Hi. I'm rather pleased that I've managed to fix a fault which was stopping my DHD4000 from powering up. I know some of this material has been posted already, but I wanted to summarise my experiences to help others with the same problem.
The symptoms were that the box wouldn't boot up at all. After plugging it in you would see a flashing orange LED which then became steady. All the while you would hear a regular ticking sound from the disk drive at about 1 second intervals. This would continue indefinitely. Nothing would get the box to power up properly.
This failure to power up is known as Yellow Light Of Death or YLD. In my case the yellow light is more of an orange, but your mileage may vary. The classic YLD can usually be overcome by powering up with the aerial disconnected. But if the YLD is accompanied by ticking from the disk drive, then this is unlikely to work.
A number of users had suggested that faulty capacitors in the power supply may be the cause. I can now confirm that this is definitely the case. The company Satcure has done an excellent job in analysing power supply problems in this box and similar satellite boxes. They can supply upgrade kits with replacement capacitors to solder in yourself. I made a temporary fix using capacitors I had in the junk box and I've sent away to Satcure to get the complete kit.
The power unit in the DHD4000 has seven different outputs at various voltages. (Who would have thought a PVR would need so many). The secondary circuit for each comprises a rectifier diode, a smoothing capacitor, a series choke and another smoothing capacitor. Satcure report that all these electrolytics are prone to failure, leading to excessive noise and ripple at the switching frequency on the outputs. I found that the worst case was the 16v supply where I had 1.5v peak to peak ripple. I systematically changed the C's as necessary to obtain clean outputs on the oscilloscope.
Obviously having noisy DC supplies can cause all sorts of strange problems to the electronics, but I didn't really understand why I was getting the ticking sound from the disk drive. This was what I investigated next. It turned out that faulty capacitors were again to blame, but for a completely different reason. The disk is the original Seagate ST340015ACE 40Gb. On the label it says it needs 5V at 0.58A and 12V at 0.31A. That may be so in the steady state, but during start-up it seems to need an awful lot more. I measured it drawing current pulses if between 1 and 2 amps from the 12v supply and pulling it down from 12V to 8V in the process. It then got into a loop where it tried to draw a big pulse of current, didn't succeed, waited a second and tried again. This accounted for the regular ticking.
I connected a known good capacitor in parallel with the existing reservoir capacitor and the disk started up normally and the box became usable again. So all it needed was a good capacitor capable of supplying the initial surge of current demanded by the drive.
So if your box is ticking and showing the YLD, try replacing the capacitors in the power supply, especially those for the 12V supply. It's probably all it needs. And if anyone has a faulty/unwanted DHD4000 then I may be in the market to buy it as a spare.
Regards, tenbob0
The symptoms were that the box wouldn't boot up at all. After plugging it in you would see a flashing orange LED which then became steady. All the while you would hear a regular ticking sound from the disk drive at about 1 second intervals. This would continue indefinitely. Nothing would get the box to power up properly.
This failure to power up is known as Yellow Light Of Death or YLD. In my case the yellow light is more of an orange, but your mileage may vary. The classic YLD can usually be overcome by powering up with the aerial disconnected. But if the YLD is accompanied by ticking from the disk drive, then this is unlikely to work.
A number of users had suggested that faulty capacitors in the power supply may be the cause. I can now confirm that this is definitely the case. The company Satcure has done an excellent job in analysing power supply problems in this box and similar satellite boxes. They can supply upgrade kits with replacement capacitors to solder in yourself. I made a temporary fix using capacitors I had in the junk box and I've sent away to Satcure to get the complete kit.
The power unit in the DHD4000 has seven different outputs at various voltages. (Who would have thought a PVR would need so many). The secondary circuit for each comprises a rectifier diode, a smoothing capacitor, a series choke and another smoothing capacitor. Satcure report that all these electrolytics are prone to failure, leading to excessive noise and ripple at the switching frequency on the outputs. I found that the worst case was the 16v supply where I had 1.5v peak to peak ripple. I systematically changed the C's as necessary to obtain clean outputs on the oscilloscope.
Obviously having noisy DC supplies can cause all sorts of strange problems to the electronics, but I didn't really understand why I was getting the ticking sound from the disk drive. This was what I investigated next. It turned out that faulty capacitors were again to blame, but for a completely different reason. The disk is the original Seagate ST340015ACE 40Gb. On the label it says it needs 5V at 0.58A and 12V at 0.31A. That may be so in the steady state, but during start-up it seems to need an awful lot more. I measured it drawing current pulses if between 1 and 2 amps from the 12v supply and pulling it down from 12V to 8V in the process. It then got into a loop where it tried to draw a big pulse of current, didn't succeed, waited a second and tried again. This accounted for the regular ticking.
I connected a known good capacitor in parallel with the existing reservoir capacitor and the disk started up normally and the box became usable again. So all it needed was a good capacitor capable of supplying the initial surge of current demanded by the drive.
So if your box is ticking and showing the YLD, try replacing the capacitors in the power supply, especially those for the 12V supply. It's probably all it needs. And if anyone has a faulty/unwanted DHD4000 then I may be in the market to buy it as a spare.
Regards, tenbob0
