08-08-2025, 06:11 AM
Hi Folks. That model number does look to have been created by a committee.
Oscar, 12” Black and White television. Model P12-H4A9
Years ago I received a schematic diagram for the above television, in a box of service data from a closed down TV repair shop. I had never seen nor heard of the brand Oscar, and therefore thought that I would never come across one. As stated elsewhere, I had supplied a copy of the schematic to another technician and thought no more about that model.
After finding and purchasing one at an auction a couple of weeks ago I decided to make its repair my next project. First I examined the set before tearing it apart. A warning label below the aerial terminals confirmed that it was intended for the Australian market. Its rarity in the market place makes me think that the importer only ever imported one container of these sets, possibly a minimum order of 500 units.
Since the last analogue transmissions ended in December of 2013 the set was likely un-powered for at least twelve years and probably many more.
So, I removed one of the compactatron valves to open circuit the heater chain. Then I was able to reform the main electos with the aid of my variac. Spoiler alert. The electro on the screen grid of the vertical output valve did go bang, after the set was brought up to operating value.
There was much fun to be had removing decades of dust from the interior of the set. I ended up replacing four of the seven electros. I cleaned the valve pins and sockets, Cleaned the tuner contacts with a business card and contact cleaner, and cleaned most of the pots. Last of all, I replaced the 1st sound I.F. transistor.
Finally, adjustments made it all well. I had forgotten how long it takes valves to fully warm up. It might be that the 33GY7 is a little weak, but I do not have one lying about.
That is enough fun for now. I will go back to working on my Philips
PM-5509 pattern generator, then onto a Pye 12G-1 television.
Oscar, 12” Black and White television. Model P12-H4A9
Years ago I received a schematic diagram for the above television, in a box of service data from a closed down TV repair shop. I had never seen nor heard of the brand Oscar, and therefore thought that I would never come across one. As stated elsewhere, I had supplied a copy of the schematic to another technician and thought no more about that model.
After finding and purchasing one at an auction a couple of weeks ago I decided to make its repair my next project. First I examined the set before tearing it apart. A warning label below the aerial terminals confirmed that it was intended for the Australian market. Its rarity in the market place makes me think that the importer only ever imported one container of these sets, possibly a minimum order of 500 units.
Since the last analogue transmissions ended in December of 2013 the set was likely un-powered for at least twelve years and probably many more.
So, I removed one of the compactatron valves to open circuit the heater chain. Then I was able to reform the main electos with the aid of my variac. Spoiler alert. The electro on the screen grid of the vertical output valve did go bang, after the set was brought up to operating value.
There was much fun to be had removing decades of dust from the interior of the set. I ended up replacing four of the seven electros. I cleaned the valve pins and sockets, Cleaned the tuner contacts with a business card and contact cleaner, and cleaned most of the pots. Last of all, I replaced the 1st sound I.F. transistor.
Finally, adjustments made it all well. I had forgotten how long it takes valves to fully warm up. It might be that the 33GY7 is a little weak, but I do not have one lying about.
That is enough fun for now. I will go back to working on my Philips
PM-5509 pattern generator, then onto a Pye 12G-1 television.
