You can't beat a Trader sheet!

[stevehertz]

I'm working on an Ekco AC64 from the early 30s. There's a Tufnol board under the chassis that is populated with components that are basically interconnected by taking their leads through holes at each side of the board and soldering them and interconnecting wires together 'solder blob in the hole' style. So far so good and relatively easy to check and work on. But there's also components underneath this board that you cannot see and not without great difficulty, get at. To add to the difficulty the board is riveted in place and the rivets are under IF cans. Anyway, difficult and time consuming as it is I've done this kind of thing before. The data available is Ekco's own service information, no Trader sheet being available for this radio. For starters, Ekco's service data does not show any component layouts. So it's very difficult knowing what's underneath that Tufnol board. First of all I took photos to enable me to unsolder connection points where the components underneath (four 0.1uF capacitors as it happens) appear to be connected to ones on top. With some difficulty, having removed the first capacitor, in the process of replacing it I thought I'd just confirm that the connections all corresponded with the circuit diagram just in case I'd disconnected a previously unseen wire underneath, or was about to make a wiring mistake. Did it match the circuit diagram and listed component values? did it ever?! It's quite different.

I've ended up trusting that what was there before was correct (not an unfair assumption), and that my re-wiring was also correct to my photos.

So on two counts a Trader sheet would have helped my greatly, firstly to provide details of the positions of components, and secondly to provide a more accurate circuit diagram and component list to work to. Now, I'm sure that there are early production run sets out there whose circuitry matches the circuit diagram, and the Ekco data would be fine. But Trader sheets tended to come out later than manufacturers' data and in any case, often detailed chassis divergences, anomalies etc.

The moral to my thread being, 'You can't beat a Trader sheet' !

[Aub]

Looks like Ekco didn't want anyone fixing this set, but to go and buy another. Well done for, effectively, making your own trader sheet.

Cheers
Aub

[stevehertz]

Indeed Aug, incorrect circuit diagram and no component layout information - create your own. Not a lot of use really, in fact it's more a case of some information being worse than none in the case of the non-matching circuit diagram - follow it at your peril! It also makes the component list unreliable.

[David Simpson]

Trader Sheets, PW Diagrams, the vast multitude of A4 circuit diagram pdf's in circulation, etc. - - the vast majority being originally A5 or smaller sized format - - I get blown up to A3. If it looks like a long job, I colour-in HT lines, GB, AGC, etc., and draw in 1" dia circles - showing each valve's pin connections. Saves a lot of time circuit tracing & helps tired old eyes.

Regards, David

[stevehertz]

Good idea David. Many is the time I've needed to measure a voltage on a valve pin, and then you think, "what pin number is that grid?". And yes, blown up diagrams too. The trouble is with most vintage data is document deterioration and recopying leading to numbers etc being indistinct or parts missing, blank. But, that's the nature of our hobby, it's antique, less than perfect material through and through.

[David Simpson]

Right enough, Steve, the documentation is often vintage & in much the same grotty condition as the set. Worst still is the circuit diagrams of test equipment, which is often in "fold-out" format in a manual. Probably copied on 3 sheets of A4, but when downloaded off the internet - when placed side by side - the heffing circuitry "lines" don't match up. I trim off the excess blank paper, and usually can carefully "sellotape" the "rear side" together, thus getting the lines to more or less match up & can be copied direct at A3.
A couple of years back, or so, I was extremely lucky with one or two Forum guys sending me some lovely old "Rotring" drawing pens, and stencils, etc., which once again I must express my gratitude. These are great for re-invigorating fading or scratched info on circuit diagrams. Some of the modern "Staedeter" pens one can buy from a stationers are also pretty good.

Regards, David

[stevehertz]

I've restored this set now bar a few little niggles, not so good valves etc. Thought I'd try tweaking the RF coils for best reception as this normally yields a small amount of improvement due to drift etc (not touching the IFs). Does the Ekco data mention alignment? Not at all! It's little more than a schematic, parts list and how to dismantle.