“LONG POP” Instrument Preset Check

This check is very similar to the normal Instrument Preset Check: an additional processor check is performed, all of the RAM locations in Digital Storage (A3A4 Memory) are checked, and the RAM memory on the Al5 Controller is verified.

Since these more extensive checks require altering information that has been stored in RAM, LONG POP requires an internal jumper on the Al5 Controller. To perform a LONG POP:

nSet the LINE switch to STANDBY.

w Place a jumper between ST or STS to T3

qOn Al5 Controller (HP part number 85660-60209) jumper A15TP4 (STS) to A15TPl-7

PO

qOn Al5 Controller (HP part number 85660-60245) jumper A15TPl-9 (ST) to A15TPl-8

P-3).

q(Refer to Al5 Controller Component Location Diagrams for location of test points).

nSet the LINE switch to ON.

When LINE switch is set to ON, the two red INSTR CHECK LEDs are forced on and the main processor steps through the Self Test routine, expanding the normal POP with the additional tests mentioned above. The expected results for a LONG POP are exactly the same as for the normal POP of Instrument Preset as described above in the Instrument Preset Check.

Because LONG POP is a “destructive test” (it alters any information that has been stored in RAM), it should be performed only as a last resort effort in troubleshooting what appears to be a memory or processor related problem.

Digital Storage Verification

The Instrument Preset Check does a fairly complete verification of the Digital Storage controller and memory. An additional check can be done, independent of the RF section, by jumpering A3A6TP3 to A3A6TP6 and pushing A3A7Sl momentarily. A test pattern should appear on the display. Refer to the A3 Digital Storage Troubleshooting Section in the HP 856628 IF-Display Section volume of the service manual for a more detailed description of this procedure. Note that when the jumper is connected, the left check LED always stays on following an INSTR PRESET, since in the test pattern mode, Digital Storage ignores all instructions from the Al5 Controller.

2 Digital Troubleshooting