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Discussion Starter · #1 ·
Hi Leonard and all,

All my family and friends who wanted big screens have them now 8-> and I've been working a lot so I haven't been big screen playing lately.

Tonight I'm working on a Sony KP65WS510 and I found PS5001 is bad. It's a pico fuse over on the G Board and the manual says it's a 5.0A 90V fuse with a part number of 1-533-597-31.

I took a look around and I can find 5.0 amp picos but most are 125V. I'm assuming that's not an issue since they're being used in 20 some odd volt circuits (don't have the service manual handy).

They come in slow or fast blow though and I can't find which these are. Fast blow protect circuits well but may give nuisance blows, slow blows eliminate the nuisance blows but may allow a circuit to be damaged before they blow. Since these are in a power supply circuit at a low well filtered voltage I'm thinking fast blow is the best option but I thought I'd ask to be sure . . . which would you recommend?

Also, this set had the convergence repaired about three years ago by a reputable shop. The chips look to be original Sanyos and although they did a neat repair there does seem to be plenty of heat sink grease on the ics (i.e. it's not slathered on and squished out all over like you see a lot of times, it appears this guy actually took the time to wipe off the excess).

Three years is kind of a short run time, isn't it? Is there something else I should be checking while I have the boards out? (I'm thinking I'll pull the resistors up and test them all and then maybe take a quick look for bulging caps)

Thanks!

Steve
 

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Personally, I would go with a fast blow to start and if you have issues with frequent fuse changes then I would change over to slow blow and see how that works for you.
 

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Discussion Starter · #3 ·
Wow! What an annoying subject! I just spent the better part of an hour researching this online and it seems the answer evades me! All the posts just say to replace them if they test bad and they usually give the 5A / 90V spec but they give no mention of fast or slow blow! I hate that kinda stuff!

I did find the OEM Sony fuses but they're eight bucks apiece. If this were a main tv that I wanted to minimize the chances of down time I would order them, but now I want to know the answer! So I ordered some fast and some slow blows and will start with the fast blows and see how they hold up.

I'll try to remember to post a follow up - if this post gets old without a follow up please post a reply and since I've subscribed to the thread it'll send me a note to remind me.

Take care all,

Steve
 

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Given that this is an old TV, save some $$$ and try a 120v 5a fast fuse too see if that works. If it fails, then spend the $8 on the sony part. Can you take a picture of the old fuse and post it online for us to see?
 

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Discussion Starter · #5 ·
I'd have to go buy a glass fuse and rig it into the circuit and stuff. The fast blows were .65 and the slow blows $1.10 From DigiKey. Their first class snail mail shipping was only a couple bucks so I just ordered a couple of each.

It's not about money, the $15 or so shipped (they rape ya on shipping) for the original part won't break me, it just annoys me we don't know the answer to this and the original parts are getting harder and harder to find so we need to know the answer for future repairs. This unit won't be a critical main tv so I can play a bit to get the answer so I figured I would go ahead and run the experiment and save someone in the future the annoyance I've went through trying to figure this out.

I'm not near the set right now to take a pic but the fuse is just a yellow pico with 5000 printed on it and a black band on one end. It appears picos have had a color band system in the past but have went to printing the value on the side. In the old system a wide red band meant fast blow but they don't say what signified a slow blow, I guess no band since they don't spec a color. The manual says it's a 90V rated fuse and that's an odd rating - 32, 125 and 250V is common. Since it's being used in a 22V circuit any of them should work but I hate to undersize usually so I went with the 125V.
 

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Discussion Starter · #6 ·
My buddy just looked at the fuses for me, he said when you blow the dust off and use a flashlight the bands are gold, not black, so I'm assuming that's a precision indicator like on resistors.

I found a post in an audio forum on pico fuses and the info there was that when fuses are called for they are usually assumed to be fast blow and if slow blows are needed it is noted in the parts list so i think I'm on the right track with the fast blows.
 

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At 5 amps you want something that reacts pretty fast, typically. Any of the pico fuses that you buy will work fine. If you are blowing fuses frequently in this circuit you have a problem somewhere. The most common cause are bad solder connections on one of the output ICs.
 

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Discussion Starter · #9 ·
Been a week or so now, 20+ hours of run time and the fast blow is still holding, looks like the fast blow is a good sub for the original.
 
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