HP8714C

[R_G_B_]

I have an HP8714C network analyzer

It has a suspected power supply fault I have looked at the service manual and have concluded this LED status:

If the green LED is on, the red LED is on steadily, and the fan is off
Check the line voltage selector switch, located below the AC power jack. If it is correct,

Not sure where this cable is:
remove the power supply/display assembly and make sure that the cable from the on/standby
switch to the power supply assembly is connected.

With the power supply/display assembly outside the analyzer, plug it in and switch the
analyzer's line power ON..

On further inspection I used a multi-meter and Peak Atlas DCA pro on the fast rectifier component on the buck converter board of the power supply. All pins seem to be shorted.

Problem is I am unable to find this component. 

Can anyone help with this?

R_G_B

[R_G_B_]

FEP16DT fast rectifier.         

[R_G_B_]

Buck converter circuit.

[tautech]

It's a 200V version of these:
https://www.fairchildsemi.com/datasheets/FE/FEP16DT.pdf

[R_G_B_]

Location of faulty rectifier on buck converter PCB

[R_G_B_]

Thanks for the rapid response tautech.

[TheSteve]

Check the caps, you'll probably find they are leaking.

[R_G_B_]

I manged to find the link to the schematics on here. The shorted diode pack seems to be pulling all the output voltages to ground.


hence I am getting no out put voltages .


I checked all the caps using the peak atlas ESR meter they seem to be with-in spec.

Thanks TheSteve.

R_G_B

 

[TheSteve]

I manged to find the link to the schematics on here. The shorted diode pack seems to be pulling all the output voltages to ground.


hence I am getting no out put voltages .


I checked all the caps using the peak atlas ESR meter they seem to be with-in spec.

Thanks TheSteve.

R_G_B

They will test fine - but may be already leaking. I repaired the exact power supply with the diode failing the same way because the caps were leaking. The crap they leak conducts all over the place and freaks out the protection circuits. They all tested fine still. The power supply design is very cool, it has tons of protection to it(as long as the supervisory supply works). Anyway, swap out the needed parts and power it up on the bench, you'll know its good right away if all 4 of the green status LED's turn on.

Also if you haven't enabled all of the optional features do it once you get it repaired, and maybe even add in a color LCD as it makes the machine look so much nicer.
Any questions at all let me know. I have an 8714C and 8712B in my lab at the moment.

[R_G_B_]

Taking out the the FEP16DT fast rectifier diode revealed it as not being shorted but instead the parallel connected diode FES8CT as being shorted .

I was not able to order this. So i had to choose the next component down  FES8BT.

So its a Peak Reverse Repetitive Voltage 150 FES8CT  vs 100V FES8BT.

we will see?


R_G_B

[TheSteve]

I used a MUR815G  to replace that part.

[R_G_B_]

managed to order MUR815G


Thanks TheSteve


R_G_B