Sencore TF151 - TF151 Troubleshooting Chart; TF151 Parts List

TROUBLE CHART
The TF151 can be broken down into three sections, the regular transistor or beta
reading section, the FET or Gm reading section and the leakage section. The leak-
age section is common to both regular transistors and FETs. It it ever becomes
necessary to trouble shoot the TF15l, check to see what section is giving the trouble.
This will narrow down the checking to the section that is faulty.
SYMPTOM PROBABLE CAUSE CORRECTIVE MEASURE
Leakage and Gm OK, but no
beta cal
Meter pegs to left or right
on Gm readings. Leakage
and beta OK
Gm zero no effect and no
leakage readings. Beta OK
No Gm readings, beta and
leakage OK
Gm readings to high or to low
, No leakage readings, Gm and
beta OK
Meter vibrates rapidly In Gm
and beta with type switch in
P or PNP position. In FET
leakage, meter pegs wjth
type
switch set to N
R2 open Check with ohm meter and
replace if necessary
CR8, CR9, TRIor Check diodes and transistors
TR2
CR7 or C1 shorted
or R8 open
CRI0 or CRll
shorted
Gm cal off
CR4 shorted
C7 shorted
Check for + 6 volts at
positive end of C1. Check
CR7 and Cl for shorts and
R8 for open
Check both diodes out of
circuit with TFl51 for short
See calibration information
and recal Gm pot
Check CR4 and replace
if necessary
Check C7 and replace if
necessary
TF 151 PARTS LIST
REFERENCE NO. PART NO. OESCR IPTION PRICE
RIO 14G176
82 OHM 1/2W 5% $
.30
R14 14G265
100 OHM 1/2W 1%
.75
R15 14G319 1. 85 OHM 1/2W 2%
.65
R18
' 14G317
20.5 OHM Ij2W 2%
.65
R19,
R20, R23
I4G318
2.26 OHM 1/2W 2%
.65
R21, R24 14G248 24.9 OHM 1/2W 2%
.65
RI, Rll I5A76 1, OK, 100 OHM DJal Control
2.25
R4 15S15A
6K Linear Control 1. 50
R17 15G26 100 OHM Linear Control
1. 50
CR1, CR2
19G18
8 Volt
Zener Diode
1. 95
CR3
19G28A
IN695 Diode
.65
CR4
19G16
IN816 Diode
.75
CR5, CR6,
CRI0
CRll
16S5
Rectifier . 5AMP @400 PIV
1. 50
CR7
50G3
6.2 Volt Zener Diode
1. 95
CR8, CR9
19G13
IN34A Diode
.SO
TRl, TR2
19G29
2N5172
Transistor
. 75
M1
23C29
6" meter, 200 microamp,
225 ohm 5%
22.00
SI
25G4
Slide Switch SPOT
f 2/}.'s
. 50
S2
25AIl3
Rotary Switch 8P2P
.-p
3.00
22