From the single post I found relating to variable speed blower problems, I've come to relize that this is most likely my problem with my Balboa controlled 1998 Coleman Horizon 400. My blower constantly runs even though the controller cycles through 3 speed levels manually. My question is can I test the Opto? And what is the full electronic component name for the opto? I will be replacing those components myself. If I'm correct the triac's name is Thyrsistor.

Thanks!

It's your basic opto-isolator.

Has an led on one side, with a light activated diac on the other.

One side of the legs are connected to the low voltage side of the board, the other to the triac. When the internal led is activated, it triggers the diac which in turn turns on the triac. Normally, on a multi-speed blower circuit the led is pulsed to limit the amount of triggering the diac gets and subsequently slow down the blower.

The only real way to check it - (and determine if it's the triggering circuitry or the diac is shorted), is to check the low voltage side (the led side) with an oscilloscope, or a very sensitive voltmeter that'll show low frequency pulses.

If, no matter the blower push button sequence, you get steady dc (or steady pulsing), no pulsing, then the controller components before this are bad.

If you get changing values depending upon the push button sequence, then it's either the opto-isolator, or the triac.

The easiest thing to do by far is just change out the triac and give it a shot. You'll need to get one rated for at least 400 volts at 8 amps. And yes a triac is a 'Thyristor', but nobody calls them that because it refers to a class of devices including scr's. You specifically need a TO-220 package triac rated for 400 volts at 8 amps minimum - with an isolated plane - eg, the heat sink tab on the back is not electrically connected to any parts of the triac - it's electrically neutral.

Do all of this at your own risk however.

Thanks, you've been very helpful. I have found the replacement components, but will wait for next spring to put them in. I figure at most $20.00 for the components (mostly shipping) versus $400 - $600 for a rebuilt circuit board, or new controller. I'll go the cheap route first.

I will give you one specific word of caution...

You cannot just buy any garden variety triac - the package tab MUST be electrically isolated from the terminals. Most triacs sold will have one terminal connected to it.

If you put one of the standard ones in, then the power will be routed straight to ground.

Anyway, you sound like you know enough of what you're doing not to make this mistake. Best of luck.

An additional note to Pageup's caution...

An unisolated tab can be used, if:

The tab is not connected to ANYTHING

The tab is isolated using a TO220 insulating kit, which consists of a very thin mica film, and an insulator for the screw.

Thanks to both of you for your comments. Luckily I was able to take the original part numbers off the Triac and Opto, which I then used to search and research their replacements and purpose.

Thanks again!

I replaced the part over a year ago. The replacement was easy and it worked like a charm! Now I have bubbles on demand. Thanks!