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Ekco TU169 lightning strike (not recently)

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freya
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I am in quandry as to what to do with set, it is in fine cosmetic condition having an unblemished cabinet but that is where it stops. The chassis is covered in a light dust and almost looks like it came off the production line yesterday.

As per the title my inspection of the underside of the chassis has revealed quite a few components blown apart, the 1st input coil one of several that are burnt to a crisp and there are several 10F1 valves that have been shattered.

All that said, i still plugged it in and would you believe it, got abright blank raster.

So the dilema is, do i rebuild most of the IF stage knowing there are several coils that need rewinds or replacement plus the many components that have been damaged one way or the other.
Or call it a day and use the parts - tube (Mazda CRM122) ?

What would you do ?

 
Posted : 18/11/2013 9:30 pm
neil1974
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It sounds to me as if it wants to work :bbc and you should restore it :aad . but it's your set and however much it might upset anyone it's up to you to decide what happens to it :) .

Cheers,Neil.

 
Posted : 18/11/2013 9:35 pm
freya
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Its the coils that i find daunting, i know they are nothing special but not having anything to go by (wire fall in bits )

 
Posted : 18/11/2013 9:42 pm
Refugee
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I would put a wanted post up for an IF strip or a set with a dead tube or LOPT.

 
Posted : 18/11/2013 10:07 pm
Anonymous
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Try to restore it first. If you cannot get hold of the parts you need then it could become a donor for other sets.

Al

 
Posted : 18/11/2013 10:38 pm
danny
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I think this set could be saved as there are spares kicking about from rougth sets i think i may have a spare schassis from a similar model but it may take me a while to locate it. a picture of the schassis will confirm im thinking of the right set. Danny

 
Posted : 19/11/2013 12:55 am
freya
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Thanks Danny,
I can not get to the set at present, but hope the picture of the layout would be enough for the identification;

 
Posted : 19/11/2013 12:03 pm
Till Eulenspiegel
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The TU169 looks like a development of the TC139 T141 series. These sets were made for AC mains only.
I notice that your set has the Mazda 6D3, a special slow warm up diode.
The RF and IF section in your set has the same appearance as the one found in the TC141, only a chance of valves. 10F1s instead of 6F13s.

Till Eulenspiegel.

 
Posted : 19/11/2013 10:37 pm
slidertogrid
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Hi I have a chassis from a T164. If there is anything the same, transformers/coils etc you are more than welcome!
I can't get to it at the moment as it is in the shed which is full of cardboard boxes (long story!).
I have no idea if it is anything like your chassis but I will dig it out if it will help save another!
regards, Rich.

 
Posted : 20/11/2013 10:49 am
mark pirate
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I would restore it, as you have a raster it proves the LOPT & CRT are ok. A donor set should yield the required parts.
Might be a bit fiddly to do, but I would rather take it on than do a rough cabinet!
I hope you manage to sort it.

 
Posted : 20/11/2013 11:23 am
freya
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Thanks Rich,
Having the ekco info i should be able to tell if the IF coils are the same on the T164 chassis. Will get back to you and let you know.

Thank you

 
Posted : 20/11/2013 12:02 pm
freya
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I notice that your set has the Mazda 6D3, a special slow warm up diode.
Till Eulenspiegel.

I had wondered given this provides protection to the CRM122 tube if Ekco could/should have used this on their other tubes in the CRM121 series tubes that failed big time.

Would a simple slow start diode have prolonged their life.

Does anyone know how the gun structure differs in the CRM122, it has to be cathode related ?

 
Posted : 20/11/2013 12:08 pm
Till Eulenspiegel
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The CRM122 is similar to the earlier CRM121 except for the special heater which is 7.3 volts @ 0.3amp.
Mazda made this tube at the behest of the TV set manufacturers demanding a CRT for inclusion in series heater chains. The triode gun assembly is otherwise similar to the CRM121.
Info on the Mazda 6D3.

Till Eulenspiegel.

 
Posted : 20/11/2013 12:45 pm
freya
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It appears quite a cleverly designed little valve really, the cathode nicely takes its time to react to the heater. Putting it in the valve tester almost gives the impression the valve is no good, then the needle swings over super fast into the good section.

 
Posted : 20/11/2013 12:51 pm
Till Eulenspiegel
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I think that the 6D3 was intended for TV sets having mains derived EHT. Reducing the possibility of phosphor burn in the event of the EHT being present before the timebases have started to function.

till Eulenspiegel.

 
Posted : 20/11/2013 12:57 pm
Till Eulenspiegel
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Info of the CRM122 and the 2 volt heater CRM123 for comparison.

Till Eulenspiegel.

 
Posted : 20/11/2013 1:44 pm
freya
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Rebooting back to black and white 405;

I have spent some time on and off this set after kindly receiving a similar donor I.F. strip to enable a few coil substitutions, I can get a signal generator signal as far as the junction of C6 and C7 but no further.

Some help would be appreciated as to the possible causes please before I start tearing out small value capacitors etc.

re-reading this sounds somewhat vague, also checked are the voltages around V1, these are all correct, the coils associated have also been checked, as has the valve with substitution and also a NOS. Very stumped.

 
Posted : 17/02/2014 11:08 am
Till Eulenspiegel
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When you say say you can't get a signal further than C6 and C7. Is this an IF frequency? Disconnect one end of C10 which is connected to the grid of V2 then wire in a termination resistor between the grid and ground, although this is not strictly necessary for signal tracing purposes. Inject the IF signal to confirm that V2 is OK as an If amplifier. If OK it's tme to check the frequency changer and RF amplifier stages. V1 and V2.

Till Eulenspiegel.

 
Posted : 17/02/2014 11:58 am
freya
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Thanks Till,

What sort of value should I use for the termination resistor, should I be injecting at the V2 grid.
This area is out of my comfort area of knowledge. :aaq

Using cossor 1320 alignment and pattern generator as it was to hand.

Thanks

 
Posted : 17/02/2014 12:17 pm
Till Eulenspiegel
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Hi Steven,
the termination resistor is optional and is 75 ohms, usually 82ohms in the real world as 75 ohms resistors are difficult to find. The truth is for signal chasing you can forget the termination resistor, it is only when doing alignment work when correct matching matters and even then many don't bother.
I'm not sure what the exact IF s are for the Ekco, but I seem to remember that 16Mc/s sound and 19.5Mc/s vision come to mind. If it is 19.5Mc/s vision than that frequency will be on the slope of the response curve so the signal generator can be set about 18Mc/s.
Fault finding in circuits with resonant components can be difficult. You might remember the fun I had with the Masteradio T852.

Till Eulenspiegel.

 
Posted : 17/02/2014 12:41 pm
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