[fixed] repair HP 4155A / 41501A power down

[tagchen]

After Power lost inhouse, HP 4155A power down and no action.
since some year SMU-5 41501A was defect and unrepaired from HP.

looks inside and tested the power supply.
Fuse are ok.

after long search, i began measure in power supply point for point to check how ends the power and i found that under the ceramic resistors (red marked), glued an thermalfuse. after changed
And for me lucky day, the power supply for 41501A are mostly the same and found the same fault.

power supply 41501A






finish

[dxl]

I had the same problem on my 4156A. Of course i discovered this thread *after* i figured out that the thermal fuse is blown

What glue did you use to glue the new thermal fuse to the resistors?

[chilternview]

I've got a 41501A which may have the same problem. On power up, the fans don't start. I have checked the voltage after the bridge rectifier and it's 350v so ok. But it appears the switching mosfets have no signal to their gates and no activity on the driver (IR2110) either. The MB3759 is oscillating but no output.

Is this a similar case to yours? What did you replace the thermal fuse with?

[Swake]

Got the same supply in a 4155A too and guess what..... the thermal fuse is blown too!

There is a marking on the PCB of 133°C. Thank you Voltex Electronics Corp. Japan for this information.

The model of the power supply is: FPS1 D2160
The HP P/N: 04155-60003
And apparently there is a replacement unit with P/N 04155-69013, but I have no information if this is indeed an improved version or just a component update.