531 Repair And Replacement

5-32. AIR FILTER.

5-33. Inspect the air filter at the rear of the instrument and clean it before it becomes clogged enough to restrict the flow of cooling air. To clean, remove the filter from the instrument and wash it thoroughly in warm water and detergent. Dry thoroughly and coat with a filter adhesive such as Filter Coat No. 3 from Research Products Inc. This adhesive is available from heating supply stores or from your Hewlett-Packard Engineering Representative.

5-34. REMOVAL OF CATHODE-RAY TUBE.

5-35. It is recommended that a face mask or goggles and gloves be used when it is necessary to handle the CRT. To remove:

a. Disconnect post-accelerator lead. This can be done by lifting the edge of the rubber cap, and using a screwdriver to compress the spring contact until it comes free.

b. Disconnect leads at neck of CRT, taking care not to bend the pins.

c. Remove CRT bezel.

d. Loosen clamp at socket of CRT.

e. Remove socket of CRT by carefully prying loose.

f. Slide CRT forward out of instrument, keeping one hand on front face of CRT.

5-36. To install CRT, reverse the above procedure. Correct connection of leads at neck of CRT is shown on the inside of bottom cover and in Figure 5-1.

Note

If a different CRT is installed, it will be necessary to: 1) Check trace alignment with procedure given in Paragraph 3-7; 2) Reset Geometry adjustment as described in Paragraph 5-16; 3) Check plug-in calibration.

5-37. FAN MOTOR REMOVAL.

a. Disconnect the white-gray and white-green-gray wires from fan terminals at bottom of instrument.

b. Remove all four transistor heat sinks from the fan assembly, and push out of the way.

c. Remove the four nuts on rear panel which secure the fan assembly to instrument frame.

d. Lift out fan assembly.

e. Remove fan motor brackets.

5-38. To install fan, reverse the above procedure. When tightening the mounting nuts on the rear panel, use long-nose pliers or similar tool to prevent rubber shock mounts from twisting.

Table 5-5. Troubleshooting High Voltage Supply, No Voltage

1. Check Q302, L301, and the associated transformer primary for open circuits or shorts. Replace any bad components.

Procedure

Indication

Conclusion

2. Remove the edge-on connector which goes to the emitter of Q301 (yellow wire). Connect this lead through a 2K resistor to -12.6 volts (any white-violet wire).

Rectifier (V302-V305) filaments light.

Filaments don't light.

Proceed to step 3. Proceed to step 4.

3. Replace edge-on connector, and change V301.

Filaments light. Filaments don't light.

Q301 was bad.

Check biasing circuitry of V301. Then check Q301 and associated circuitry.

4. Check T301 and rectifier load circuit for opens or shorts. Then lift one lead of C313, C314, C315, C316, C317, C321, and turn instrument on again.

Filaments light. Filaments don't light.

Put capacitors back one at a time until the bad one causes filaments to go out.

Trouble probably with transformer T301.

Table 5-6. Troubleshooting High-Voltage Supply, Incorrect Voltage

Procedure

Effect

Conclusion

1. Remove Nuvistor V301 from its socket.

Output drops to zero.

Output remains at an incorrect value.

Proceed to step 2. Q301 shorted

2. Replace V301 in its socket, and lift one end of R301.

Output drops.

Output remains at an incorrect value.

Trouble probably in the resistor divider network R311, R325, R326, R327, R328, R329, R318, and R319

V301 bad.

5-39. REMOVAL OF HIGH-VOLTAGE ASSEMBLY.

a. Disconnect the six leads identified in Figure 5-3.

b. Disconnect post-accelerator lead as described in Paragraph 5-35a.

c. Remove the four screws identified in Figure 5-3.

d. Tip assembly away from left side of instrument and lift out from top.

5-40. To install high-voltage assembly, reverse the above procedure.

5-41. SERVICING ETCHED CIRCUIT BOARDS.

5-42. Etched circuit boards used in the Model 140A have components on one side of the board with a plated conductive layer of metal through component holes. ($) Service Note M-20D also contains useful information on etched circuit repair. The important steps and considerations are:

a. Use a low heat (37 to 47.5 watts, less than 800°F idling temperature), slightly bent chisel tip (1/16 to 1/8 inch diameter) soldering iron, and a small diameter, high tin content solder. If a rosin solder is used, clean the area thoroughly after soldering.

b. Components may be removed by placing the soldering iron on the component lead on either side of the board, and pulling up on the lead. If heat is applied to the component side of the board, greater care is required to avoid damage to the component (especially true for diodes). If heat damage may occur, grip the lead with a pair of pliers to provide a heat sink between the soldering iron and component.

c. If a component is obviously damaged or faulty, clip the leads close to the component and then unsolder the leads from the board.

d. Large components such as potentiometers and tube sockets may be removed by rotating the soldering iron from lead to lead and apply steady pressure to lift the part free (the alternative is to clip the leads of a damaged part).

e. Since the conductor part of the etched circuit board is a metal plated surface, covered with solder, use care to avoid overheating and lifting the conductor disconnect post-accelerator lead>

remove four screws disconnect post-accelerator lead>

remove four screws

blk wht-vio

Figure 5-3. Removal of HighDeck Assembly blk wht-vio ri83

yel wht-red-yel

Figure 5-3. Removal of HighDeck Assembly from the board. A conductor may be cemented back in place with a quick-drying acetate base cement (use sparingly) having good insulating properties. Another method for repair is to solder a section of good conducting wire along the damaged area.

f. Clear the solder from the circuit board hole before inserting a new component lead. Heat the solder in the hole, remove the iron, and quickly insert a pointed non-metallic object, such as a toothpick.

g. Shape the new component leads and clip to proper length. Insert the leads in the holes and apply heat and solder, preferably on the conductor side.

Figure 5-4. Component Locations on High Voltage Deck

■ 1 IB I

1 1 1 IB 1

1 1 11^1

IV PJ

QIS' f

-

A «

m

Ü

ß*

L. e — i

m w m= 1

ÜH

I

1

11

CI46

CI46

QI66 K o

cvj u

RI56 R155 RI53 RI77

RI93' RI79

R200A R200B R200C

CRI83 tc tc RI8I RI97 CI83

RI99

CJ O

cvj tc o

R205

Figure 5-5. Component Location on Low-Voltage Board 5-10 01638-1

to c

DSIOI

SIOI, 102

TIOI

V161

UNASSIGNED:

CRI00-I20, 125-140, 147-160,

166-180, 185-199

0100-120, 124-140, 144-160,

167-180, 186-199

NOTES

2. RIPPLE VOLTAGES SHOWN FOR MAXIMUM LOAD CONDITION.

COPYRIGHT 1963 BY HEWLETT-PACKARD CO

DSIOI

RIOI, 121-123, 125-130,136-137, 140-148, 150-156, 160-168, 170-174, 177-179, 181-185, 188 - 190, 192-202 205 - 208

SIOI, 102

TIOI

V161

WIOI

UNASSIGNED:

CIOO -119,123.130-140 142-144, 148-159, 162-164, 169-180, 185-199

CRI00-I20, 125-140, 147-160,

166-180, 185-199

0100-120, 124-140, 144-160,

167-180, 186-199

RIOO, 102-120. 124, 131 -134, 138-139 , 149,157-159, 169, 175, 176, 180, 186, 187, 191, 203,204

tXELtl-EO^

178, 185, 198 CI24, 127 CRI45

NOTES

ALL RESISTOR AND CAPACITOR VALUES IN OHMS AND MICROFARADS UNLESS OTHERWISE INDICATED.

2. RIPPLE VOLTAGES SHOWN FOR MAXIMUM LOAD CONDITION.

COPYRIGHT 1963 BY HEWLETT-PACKARD CO

F

R352 v R35I

CR3C

OJ CJ

Cd ro or

V306 C30I

R328

R3I8

R3I9

_ R329

1

I40A-A—1

Figure 5-7. Component Locations on High-Voltage Board

Figure 5-7. Component Locations on High-Voltage Board

Figure V Figure 5-8

-12.6v t chopped blanking from pin 15, jl wht-red-yel unblanking from pin i, J2

t chopped blanking from pin 15, jl wht-red-yel unblanking from pin i, J2

■ioov i o s3q2 beam finder t to pin 5 jl to pin 5 j2

notes i. all resistors and capacitors in ohms and microfarads unless otherwise indicated.

2. indicates rear panel function.

reference designators a2, 3

c30i-303, 310-318, 321,322 j 301

l301, 302 0301,302

s30i.302 t30i v30i-308, 310

deleted:

v309, r33i.332 cr30i

COPYRIGHT 1963 BY HEWLETT - PACK AHO CO.

I40A-HVPS-3Z6

Figure 5-8. High Voltage Power Supply ji vertical plug-in jack j 2

horizontal plug-in jack l>

wht-red

wht-orn

wht-yel-grn wht-yel-blu

wht-0rn-vi0

wht-vio-gy

red io>

wht-blk-orn

wht-blk-grn

brn i4>

wht-brn

wht-yel

wht-red-orn i8>

wht-blk i9>

WHT-ORN-GRN

wht-orn- gy

wht-vio

wht-blk-yel

wht-blk-blu

unblanking gate to hvps ,«wht'red~yel<|

wht-orn

dual trace sync from sweep plug-in wht- red- blu to pin 16

to i beam finder i s302

wht-grn-blu

from ri68a (-ioov shunt) from ri68b --► —12.6v ground return ■«--

wht-orn-vio

wht-vio-gy

-int trig

-int trig wht-blk-grn

wht-blk-orn d3 (to crt deflection plates) dl -6.3vac from tioi (14) -

wht-brn

•chopped blanking to hvps to j2

from ri42a ( + ioov shunt) from ri42b-* --► SIGNAL GROUND <--

to ji pin 4k wht-yel-grn wht-red-orn

wht-blk

wht-orn-grn

from ri84a (-12.6v shunt) from ri84b wht-orn-gy

WHT- VIO

+ INT TRIG

+ INT TRIG

wht-blk-blu

wht-blk-yel

d4 (to crt deflection plates) d2-* COPYRIGHT 1963 BY HEWLETT-PACKARD CO.

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