Reviving VT220?

[Aaron Jackson]

Thanks for the information, Peter. It makes me want to try and test a
few of the components around the flyback.

Thanks again,

Aaron.


Peter Coghlan via cctalk writes:

>> Hi all,
>>
>> A colleague and I are trying to get a VT220 working again as it recently
>> died on us. We are hoping to set up a few items for the mid-80s
>> (including this terminal) to show the graduands what it would have been
>> like if they were doing their CompSci degree 30 years ago.
>>
>> It looks to me like the flyback is dead. There is a lot of soot and
>> there looks like there is some damage to the top of the transformer,
>> better seen in the second image.
>>
>> http://www.cs.nott.ac.uk/~psxasj/sparse/flyback1.jpg
>> http://www.cs.nott.ac.uk/~psxasj/sparse/flyback2.jpg
>>
>
> I think the soot is fairly typical of what accumulates on high voltage
> components in a city environment.  I'm not sure this indicates any damage to
> it but it may well be faulty without showing any signs of damage.
>
>>
>> The terminal powers on and does the usual beeping but nothing is
>> displayed on the screen. Does anyone have any advice about what to do
>> here? Are there any sources of compatible flyback transformers?
>>
>
> I have a VT220 which also appears to have a faulty flyback.  This results in
> it drawing too much current from the power supply.  I am not certain the
> flyback is faulty but I have eliminated most of the other components which
> are likely to be responsible.
>
> I have looked for replacement flybacks or equivelants but I have never found
> any.  Someone mentioned that they might have VT220 parts available on the list
> some time ago but I didn't get anywhere in following that up.
>
>> 
>> We have a second VT220 which exhibits the same behaviour, hopefully for
>> a different reason so we can try and cobble two into one.
>>
>
> I have a second VT220 which works and I have used it to compare readings
> with my faulty one.  I also tried swapping some of the suspect components
> but this failed to take suspicion off the flyback.  I am reluctant to try
> swapping the flybacks over in case I cause damage to the working VT220.
>
> While the two flybacks appear likely to be electrically similar, I am not
> certain of this and they are physically different - one is PCB mounted
> and the other is chassis mounted with flying leads to the PCB as far as
> I recall.  They have different part numbers, 16-21181-01 and 16-26299-01.
>
>>
>> Any thoughts / advice would be greatly appreciated.
>>
>
> Sorry, I haven't been able to provide much help or hope.
>
> Regards,
> Peter Coghlan
>
>>
>> Thanks,
>>
>> Aaron.
>>
>>
>>
>> --
>> Aaron Jackson
>> PhD Student, Computer Vision Laboratory
>> http://cs.nott.ac.uk/~psxasj