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R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Tue Nov 06, 2018 12:25 am
by Icky
Tonight I turned on my STF Remake and the SR98 PSU resistor R205 100 Ohm 3W started to get hot and smell.
Fortunately nothing went bang and checked for shorts etc and there are none.
I notice in the schematic its the resistor on the end of the 12V to GND line.
- Screen Shot 2018-11-06 at 00.19.50.png (250.47 KiB) Viewed 5600 times
On the STF remake the 12V line goes to R15 and then to the monitor socket pin only nowhere else.
Re: R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Tue Nov 06, 2018 7:07 am
by Icky
Icky wrote: ↑Tue Nov 06, 2018 12:25 am
Tonight I turned on my STF Remake and the SR98 PSU resistor R205 100 Ohm 3W started to get hot and smell.
Fortunately nothing went bang and checked for shorts etc and there are none.
I notice in the schematic its the resistor on the end of the 12V to GND line.
On the STF remake the 12V line goes to R15 and then to the monitor socket pin only nowhere else.
So question is what needs to be done to fix / make sure it’s ok. The psu has not been recapped but I had just ordered a recap kit over the weekend.
Think I’ll recap it replace the R205 and then test it out.
Re: R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Tue Nov 06, 2018 8:17 am
by exxos
If you have 12V then its normal... its a dummy load resistors to keep the PSU stable.. normally a few watts resistor.
Re: R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Tue Nov 06, 2018 8:29 am
by frank.lukas
When the machine has a EPSON SMD diskdrive nothing except the -12V circuit need 20mA or so over the +12V line ...
Re: R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Tue Nov 06, 2018 3:08 pm
by PaulJ
Icky wrote: ↑Tue Nov 06, 2018 12:25 am
Tonight I turned on my STF Remake and the SR98 PSU resistor R205 100 Ohm 3W started to get hot and smell.
Fortunately nothing went bang and checked for shorts etc and there are none.
I notice in the schematic its the resistor on the end of the 12V to GND line.
Screen Shot 2018-11-06 at 00.19.50.png
On the STF remake the 12V line goes to R15 and then to the monitor socket pin only nowhere else.
As Exxos said its there to load the 12 v supply. At 12 volts its drawing 120 ma which means under normal conditions its disapating 1.44 watts which is well under the 3 watt resisters capability however dissipating 1.5 watts in a resister of that size its going to get hot. It could just be wore out. I'd try just replacing that resister.
Re: R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Tue Nov 06, 2018 9:04 pm
by Icky
Thanks all for suggestions.
Exxos’ recap kit arrived today.
Have decided to replace all the metal film resistors too as that 100R really isn’t looking to good.
I put the unit on load resistors to measure and it was getting really hot. Way too hot.
If you are going to replace one you may as well do the others.
Re: R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Mon Nov 12, 2018 10:00 pm
by Icky
Well I tried to start recapping this PSU over the weekend but got caught up in the STF Remake Reset Circuit fun
https://www.exxosforum.co.uk/forum/viewt ... =19&t=1234
So I thought I would post a pic before this bad boy gets a make over.
Before:
- IMG_3270.png (1023.92 KiB) Viewed 5478 times
Re: R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Mon Nov 12, 2018 10:03 pm
by Icky
And here are the bags of fun that are going towards this make over
One Exxos recap kit and a bunch of metal film resistor replacements:
- IMG_3271.png (755.51 KiB) Viewed 5477 times
Re: R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Tue Nov 13, 2018 9:57 pm
by Icky
The metal films have escaped
- IMG_3272 (1).png (523.19 KiB) Viewed 5434 times
Re: R205 100 ohm resistor in SR98 starting to get hot and smell
Posted: Tue Nov 13, 2018 10:23 pm
by exxos
Icky wrote: ↑Tue Nov 13, 2018 9:57 pm
The metal films have escaped
They do that when your not looking! gotta watch um!