"ian field" wrote in message
news:5ZkZn.141157$_F1.130807@hurricane...

"Tony" wrote in message
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ian field wrote:
"Tony" wrote in message
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ian field wrote:
"Tony" wrote in message
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ian field wrote:
"Tony" wrote in message
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ian field wrote:
Having turned out not to have been affected by the end of InView
EPG service - my FVRT90 promptly died.

When I went to use it the power LED came on and then it froze, so
I unplugged it for 30 seconds and plugged it back in, whereupon
the 7 segment display run through the Klingon alphabet and then
went blank.

Hopefully it only needs a PSU recap or dry joints sorting out -
otherwise I'll have to put up with the less than favourite
Techwood (Vestel) and the POS Nikkai barebones.
Does it do that every time you cold boot it now?

Could be the flash is worn out or the drive is knackered. I think
the test pattern comes up when there are channels stored but the
drive is not formatted (ie it thinks its in the factory). I'm not
entirely sure.
A full PSU recap fixed it - its my favourite PVR so I beefed up the
main smoothing electrolytics with 10uF multilayer ceramic chip
capacitors on the print side.

There's also a 1uF electrolytic in the regulation circuit on the
primary side, if this fails the PSU can go bang - it wasn't hard to
find a non-electrolytic 1uF that will never dry out.

The mains rectifier reservoir capacitor was a flimsy ordinary type
with lead wires instead of riveted tags like this component should
have - I drilled new holes and fitted a propper one.

All of the electrolytics (except the 3 directly on the cathodes of
the 3 rectifiers) looked cheap & nasty - the ESR readings didn't
look all that bad, but evidently too high for the PSU to work
correctly.
Cool, useful to know when mine goes. Perhaps the 12v for the drive
went down. Did you find the faulty location(s)?
The PSU was working (sort of) but the voltages were all high except
the 3.3V and it probably had too much HF ripple upsetting the logic
board.

I was lucky the overal deterioration of the electrolytics caused
symptoms I couldn't ignore.

There's a couple of small electrolytics on the primary side that can
cause gradual regulation failure as the ESR increases - capacitors
with high ESR get a degree of self heating from the ripple current, if
allowed to cool the ESR increases a lot with the result that the PSU
can go bang if the mains goes off for a while and comes back on.

One of these critical electrolytics is only 1uF - not hard to find a
non-electrolytic replacement small enough to fit.

If your's is anywhere near 10 years or more old, I'd reccomend a recap
before it does go bang. Use the best high temp - low ESR electrolytics
you can get hold of.

I got 10uF multilayer ceramic chip capacitors to pad the 6 secondary
side smoothers from a scrap LCD TV, but you should be able to order
similar from the likes of Farnell.
I may have been involved in its manufacture. Does it have an 'N' in
the serial number?

Didn't look and its wedged in the AV stack with me watching TV its
decoding.

The PSU was bought in assembled from a reputable manufacturer but we
didn't control the AVL for the parts in it. I am very particular about
electrolitics.


Something I should have made a note of is the part number of the
TOPswitch chip - if at any time the PSU blows, the chip usually shatters
making the number unreadable.


In this product or just SMPS in general? The part is a Power
Integrations TOP244P according to my schematic.


Would you consider scanning & posting that please???

May I suggest News:alt.binaries.schematics.electronic to upload.


For some reason clicking the link I gave doesn't take me to the group - has
anyone spotted what I mucked up?