UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - EKCO TP-308 restoration

RestorationRod · 30th Sep 2019, 3:16 am

A couple of weeks ago I managed to get an EKCO TP-308 off e-bay for an outlay of £5.00

It was dirty but complete. The plastic top cover and screen bezel were removed and cleaned up a treat. Needless to say a full restoration was required. All of the electrolytic and wax capacitors were replaced. This necessitated the removal of the tube. Fortunately the service instructions tell you how to do this as its required to do an alignment.

Next I traced the wiring from the mains input and found the on/off + volume switch had fallen apart. This was duly replaced and a resistance reading across the heater chain obtained. (including the tube)

A comment at this point. Hold the safety advice guys - I have 50+ years of experience of working on live chassis TV and used to test cables up to 264 kV

So with the HT rectifier mains feed disconnected and using an isolation transformer, switched series incandescent bulb and a variac slowly brought up the voltage. Hoo - flipping - ray!! The valves lit up (series heaters so all or nothing).
Turn off and say Phew!

Next connect in HT rectifier, isolate output and check HT - yup 200v DC + (open circuit)

Turn off - discharge caps and connect HT to rest of set. Attach EHT meter to tube connector, AVO on DC current in series with HT and voltmeter across it.

Turn up variac and .... 12 kV on the tube connector, 195v DC at 200 mA HT and a nice healthy set of heaters. Turn off and say Phew! (again)

Next up tube back in and check for a raster.

30th Sep 2019, 3:16 am	#1
RestorationRod Triode Join Date: Feb 2018 Location: Reading, Berkshire, UK. Posts: 16	EKCO TP-308 restoration A couple of weeks ago I managed to get an EKCO TP-308 off e-bay for an outlay of £5.00 It was dirty but complete. The plastic top cover and screen bezel were removed and cleaned up a treat. Needless to say a full restoration was required. All of the electrolytic and wax capacitors were replaced. This necessitated the removal of the tube. Fortunately the service instructions tell you how to do this as its required to do an alignment. Next I traced the wiring from the mains input and found the on/off + volume switch had fallen apart. This was duly replaced and a resistance reading across the heater chain obtained. (including the tube) A comment at this point. Hold the safety advice guys - I have 50+ years of experience of working on live chassis TV and used to test cables up to 264 kV So with the HT rectifier mains feed disconnected and using an isolation transformer, switched series incandescent bulb and a variac slowly brought up the voltage. Hoo - flipping - ray!! The valves lit up (series heaters so all or nothing). Turn off and say Phew! Next connect in HT rectifier, isolate output and check HT - yup 200v DC + (open circuit) Turn off - discharge caps and connect HT to rest of set. Attach EHT meter to tube connector, AVO on DC current in series with HT and voltmeter across it. Turn up variac and .... 12 kV on the tube connector, 195v DC at 200 mA HT and a nice healthy set of heaters. Turn off and say Phew! (again) Next up tube back in and check for a raster.