[GreenKeys] ASR33 debugging

[Hugh Pyle]

Sorry, wrong resistor... I think the big one is R7 (14, 10W).



On Mon, May 20, 2019 at 12:40 PM Hugh Pyle <hpyle at cabezal.com> wrote:

> The selector driver is the FS-1 Receive schematic here:
>
> http://www.bitsavers.org/communications/teletype/33/Model_33_Schematic_Jun75.pdf
>
> Q2 is the heatsink-mounted TO3 case.
> R5 (8 ohm, 5W) often overheats.  So I'd start by removing the card and
> looking for lifted or broken traces due to heat damage.
>
>
>
> On Mon, May 20, 2019 at 11:55 AM Bob Coggeshall <bob at cogwheel.com> wrote:
>
>> Hi Folks
>>
>> I've got an ASR33 whose selector magnet stays energized all the time with
>> nothing connected to the P2 Connector. I think the drive circuitry might be
>> blown out.
>>
>> I've been trying to decipher where those components are from the
>> schematics http://tty.nerdology.org/schematics/
>> But they are notoriously clear as mud.
>>
>> Any pointers on how to debug the selector magnet driver ? TIA
>> ..c
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