Ekco T310 Restoration - complete novice

[Autozavod]

The set came with the original plug with the two differently sized pins to ensure correct polarity, I haven’t checked to see if they are correctly wired at the wall plug end.

Channel 1 selected and aurora set to 1.

When changing channels there is no discernible change to the screen, or pattern.

Also, last night I tried a long piece of wire as an fm aerial, with gloved hands I put the wire into the aerial when running to see if it’d produce a scratching sound. Nothing, she is deaf.

Could it be V9 is dead? Checking pins 7&8 when cold didn’t indicate a short, unfortunately I don’t have a spare.

Thanks again,
Matt

[Freya]

There are a few critical capacitors that could be affecting the signal, to name a few from the genuine Ekco sheet, these are a suggestion only. Take your time as there is no rush and its better to learn.
C98 0.5uF
C92 0.003uF
C35 0.047uF
C45 0.047uF
C68 0.1uF
C64 0.25uF
C62 0.1uF
Do you have valve heaters on the IF strip ? they are switched on/off via the trumpet switch.

[Heatercathodeshort]

Also check/replace all the small decoupling capacitors connected to pin 8 [screen grid] and 1/3 [cathode] of the 30F5 IF valves. A similar procedure can be carried out with the sound IF valves
V8 V9 [Newnes] They tend to go O/C resulting in instability and complete lack of signals. They may look like banded resistors typically .001uf. Replace with ceramic types and as far as possible put them in the same physical position as the originals.

Pay particular attention to those decoupling the final vision IF amplifier V4.

Identify them with the aid of the service manual/sheet and change one at at time.
John.

[dazzlevision]

Originally Posted by Freya

Do you have valve heaters on the IF strip ? they are switched on/off via the trumpet switch.

I've never heard of these "slider" switches referred to as "trumpet" types before.

Perhaps "trombone" would be more appropriate? ;-)

I'd certainly check that:

the HT supplies to the RF/IF chassis are present

the VHF tuner turret has the necessary TV and VHF radio coils loaded in it and their positions in the turret are such as to operate the TV/FM switch correctly (in case the "phantom twiddler" has been at the TV)

none of the vales are gassy (i.e. the tops have a "milky" coloured getter) and they are the correct types in the correct positions.

[1100 man]

Originally Posted by dazzlevision

I've never heard of these "slider" switches referred to as "trumpet" types before.

none of the vales are gassy (i.e. the tops have a "milky" coloured getter) and they are the correct types in the correct positions.

I thought a trumpet switch sounded rather fun!! Makes it sound much more exciting than it actually is

Further to the point about gassy valves, one or other of the tuner valves may be faulty. If the oscillator valve (V2, 30C1) is not oscillating, you would get no sound or vision.
I have had problems with several 30C1's and 30L1's resulting in no signals, so might be worth changing.
The tuner is the only thing common to both sound and vision (apart from HT rails) as the sound signal is split off just after the tuner and has it's own IF stages.
It needs some proper, methodical fault finding and voltage measurements to pinpoint exactly what's going on:- or not going on in this case!
Good luck
Cheers
Nick

[Autozavod]

After replacing the Hunts c35 and c45, the little bridging resistor over the positive terminals of c26 and c27 started smoking, as well as r59 (well, I think it is r59, it’s a dog’s breakfast in there).

As suggested, c26 and c27 are s/c.

Does anyone have a scan of one of those pictorial layouts of the chassis to be 100%
I have identified the correct component? There are a number of minor differences in the circuit and between published schematics.

Cheers,
Matt

[Freya]

here you go, these are a small part of the genuine Ekco drawings from the sheets, they enlarge nicely.

[Boater Sam]

If you have created a short on the HT line, as it seems, you have done something wrong or moved something to touch whilst doing the last operation. Go back and check before doing anything else.

Its a long dark alleyway once you set out on the wrong foot and keep going. Steady.

[Freya]

here is a small snippet of that area, if R59 is smoking the it suggests the new C26 could be the problem.

[Autozavod]

Thanks again gents.

The plan is to go right back to the beginning and triple check.

There are a couple of anomalies, and I believe it may have been the beginning of the smoking, C62 in the schematic goes from V10 pin 3 to V7 pin 1, however mine goes to V7 pin 5. I’m certain of this as I always leave a little original “tail” as a double check.

Oh, by the way, C26 and C27 are the originals, not my replacement.

Could someone provide me with the complete original schematic please? This isn’t the first anomaly.

Many many thanks,
Matt

[Freya]

PM sent requesting email address to send genuine circuit.
Its a bit confusing, if R59 100 ohm is burnt out as a result of C26 being shorted then you wont have HT to any of the IF strip. But it had to have done this quite early on when you first got the set.
It would certainly explain the loss of everything. C26 can be disconnected for testing purposes and will do no harm not being there temporarily.

[Boater Sam]

Originally Posted by Autozavod

After replacing the Hunts c35 and c45, the little bridging resistor over the positive terminals of c26 and c27 started smoking, as well as r59 (well, I think it is r59, it’s a dog’s breakfast in there).

As suggested, c26 and c27 are s/c.

Does anyone have a scan of one of those pictorial layouts of the chassis to be 100%
I have identified the correct component? There are a number of minor differences in the circuit and between published schematics.

Stephen, it would seem that the burning R59 occurred after some caps were changed which is why I suggested caution and a check.

I really don't want this renovation to turn into a fail, there is a lot of guesswork on the OPs part instead of systematic work.
Sam.

[Freya]

The OP now has the Ekco service sheet.

[Autozavod]

Thanks!!

Replaced C26&27, and R59.

Smoke stayed in this time ��

[Boater Sam]

R59 will probably still be serviceable, tough little blighters those carbons, its the paint that smokes.

[Autozavod]

Still no joy, that's ok as most of the larger capacitors are now replaced. No more smoke

The mains hum capacitor was in particularly bad shape, it'd disgorged all its wax.

Still no screen changes when changing channels, except for a slight click on the speaker. I'm starting to think it may be one of the early rf valves. Tapping them with a plastic rod doesn't generate a crackle, except the sound output.

My uneducated suspicion is falling on the rf amplifier and/or frequency changer. Valves are normally the last thing to suspect, maybe not in this case. I'll scan eBay for replacements.

I'm really keen to get this set up and running as the cat is in such great condition.

[Heatercathodeshort]

This is where you will need a simple signal injector to determine if the tuner is at fault [I doubt it] or if there is something playing up in the IF stages.

You will need to check the anode pin 7, screen grid pin 8 and cathode pins 1/3 of the 30F5 valves.

The smoke is odd. Are you sure you have put everything back correctly? Did you remove the vision detector diode and did you replace it the correct way round?

There is a methodical approach to repair and servicing. Random replacement of components as has been said many times on this Forum is a disaster and leads to added complications.

Are the PCC84 [30L1] and PCF80 [30C1] valves correctly positioned in the tuner?
The 30C1 must be at the front nearest the channel selector. If they have been accidentally swapped over a resistor will be burned out in the tuner.

It is extremely rare in this series of Ekco receivers to get a 'no signals' fault even when the chassis is in a poor condition. That is why I am pressing home the possibility of a man made fault. It's very easy to do and we have all done it.

Remove the screening cans from the tuner valves and check the heaters are glowing.

A logic check of the valve voltages plus the help of a very simple signal injector should reveal something, as you have absolutely no signals with the full output of the Aurora.

John.

[Autozavod]

Thanks for the advice John.

All the valves are in the correct position and have glowing heaters. Where the set has duplicates of the same valve I swapped them round.

The set hasn't worked since I brought it home, perhaps something in transit was bumped causing a short? The other possibility is when the set was plugged into the aerial, the aerial had a signal booster? Would that have done something?

Alas I don't have any test equipment :-(

[Autozavod]

Oh, and I haven't touched the signal diode, just checked it looked ok (not much of a test I know)

[Autozavod]

Silly question, since I don’t have a signal generator, would it be possible to use the aurora instead? Maybe inject it’s signal post rf stage??