EKCO SH25 Restoration
I bought this EKCO SH25 at an auction for £20 as I thought it would go well with my restored EKCO ACT96. Little did I know what the condition of it was or I might have thought twice.
Fortunately, the case was in good condition with no chips or cracks and the back was intact and original, but there wasn’t mains lead with it or the connector for a mains lead. Removing the back and base revealed a rather rusty mess and the home of a small rodent in the bottom left corner of the chassis. The first challenge was removing the chassis from the case as the grub screws in the small knobs were rusted solid and no amount of anything would shift them, so I had to drill them out hoping that I could later tap a thread and create some new grub screws.
Once out of the case I tested the valves (which all tested OK) cleaned off all the dust and dirt and removed the mess in the bottom of the chassis, I then tested all the coils and the transformers for continuity and they all tested OK apart from the interstage transformer. I thought the best way to deal with this set was to take pictures and then strip it down completely to its individual chassis components. The way I normally do this is to drill off the rivets on the valve holders and remove any nuts and screws holding in other components then drop the whole assembly out of the chassis, but on this set the power supply is a separate assemble so this had to be removed first.
After everything was removed and the chassis and the loudspeaker stripped to its individual components it all went off to a local company for sand blasting which gave me time to test all the other components. Obviously, the capacitors would all need replacing testing the resistors showed a few of them were either open circuit or way out of value, the volume pot (which is wire wound) was for some reason burnt out so I had to strip another pot of its element and fit that in the original - not quite the same value but it works just fine. I tested the mains transformer for insulation and output at load and amazingly it was fine, I also tested the rectifier with the transformer and again that was OK as well.
Once everything came back from sand blasting, I sprayed all the chassis parts with a galvanising spray from Screwfix, and then sprayed the metal parts of the loudspeaker. The loudspeaker was then re-assembled along with the output transformer, tested and centred, and then put to one side for later - don't you just love a loudspeaker you can disassembled to its component parts!
Them started the long process of recreating the tuning dials by scanning in the originals and then painstakingly re-creating the lettering before removing the original image. At one point I though I wasn’t going to be able to do this as a large amount of lettering had been rubbed away, but through various images and help from people on this forum I managed to complete the task. The dials were rubbed down and primed then sprayed with a colour called ‘strawflower’ available from B&Q and an almost perfect match to the original.
Then started the task of removing the capacitors from the two ‘blocks’ re-spraying these black and fitting modern substitutes. This was not an easy task as they had to be de-soldered before prising the contents out! The tall electrolytic capacitor had it’s top cut off and a modern capacitor fitted inside.
I then set about the re-build, checking and testing as I went, until I finally had a chassis that worked so I could align the IF. Surprisingly the set is quite sensitive, and even a short piece of wire was pulling in a good many stations. The pointer and tuning condenser needed to be re-strung but as there was no diagram in the service data for this it made it quite tricky, even though I had been supplied with a picture of the pointer stringing, which turned out to be wrong! Eventually I had the set complete, the case cleaned, new grub screws created and the whole thing back together. Unfortunately, the ‘distant / local’ switch stopped working but fortunately it’s in distant mode so I’m not about to strip it down again anytime soon to fix it.
This is one of the most difficult sets I have ever worked on, and the difference between this and the ACT96, which is just 3 years later, is day and night. Not sure I would do another SH25 any time soon!
Hope you like the pictures…
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