[GreenKeys] What an Idiot!

[Alf Fisher]

Hi Rob,
I cant see anything wrong with replacing the blown fuses in the CCU as long 
as they are the same current rating.
The machine will either work properly and you've got away with it, or it 
will still run open, in which case, other components have failed.
Unfortunately, the transistors all have Teletype part numbers which are 
meaningless unless you are in-the-know.
I find the drawings very difficult to understand as I never did a TTY 
training course but maybe Wayne can help.

Alf

----- Original Message ----- 
From: "Robert Jarratt" <robert.jarratt at ntlworld.com>
To: "'Simon Claessen'" <info at drukknop.nl>; <greenkeys at mailman.qth.net>
Sent: Sunday, May 26, 2013 10:27 AM
Subject: Re: [GreenKeys] What an Idiot!


> 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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