[TenTec] Argosy 2

[Martin Sole]

Hi Snowy,

Trust all is well with you. Back in the day, 1980-1990 when I worked on 
a lot of that kind of equipment, pro and amateur but using similar 
devices, we found 4558 dual op-amps and 4016 CMOS switches to have 
particularly bad yields, at least both were very sensitive to damage it 
seemed. Recall this was before a lot of people, including companies, 
took anti-static precautions seriously so you have a lot of product 
potentially out in the world with devices possibly harmed to the point 
of a shortened life.

I don't know the particular application but as a mic amp I would expect 
you should have DC supply on 8, a good ground on 4 and mid rail approx 
on the inputs and outputs. A few mV of audio on the inputs should see a 
gain at the output as per R choices. Anything other than that is a dead 
chip and I would pull it. Measure supply and bias volts on the board 
before you fit another to be sure its not somewhere else.

Martin, HS0ZED


On 10/6/63 04:21, ROLAND HOWELL via TenTec wrote:
>
> Hi Gents
>
> This may be a duplicate of an email already sent, however I may have 
> sent it to the wrong email address, so here is my plea again.
>
> I have just put a Argosy 525d on the bench, TX is fine on tune and cw, 
> 50 watts at full power or 5 watts with rear switch in low position, 
> the reported problem is no TX audio on SSB, tried another mic, still 
> the same.
>
> Looking at the diagram I see mic audio goes thru' a 4558 I/c, are they 
> a known problem or should I look elsewhere, going to do voltage checks 
> Wednesday.
>
> Have any of learned gents met this problem, if so what did you find.
>
> Stay well and healthy
>
> 73
>
> Snowy G0HZE
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