🚀 go-pugleaf

In article <8783@jhunix.HCF.JHU.EDU> ins_asag@jhunix.hcf.jhu.edu (Steven Gabriel) writes:
>I hope it is not too gauche to write to this newsgroup about
>a dumb terminal, the Z19.  I am very fond of it, but the power
>circuit board gets extremely hot.  We have to resolder certain
>connections periodically to keep it going.  I wonder if there
>are any replacements or tips on how the scorched diodes can
>be modified/enhanced to prevent this heat buildup.  Grateful
>for any suggestions; the local Heath store does not want to talk
>about this part.

Zenith came out with a standard mod for the power supply board in both the 
H/Z-19 and H/Z-89.  The mod basically moved one set of secondary transformer
leads from a molex connector directly to the large bridge rectifier.  This
did two things.  It prevented the circuit traces on the power supply board
from acting like fuses in case the bridge rectifier shorted out.  It also 
prevented the molex connectors from overheating and causing the solder
connections on the circuit board to become brittle.  After the mod is
installed, if your bridge ever shorts, the fuse will work as designed and
the circuit will not be damaged.

To install the mod, remove the molex connector that attaches to the power
transformer secondary.  There will be two large yellow wires.  Push down on the
molex pins and pull the yellow wires out.  Cut off the molex pins.  Remove the
molex connector that attaches to the big bridge rectifier.  Identify the leads
that carry AC to the bridge.  Unsolder these two leads from the bridge and 
remove them from the molex connector also.  Strip the ends of the yellow wires
and solder them to the bridge rectifier where the previous two wires had been
removed.

It's also a good idea to remove the power supply board and resolder any solder
connections that look cracked or brittle.  When I was a Heath tech, I made it
a practice to always do this mod on every H/Z-19/89 that walked into the store.