Philips 6652C - What Went Wrong

WHAT WENT WRONG?
The PM 6652 and PM 6654 feature a high MTBF fi-
gure (more than 20000n.) thus ens u ring reliab le
operation. If a measurement failure occ ures, the
problem will most cert a inly be one associated
with the op eratio n of t he instrument. Below is
listed some of the possible failure symptoms,
asst.roing that the input signals t o be measured
are present and con nected.
The instrument fails to measure
_ Sy=--m.....:p _t_o_m_: __ T _ h _ e _ d _ isp~ X - sh~ws al _l _ __ zeroes
F irst press RESET and t r y agai n.
- Th e c ounter is not triggering. Check the trig-
ger l eve ls, AC / DC coupling, impedance and at -
tenuation, if n ecessary , go to KEYBOARD or po-
tentiometer contro l.
- The i nput frequency is too high, or t he pulses
present at th e input are too shor t.
- A very long measuring time has been selected.
Adjust the meas uring time - or wa it.
Th e S TORE button is lit (i.e . , the co un ter is
waiting for a program to be stored ) . Press
STORE or RESET .
E xte rnal con tro l is being used, and ther e is
an incorrec t sig n al pre sent on inp ut E.
Symptom: Th e displ ay is "frozen"
- First activate RESET and try again.
- A long measuring or display time has been se -
lected. Adjust the measuring/display time, or
w ait .
- DISP HO LD is on.
EXT GATE is in operation, and t he gating si g-
nal has become di sc onnected .
Symptom:
The di sp lay s hows an owerfl ow
The MATH control is active, with a large expo-
nent value set as K. Disable t he MATH feature,
or change the K val ue.
In
PM 6652 frequency mea s ur emen ts , the !NT/EX T
STD IN has been switch ed to EX T, and there is
no Input D signal.
The measurement is incorrect
S ymptom: The m eas urem ent is sl ightly incorrect
An ERR OR E4 has been reset with the !NT/ EXT
STD IN switch in the EXT pos it io n. Either
switch to INT, or suppl y an external re f erence
signal. ( PM 6654 only, in T IME IN TERV AL s ingl e
mode).
- MATH is on, and there are va lues other than 1
and
0 in K and L, respectively. Either switch
off MATH, or set correct values in K and L.
Symptom: The display showi ng a more or less
constant valu e
- Either CHEC K or COM are on; the latter in
c ases when a si gnal on channel 8 is r equired
for the measurement. Switch ( them) off .
- MATH is ON, and there are invalid values ( for
this measuremen t) in K and/ or L.
Symptom: The measurement varies widely
- HOLD OFF is on, and the time is set to an in-
correct value for the measurement. Either
switch HOLD OFF off , or adj u st i ts value.
The si gnal is v ery noisy . See the reference
chart.
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