Is this a Potterton EP2002 Lockout symptom?

[rav...@googlemail.com]

The Potternton EP2002 is a timer control unit for a boiler, mine being
a Prima F.
I came home to discover I could not manually press ADV, which would
normally activate the HW or CH, this is confirmed by the red colout LED
on the right hand side illuminating.

Nothing illuminates at all, but the the time is displayed and is
correct.

I also discovered that I could not set the time, or modify any other
settings on the timer unit.

I removed power to the unit, (fuse isolation) and waited until the LED
displaying the time faded. But when I turned it back on - SAME
symptoms, I also noticed the time was exactly the same. So either this
unit has a large capactitor in there, or a back up battery keeping the
time backed up... I don't know.

I do know that I cannot control my heating.

Should I simply change the unit?

Regards
Ravi Tek :(

[rav...@googlemail.com]

I have fixed this problem myself.

Being an engineer I know that some logic circuits with IC can get into
a lockout, and occasionally need a reset, this circuit in the EP2002
has a battery back inside, Green coloured thing like 2 watch batteries
back to back.

To enable a power outage on this, like you would need to reset the CMOS
on a PC motherboard.

I had to take the unit off, disassemble, but not only to view the top
(component side) but also the underside and short the positive and
negative terminals on the battery (I used a screwdriver and simply
touched the solder side terminals for 1 second), this kills the clock
and brings it back to factory default settings.

When I finally put it all back together, my mini Christmans tree of a
timer came back to life.

Actually thinking about it again, you would only need to take the top
cover of, and you could bend a paper clip into a "U" shape to shorts
the terminals.

This worked for me, and has saved my £50 in a replacement (probably
more with the labour etc.)

I answered my own question here in case it helps others. Please do the
same if you have found a solution to your own.

Ravi Tekchandani
Stevenage
Herts

[raden]

In message <1137180095.4...@o13g2000cwo.googlegroups.com>,
"rav...@googlemail.com" <rav...@googlemail.com> writes

Yes, it has a battery for back up

It's so long since I repaired one I can't remember, but IIRC there's a
battery in the back

unscrew it (2 screws on the bottom face and rotate it upwards to remove
it from the backplate

--
geoff

[raden]

In message <1137185340....@g14g2000cwa.googlegroups.com>,
"rav...@googlemail.com" <rav...@googlemail.com> writes

>I have fixed this problem myself.
>

Easy if you engage brain isn't it

--
geoff