear as it could be and with hindsight had errors.  Send me an e-mail if you want the info.  

I drew a circuit diagram from the AVO one but it doesn't include all switching.   However, there is one in a back edition of a magazine called Radio Bygones, in a pair of articles from about 3 years ago.  This was written by a couple of learned guys who's approach was to replace every passive, metal rectifier and valve component inside (and even recommends new meters if needed).  You could call this restoration where as I called mine repair.  You could try and get copies of these.

Gary

Hi Bud

I received your e-mail address and will send info. You have "Private Messaging Disabled" so I cant reply to your PM.

Gary

Thanks Gary...fixed. And thank you for the assistance.