Re: TM500 Plug-in Extention

Colin Herbert

I can either connect the appropriate end of the Dan Meeks extender to a plug-in or not. The extender has a number of leds to indicate the status of some of the power-lines. It doesn't need to be connected to a plug-in any more than the backplane needs to have any plug-ins plugged in. If there is nothing connected to the pass-transistors (i.e. there is no plug-in present, no extender present, nor are they otherwise electrically connected to anything, then surely they cannot oscillate?)

-----Original Message-----
From: [] On Behalf Of Stephen
Sent: 10 August 2020 17:28
Subject: Re: [TekScopes] TM500 Plug-in Extention

On Mon, Aug 10, 2020 at 03:43 AM, Colin Herbert wrote:

My TM 500 extenders were supplied as a kit from Dan Meeks (though I doubt he
has any left) and the ribbon-cable is ~87 cm long. I can't say that I've seen
any problems with oscillation of the pass-transistors in the mainframe, but
wouldn't they need to be connected to some circuitry in a plug-in at the other
end of the extender? I can't see how an unpowered transistor can oscillate.
My cable measures ~57cm. Probably I didn’t understand you correctly, but the extender is connected
to the circuit of the plugin itself??

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