Humax 5410Z PSU wowes...

[Mark]

Well it had to happen (yet again) that stupid design of the heat sink next to the 1000uF cap on the psu.
Looked at the receiver the other day & dead as a maggot (as they do).
Replaced the offending cap and up and running again.
I'm seroiusly looking at a bigger heat sink accross the two transistors and a small fan to circulate the heat.(or physically move the cap somewhere else?)

[Jacko]

I know the feeling. Mine gets rebuilt each year. Its good to have a supply of caps on the bench!

[troyboy]

Ive been lucky....Ive got 3 and have never had an issue (Obviously will now that I have said that :))

[Ocean]

I still have a stock of capacitors ready for when it stops ! :)

[mr sat]

I've got my hands on a spare psu repaired and ready to go. So it's a matter of swap install and watch and repair the buggered one at my lesuire. The repaired one in box is still going after 2 years touch wood.

[Mark]

Well it had to happen (yet again) that stupid design of the heat sink next to the 1000uF cap on the psu.
Looked at the receiver the other day & dead as a maggot (as they do).
Replaced the offending cap and up and running again.
I'm seroiusly looking at a bigger heat sink accross the two transistors and a small fan to circulate the heat.(or physically move the cap somewhere else?)
Well yet again it happened!!!:( :(
This time I've replaced the cap (again, grrrrr) and this time I used a piece from the rear of a computer case (you know the ones that cover the extra slots for PCI cards etc) and have mounted it either side of the heatsink, with a sinble screw into the existing heatsink.:rolleyes:
It may not really help with dissipation of heat but I had to give it a go just see what might happen.
Cheers all.:D

[Chafrill]

I trying to fix my burned out power supply of the Humax 5400. I replaced C09, C07,C21,R21 and ZD3 Despite replacing them three times and each time the ZD3 30v Zener Diode 1.3w gets burned when I power on the Humax.
I could not find R21 100 Ohm 0.3w at Jaycar or RS Australia so I used .25w. Could that be the reason for the burn outs or something else. Can anyone help please.

[Ocean]

The supply is probably running flat-out as in no feedback regulation. The opto-coupler might be cooked, or another component in the regulation department . This means the other voltage rails will be too high, you can run these supplies with the plug to the main receiver board disconnected to prevent the Humax being destroyed.

The rectifier diode after the transformer may be shorted placing AC across the Zener, this will cook the Zener but may explode its bypass electro too, but Zeners usually go short so this hasn't happened..

The R21 resistor dissipation rating is near enough and won't be the problem.

This supply may need to go to someone with more experience/test gear.

Check all the diodes first.

[Chafrill]

The resister r21 100 ohm is getting burned not the zd3 30v zener diode. sorry I got confused with the numbers.

[Ocean]

The resistor R21 will burn if the Zener OR the bypass electrolytic is shorted.

If the supply is running unregulated R21 can burn, but I would expect to hear electrolytic capacitors exploding....

Caution : watch your eyes as the electrolytic capacitors can generate high pressures sending the aluminium cans flying at high speeds. The chemicals in these capacitors are toxic,corrosive and taste really bad. . :)


Multimeter check ALL diodes !.... I expect the Zener diode is shorted.