HP 33s - Manual (Page 299)

Support, Batteries, and Service A–5
„ If the calculator responds to keystrokes but you suspect
that it is malfunctioning:
1. Do the self–test described in the next section. If the calculator fails the self
test, it requires service.
2. If the calculator passes the self–test, you may have made a mistake
operating the calculator. Reread portions of the manual and check
"Answers to Common Questions" (page A–1).
3. Contact the Calculator Support Department listed on page A–7.
The Self–Test
If the display can be turned on, but the calculator does not seem to be operating
properly, do the following diagnostic self–test.
1. Hold down the ‡ key, then press at the same time.
2. Press any key eight times and watch the various patterns displayed. After
you've pressed the key eight times, the calculator displays the copyright
message ©
 # )) )and then the message 
.
3. Starting from  and moving from left to right, press each key in the top row.
Then, moving left to right, press each key in the second row, the third row, and
so on, until you've pressed
› . Then, continue to press these keys in order:
C ™ Ÿ ˜ —  š .
„ If you press the keys in the proper order and they are functioning properly,
the calculator displays  followed by two–digit numbers. (The
calculator is counting the keys using hexadecimal base.)
„ If you press a key out of order, or if a key isn't functioning properly, the
next keystroke displays a fail message (see step 4).
4. The self–test produces one of these two results:
„ The calculator displays  .  if it passed the self–test. Go to step 5.
„ The calculator displays  . followed by a one–digit number, if it
failed the self–test. If you received the message because you pressed a key
out of order, reset the calculator (hold down
‡ , press ) and do the
self test again. If you pressed the keys in order, but got this message,
repeat the self–test to verify the results. If the calculator fails again, it
requires service (see page A–7). Include a copy of the fail message with
the calculator when you ship it for service.
5. To exit the self–test, reset the calculator (hold down ‡ and press ).
Pressing ‡ and  starts a continuous self–test that is used at the factory. You
can halt this factory test by pressing any key.