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Saturday, 24 January 2015

Ekco U353 Basket Case repaired!

There's a lovely chap at work called Terry, who likes to restore old radios and record players. He arrived with this old Ecko U353 in bits in a box. "It's got cut wires and labels and has been got at. Would you like it?" Why not ...


 Wires cut. Looks like someone was going to change the mains smoothing capacitor.
 UL84 getter looks bad.
Most of the white lettering from the scale has gone...
... but on the whole the chassis looks reasonable.










The mains smoothing cap is not original, has been disconnected and is dated Feb '65. It has poor ESR....











.. so each of it's 3 sections is given a few hours on the ole' MK87 Dreadnaught capacitor reformer.....









 .... meanwhile the sad looking UL84 is tested on the AVO two-panel valve tester...

A sad 1.5 mA per Volt. Minimum for a new valve is 9 mA per Volt. No good at all....


Thankfully, we have a NOS replacement. Just look at the difference in the gettering (that's the shiny bit at the top). The new valve is on the left. The gettering is bright and has a nice sharp edge. The blacker the gettering is, the better. This new valve reads 15mA per Volt on the AVO!





Stamped on the chassis is a date ... 1st Sept ...19 ?? 1957 perhaps? Seems a bit early for this receiver...








There were many leaking and cracked Hunts capacitors to be changed, along with some suspect TCC electrolytics. The cathode bypass capacitor for the UL84 was short-circuit. That's probably why the valve was worn out.






 Remembering how there was a small decoupling capacitor in the U319 VHF tuner, which caused issues, I removed the cover to this unit (a much easier job that the U319!!!)
But the decoupling caps are Eire types, and all read in very good condition...


So, after leaving the mains smoother on the reformer with all 3 sections in parallel, the leakage had dropped to a very low 50uA!  ESR was good too, so it was re-installed and connected up. So all in all, 1 valve and 9 capacitors, and we're ready to go! Connect to the safety mains isolation transformer, switch on ....






... and after a few minutes warm up time, the DM70 indicator tube lights, and the set performs well...








In common with most mains sets of the period, the metal chassis is connected straight to one side of our AC line (in normal practice, the neutral)... this is referred to as a "live chassis" (even if it is neutral) , which mean the shafts for the controls are also "live". Now, until a set of insulating knobs can be found, this set can only be safely operated though an isolation transformer.


I did locate a nice shiny set of plastic knobs at a dealer locally. Whilst the knobs are plastic, the shiny coating must be metallic, as they conduct very well! These will NOT be safe!







Anyways, here's some good-looking chap to explain the set to you!

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