D116 is a 16 volt Zener diode on the I/O board, near the power connector. Its
job is to prevent the radio from turning on if supply voltage exceeds 16 volts.
Gary
W0DVN
> On Jan 18, 2020, at 9:55 PM, Bernie Skoch via TenTec <tentec@contesting.com>
> wrote:
>
> Thanks. Where and what type is D116?
>
>
> -----Original Message-----
> From: Gary Follett <dukeshifi@comcast.net>
> To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
> Sent: Sat, Jan 18, 2020 9:47 pm
> Subject: Re: [TenTec] Orion II Won't Power Up
>
> The 5KP15A device is designed specifically to protect sensitive electronic
> equipment from voltage transients induced by lightning and other transient
> voltage events. Its job it is to short the supply of the transient to ground
> in a picosecond (1E-12 seconds).
>
> Failure of this part in the open mode would have no effect on radio
> operation. If shorted, it would pop the main fuse, but only if the relay K1
> were on. Since you do not hear that relay clicking on, the transient
> suppressor is not even in the circuit.
>
> If D116 were shorted, it would put Q77 base high, pulling Q23 base low. This
> would override the Power Switch turn on signal at J8 on the I/O board and
> this would prevent the power switch from turning the radio on.
>
> Gary
>
> W0DVN
>
>> On Jan 18, 2020, at 9:14 PM, Bernie Skoch via TenTec <tentec@contesting.com>
>> wrote:
>>
>> 5KP15A
>
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