[Heathkit] Heathkit SB-610 monitor scope

[Dick KF4NS]

Hi Dennis,
I have run into a huge bag of worms. I still have to replace the can caps. I have all I need except the 
33mfd 450v. The main problem now is I cannot get any vertical gain,V2 tests fine. I am replacing lots of 
high value resistors which test way high. I am finding this a real pain due to the tight space so I am 
attaching the replacements to the stubs I leave after clipping off some of the resistors. Just for 
update, the HV caps and diodes are all new now. The B+ needs attention.

There are some Sprague 160P caps that I have to replace but not too sure what is the best cap to replace 
these. Seems to me that in the past I used orange drops. They are a bit expensive so may just go with 
poly.

I have tried injecting the .1V sig from the HW100 (which is more than enough to drive the amp) after the 
grid cap at V2 and before and after R1 2700 and had zero difference. I need to tune the grid and  plate 
LC circuits but not sure what to use for sig injection. I believe if I just inject a 3395khz and read it 
on my counter I should be able to diagnose that area.

All the power xfmr voltages are right on but most of the DC voltages in the power supply are low by 
10-20%. The can cap replacement should fix that.

Any ideas are welcome so just chime in. Wish me luck. I seem to get all these things that somebody else 
has messed with.

73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow!



----- Original Message ----- 
From: "Dennis Berry" <dennisberry at att.net>
To: "Dick KF4NS" <kf4nsradio at verizon.net>
Sent: Monday, November 07, 2011 9:11 PM
Subject: Re: [Heathkit] Heathkit SB-610 monitor scope


| Dick,
|
| If you will, please share or post what you find out.  I've got a 610 here I
| need to dig into this winter.  Any troubleshooting tips are always good!
|
| dennis, nu8s
|
|
|
|
| > Decided to dig into it again since I had not done much with it since I got
| > it 2002 and replaced all the
| > power supply caps. Recent testing showed poor focus and low vertical gain.
| >
| > I found the two B+ diodes shorted. Wow, never saw any selenium rectifiers
| > that looked like those two. The
| > focus problem should be fixed after replacing the rectifiers and a few
| > resistors. About those diodes, I
| > will likely use a couple 1N5408s but the usual thing would be to series a
| > resistor with each anode lead
| > which is usually a good idea in power supplies with original seleniums. In
| > this case though I wanted to
| > get you input because I noticed that the capacitors are not electrolytic
| > and there shouldn't be the usual
| > increase in voltage. What do you think? One chap has a solution online
| > whereby he used 4 1N4007s in
| > series for each replaced diode which I guess he thinks will make up for
| > not using series resistors.
| >
| > I also observed that the blue and yellow xfmr leads are reversed but don't
| > believe that should be a
| > problem since we are looking at AC here and don't think secondary polarity
| > should be of concern here.
| >
| > I have a couple options here will take care of the vertical gain
| > situation. Got that covered.
| >
| > 73, Dick KF4NS
| > St Petersburg, FL 33714 USA
| > Keep The Glow!
| >
| >
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