[GreenKeys] What an Idiot!

[Robert Jarratt]

Some additional information.

When I first blew the plug fuses I suspected a short. So I tested across the
pins of the plug, sure enough when I switched the switch to LOCAL I measured
a short. Removing all the plugs from the back of the CCU (this is a computer
i/o set) the short went away. I narrowed it down to the connector marked
with a '4' on the CCU back panel. The wires are very hard to trace because
they are tightly packed so I am not sure where the wires for this go. I
suspect this is not normal. However, once I connected it back to 110V, the
machine stayed on, running open, and the fuse in the plug did not blow
again, so I wonder if that apparent short is normal?

I have since checked the internal fuses and found that two of them have
blown. Looking from the back of the CCU they are the two on the right. I
also checked the fuse on the far right, near the paper tape punch , which is
fine. I wonder if it would be safe to replace the blown fuses and try
switching on again? With other potentially damaged components could I end up
doing more damage if I don't check and repair them first?

I believe the fuses have to be "slow blow". Farnell lists some as "slow
blow" and some as "time delay", not sure if there is a difference, but for
one of the fuses they list "time delay" ones but not any "slow blow" ones.
Is there a difference?

Regards

Rob

> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-
> bounces at mailman.qth.net] On Behalf Of Simon Claessen
> Sent: 25 May 2013 21:04
> To: greenkeys at mailman.qth.net
> Subject: Re: [GreenKeys] What an Idiot!
> 
> probably the switching transistor. the thing on the big cooling metal.
> also the connected pcb might contain some blown transistors as well.
> fortunate the documentation is readily downloadable but extensive. You
> may want to look at doc 574-100-103TC page 20 for a schematic. also check
> the power supplies and measure the coil resistance. if it is infinite, the
coil
> sould be replaced as well as the transistors.
> 
> good luck!
> 
> On 25-05-13 20:50, Robert Jarratt wrote:
> > I mistakenly plugged my ASR33 directly into the UK mains (240V/50Hz)
> > rather than via the 110V transformer. It blew two fuses in the plug
> > before I realised what I had done wrong.
> >
> > The machine now runs open (i.e. "chatters") even in LOCAL mode.
> >
> > What might I have damaged?
> >
> > Regards
> >
> > Rob
> >
> >
> >
> >
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> --
> Met vriendelijke Groet,
> 
> Simon Claessen
> drukknop.nl
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