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Old 19th May 2018, 12:50 am   #1
martin.m
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Join Date: Mar 2018
Location: Bishop Auckland, County Durham, UK.
Posts: 101
Default Ekco A144 repair

This radio has sentimental value as it belonged to my parents. I can remember listening to Alan Freeman's "Pick of the Pops" on it way back in the 1960s. My mother used the Ekco in a spare room until it was taken out of service in the early 2000s.
This model dates from around 1950 and uses a set of "U" series B8A valves with heaters connected in series and fed from a tap on the HT winding of the mains transformer. HT is provided by a UY41 half wave rectifier and the chassis is isolated from the mains.
I removed the chassis from the cabinet and a quick visual inspection revealed that one of the waxy capacitors must have been getting warm and had dripped wax into the bottom of the cabinet. A modern polyester 0.1uF 400v capacitor was fitted and after checking for shorts on the HT supply I switched on. The voltage on the cathode of the UY41 rectifier slowly rose to around 140 volts and moving the meter probe to pin 6 (grid) of the UL41 output valve gave a reading of around 3 volts positive, not a happy state of affairs. Time to switch off.
I had a circuit diagram for this model and, to cut a long story short, changed all the waxy tubular capacitors in the audio circuit (some are hidden on a sub panel) and any that were subject to HT voltage in the rest of the set. Much of the rubber covered wiring on the chassis had to be replaced along with the fabric covered mains flex. The resistors were measured and were found to be within tolerance.
Now on switching on stations could be tuned in, though the controls were crackly and the HT voltage remained at 140 volts. A secondhand UY41 restored this to just over 200 volts and squirts of switch cleaner completed the repair. The sound quality on this model is very good and I am amazed at the improvement in MW and LW reception when using the wire loop aerial built into the set's back cover. Droitwich on 200KHz comes through loud and clear with no electrical interference. Strangely, the lack of HT voltage seemed to make no difference to the sound or reception.
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