Add voltages at CPU pins

_source/_posts/2025-03-23-ti99-4a-restoration.md

@@ -61,6 +61,10 @@ The PSU board shows no obvious sign of damage, either.
 
 * the voltages provided by the mains transformer look good
 * the DC voltages at the output of the power supply board look good
+* voltage readings at CPU pins:
+  * pin 1 (Vbb) -4.88 to -4.64V
+  * pin 2 (Vcc) +4.8 to +5.2V
+  * pin 27 (Vdd)  +11.4 to +11.9V
 
 ### Clock signaks