Ian !! your feeling about the Booster Cap having problems appears to be right.

1/ I discharged Booster cap pol 100" Rating is .022μF, 1000 volts VDC + 10%. Removed it from chassis and attached alligator clips to do the test. Reading was 38,68 NF So I calculate thats way to high.

I will have to buy some caps //////pete

I feel that maybe your measuring technique or meter may not be accurate.
As you know .022 should be 22 nF.
Caps generally go leaky, short, open circuit but very very rarely if ever go high in capacitance.
So from this info I doubt whether the cap is faulty.
But of course its always difficult to give tips/advise if the problem is not right in front of you.
JJ

Hello,,Johnny,,,,You maybe right,,,Im wearing L plates ,,I understand that .022 should be 22μF ,,The meter is new and autorange ,I will do it again and check ,,I also Re-sold soldered filament wire back on,, Ok Johnny Iwill check it again tonight and get back to you,,,Thank you for help,,,pete

If cap is leaky you will get a wrong reading.

Boost caps usually break down under load. but can still look OK at low testing voltages. Just replace it with one of similar or higher voltage rating.

In solid state TVs, when the equivalent part fails, it usually leaves you in no doubt by exploding or going up in flames!

Ok,,,,new meter Digitech Qm1321 Autorange
Choices on AutoRange Function button are MΩ...V.....Hz...hFE,,,Ω.....nf,,,,,,kΩ

Selected nf

1/ placed cap on plasticine to reduced movement.
2 Zero out leads
3 Connected alligator clips to cap and waited for reading.
Reading was
38,38nf


Removed Aligator Clips and test with just probes
Reading was 38,52nf


Hmmmm Test it on anther Capacitor

Removed UCC Cap 300v.wkg+ 8uf
Repeated test and the reading was

8.113uf
hmmm dont think I like Autorange

Hi Pete

There's normally no need to ever read capacitance. Capacitance change never happens, leaky or open circuit does.

Resistors are another story. Carbon composition resistors go high or, if a low value like 1k or under, can actually go LOW if stressed, Carbon film resistors (e.g. Philips) on the other hand are either OK or open circuit - rare.

Certain types of components, e.g. wax paper capacitors, you just replace wherever you see them, after 50 years they will ALL be bad.. Polyester capacitors on the other hand are very rarely defective, you should trust them.

Your set has polyester caps and, in critical locations, carbon film resistors. So forget about testing components, it's a waste of time, they are almost certainly OK. Except for the boost cap, don't test it, if it's suspect, just replace it.

Follow my faultfinding procedure and you'll get there.

Unfortunately the EHT transformer ("flyback" in Yank speak) in those sets is known to fail shorted turns or catch fire. I hope yours is OK.

Hello Ian,

I understand ,I have no real way of testing for leaking caps anyway
Ok I will just Replace Booster cap and then continue with the test

Do you know where I might buy a new booster cap from????????

Thanks for your patiences with your 48 year old apprentice!!!

Pete

Hard to get locally, I have had to source some from US after using up my old stock

I have some stock, if no-one else can help.

Thanks Ian,,,,,I'll find one,,,I know a guy who is a Hoarder of vintage TV parts in Ryde ,,Ill give him a ring
Thanks again,,pete

I'm at Belrose if that helps.

But first, check for that negative voltage I told you about.

Hello Ian,, I re-soldered the 2 caps back in place,,,Checked all the mains etc etc where I had been working,,All good no shorts etc 1 turned TV on 2 all valves light up and s12 has a small glow a little smaller than size a match head,
3 picture screen lights up and has waves ,
4 switched TV off,,,White dot in center of screen is no longer there """all good'''
5 turned TV back on...Screen lights up

6 Place Screwdriver near cap of 6CM5 ,,NO Arc ?????? But valve is lighting up still???????????
8 switched TV off,,,,,Removed 6CM5 placed multimeter probe in G1 and and negitive probe to chassis ground ,Then turned TV on !
No voltage ??????

At this stage it was midnight and I thought I best re-do this tomorrow as I was getting tired as I must of done something wrong in my reading??? But if so that does not explain no arc on the screwdriver either????? but how can this be... if the valve lights up??

ZZZZZZZZZZZZZZZZZZZ time for bed too tired to think,,,Thank you,,pete

Also I noticed there has been a very Recent Repair on Booster cap Terminal ..""see Red Cap"" It a DXR 250k 1% That may give you some clue ?



This is with DVD set up

That red "capacitor" on the boost cap terminal is a resistor. It's OK.

6CM5 has to be in the socket to get negative voltage.

Just because a valve's heater lights up doesn't mean it's working!

Are you telling me that sometimes it works and sometimes it doesn't?

Hello Ian Thank you Typo I meant to type Resistor,,

Eg ''' Are you telling me that sometimes it works and sometimes it doesn't?""" no

Ok will do the voltage test again and see what that tells us ,,Thank you..pete

I am trying to compare the picture with the schematic. It doesn't look right, but that could be just the angle of the shot. Those 2 white UCC paper caps must be replaced. And check the value of 2.2M & 4.7M 1 watt resistors (R101 & R104).

Another face down shot of the same area would be helpful to compare with the schematic.