I had a similar intermittent fault. Found dry joint on collector Q2 of sub
receiver if chain A6 81907_4/4
Powered up pcb on bench with external psu to find
I had tested transistors by poking onto leads. was caught out by not
checking connection to pc track.
On Mon, 18 Jan 2021 at 10:00, Barry Simpson <vk2bj@optusnet.com.au> wrote:
> I have a very recently acquired late serial number (black knobs) Orion II
> which is in immaculate condition outside and inside.
>
> I have not used it very much since I bought it just prior to Christmas but
> yesterday I noticed that the sub receiver (standard model sub receiver) was
> making intermittent loud crashing noises like receiving static and the sub
> S meter was registering those crashes. The rig had been on most of the day
> in a fairly warm room.
>
> However, there were no such static crashes as the main receiver was working
> perfectly.
>
> Tonight, I took out the sub receiver board and cleaned all the
> pins/connectors although I could not see any tarnishing anywhere.
>
> That did nothing to cure the problem which still occurs with the antenna
> connected to a dummy load.
>
> It does not seem to occur immediately when the rig is switched on from cold
> but it gradually gets worse as it warms up.
>
> I have not identified anything specific to trigger or make the crashes
> worse by tapping on components and screening boxes and wiggling capacitors
> and connecting leads.
>
> Before I start dismantling the rig and investigating further, I wonder if
> anyone can identify the symptoms and suggest a possible cause.
>
> The only thing I can think of at the moment is the power board capacitor
> problem but I do not know how that would result in what I am experiencing.
>
> All and any suggestions and pearls of wisdom would be appreciated.
>
> Thank you in advance.
>
> Barry Simpson VK2BJ
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