![Tektronix 2440 User Manual Download Page 285](http://html1.mh-extra.com/html/tektronix/2440/2440_user-manual_1078860285.webp)
Table 6-6 (cont)
Maintenance— 2440 Service
Troubleshooting Procedure:
If test = FAIL then look for failure and correct, using the following steps:
Run test 3610 in the CONTINUOUS mode.
Using the CH 1 probe:
1.
Check for activity on the chip select line to A12U440 (pin 20), and trigger the scope on the signal if
active. If no activity, work backwards through U250C and find the problem.
Using the CH 2 probe:
2.
Check the data I/O pins of U440 (pins 11, 12, 13, 15, 16, 17, 18, and 19) for activity. If no activity
when output enable is LO, then suspect U440; otherwise check U352.
3700 or 3800
A12U664
A12U664 (schematic diagram 2)
N O T E
T h e te s t o f R A M d e v ic e A 1 2 U 6 4 4 is d iv id e d in to tw o te s t le v e ls , 3 7 0 0 a n d 3 8 0 0 . T h e s e c
tio n s o f U 6 4 4 th a t m a y b e a c c e s s e d d e p e n d s o n th e c o n d itio n o f th e B U S R E Q o u tp u t o f
A 1 2 U 8 6 0 . W ith B U S R E Q s e t H I, th e 8 K x 8 m e m o ry s p a c e c o rre s p o n d in g to a d d re s s e s
7 0 0 0 H to 8 F F F H is th e o n ly s p a c e a v a ila b le ; w ith B U S R E Q s e t L O , th e 2 4 K x 8 m e m o ry
s p a c e c o rre s p o n d in g to a d d re s s e s 0 0 0 0 H to S F F F H a re b o th a v a ila b le . L e v e l 3 7 0 0 te s ts
th e 7 0 0 0 H to 8 F F F H b lo c k w h ile le v e l 3 8 0 0 te s ts th e 0 0 0 0 H -5 F F F b lo c k re s u ltin g in th e
e n tire 3 2 K x 8 R A M b e in g te s te d . T h e T ro u b le s h o o tin g P ro c e d u re th a t fo llo w s a p p lie s to
b o th te s t levels.
Troubleshooting Procedure:
N O T E
I f th e S y s te m R a m d a ta b u s , c h ip s e le c ts , o r o u tp u t e n a b le lin e s a re d e fe c tiv e , th e S y s te m
fiP c a n n o t ru n th e th e d ia g n o s tic s te s tin g . T h e re fo re , if te s t 3 7 0 0 /3 8 0 0 fa ils , th e m o s t lik e ly
p ro b le m is U 6 6 4 . I f th e d ia g n o s tic s te s ts d o n o t ru n , th e K e rn e l te s t w ill h a v e to b e u s e d to
is o la te a s y s te m b u s o r a d d re s s d e c o d in g p ro b le m . A n N V R A M fa ilu re d u e to s to re d d a ta
b e in g s c ra m b le d re q u ire s a ‘ C O L D S T A R T ’ to re lo a d th e N V R A M w ith c o rre c t n o m in a l
valu es. T he C O L D S T A R T s h o u ld b e fo llo w e d b y a S E L F C A L a n d th e n a n E X T E N D E D
C A L o f A T T E N , T R IG G E R S , a n d R E P E T to re tu rn it to a c o m p le te ly c a lib ra te d s ta te .
If test = FAIL, look for failure and correct using the following steps:
Run test 3710 or 3810 in CONTINUOUS mode.
Using the CH 1 probe:
Check for a LO on pin 20. If it is HI, check back to the source of the problem starting with Q960.
Check for a HI on chip select 2 (pin 26). If not HI, check back to the source of the problem start
with U424A.
6-77
Summary of Contents for 2440
Page 4: ......
Page 12: ......
Page 38: ......
Page 91: ...Theory of Operation 2440 Service 3 49 Figure 3 5 Simplified CCD architecture ...
Page 120: ...Theory of Operation 2440 Service Figure 3 10 DC Restorer 3 78 ...
Page 130: ...Theory of Operation 2440 Service 3 88 ...
Page 136: ...Theory of Operation 2440 Service Figure 3 15 PWM Regulator and Inverter 3 94 ...
Page 138: ...Theory of Operation 2440 Service Figure 3 16 PWM switching waveforms 3 96 ...
Page 208: ......
Page 322: ......
Page 419: ......
Page 423: ...2440 Service Figure 9 4b 2440 Block diagram part 2 6330 27 BLOCK DIAGRAM PART 2 ...
Page 427: ......
Page 428: ...2440 Service WAVEFORMS FOR DIAGRAM 1 6 2 8 5 3 2 ...
Page 429: ......
Page 432: ...2440 Service WAVEFORMS FOR DIAGRAM 2 BUS ISOLATED 6 6 0 3 4 9 ...
Page 433: ...WAVEFORMS FOR DIAGRAM 2 ...
Page 439: ......
Page 445: ......
Page 450: ...2440 Service WAVEFORMS FOR DIAGRAM 8 6603 27 ...
Page 455: ...W A V EFO R M S FOR D IAG RAM 11 WAVEFORMS FOR DIAGRAM 11 6603 29 ...
Page 458: ...WAVEFORMS FOR DIAGRAM 12 ...
Page 463: ...WAVEFORMS FOR DIAGRAM 14 ...
Page 471: ... C N i u i t e x r 4 j u J l i 1 i 6 28 5 44 WAVEFORMS FOR DIAGRAM 18 ...
Page 476: ...WAVEFORMS FOR DIAGRAM 20 ...
Page 490: ...YES ...
Page 492: ......
Page 494: ......
Page 499: ...YES ...
Page 501: ......
Page 502: ...2440 Service FIG 1 C A B IN E T ...
Page 503: ......
Page 510: ...2440 Service SISSVHO Z Old ...
Page 511: ......
Page 512: ...A12 2440 Service F IG 3 C IR C U IT BOARDS ...
Page 513: ......
Page 517: ...10 16 R E V J U L 1993 Replaceable Mechanical Parts ...
Page 518: ...2440 Service ...
Page 519: ...FIG 4 L V H V PWR SUPPLY ...
Page 520: ...FIG 5 ACCESSORIES 2440 Service ...
Page 521: ......
Page 523: ......
Page 529: ......
Page 530: ......
Page 531: ......