Right - soldered in the new resistors and "fiizzzzzzz", funny burning smell and blown resistors. Am I missing something fundimental? Yes - I connected them in the same place as the resistor wire. Bit stuck. Setting 3 still works but that does have a big chonking resistor wire that could probably take a bloomin glow plug. The rest are now sadly burned out. Help anyone????:confused:
 
tinytdi said:
Right - soldered in the new resistors and "fiizzzzzzz", funny burning smell and blown resistors. Am I missing something fundimental? Yes - I connected them in the same place as the resistor wire. Bit stuck. Setting 3 still works but that does have a big chonking resistor wire that could probably take a bloomin glow plug. The rest are now sadly burned out. Help anyone????:confused:
Click to expand...

yu said yu soldered in resistors - not resistor wire!
what value (wattage) were the resistors - you MUST use resistor wire - if the fan motor takes (for example) 5 amps - you would need 5*12 = 60watt resistors - and they is very expensive! - thats why the manufs often use resistor wire and cut the length to get the correct value, coil it up to allow for expansion and to reduce space, unless you can fit hi wattage resistors in the space.

good luck next time :D
 
MHM - on the originals there is some sort of fire cement to keep the wire in place. This crumbles and next thing the resistor burns itself out.

Is this purely down to coils touching??? :confused:
 
I wouldnt think so - if it is resistor wire - if any coils touched - it would just reduce the value and the fan would run faster. I think it is more likely to be caused by embrittling of the wire over time. The vibration of the unit, without any wire support (fire cement) might then be enough for the wire to break.
 
Ahh..and there was silly me thinking boggo standard resistors would do.
Resistor wire it is then. Excuse my electronic ignorance!!!;)
Thanks for the link also.
 
clear silicone would do the trick , good insulation resistance, un high temp absorbtion [when dry],jist a thought. . . .:)
 
ming said:
clear silicone would do the trick , good insulation resistance, un high temp absorbtion [when dry],jist a thought. . . .:)
Click to expand...

be careful though - if the wire is insulated too much the wire can get hot - and I mean HOT! - AT LEAST A COUPLE OF HUNDRED DEGREES C! All you need is enuf stuff to stop the wires shaking about too much.
 
Well when i soldered the original springy wires back together they actually glowed anyway! Quite scary - is this normal?:confused:
 
If they glow - its ALOT hotter -
High Temperatures judged by Colour
Degrees Centigrade Degrees Fahrenheit High Temperatures judged by Colour
400 752 Red heat, visible in the dark
474 885 Red heat, visible in the twilight
525 975 Red heat, visible in the daylight
581 1077 Red heat, visible in the sunlight
700 1292 Dark red
800 1472 Dull cherry-red
900 1652 Cherry-red
1000 1832 Bright cherry-red
1100 2012 Orange-red
1200 2192 Orange-yellow
1300 2372 Yellow-white
1400 2552 White welding heat
1500 2732 Brilliant white
1600 2912 Dazzling white (bluish-white)
 
I had a quick look at CPC and found they have quite a range of high power resistors. A quick search found the following:

2.2 Ohm 50W £2.09
WELWYN WH50 2R2 JI (RE03488)

You need ~2.6 Ohm, ~1.32 Ohm & ~0.27 Ohm, so possible CPC candidates include: 0.1Ohm (0R1), 0.47Ohm (0R47), 1-Ohm (1R), 2.2Ohm (2R2)....

You may be able to put together a reliable resistor pack for about £7 rather than messing with resistor wire...? I'm not sure of the power draw on the fan, but I can't see it being higher than 5A (He says, waiting to be corrected!!) What is it fused at?
 
The Mad Hat Man said:
If they glow - its ALOT hotter -
High Temperatures judged by Colour
Degrees Centigrade Degrees Fahrenheit High Temperatures judged by Colour
400 752 Red heat, visible in the dark
474 885 Red heat, visible in the twilight
525 975 Red heat, visible in the daylight
581 1077 Red heat, visible in the sunlight
700 1292 Dark red
800 1472 Dull cherry-red
900 1652 Cherry-red
1000 1832 Bright cherry-red
1100 2012 Orange-red
1200 2192 Orange-yellow
1300 2372 Yellow-white
1400 2552 White welding heat
1500 2732 Brilliant white
1600 2912 Dazzling white (bluish-white)
Click to expand...

Brilliant MHM did you get that from your RAVE disc too? LOL

not forgetting that the coils are air cooled by the fan
 
Nope - its coz i is a mechanicle injunear. I should say these colours are for STEEL wire. Other materials vary - but it gives a good indication. Ie if it is glowing visibly in daylight - yu looking at temps between 450 and 600 degC - its a definate - no touchy and plastic melty temperature.
 
Hmm...well on heater setting 1 the thinnest coil does glow slightly when its hanging in the footwell occasionally melting a bit of carpet on contact as it swings. Wouldn't like to lick it - lets put it that way.

Whats the verdict on the above listed resistors then? Worth a go or do you recon they will go pop also?
 
if mine ever go's ,not gonna fiddle wiv silly hot resistors, one pot 0- full speed un pot driving a power transistor [called er power regulator] with a heat sink , thats how they should have done it in first place, . . . .:)
 
No need to design it , its old earth hat[smirk] but i would recommend uprating the power amp, this circuit would work fine , you would have no resistors of course, and if yer really clever could match the original knob with the speed pot. . . .if i can find a simpler circuit i will post that, the reason for all the ickle bits un bobs is that an eclectic dc motor / with a non permanent field coils , will produce noise [electrical] this could effect things like radios ,phones, on board puters, un yer dint want that do ya. . . . .:)sorry ma puter wint tits PWM DC Motor Speed Control
 
ming said:
No need to design it , its old earth hat[smirk] but i would recommend uprating the power amp, this circuit would work fine , you would have no resistors of course, and if yer really clever could match the original knob with the speed pot. . . .if i can find a simpler circuit i will post that, the reason for all the ickle bits un bobs is that an eclectic dc motor / with a non permanent field coils , will produce noise [electrical] this could effect things like radios ,phones, on board puters, un yer dint want that do ya. . . . .:)
Click to expand...
do yu mean this? - PWM Motor Speed Controller / DC Light Dimmer - bloomin eck - its a bit overkill to replace 3 resistors, aint it? - i fancy my 50watt pot above - its basic but cheap.
 
erm yep your right flips ott but the noise factor is the reason un yes the pot might be the best. . . .sorry bout ma post puter crashed as as i was url in , funny world int it.er is you lookin over ma shoulder flips ,copyin ma home work, tell zippy . . .
 
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