SB200 - No HV

[Keith Rowland]

Emile:

The Radio Shack diodes will probably work if you just want to do the absolute
minimum to get your SB-200 operational, however I would personally replace all
16 of the diodes, and check all the electrolytics for leakage as well, since it
could be that one or more of them caused the diode or diodes to blow (if that's
the problem, and it looks as if it is).  If it were my amp, I'd replace them
with 3 amp, 6 kv units. I know that's overkill, but the diodes are not
expensive.

Better yet, there is a source of update modification kits for Heatkit amps that
can be had at very reasonable prices.  These kits will solve the chronic
problems inherent in the SB-line amps, including the problem of inrush current,
which is probably what causes these problems in the first place.  The kits are
beautifully made and quite inexpensive.  The're made by:

Harbach Electronics, WA4DRU
2318 S. Country Club Rd.
Melbourne, FL  32901-5809
http://www.harbach.com

Good luck with your amp fix.

73,

Keith

Emile Imberman wrote:

> Hi All,
>          I have recently purchased an SB200. This Amp was part of a Drake
> Station that I bought. This is my first Heath Amp. Anyway, the Amp does not
> work, it seems that there is no High Voltage. In the manual, as part of the
> initial test, they want you to rotate the meter switch through all of its
> positions. The only meter deflection should be in the HV position and
> should read approx. 2400 Volts.
>          I do have filament voltage as the tubes light up,  the Meter Lamp
> lights  and the Fan Turns (no smoke!). I measured the HV with a probe and I
> do see HV going to the circuit board where the diode string and capacitors
> are.  Someone told me it is probably an open diode and that has been an
> inherent problem with the SB series of Amps.
>          I would like to get some opinions here if you guys think it could
> be the diodes and some advice on how to test which one or more of the
> sixteen diodes on the circuit board may be bad. Also, does anyone know the
> value of the diodes as the manual does not tell you.  Radio Shack has some
> 1KV at 1.5Amps, would that work?.
>         I appreciate in advance any helpful information that I can get,
> especially from those who have experienced this problem with their SB200's.
> 73.  Emile
>
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