Power supply and hard disk for Digifusion Freeview unit - Details of failure and repair.
Switched mode power supply Housed in black plastic box with integral 3 pin 13A plug
I was not very pleased when my Freeview digital set top box failed to work after only 18 months. The display indicated the word "hold" and nothing else seemed to work. Googling revealed that I was not alone, the power supply was apparently under rated and as some people had mentioned was bound to fail. I confirmed that my unit was no good, it gave out about 12 volts on open circuit but any slight load brought the output crashing down. I had a redundant computer power supply which with a dummy load on the 5 volt supply was brought swiftly into action to enable digital viewing once again.
I had nothing to lose, Digifusion were not going to replace the faulty under powered unit, so it went in the vice and was gently squeezed in both directions. This enabled the case to fairly neatly open to reveal the compact nature of the power conversion unit. Examination of the components revealed that the smoothing capacitors on the 12 volt side of the transformer were discoloured and looking at the output on my oscilloscope confirmed that smoothing was not taking place. The two capacitors wired in parallel were removed and replaced with similar ones that I had removed from some other piece of equipment.
The unit now performs as originally intended, though I think my replacements may not last for long since the unit gets very warm when switched on continuously.
Hard Drive Failure Although my repair to the power supply enabled the set top box to work for a few weeks the box itself subsequently failed and I experimented (without success) increasing the size of the internal smoothing capacitors as suggested elsewhere on the net. I then purchased a Matsui replacement which has been working well for over six months. More recently I opened up the Digifusion box and removed the "Maxtor" 40GB hard disk and set the jumper on it so it would act as a slave. I then plugged it in to my Compaq PC and formatted it using a utility downloaded from the Maxtor/ Seagate website. For this to work you need to download the software and prepare a self bootable floppy disk which will guide you through the procedure. It all went well and the drive worked in my PC so I then set the jumper back to its original position and inserted the drive back into the Digifusion box and switched on. EUREKA, it worked, I then had two Freeview boxes. Well worth the effort.