I thought I'd messed up the USB lead of my HP 1020 laserjet , measuring
voltages etc, trying to learn about USB function. Turned out I must have
strained a USB A to B adaptor and nothing wrong with the printer. Is one
rule of thumb (for a suspect USB connection) that a maximum USB insertion
force of 250 gram is too low and above 450 gram is generally good ? ( I
later went around a number of leads /connectors, adaptors with the kitchen
scales).
Anyway inside the printer there were 6 unmarked 2 land SMD lumps marked on
the overlay as E1 to E6 , is E a designation for fuse?, all were 0 ohms
across. There were 2 unmarked green 2 land lumps on the USB lines marked VR
on the overlay, bidirectional transient suppressors ?
and 2 SMD contacting the USB lines marked CR, presumably rectifiers, but can
anyone identify with more certainty
4 land device marked topmark D132
found on topcode listings
D13 AZZ23C8V2 Diode SOT23 dual zener 8.2V 0.3W, 3 pin
related?

2 land device marked WU1
found
WU BZX284-B4V3 Phi I SOD110 0.4W zener 4.3V E24 ±2%, 2 pin
related ?

Generally do truncated 3 and 4 character topcodes have any relation to the
full code ?