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Useful info
1. A production change:
A production change has been introduced adding a shield to the main control micro processor to prevent the processor being influenced
by external fields In future, replacements will be supplied as a kit comprising the processor shield and fitting instruction. The shield will
also be available separately.
:Old mask No. Code No. ``````````` ```````
:CP90/110 TMP47C432P :8188 209 72038 :8189 209 73665
:New mask No. Kit code No. `````````` ```````````
:8188 310 31849 :8188 310 31849 :8189 310 31851
:Shield only. ``````````
:Chassis Processor
:CP90 TMP47C432P
2. There are two types of micro used on this chassis.
Fault 1 Fast text use part number 20987305, non fast text use part number 20911391.
3. U743 tuner replacement.
The U743 UHF tuner has been replaced by the U943. In all applications it is a direct replacement. Where the substitution was made
during production some components, being no longer required, were deleted at the same time. This means that in some chassis the
tuners are not reverse compatible ie. a U743 cannot be fitted in place of a U943 without first refitting components concerned with the
+12V supply to pin 10 of the U743 tuner. The list of changes are as follows:
:Old Tuner New Tuner Deleted
:U743-600 U943-600 None
:4822 210 50118 4822 210 10394.
5. Euroconnector code number.
Note: The code number for the euroconnector mentioned in the documentation is incorrect. The correct code number is: 4822 267
60243. Please change this in your documentation.
6. Picture tube panel adjustments.
Note: In the chassis documentation, chapter B; electrical instructions, picture tube adjustments, appears in line 6: "black level on the
picture tube base on 1304". 1304 should be 130V. Add connection 7-IC7260 and remove earth.
7. Connection of a loop system to the TV.
Note: A problem usually occurs when connecting a loop system to a modern TV. A solution is available from the hearing aid suppliers
in the form of a specific loop system amplifier which is supplied from the mains and which functions with a scart or phono plug signal.
On the advice of a specialist a large part of the cost is usually covered by insurance.
8. Microprocessor screening plate.
Note: Connect the screening plate with the side of R3726 which is pointing towards the front of the chassis.
9. Replacing control IC7840.
Fault 1: When replacing the control IC (IC7840) it is essential to ensure
that the correct type is fitted. Type: TMP47C432AP-8187, TMP47C432AP-8188, standard teletext 4822 209 72038 or remote control
only. TMP47C432AP-8189, FLOF (Fastext) or remote control only, 4822 209 87305
HA11484, CP90 Non remote 4822 209 83199. Note: FLOF (Full Level One Features) is a term frequently used in the service manual
to describe a decoder equipped to handle Fastext commands.
A supplement CT88-11 giving information on the FLOF decoder, is available under service code no. 4822 727 16185.
10. New type stands.During production of CP90 and CP110 receivers the type of stand supplied was changed. In some cases this
involved a new housing due to the need for different stand fixing centres. The models are listed and individual sets affected can be
identified by the factory code on the type no. label.
21CE1250/05B, 21CE1558/05B, 21CE1251/05B, 21CE1557/05B, 21CE1557/05Z,
52KE1510/05M, 52KE1512/05M, 52KE1585/05M, 24CE3271/05B, 24CE3588/05B
59KE3785/05M, 59KE3702/05M, 59KE3775/05M, 68KE3985/05M, 27CE3598/05B
Note: These stands are supplied as a complete kit only. Individual parts will not be available.
11. Alternative 21" picture tubes. During production of 21" CP90 receivers, three different types of picture tube were used. In some
cases this involved circuit changes. It is essential therefore that replacements should be of the same type. The various tube types
together with component difference are listed on the following pages. This and other information are also contained in Service
information supplements CT87-38 and CT88-22.
CRT A51EAM32X16 131 27119 or A51JAR30X01M2 131 20225
MAIN PANEL C2504 68nF 121 42688 C2596 82nF 121 41754 C2610 8n2nF 121 42523
C2611 470nF 121 42917 R3496 56K 111 30772 R3594 100K 111 30685
R3595 100K 111 42679
CRT BASE (9 pin CRT SKT) 212 22606 A51EAL30X05 131 27116
Not fitted 47nF 121 41791 11nF 121 43058 560nF 121 43057 200K 116 52255
Link wire 240K 116 52262 BUT12A 130 43919 (12 pin CRT SKT) 212 22812
SERVICE INFORMATION CT87 - 38 727 15953 CT88 - 22 727 16269
12. Page header suppression. Since the BBC changed the CEEFAX format, receivers with fastext will display the page header
continuously when the set is in subtitle mode (page 888). The problem is only observed on BBC recorded programmes with subtitles
(subtitles on live programmes, and on independent television are not affected). The BBC have agreed to suppress the header on future
recorded subtitled programmes. However, many programmes are already "in the can" and could be transmitted at any time with the
page header not suppressed. To accommodate this, the teletext microcomputer MAB8461P/W107 has been reprogrammed to suppress
the page header when subtitles are being received. The new version (MAB8461P/W196) is available from service under code no. 4822
209 62479. In cases of specific complaint the new version may be fitted as a drop-in replacement.
13. Control micro processors. A production change has been introduced adding a shield to the control micro processor to prevent the
processor being influenced by external fields. In future replacements will be supplied as a kit comprising the processor, shield and
fitting instruction. The shield will also be available separately.
Old mask no. Code no. CP90/110 TMP47C432P 8187 -
8188 4822 209 72038 8189 4822 209 73665
New mask no. Kit code no.
8188 4822 310 31849
8189 4822 310 31851
14. Safety test after repair.
Note: Due to defective components in an appliance (capacitors etc.) parts of the appliance can become charged. This cannot be
established when an appliance is tested on an isoformer. For safety reasons the appliance must also be connected to a non separated
socket and then checked that touchable parts (aerial, external connections etc.) are not charged.
15. Multiple defects of the BUT11AF.
Fault 1: To remedy this it is advisable to replace diode 6674 with a BYD33J, code number 4822 130 42606.
16. Picture tube A51EAM32X16
Note: Picture tube A51EAM32X16 (9301 206 10142) is used for 21" appliances from production code PM04 or BA04 onwards. Fixing
bracket for demagnetization coil must be used with this picture tube (4822 404 30945).
Introduction of picture tube brings along changed to tube base PCB. Part no. picture tube base PCB 4822 116 23121. On this tube base
PCB R3409, R3429 and R3449 have changed to 620R (4822 116 52227).
Picture tube A51EAM32X16 : 9301 206 10142
17. Code numbers for locking HT- and focus cable. Note: :Locking for HT-cable (red) 4822 417 50225
:Locking for focus cabel (blue) 4822 417 50226
18. Service note. It is worthwhile replacing the flyback tuning capacitor C2619 (1kV/1.5nF) with the 2kV type whenever one of these
sets is serviced. Part no.: 4822 122 32501.
19. uP + screening. Note: TMP47C432AP with screening:
-8188: 4822 310 31849 replaces 8187, standard TXT (provided decoder is present).
-8189: 4822 310 31851, TOP/FLOF TXT (Fastext) (provided decoder is present).
Connect screen to bridging wire 9732.
20. Testing the power supply.
Note 1: Remove connector M6 and connect a 60W light bulb across C2696 and monitor the DC voltage. Apply Mains via a variac, the
bulb should light when the DC voltage is about 70V and it should stabilise at 95V. If the voltage does not stabilise then check the
components around the optocoupler CNX62 and set the HT control to 95V.
21. When checking for dry joints. Look in the IF/sync can, especially around the TDA2579 chip.

1. The line transistor BU11AF always breaks down after a few seconds. Fault 1: C2610 has leaked (8.2nF/2KV).
2. Top of raster folds together. Fault 1: Replace C2572 (1.5