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Old 8th Feb 2012, 7:02 pm   #1
matspar
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Join Date: Aug 2009
Location: Portsmouth, Hampshire, UK.
Posts: 230
Default Pye VT2 EHT problems

Hi all,

I've been working on a bakelite Pye VT2 for the last few days, it is a bit of a wreck but is coming together slowly. It has been hidden away in a lockup garage since 1963.

So far I've done the usual cleaning, de-rusting, and recapped the chassis, and today powered it up to see how it fared. It didn't disgrace itself entirely but there is an issue with the EHT which needs a proper look into.

I'm getting a nice strong line whistle but no raster. All the valves and tube heater are lighting up nicely and it looks like there's plenty of line drive, but the EHT is too low.

I can draw a very tiny spark (about 3mm) from the anode of the EY51 EHT rectifier, and there is a very faint glow from the heater, but not as bright as it should be.

I can't get a spark from the top caps of the line output or boost diode valves, a PL81 and PY81 but the voltage readings on the valve bases aren't far off the circuit.

I'm getting about 168v HT and the A1 voltage is around 190v which seems a bit low. I'm suspecting the Lopt may be at fault, unless there's something I may have missed. The EY51 heater winding is intact and reading just under 1 ohm.

All the valves are known good ones, and apart from the new capacitors I've checked all the resistors in the area and they all seem ok.

If anyone has any thoughts or ideas, or even a spare Lopt which I could buy, I'd be more than grateful!
I've wanted one of these sets for years and am really hoping to get this one minted and mended. I've attached some photo's to give you an idea. The chassis now looks a lot better than it did!!

P.s. Ignore the bodged in EY86 recifier which is shown in pic 3 (this has been replaced with the correct EY51)

Best regards

Matt Spanner

Portsmouth
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Last edited by matspar; 8th Feb 2012 at 7:11 pm.
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