[Johnson] Viking Thunderbolt

[Steve H]

Chris

Thanks, did not see where it was till you pointed it out.

In my case there is an external power supply with a jack on the Tbolt 
chassis it connects to.
My dmm shows indeed the interlock is still connected to it, shorting it to 
ground with
the cover off, so if I am to do any testing with the cover off, I need to 
defeat the switch.

Was curious about the bleeder resistor network in the schematic accross the 
switch and with
the switch held open, I get about 2 meg ohms accross the switch. So I guess 
they disconnected the bleeder resistor
network. Turns out the external PS we are hooking in has a beefy bleeder 
network on the DC output, so
at least there will be something discharging the capacitors.

I plan on waiting a long time in between applying plate voltage, and doing 
any additional work inside the chassis
and I have a HV probe for my DMM to make sure the voltage is no longer a 
worry. I have heard the voltage
can be fatal so I plan on being very careful.

 Steve Hearns
 KA2PTE


----- Original Message ----- 
From: "Chris Farley via Johnson" <johnson at mailman.qth.net>
To: <johnson at mailman.qth.net>
Sent: Wednesday, February 03, 2021 8:06 AM
Subject: Re: [Johnson] Viking Thunderbolt


> Steve,
> A quick look at the schematic will confirm that the interlock (SW105) 
> places a direct short across the HV supply when engaged (closed). This 
> would obviously blow the primary fuses.
> Regards,Chris
>
> Sent from Yahoo Mail on Android
>
>  On Tue, Feb 2, 2021 at 8:37 PM, Steve H<teknoskillz at comcast.net> wrote: 
> Pete
>
> Ok I do see the interlock you described. It looks like its closed / 
> shorted
> and when
> the cover is on the connection opens? Is it shorting out something to
> prevent operation?
>
> Since my Tbolt's internal PS has been gutted, its probably not doing
> anything anyhow
> but just curious how it was designed.
>
> --
> Steve Hearns
> KA2PTE
>
>
> ----- Original Message ----- 
> From: <manualman at juno.com>
> To: <teknoskillz at comcast.net>
> Cc: <johnson at mailman.qth.net>
> Sent: Tuesday, January 26, 2021 1:13 PM
> Subject: Re: [Johnson] Viking Thunderbolt
>
>
>> The same transformer also lights the 3B28's or 866A's filaments.
>> Interlock power mechanism is at end of the spring loaded moveable
>> phenolic rod sticking out the back on the top of the chassis.
>>
>> Pete, wa2cwa
>> www.manualman.com
>
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