A clue to wired fuses - if you can still see wire then the fault is an overload, if all the wire disappears then it's a short circuit.

Brad, do you have any idea as to what could cause an overload in a television set like this?

Cheers,

Chris

To be honest - not really. I could list half a dozen things but I'd just be guessing as I've never really delved into televisions.

The only causes of blown fuses in these early Philips sets is either a problem with the degaussing coils and associated wiring on the mains side or a fault in the power supply. Any faults in the TV itself will cause the power supply to shut down without blowing fuses.

Did your TV still have it's circuit diagram inside the back cover still? If not I'll email you the circuit, you won't get far without it. Also can you confirm the model number and serial number please. Two variations of the chassis was fitted to these sets and I'm not sure which yours has.

You'll need to inspect that line filter PCB carefully and make sure it is clean. Also, what are your soldering skills like? I need to ask as you may have left traces of solder on the board when you replaced the cap. That may be a cause of the sparks, otherwise all I can think of is dirt.

You'll need to remove the power supply pcb as I detailed in my earlier post for some basic safety checks. The main filter cap sometimes bursts it's seal and dumps electrolyte all over the pcb causing shorts in the power supply. Make sure you read my earlier post, the main filter cap may still have a 340v charge on it. If it does, bridge the terminals with a 4.7k or more resistor (with a 1 watt or higher rating) this will discharge the cap safely. The resistor needs to be connected for 20 or more seconds. Always check for voltage on this cap before touching any part of the power supply circuit.

There are some checks to be done on the power supply once it is removed. Aside from the filter cap, there is another fuse to check, the bridge rectifier diodes and the main chopper transistor and its driver circuit. I can explain what to do once you have the board out.

TV collector, I'll find out the serial number for you. My soldering skills are 'okay', so solder shouldn't have been an issue. I'll pull the power board out tomorrow though, when I can see what I am doing in the sunlight.

Chris

Check the degaussing thermistor on the power -supply board. It is blue on the early chassis, and white on the later chassis types. See if it rattles when shaken. These were common offenders with intermittent fuse blowing problems. Remember, you could have more than one fault.

The first thing to do is to make sure that you have 300volts or more on the main filter cap of the power-supply.

Caution. The power-supply primary circuits are not mains isolated.

Wayne

Thanks Wayne. This set has the white thermistor I'm pretty sure. I'm unsure about the 300+v cap, as it appears to have multiple legs soldered to the board (how the heck would that work!?), so I have no flippin' clue which is which. I'll have to tinker around with it at a later stage though - I'm going away for ten days to see my dad.

Cheers,

Chris

Hi all,

I finally got around to opening up my large, heavy and cumbersome Philips Series 78, and have started poking and prodding around inside.

I will have another look at the PSU when I get it out, but here's some information on the set.

It is a Philips Series 78 model 02KJ656, serial number 51052, from the 31st July, 1978. The CRT is an A66-510X (no. 231 999), and the chassis is marked "CHASSIS K11".

As mentioned above, I'll take the PSU out later and start shaking the degaussing thermistor!

EDIT: The fuse on the filter board is blown (I can't remember which one, maybe both?), but the two fuses on the PSU and the fuse in the horizontal/flyback circuit all appear to be intact and okay.

Also, I shook the thermistor, and it didn't rattle. I hope that's a good sign?

Thanks for all the help,

Chris

Thanks for the model and serial number information.

Things are looking good so far. If the fuse on the power supply panel is ok the power supply should be still working.

The only things you need to check on the power supply panel are the parts before the fuse. The main items to check are the rectifier diodes and main filter cap. Have a look in the gap between the capacitor and pcb and make sure the gap is empty apart from the capacitor pins. If you see a big crusty brown mess, the cap has started leaking.

Do some resistance checks across the AC supply connections to the power supply and also to the filter PCB. Let us know what readings you get.