Date   : Wed, 18 Jul 2012 22:44:05 +0200
From   : vanekp@... (P. Van Ek)
Subject: RS423 won't transmit. Dead 6850?

Ha ha we all make mistakes like that, but sounds like you have found the 
source of your problem, I have no idea how easy those chips are to come by, 
but good luck.

Reg. Peter.
----- Original Message ----- 
From: "Matthew Walker" <walker_matt@...>
To: <bbc-micro@...>
Sent: Wednesday, July 18, 2012 22:38
Subject: Re: [BBC-Micro] RS423 won't transmit. Dead 6850?


> >Normally with serial ports its the TX/RX chips that go, which in the
>>case of the BBC micro are IC74(RX) (DS88LS120N) IC75(TX) (DS3691N)
>
> Ah that makes sense, I missed that when I was probing things. I thought
> I'd start at the DIN socket and work back with the probe, but when I
> probed IC75, I probed pin 2 (RTS) rather than 7. Oops.
> I also should have noticed that IC75 is getting mad hot.
> Now I feel a bit of an idiot.
>
> Thanks for the advice Peter!
>
>
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