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-   -   Need schematic for Ekco A218 (https://www.vintage-radio.net/forum/showthread.php?t=14162)

brenda 17th Jan 2007 9:45 am

Need schematic for Ekco A218
 
Just got all your service disks, Paul. Figures that the first radio I try to find in it isn't there. Murphy's Law. :)

If anyone has a schematic for this radio, it would be greatly appreciated.

Will also need a dial glass, if I ever get it working.

TIA

Brenda Ann

Dave Moll 17th Jan 2007 10:17 am

Re: Need schematic for Ecko A218
 
It doesn't appear to be in R&TVS either.

paulsherwin 17th Jan 2007 1:09 pm

Re: Need schematic for Ecko A218
 
Hi Brenda. Could you post a picture?

Ekco numbered their sets sequentially, so it will come between the A160 and A222 / A239 on Paul's disks. The A160 and A239 are cosmetically similar being big woodies, the A222 is a clock radio. The A160 is SW/MW/LW using 'U' series B8A rimlocks and the A239 is VHF/MW/LW using 'E' series B9A novals. I would guess all these radios date from 1955/1956.

Ekco used similar circuits in most of their early 50s sets and they aren't difficult to work on without the right schematic. The wax caps are big yellow things and it's easy to read the voltage and value if you scrape a bit of crud off. Basically there were 2 variants, one with a live chassis using an autotransformer and 'U' series valves and the other with a fully isolated chassis and 'E' series valves.

Good luck, Paul

brenda 17th Jan 2007 1:56 pm

Re: Need schematic for Ecko A218
 
http://www.geocities.com/lectroncity/Ecko218.jpg

Sideband 17th Jan 2007 2:17 pm

Re: Need schematic for Ecko A218
 
That could be a non-UK set judging by the number of wavebands it has. May make finding a diagram a bit more difficult.



Rich

paulsherwin 17th Jan 2007 2:30 pm

Re: Need schematic for Ecko A218
 
Strewth, good luck with that one, you'll need it :D

It may be related to the the A160 but is obviously not identical: http://www.vintage-radio-resources.com/ekcoa160.htm

If it's an export only model then it's not surprising there's no service data in the usual UK sources. It's very rare for a UK domestic radio to have so many SW bands, and it almost always indicates an export set. They usually have the same 4 valve plus rectifier designs as the UK versions.

The cabinet has some similarities to the A277, but that's an FM only set: http://www.richardsradios.co.uk/ekcoa277.html

Paul

brenda 17th Jan 2007 2:46 pm

Re: Need schematic for Ecko A218
 
http://www.geocities.com/lectroncity/Ecko218chassis.jpg

brenda 17th Jan 2007 2:48 pm

Re: Need schematic for Ecko A218
 
As you can see, it's a fairly complex chassis. It has 7 valves, including an interesting little eye tube. It also seems to have a VHF band of some sort, though I can't tell it from the dial glass.

brenda 17th Jan 2007 2:49 pm

Re: Need schematic for Ecko A218
 
It also seems to have an interesting power supply setup. The transformer doesn't appear to be an autotransformer, but the heaters do seem to be in series.

paulsherwin 17th Jan 2007 3:00 pm

Re: Need schematic for Ecko A218
 
I'd be very surprised if that set has VHF. FM started in the UK in 1956 and I don't know of any FM sets that use those B8A rimlock valves. More likely it's got an RF amplifier stage. If so the lineup will be something like UF41, UCH42, UF41, UBC41, UL41, UY41. The tuning indicator is almost certainly a DM70/DM71.

Some Ekco sets of that period did use a fully isolated transformer but series heaters, the only manufacturer I know of that did this.

It's an interesting set and a pity it's in such poor condition. If I were you I'd try to remove the tuning scale as carefully as possible and immediately scan it without cleaning, then clean the worst of the filth off and scan it again. You'll probably need to make a new scale with two pieces of picture glass and an inkjet printed transparency.

Paul

Sideband 17th Jan 2007 3:08 pm

Re: Need schematic for Ecko A218
 
Notice the two-pin mains plug so it is definately continental.

Brenda. That tuning indicator looks like a DM70.


Rich.

Paul Stenning 17th Jan 2007 5:25 pm

Re: Need schematic for Ecko A218
 
Quote:

Originally Posted by Richard_Newman (Post 98116)
Notice the two-pin mains plug so it is definately continental.

That looks like a modern moulded plug and lead though, not original.

paulsherwin 17th Jan 2007 5:34 pm

Re: Need schematic for Ecko A218
 
Quote:

Originally Posted by Paul Stenning (Post 98126)
That looks like a modern moulded plug and lead though, not original.

If it's in Seoul it's probably been there since the British Army was fighting in the Korean War, so you wouldn't expect to find a UK BS1363 plug on it :D

Paul

newlite4 17th Jan 2007 5:36 pm

Re: Need schematic for Ecko A218
 
Brenda, that scale looks a nightmare 8-o. I see that all four control knobs pass through it via large holes. If you were able to scan the remains of the existing scale and touch-up the missing graphics :o, you could use perspex sheet which would be easier to drill holes into. Phew! looks like a tough one!
Neil

paulsherwin 17th Jan 2007 5:44 pm

Re: Need schematic for Ecko A218
 
A good glass merchant or picture framer should be able to drill the holes, but it won't be an easy job and is one for the professionals. Some sort of plexiglass would certainly be easier.

It seems very unlikely that a replacement scale or even a good scan will be forthcoming for this set, but it's amazing what can be done with image editing software.

Paul

jjl 17th Jan 2007 6:14 pm

Re: Need schematic for Ecko A218
 
Quote:

Originally Posted by paulsherwin (Post 98112)
More likely it's got an RF amplifier stage.

It appears to have a 3 gang tuning capacitor, if so it's almost certain that it has a RF amp stage. The RF amp is probably an EF41 by the looks of things and is most likely to be one of the 2 valves next to the stacks of coils.
It should be a good set if you can get it going Brenda, but it looks like it will take up quite a few of your evenings and weekends.

John

Paul Stenning 17th Jan 2007 7:51 pm

Re: Need schematic for Ecko A218
 
Quote:

Originally Posted by Richard_Newman
Notice the two-pin mains plug so it is definately continental.

Quote:

Originally Posted by Paul Stenning (Post 98126)
That looks like a modern moulded plug and lead though, not original.

Quote:

Originally Posted by paulsherwin (Post 98128)
If it's in Seoul it's probably been there since the British Army was fighting in the Korean War, so you wouldn't expect to find a UK BS1363 plug on it :D

The point I was trying to make is that since the cable is not original, it can't be used as a guide to the origin of the set.

When I was in South Korea several years ago they used continental plugs like that for 230V and USA type plugs for 115V. So it is likely that the cable was fitted there at some point in the set's history.

brenda 17th Jan 2007 9:06 pm

Re: Need schematic for Ecko A218
 
I'm pretty sure that the set came from Myanmar (Burma). I have a friend here that makes trips there fairly frequently and comes back with British and Japanese sets from the 40's and mostly 50's. The old Burmese plugs look much like the current Korean ones, with the thick pins, but the spacing was different, a bit closer together. I'm certain the current cordset is a semi-modern Korean one that my friend has installed to the radio.

The thing that indicates a VHF band to me (perhaps it's used on one of the higher SW bands) is the extra three sections on the tuner. Note the sets of widely spaced plates on the tuner just back of the main sets. Usually these would be used only in VHF sets, or on separate tuners for bandspread.

I have found what appears may be a similar set schematic for an A239, though it seems to use noval valves.

I can get audio on the set, but with a lot of hum. The mains filters seem to be OK, with the hum coming from wiring that's not been reconnected right in some former repair attempt.

I get no LO at all.

Yes, it will be a challenging project, for certain.

paulsherwin 17th Jan 2007 9:36 pm

Re: Need schematic for Ecko A218
 
Quote:

Originally Posted by brenda (Post 98152)
The thing that indicates a VHF band to me (perhaps it's used on one of the higher SW bands) is the extra three sections on the tuner. Note the sets of widely spaced plates on the tuner just back of the main sets. Usually these would be used only in VHF sets, or on separate tuners for bandspread.

I have found what appears may be a similar set schematic for an A239, though it seems to use noval valves.

I think the small tuning cap sections are for SW bandspread. This set looks as if it has sections for the different SW BC bands - 19M, 25M, 31M etc. All the early Ekco FM sets I know were permeability tuned, though they started to use capacitor tuning in the late 50s. The B8A valves point to the first half of the 50s.

The A239 is likely to be a red herring - it is a VHF/MW/LW set using 6.3V noval valves. I think that, if you forget about all the SW coils, the RF preamp and the tuning indicator, the circuit will be very like the A160.

DM70 tuning indicators are directly heated valves with 1.4V filaments originally designed for use in battery portables. They typically take their filament voltage from the output valve cathode. This has a tendency to rise in old radios as a result of a number of fault conditions, blowing the filament. They're still quite easy to find though aren't very impressive.

As John says, it's likely to perform well if you can sort the problems out. Change the UL41 grid coupling cap immediately if it hasn't been done yet, and check the current going through the UL41 cathode resistor.

Paul

stephanie 23rd Aug 2007 10:22 pm

Re: Need schematic for Ecko A218
 
Quote:

Originally Posted by brenda (Post 98152)
The old Burmese plugs look much like the current Korean ones, with the thick pins, but the spacing was different, a bit closer together. I'm certain the current cordset is a semi-modern Korean one that my friend has installed to the radio.

The old Burmese plugs were two-pin 5 amp British plugs (BS 546 types) - I have one lying around the house (made by National in Burma).

Korean plugs are Schuko and Europlug types, the pins are just spaced every-so-slightly-different (enough that they won't fit without considerable FORCE in old two-pin 5 amp Burmese sockets and vice versa).

The cordset on your radio is Korean, Brenda -- most definitely either installed by your friend or whoever he bought the set from. I think I sneaked a peek at it one day and just remember from the size and shape of the pins, not to mention the lettering on the cord. *shrug*


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