Re: BenQ FP71e Q7C4 2 seconds to dead

Repaired again.

Hopefully it'll last a bit longer this time.

Re: BenQ FP71e Q7C4 2 seconds to dead


Well that didn't last long!

It failed again, but this time it took out one of the C5707s. I have ordered a repair kit from eBay - 4 x C5707, 2 x FU9024N, 1x 3A 125V fuse for £3.85 delivered.

I have gone over all the solder joints on the transformers and associated components.

Hopefully the fix will last a bit longer this time....

Re: BenQ FP71e Q7C4 2 seconds to dead


I did a visual check of the joints before I put it back together. If (when) the fuse blows again, I'll resolder the joints as you suggest. Thank you for the tip.

I assumed, perhaps wrongly, that the fuse had blown as a result of excessive ripple on the supply due to failed capacitors....

Re: Topfield TF4000T STB with bad Samxon GF

Topfield PVRs are popular amongst enthusiasts in the UK (models TF5800 & TF5810). I have been fixing PSUs and supplying DIY kits for a couple of years.

Early 5800 models used brown Sam Young capacitors, which failed quite quickly. The 5V cap usually failed first, leading to excessive voltages on other rails, sometimes taking out the HDD and/or mainboard components.

Later models used Samxon capacitors which were better, except the green ones (GF), which failed sooner than the black ones (KM), usually with a...

Re: BenQ FP71e Q7C4 2 seconds to dead

Thanks for the circuit diagram and info. I have just managed to fix my FP737s after its 470uF 35V caps had failed.

Sadly it still did not work after replacing the capacitors, as there was no backlight. Although the circuits for the FP71e were not exactly the same, they were close enough and I was able to ascertain that the fuse (PF801 on the Q7C4) had blown. Fortunately, no semiconductors had been damaged and it's all working again.