Heathkit SB221 Inspection

[nomadradio]

The 330uf filter caps will improve the regulation of the HV supply, but they have a drawback. The power-on surge will be large enough to weld the contacts on the power switch before long.

Bigger filter caps are okay, but some kind of soft start would be a good idea. That power switch is a pain to replace, if you can find one.

And a bigger pain if you can't.

Harbach has a board for this that will fit under the chassis of a SB-220.

73

 

[357]

Thanks I took your advice and got the softstart coming along with the diode board, softkey and cap board.

 

[357]

 

[357]

Gettin er done

 

[357]

 

[Dmans]

73
David

 

[357]

I still gotta go over everything with some iso or alcohol swabs to get the flux

 

[Dmans]

357,
You ever use Acetone for flux removal? I buy it at Lowe's for about $7.00 a quart. It can be had other places as "Nail polish remover" for about $10.00 a half pint.

I have found it to work better than alcohol.

73
David

 

[357]

ok maybe i'll grab some today. I always thought it was harsh and maybe melt plastic but maybe thats thinner.
thanks!

 

[nomadradio]

Rubbing alcohol from the local drug store works pretty well on most rosin flux. Use the 91 percent flavor, not the 70 percent.

73

 

[357]

I ran into a snag.
I noticed that the screws in the capacitor box are supposed to be "flat head" to sit flush and they are pan head in there and hanging up and distorting the plastic holders.
Gotta go to the hardware store tomorrow.




Also the acetone seems to smear the flux around and get sticky.
I think the alcohol is easy to use.











This is after with alcohol swabs

 

[nomadradio]

Time for a trip the hardware store for flat-head screws.

Looks really good so far.

73

 

[Dmans]

Also the acetone seems to s,ear the flux abound and get sticky.
I think the alcohol is easy to use.

Maybe it has something to do with the material the boards are made of. I can't seem to put my hands on anything newer than 30 years old!

It's looking like you will soon have a brand new Heathkit soon!!

73
David

 

[357]

I went to every hardware store in town.
Shortest they got is 6/32- 1/2"
I need 6/32 - 1/4 or maybe 3/8.
Now everythings on hold, I'm kinda pissed.

Harbach didnt mention if I should use the flat washers, anyone know?
The other thing is the plastic "blocks" hang out the bottom of the capacitor bracket.
Is that normal?

 

[357]

Getting closer