I was given this Philips switched mode power supply unit for a future project. The plan is to modernise a Philips G8 TV receiver.
The PCB measures 210 X 150mm. The whole assembly including the screening box originated from New Zealand or Australia.
No IC's are employed so it should be an easy matter to trace out the circuit.
Till Eulenspiegel.
No need to trace that PSU out, it's a Philips K9 PSU.
Looks just the job and you’ve a bit more space to play with than in my A823 of which I also have a SMPS planned for future. I’m not sure but I believe the HT on the G8 is around 200V as with the A823 so an extra 45V output required. I see like the Thorn 3000 it has a crowbar but on the output side. That’s going to put the chopper transistor under a lot of stress if it fires.
Can anyone tell me what year the K9 was released?
Can anyone tell me what year the K9 was released?
Can't give you an exact date, but I can say I believe it was before Dec 1972. My reasoning; I have service supplements for the K9 chassis starting from Dec 1972 through to July 1983.
@crustytv Thanks, just wondering how long after the 3000 appeared. Looks a bit more refined and probably cooler running.
The BRC 3000 was released late 1969. At that time, the switched mode power supply was considered something exotic and very complex, shrouded with mystery. Only very clever service engineers could repair the PSU, so we were told. Looking at the circuit diagram now, it's all too evident it's quite a simple unit. I do remember keeping six spare 3000 series power supply units in a repaired state for quick repairs in the customer home.
Hi Chris, thanks for identifying the Philips SM PSU and posting up the circuit diagram of the main PCB. It should be an easy task to trace out the circuit of the control module. I knew of the existence of the K9, but have no hands-on servicing experience of any of the sets fitted with the K9 chassis.
Till Eulenspiegel.
The date code on the BU126 switching transistor is: F3174.
Till Eulenpiegel.
