SB-610 questions

[Steve]

Hi Sandy,

I replaced all of the fixed resistors in an SB-610 several years ago. 
It's been too long for me to be of any help in advising you about which 
resistors to change with regard to the specific problems you mention.

A couple of thoughts . . . .

I used metal film resistors for the replacements, got them from either 
Mouser or DigiKey.

For the most part, I doubled the wattage as compared to what was in the 
original Heath design. I measured the values of the carbon composition 
resistors as I removed them and found many had drifted out of tolerance, 
a few were way off. They had drifted higher in value as I recall.

Some of the resistors are in relatively high voltage circuits. While it 
is not usually an issue, resistors have voltage ratings. It would be 
well to pay attention to those ratings in the higher voltage circuits.

Good luck.

Steve K8JQ

On 5/24/2010 4:20 PM, Alexander N Gerli Sr wrote:
> Hi, folks!
>
> Just cleaning up a ‘610 I bought on that auction site. It was really dirty
> which I expected, bit it’s all there. Lectra Clean and a paintbrush does
> wonders. It looks really nice now, and as I type, it’s coming up slow on my
> Variac.
>
> Several of the pot shafts were really stiff so I applied Liquid Wrench to
> the shaft bearings with a Q-tip. Two of the shafts loosened right up, but
> one (Vert Gain) is still pretty stiff. It turns, but not as easily as it
> should. Does anyone have any idea what other penetrating lube(s) I might
> try?
>
> I notice that the Vert and Horiz position pots are smack on. At mid-range,
> the trace spot is perfectly centered and those pots work without a hitch.
> Great.
>
> Focus isn’t very good. In fact, the trace spot is pretty big, about ¼ inch
> in diameter and doesn’t want to shrink down. The Focus pot is working, so I
> suspect that a resistor in that chain is probably way out of spec.
> Recommendations on which one to check??
>
> Intensity pot works, but the spot is fairly bright at the lowest Intensity
> setting. Sounds like another resistor is out of spec??
>
> All the wiring is original and very neat. No caps have been changed,
> although I have an order coming from Allied Electronics to replace all the
> .1 and .15uF HV caps as well as the two 40UF/350V electros. I found some
> nice .1 and .15uF/3kV caps at Allied, too.
>
> Seems like if I can check and replace several resistors in the strings I
> mentions, we should be back on track. I just need a recommendation as to
> which ones might be most suspect. Probably should use 1W or 2W resistors
> too?
>
> Thanks for the help, gang!
>
> 73,
>
> Sandy AC1Y
>
>
> Alexander N. (Sandy) Gerli, AC1Y/G5CPJ
> 4012 Bristol Road
> Durham, NC  27707-5403
> (919) 489-9638
> CCA #AC96-00001
>
> The average Scotsman walks about 900 miles a year.
> The average  Scotsman drinks about 22 gallons of alcohol a year.
>
> Scotsmen get about 41 miles to the gallon!
>
> Sandy Gerli AC1Y
> 4012 Bristol Rd
> Durham NC 27707
> 			
>
>
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