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GraphicMan · 05-31-2026, 08:28 PM

A thermistor-based system is usually much easier to make (sensor → circuit → temperature control) than a thermocouple system.

Here’s the practical difference: 1. Thermistor (easier)

A thermistor is basically a temperature-sensitive resistor.

You usually just need a voltage divider (one resistor + the thermistor).
The circuit measures resistance change.
Signal levels are relatively large and easy to read.
Can connect directly to many analog inputs or simple control circuits.

Typical setup:
5V → resistor → thermistor → ground
Then measure...

GraphicMan · 05-31-2026, 08:25 PM

yes i heard that mv-dc is senstive to noise also and perhaps thats why my new heating elements have their labels written on them 1999 ! not sure if that is really from 1999 or just old prints....

GraphicMan · 05-31-2026, 11:40 AM

so my information was flipped, since you know better, what are the benefits of the more complex thermistor then ?
in another words why a station would chose a thermistor then since a thermocouple can do the trick easily and wont burn?...

GraphicMan · 05-31-2026, 10:39 AM

that is interesting and the real question remains, AFAIK the thermistor type is much easier to make its pcb, so why a cheap/clone would choose the harder/more complex/more expensive design?!...

GraphicMan · 05-31-2026, 05:17 AM

treasure! that is for the original or a clone station and what type of sensor does it use?
thanks...

GraphicMan · 05-30-2026, 11:43 PM

thanks a lot for the share , btw is there a way to know the real type of the heating element without cracking it?...

GraphicMan · 05-30-2026, 04:42 PM

oh sorry i missunderstood you, yes i have been thinking a LOT about that, the sensor and i think they are all the same are built inside the heater, it is a ceramic thin rod with 3 tiny holes! 2 holes for the sensor leads and the third one is for one of the heating coil (the start of it) then the coil is wrapped around that ceramic rod, then another ceramic tube is over covering all that, now i have the old sensor yes with its rod, i did try it as a test after sticking it to the new heater and soldering all the leads to the pcb, that worked fine as expected, new heater to the board with old sensor,...

GraphicMan · 05-30-2026, 02:27 PM

it is not available here, consider it a challenge/adventure
also i got 5 of them, so it will be nice if i can use them for the future, also these newer ones heat up much faster and suppose to be of a much higher quality...

GraphicMan · 05-29-2026, 08:20 PM

very possibly, can you share a link for the station that you have?...

GraphicMan · 05-29-2026, 09:21 AM

i agree about the base end shape style, but i think it is not a problem because i have that from the original one, the soldering iron was barely used and i always use it at a very very low temps compared to what it can do, so i am assuming these cheap heating elements are already poorly made and i assume the replacements will be identical! but on the other hand the A1321 seems like proper ones and far superior to them, i wish i can made the mod and that it is not very difficult and durable, i want to give it a shot specially if it is reversible , i dont think that the wire are a problem it seems...

GraphicMan · 05-27-2026, 01:18 PM

yes i understand how both work, the question is , where did he get the initial voltage to begin with ?
if i open the unit can you help me out make it?...

GraphicMan · 05-27-2026, 11:23 AM

I have not made that mod, here is the link
https://www.youtube.com/watch?v=pG0xtk9URAI
but i am not sure, that is why i am asking perhaps my soldering station is also different than his
I dont understand how adding a resistor can make such a conversion! I wish someone here can enlighten us...

GraphicMan · 06-15-2025, 04:37 AM

yes i did replace all 3 caps around the STR, they are all 50v 10uF, they read fine with reasonable esr though, after replacing i noticed the tv show the screen a bit faster than before and i really thought i fixed the problem specially that i tried to warm that area before on the old caps and the screen shows right after that rather than a colt start,, so i kept testing (on/off) after few attempts it did not want to show a screen anymore and just goto sleep again however i want to give an important hint,

i did notice many times before (with and without the new caps) that there is...

GraphicMan · 06-14-2025, 01:01 PM

I noticed that sometimes when the tv shuts down the screen horizontally scales down a little first then shuts down completely, i checked a cap close to the vertical IC outside the board and it read good, what else could it be?

GraphicMan · 06-10-2025, 06:16 AM

The tv is working for longer times but it still goto standby , i tried to lower the brightness and contrast by a lot but it still shut down after few minutes or randomly , plz guide me where to check
thanks

GraphicMan · 06-10-2025, 04:22 AM

it looks like the main cap was the problem, i did replace it with a 450v 330uF instead the original 450v 150uF, according to my LCR the replacement was giving me 303uF but a bit less ESR, however it does have a belly on above and have been sitting for years with no use it looks like it did the trick, at the begining the tv did goto sleep but soon went back on by itself, the more i test the less the turning off, i know from experience that old caps need time to wake up again, only time will prove that
the other subject is that it seems like i cant find the right spots to measure voltages,...

GraphicMan · 06-10-2025, 03:32 AM

yes the 300v is about 334v ( i think while on sleep) i have pulled out the biggest cap on the psu and measured it good, i can replace also just to make sure, it is difficult to measure the voltages while on because the tv now barely turns on, it just switch back to sleep almost instantly giving me no time to measure anything, i dont have the schematics , do you mean i should looks for C509 and C531 and replace then where they are? or they might have different numbers?...

GraphicMan · 06-08-2025, 08:58 AM

Now i am at the original problem the customer was complaining from, which is the tv works sometimes and then goto standby , then might work again by itself and so on randomly,
what do you think specially that i did not find any blown nor a swollen cap

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852D close soldering station heating element replacement issue

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21SF8XEL 21" CRT TV Turns off by itself

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