Pye T25Y 16" Portable TV - Updated 24/5/2019

Here is a smaller set from my collection, it has a 16 inch CRT and of a hybrid construction so has valves and transistors combined together. Has a total of nine valves.
This one was manufactured around 1969 which was getting towards the end of the monochrome era. I believe that black & whites sets stopped being made here in 1973 with the advent of colour just around the corner.
These were popular sets in their day and were pretty reliable, this one I've owned for many years and recall getting it for free. I did work on it briefly back in 2003 and from memory had some problems with the vertical and didn't go any further with it.
Nice and easy to work and nothing in these are too difficult to get at. The flyback sections uses a compactron valve 38HE7. This valve has the boost diode and line output pentode all in one. A lot of American sets used valves like this in their portables and larger sets as well.
More below...

Front

Rear

Chassis hinged down

Close up of line output/EHT section

Valve/Transistor locations.

I decided that for my first project for the resuming hobby and the new workshop being all setup and ready to go was to resume repairing this and to get it working properly this time around.

Upon applying some mains after its long slumber the set came to life displaying a crappy raster crackling audio and some arcing noise accompanied by hissing EHT which turned out to be the lead from the line output transformer to the top cap of the DY87 was about to fall apart. Once that was repaired and sorted I moved on to looking into the vertical to see what was up there.

Discovered pretty quickly with the aid of the circuit that some twat (not me) had attempted to repair it by putting wrong value components in place not to mention a cap tacked across pins on ECL85 on the print side to try and compensate for whacked out frame operation which wasn't even meant to be there! So the putting the correct parts back in place and removing the bodged capacitor, the vertical was starting to look more normal again and height/linearity controls now worked properly!

Now moving onto the horizontal, it worked but the sync was poor and lock was very touchy etc and it didn't take long to discover that the phantom bodger had been there as well changing component values and linking things out again around the ECF802. I wonder what the logic behind doing this and obviously there was some fault that kept this person experimenting around with the circuit and the reasons why - who knows? Putting the right value components back in this area made things a bit happier and more stable and I could now obtain good horizontal sync and lock.

With these two areas sorted I then focused on the resistors that were used in this model and several others. These mustard bodied types are notorious for going high ie 47k reading 70k, 100k reading 180K etc so I make a point of checking all of them and replacing and this was no exception as I ended up changing nearly all of them, I probably didn't have to due to tolerances within the circuit but as I have a 'ton' of NOS resistors and paranoid about old crappy resistors! Its more a piece of mind thing knowing that they've been done. I did leave one or two in there that weren't in any crucial positions and did notice slight improvement as I methodically put new ones in and tested the set in between.

Once I'd done the resistor-rectomy, then removed the leaky/aged old can multi section filter capacitor and fitted replacements using three separate ones. Went through and replaced other old capacitors that looked a bit tired or were not reading right on the cap tester.

Things were now starting to look quite good by this stage so I set about cleaning the case and the front panel/glass etc when the picture vanished...Hmm ok what did I do?? A bit of probing and it returned. Swing the chassis up - no picture, swing it down - picture! Turned out to be a poor solder joint on tag strip in the fly back area probably done by me as I did work on that bit in the past. Then the picture began to fade away at will now - what the heck! Glancing at the filament on the CRT it was dimming up and down. This was an intermittent break in one of the filament wires so fixed that and then the other filament pin terminal decided to break off on tube neck socket!

A few other things went wrong as they do put a wrong value resistor in and was greeted with magic smoke from it the moment I applied power, slipped with the meter probe and blew up the 2nd vision IF Bf137 transistor, burnt the side of my hand a little on the baking 38HE7 during a moment of being careless- man those things get super toasty hot! But not too many hiccups really.

Once I had the set running stable, went to set the picture up using the test pattern and got it reasonably well adjusted there's a slight geometry error horizontally but not going worry about that after all its a 50 year old TV. The yoke correction rings have been adjusted to best as possible.

So after all that and taking 15 years to finally fix this thing,we now have working usable TV! The photos don't do the image justice its bright, sharp with good contrast so the CRT is showing no signs of any issues.

I'll run it over the next weeks to see if any further teething issues crop if but overall am happy with the outcome and feel a sense of achievement on this since it was probably one of the very first valve sets I decided to restore back in the 2000's.

Final Result - The photo doesn't do the picture quality justice.

The pile of worn out/dead parts

Birds Eye view - Most resistors/capacitors replaced.