SB610 and manuals for AM1 and SB604

[John Campbell]

Hello Group;
 The problem of changed-value resistors seemed to be rather common in
the late sixties/early seventies Heath tubed gear. Over the years I have
found that most of the problems that occurred with my SB-401 and SB-220
were due to various resistors going out of tolerance. Suggestion...if
you are experiencing a problem with a  piece of Heath tubed gear (and
replacing the associated tube(s) doesnt help, get out the voltage chart
and start checking all of the associated circuit voltages. This is
especially true if the problem seemed to slowly appear and worsen over a
period of time. Be especially suspicious of any high value resistors
which are part of bias voltage dividers connected to a B+ supply and
supplying bias to a tube element. Any suspicious resistors should be
checked with an accurate DVM for proper resistance. Any out-of-tolerance
resistors should be replaced with film type resistors of the next higher
wattage rating. At least in my case, this has proven to be a very
effective solution.
                              73....John (W8JNC)


>Date:         Tue, 5 Jan 1999 19:44:49 +0000
>Reply-To:     mark allison <mallis at GLOBALNET.CO.UK>
>From:         mark allison <mallis at GLOBALNET.CO.UK>
>Subject:      Re: SB610 and manuals for AM1 and SB604
>To:           HEATH at LISTSERV.TEMPE.GOV
>
>John King wrote:
>
>> Hello Folks:
>>
>> Have sick SB610 monitor scope and no manual. Problem sounds like a
ground
>> missing or open pot. It has dot on screen about 1/2 inch in diameter
and it
>> is bright. The vertical position and horizontal position pots work
and the
>> trace can be moved with them. The Focus control doesn't work, The
Intensity
>> control doesn't work, the Vertical gain pot doesn't work and the
Horizontal
>> gain pot doesn't work. So sounds to me like the string of pots are
>> effectively not in the circuit and are not varying the voltages to
the
>> elements of the CRT.
>> WHAT DO YOU THINK??
>>
>> I could use a manual for the SB610, also Heath AM 1 impedeance
bridge, and
>> Heath SB 604 A.C. power supply for the SB 104A.  Please advise if you
have
>> any of these and if you are willing to part with one or a copy.
>>
>> Please reply via email direct. Thanks and 73, John, K5PGW
>>
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>
>Have had a similar problem with mine, I found ot to be down to the high
value
>resistors.  I had to replace all of the 1 meg ones as the had gone low
in
>value, around 100 K or so,  also the 330K ones had virtually doubled
their
>values.  I havent had any need to change any of the others, most have
stayed
>within there tolerances.
>
>hope this helps
>
>mark allison
>G0BTP
>
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