Ekco ACT96 restoration

[stevehertz]

Today I've taken a look at this second open circuit coil (third one all told - so far..) and remade the end connections, both of which appeared broken when I carefully slid off their insulation tubing. But to no avail, there must be another break within the coil itself. So, it's off to Mike for another rewind I'm afraid. There's a few niggling things that I can be getting on with (on this set) and likewise other sets and stuff to do. It's proving to be quite an epic this one..

[stevehertz]

Here's the guts of the tuning can in question, now dismantled ready to send off for rewinding. Interestingly, although the Trader service sheet depicts the can as containing two coils (a trf) and two variable caps, also tucked away in there and not shown on the schematic are two resistors, a cap and a small 'flying saucer' shaped component that I am not sure of, and in fact when I tried to unsolder one end as I needed to separate the top and bottom end pieces of the assembly, one of its legs fell off so I'll need to replace the component. Can anyone ID it please? It reads something like 15 cm+-20%. The 'c' could be 'o' though. What is it? a temperature dependent cap or resistor?

[cathoderay57]

Hi Steve. It's a capacitor. On the Ekco service sheet it is C15, shown in the component list as 15 cm. On the Trader sheet it's C14 0.000015uF or 15 pF. It couples the IF output to the AGC (thanks Lawrence!) diode V4. That can contains two capacitors and two resistors (C15, C18, R14, R15 as listed in the Ekco sheet). I've never seen the use of cm to represent pF so I learned something today. Cheers, Jerry

[ms660]

It's a capacitor, it's the coupling capacitor to the AGC diode (C14,15pF) CM is a unit of capacity.

The two 100k resistors are R13 and R14 both 100k in the Trader sheet (IF stopper and detector load)

EDIT: Post crossed

Lawrence.

[stevehertz]

Thanks guys, appreciated, a 15pF cap it is then. It would be good if the schematics showed a dotted line to indicate components that are contained in a common sub-housing.

[ms660]

Originally Posted by stevehertz

Thanks guys, appreciated, a 15pF cap it is then. It would be good if the schematics showed a dotted line to indicate components that are contained in a common sub-housing.

They are identified on the Trader sheet layout (To the right of L14, L15 chassis topside)

Lawrence.

[stevehertz]

Thanks Lawrence I'll take a look tomorrow.

[stevehertz]

Ok, I have now received the rewound coil courtesy of Mike Barker, thanks Mike. I'm back on it and trying desperately, using photos I took at the time to refit the guts of the coil and then the whole can back into the set.

[stevehertz]

I've now reassembled the coil and associated components in its can, and in turn refitted and rewired the unit back into the set. Switched on, no stations. As previously there's a healthy buzz from the gram socket when touched, and the volume control does raise and lower the general background noise level. But any 'front end' stuff like operating the band switch or rotating the tuner results in zero audible effect. Refitting the coil was quite a difficult task mentally and physically; awkward, access limited and hard to see. So after a couple of hours doing that, I'd had enough. Hopefully today I'll start measuring valve voltages etc. I've done so much and come so far with this set it's not going to beat me!

[stevehertz]

Ok, I've located the fault. First off, I checked the valve voltages and they all seemed there or thereabouts. I tried my ipod via the gram socket and the sound was shockingly good. So, as I surmised earlier, it's definitely a front end problem. I decided to check resistances of the remaining 'coils in cans' ie the ones that have not already been identified as faulty and rewound. Sure enough L13 (trader sheet) is open circuit. As yet I haven't gone through the relatively long process of removing connecting wires from the can and obviously, not accessed the coil itself to see if the break is somewhere where I can repair it. If it isn't, I'll be knocking on dear old Mike Barker's door again (third time on this set). This is definitely the 'faultiest' set I have ever worked on. We'll get there.

[stevehertz]

As per sod's law the break in the coil seems to be buried deep within, so off to Mike for a rewind it goes. But I'll be back..

[Lloyd 1985]

Do you ever get the feeling a set just doesn’t want to do any work?!

Fingers crossed this is the last coil to play up

Regards,
Lloyd

[stevehertz]

Thanks Lloyd. One day it will sing again even if I have to whip it.

[stevehertz]

This latest coil is now back in my hands from Mike after a rewind of both coils on the former. Actually only one of the two coils was open circuit, but due to the physical layout of the assembly, both had to be rewound. This one was slightly easier to refit compared to the previous two as there was greater access and fewer wires to resolder. Anyway, despite high expectations the radio still does not work. I have a degree of background noise that can be adjusted by the volume control (I had that before). It was late yesterday when I got this far so sensing a long dig in I called it a day. I'll begin investigations again and check voltages etc. In terms of man hours spent on it I reckon I am now the owner of the most expensive vintage radio in the country. Possibly..

[vinrads]

Hi Steve I feel your pain ! but what joy you will have when it burst into life ,which it will I am sure ,following with interest. Mick.

[stevehertz]

Thanks Mick - I need encouragement!

[Mr 1936]

Hi

Not that it makes any difference to the working of your set, but a 1 cm (centimetre) capacitor is 1.113 picofarads. This measurement was part of the CGS system of units, and appears to have been in use till the middle of the 20th century.

Jars (from Leyden Jars) were 1000 cm or 1113 pF and were still in textbooks in the 1930's.

Keep up the good work, surely full operation will happen soon !

[stevehertz]

Right. Thanks for that.

[stevehertz]

It works!! having taken getting on for a year so far, I'd forgotten that a couple of the valves were less than great. I just retested all the valves on my HSVT, and frankly a couple were duds. Now replaced, we have lift off. I've tweaked the IFs and tuning caps to get best reception and it works great.

Not quite finished yet though, a couple or so more jobs to do. The rubber grommet that supports the back end of the main tuning cap has collapsed but I'm not sure how accessible it is as yet, it may prove to be an awkward job, but certainly not insurmountable. The newly made dial is fine, but I've since got a better shade of paper for the 'filter' so I may redo that. There's also a metal screening plate that needs a bit of reforming and refitting underneath the main chassis. A few other relatively minor cosmetic points and it should be ready for inspection.

[Lloyd 1985]

Great news!

I’ve used tap washers to replace tuning cap rubber supports before, but they are probably a bit too solid.

Regards
Lloyd