Mercurial > whatever / changeset

--- a/content/hp8662a.rst	Sat Mar 24 01:43:02 2018 +0100
+++ b/content/hp8662a.rst	Wed Apr 11 23:09:27 2018 +0200
@@ -111,12 +111,13 @@
 the culprit for the smoke: the input protection thermistor. Strangely, it still
 measures a decent resistance value, but hey.
 
-The thermisor is descrived the old fashion way: it's a 5ohm@25°C with a
+The thermistor is described the old fashion way: it's a 5Ω @25°C with a
 temperature coefficient of -3.8%/°C. I did not find an exact replacement in my
 junk parts; only a slighty highter value one (a XXX, which is more like
-20ohms@25°C). Not ideal, but for now, it seems to work fine.
+20Ω @25°C). Not ideal, but for now, it seems to work fine.
 
 .. image:: {filename}images/hp8662a/smoking_thermistor.jpg
+   :class: image-process-large-photo
 
 After this first step forward, I was not confident enought to plug the boards
 back in place and try again (I am always worried when I repair switching
@@ -136,6 +137,8 @@
 did not stay on, and the error LED did turn on. All the voltages produced by
 the inverter board were very low. Somethin was wrong.
 
+.. image:: {filename}images/hp8662a/PSU_inverter_schematic.jpeg
+
 Looking at the schematics and the boards, I did find several failure points:
 
 - one of the 2 150µH inductors on the 160VDC rails (L6 anf L7 on A7A3) ) looked
@@ -151,21 +154,21 @@
   the 2 switching (bipolar!) transistors (first time I see the base of an NPN
   transistor protected by a fuse, but it's also the first time I repair a
   switching PSU which the main switching transistors are bipolar ones and not
-  MOSFET or so). These are small XXX fuses, they look nice and so but are very
-  expensive (and a bit hard to find): something like 15€ each. So for now, I've
-  replaced it with a simple 5x20 glass fuse: not as pretty but does the job for
-  a few cents.
+  MOSFET or so). These are small BUSS GMW 4/10 (400mA) fuses, they look nice
+  and so but are very expensive (and a bit hard to find): something like 15€
+  each. So for now, I've replaced it with a simple 5x20 glass fuse: not as
+  skookum but does the job for a few cents.
 
 .. image:: {filename}images/hp8662a/broken_choke.jpg
 
 After these fixes, I reassembled the PSU and tried again: the result was quite
 promising, but not a complete success: the PSU seemed to start, but very
 quickly stops itself with an error LED on: the overvoltage protection was
-activated.
+shuting down the power.
 
 I tried to check several things on the error detection circuits with no succes,
-and followed the service manual instruction, until I found this in the service
-manual, about this overvoltage error:
+and when (at last) I began to follow the service manual instructions, I found
+this paragraph about this overvoltage error:
 
   If red LED in the upper left hand corner of the board is lit indicating the
   input voltagr from the A7A3 Inverter assembly was too high and the supply was

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