736 Smoke Unit Problem

A couple of pieces of heat shrink tubing works well. It won't melt.

Chuck Sartor posted:

A couple of pieces of heat shrink tubing works well. It won't melt.

Thanks Chuck!

Perhaps something is out of alignment inside the unit?

midnightwrecking posted:

Perhaps something is out of alignment inside the unit?

 

I didn't see anything that raised any flags, it's possible I could've shifted the element when I replaced the wicking but seeing as it was shorting beforehand I don't think that would've been it.

It looks to me like that element is VERY small. They barely fit in the top of the cap (I usually trim the mica a bit to fit it in). That one looks so small that the slot for the breather hole will contact it (or so it appears). I would just replace the element.

Roger

That element has been cut down. 

C W Burfle posted:

That element has been cut down. 

I can only assume the previous owner must have had a problem with the smoke unit too and modified it.

I'd replace the heater assembly. There were two style smoke units, you need a #671-225 element, which runs about $8.
The mica plate is almost the same diameter as the cap, so they don't really go up inside the cap. The plate should just fit into the smoke pot, and is held down by the cap.
IMHO, the 18 ohm resistance of modern reproduction smoke elements is a bit high. Not sure how well they will smoke.
What has other people's experience with them been?

C W Burfle posted:

I'd replace the heater assembly. There were two style smoke units, you need a #671-225 element, which runs about $8.
The mica plate is almost the same diameter as the cap, so they don't really go up inside the cap. The plate should just fit into the smoke pot, and is held down by the cap.
IMHO, the 18 ohm resistance of modern reproduction smoke elements is a bit high. Not sure how well they will smoke.
What has other people's experience with them been?

I have replaced several with new reproductions with great results.

With the element jammed so far into the top, I doubt it makes much contact with the wicking to produce smoke.  The element should be pressing in to the wicking in order for it to smoke well.  That's the more likely reason its shorting out.  The element should not be in the cap like that.

I've rebuilt many post war smoke units using both original and reproduction elements and have NEVER cut it down. They should wedge into the pot to maintain contact with the batting. Once in place inside the pot and the copper grounding tab is through the slot and bent over the lid it will stay in position. I recommend changing the element. Just my $.02.

Mike

C W Burfle posted:

I'd replace the heater assembly. There were two style smoke units, you need a #671-225 element, which runs about $8.
The mica plate is almost the same diameter as the cap, so they don't really go up inside the cap. The plate should just fit into the smoke pot, and is held down by the cap.
IMHO, the 18 ohm resistance of modern reproduction smoke elements is a bit high. Not sure how well they will smoke.
What has other people's experience with them been?

I just checked my parts bin and actually have a new (reproduction) 671-225 element so I'll install it later tonight and report back with the results!

Well, don't trim the mica base, or force it into the cap!

Here is how I assemble smoke units.
I thread the wire through it's hole in the lid, and slide the ground strap through it's slot in the lid.
Slide things together until the mica base is touching the edges of the cap.
Bend over the ground strap.
Insert the cap into the smoke pot, leading with the ground strap.

I've done them this way for years, and have rebuilt many Postwar smoke units. Still, I am certain that other folks have their own techniques.