R205 100 ohm resistor in SR98 starting to get hot and smell

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Icky
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Re: R205 100 ohm resistor in SR98 starting to get hot and smell

Post by Icky » Fri Nov 16, 2018 12:35 pm

exxos wrote:
Fri Nov 16, 2018 12:34 pm
Icky wrote:
Fri Nov 16, 2018 12:19 pm
DONE - Recapped and re-metal filmed
:bravo:
Thanks - that was a fun easy relaxing Atari morning whilst waiting for half a dozen other jobs to finish :)

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Re: R205 100 ohm resistor in SR98 starting to get hot and smell

Post by PhilC » Fri Nov 16, 2018 12:50 pm

It is funny how we can find some jobs stressful but others relaxing, even if they are more complicated.

My missus thinks I'm nuts fixing computers to relax.
If it ain't broke, test it to Destruction.

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Re: R205 100 ohm resistor in SR98 starting to get hot and smell

Post by atari030 » Sat Jan 18, 2020 12:32 am

G'day, I've been reading, reading and more reading a bit about PSU's lately. And this thread popped up a few times. Couple of quick questions, if a modern floppy is used on an old PSU, can that cause issues? I'm starting to think it would cause some 12v drama and it might explain a few odd things I've been seeing with Mega PSU's and the like.
I am about to rebuild an STe PSU with the same hot resistor dramas.

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Re: R205 100 ohm resistor in SR98 starting to get hot and smell

Post by exxos » Sat Jan 18, 2020 1:07 am

12v isn't used on modern drives, only really old brick style type stuff. I would suggest you check out here viewforum.php?f=17
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Re: R205 100 ohm resistor in SR98 starting to get hot and smell

Post by atari030 » Sat Jan 18, 2020 10:41 am

I did read some posts where you mentioned dummy loads on the Mongrel boards due to a lack of 12v on the floppy. I couldn't see that in your mandatory fixes though. I'll keep looking. Would that cause a PSU not to kick over?

I'm going to dump a 5w resistor in R205 on my STe PSU. The current 3w one is in burnt fingers territory. I might place D203 under the board as there is heaps of room to clear it from the PSU plate.

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Re: R205 100 ohm resistor in SR98 starting to get hot and smell

Post by exxos » Sat Jan 18, 2020 10:52 am

atari030 wrote:
Sat Jan 18, 2020 10:41 am
I did read some posts where you mentioned dummy loads on the Mongrel boards due to a lack of 12v on the floppy.
I think you must be confusing 3 subjects there... dummy loads are for testing the PSU. Resistors on the PSU are to load it while nothing is connected else it would probably explode otherwise. Mongrel 12V I was talking about trying to not use 12V at all, or a small step up converter from 5V.
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Re: R205 100 ohm resistor in SR98 starting to get hot and smell

Post by atari030 » Sat Jan 18, 2020 11:30 am

No, I understand that. If you use a standard STe (or FM) PSU with low or no 12v load, what would be the impact of that?

R205 I'm just doing while I recap the PSU as its roasting.

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Re: R205 100 ohm resistor in SR98 starting to get hot and smell

Post by exxos » Sat Jan 18, 2020 1:42 pm

atari030 wrote:
Sat Jan 18, 2020 11:30 am
If you use a standard STe (or FM) PSU with low or no 12v load, what would be the impact of tha
No, it won't matter.
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