[Heatercathodeshort]

I have listed some of the stock faults that I encountered with the Ekco 300 series receivers that may be of use.

1 Mains fuse blown. PY32/33 heater O/C. [Models with radio only]
TV/Radio 'trombone' switch blown up. Rewire for TV only.
2 Mains fuse blown.
Mains filter capacitor usually mounted behind mains dropper tag board S/C. [May have popped open.]
3 Line output transformer case broken down and burnt. Usually across top to start with. Early
signs are discolouration and a sweet ' vinegar' smell when you poke your head inside the
cabinet. The windings, incredibly, usually survive the abuse.
Cases are easily fabricated from Paxolin or any good pastic/thermo plastic material. Take
great care with delicate wires particularly the output from the EHT overwind.
4 No EHT. Strained line whistle. Boost diode U191 overheating.
Line linearity coil has slipped down former and shorted to chassis. It is mounted on the back
of the line output box. Warm it up and push it back up placing a grommet under the former to
prevent a repeat performance.
5 Strained line whistle after EHT rectifier heats up. Sometimes rectifier glows blue and
anode 'bell' glows a dull red.
EHT smoothing capacitor .001uf heavy leak or S/C. This can be removed with no noticeable
effect in most models. Slight line tearing at very high brightness settings may be noticed.
The 'carbon rod' is a voltage dependant resistor to aid EHT stabilization.
Again the set will work very well without it with its absence hardly noticed.
6 Bright raster. No picture. Weak washed out picture but no grain. Contrast
control when advanced causes picture to go negative or white.Sound normal.
Vision detector diode mounted under clip on top of final vision I.F. transformer EXTERNALLY
O/C or leaky.
7 Strange AGC effects with odd operation of contrast control.
You forgot to change the .1uf waxie INSIDE the tuner unit. You will have to unclip the R.F.
tuning biscuits to gain access. Make a note where there go back...
8 No frame sync.
Q3/4 clipper diode O/C. It looks like a fat resistor and is band coded Orange/Yellow. Replace
with any diode such as !N4148 or IN4001 etc.
9 No operation of fine tuner.
Fine tuning slug snapped in half.
Tune oscillator biscuit through hole in side of cabinet for best position. The tuners are so
stable and will not drift. Best to remove old slug under cam and spring. [Examine mechanism]
to prevent it floating about.
10 Buzz on sound that can be removed when volume control is backed off.
[Not miss tuning]
O/C very small common electrolytic usually chassis mounted.
11 Frame cramp.
Same as above. 500uf section.
12 Purple glow in EHT rectifier [More U25 than U26] together with picture enlarging when
brightness advanced.
Faulty rectifier valve. [Very common]
13 Picture 'splutters' together with sound of arcing.
Boost diode has flaking cathode. [Good old Mazda] U191 in 300 series. U301 in 200 series.
14. Low sound.
Check all the screen decoupling capacitors .003uf in the I.F. amplifiers.
They again look like resistors and you will discover them to be O/C.
15 Vision instability. Difficult tuning. Heavy patterning.
Check the .003uf' capacitors but this time in the vision I.F. amplifiers.

You may be tempted to do the lot in one go, fine if your experienced at doing this type of work but
mistakes can very easily be made that take hours of back tracking to locate. Ekco receivers warm up
quickly so take your time, one component at a time. [It's fun to see the faults unfold]
All the waxies will have to be changed. I would suggest the CRT first anode decoupling, boost capacitor and the line coupling to be top of the list and the first to replace.

This about covers the non flywheel sync models and should be enough information to allow you to obtain
'First Light'.

Ekco receivers should have masses of extra height available and the timebases should lock absolutely solid
with no drift whatsoever. All the controls will be at their correct settings around mid way and will remain so for
many years. I will probably remember a few more odd faults as the day goes on. If I do I will post them!
Good luck with it. Regards, John.