Worcester ZWBR 7-30 R 30 HE PLUS COMBI Service Booklet page 20

Rectifying faults
Error A8
A8
flashing.
No correct electrical connection
Check
B Power OFF the appliance.
1.
B Check Wiring between Textdis-
play and TR 2:
– Terminal 3 on Textdisplay con-
nected to Terminal 3 TR 2?
– Terminal 4 ...Terminal 4
– Terminal F ...Terminal F?
B Check continuity on wiring to TR 2.
2.
Is there continuity?
B Check resistance from connections
3.
4 to F and 3 to 4.
Is resistance between XX and XX?
4. The PCB control board is damaged.
20
Supplied By www.heating spares.co Tel. 0161 620 6677
Action
↓2.
yes:
B Rewire correctly as specified in the installation
no:
instructions.
B Turn ON the appliance.
After 90 sec.:
A8?
B Power OFF the appliance.
↓2.
↓3.
yes:
B Replace or repair wiring and/or connections.
no:
B Turn ON the appliance.
After 90 sec.:
A8?
B Power OFF the appliance.
↓3.
B Replace TR 2.
yes:
↓4.
no:
B Make a note of the altered service function set-
tings (see table 1 on page 7) in order to keep
the altered values.
B Power OFF the appliance.
B Disconnect the boiler electrical connection.
B Change PCB control board.
B Reconnect the boiler electrical connection.
B Turn ON the appliance.
B Restore service settings previously noted down.
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