horstmann electronic 7 power/display issue

[hodge228]

Hi All, I have been having an odd issue with My Horstmann Electronic 7. It had been working normally and then I found that the display had turned off (seemed like no power). This is despite the mains being on. When switching the main switch off, the display then comes back, albeit with no power to the immersion boiler. If I wait a bit and then turn the mains back on, the display will still be there and it will function as normal for a while before turning back off again (say 12 hours). I can't work out why this is happening - I have tried to reset etc. It feels like when the mains are off it is almost charging the unit as it works for a while and then not again, but this doesn't really make much sense. Any help/ideas would be greatly appreciated.

Thanks

 

[nicebutdim]

I take it by 'reset', you mean factory reset as described in user manual?

User manual does highlight one potential remedy for a blankscreen, but it may be that the timer has reached the end of its serviceable life.

Service And Repair - Horstmann Electronic 7 User Operating Instructions Manual [Page 7]

Horstmann Electronic 7 Manual Online: Service And Repair. The Horstmann Electronic 7 is not user serviceable, so please do not try to dismantle the unit. In the unlikely event of a fault developing try resetting the unit, which is in this manual under ''RESETTING THE UNIT''. If this...

www.manualslib.com

 

[i=p/u]

Had this before and reset it with a pin at back was soloution. they are pretty old them units, so could need replaced

 

[Avo Mk8]

Edit now lots of responses!! !Since no other responses, here's some thoughts.
There's one thing that isn't clear to me from your post - is it just a lack of display, but the immersion(s) still come on at their allotted times, or do the immersions not come on once the display is blank?

Apparently the programmer has a battery backup for the clock, that will keep it going in the absence of power, allegedly for up to two years. It sounds to me that there might be a fault on the circuit board, maybe to do with managing the backup battery, causing the symptoms you describe. Sounds like you had a similar idea.

The instruction booklet Q&A includes the following gem:
(Q) There is no display on the screen?
(A) Ensure there is mains supply getting to the unit and that the battery switch on the rear of the unit is in either the GMT/BST or GMT ONLY position.
I think the idea of the answer is to make sure the switch is firmly over one side or the other, making contact properly.

I wasn't aware there was such a switch, despite installing and using one of these a few years ago!

Might be worth investigating this switch if you haven't already.

Otherwise I don't think there is much you can do, so it will probably mean replacing the unit, which is straightforward for a like for like swap.

 

[brianmoooore]

. they are pretty old them units, so could need replaced

Not necessarily, since they're still available new.
Had the battery fail in the mechanical version of these once, and that was fairly easy to replace, so, before binning it, I'd check the condition of the battery and how easy it is to replace.

 

[nicebutdim]

Not necessarily, since they're still available new.
Had the battery fail in the mechanical version of these once, and that was fairly easy to replace, so, before binning it, I'd check the condition of the battery and how easy it is to replace.

User manual indicates that battery is integrated in this particular unit. It may be easy enough to replace, but doesn't seem to be a model which has a button cell sticking out of its rear.

 

[brianmoooore]

Battery is 'integrated' in the mechanical version, but simple to change for anyone with a soldering iron.
Never had to try with the electronic version, so I don't know how much is involved.

 

[i=p/u]

these units are not meant to be repaired.. replace replace replace.

 

[brianmoooore]

these units are not meant to be repaired.. replace replace replace.

That's not a very 'green' attitude!

 

[bobmeades]

That's not a very 'green' attitude!

No, not very green at all ! These nearly all suffer from the same problem, the original Ni-cads, either short out & stop the clock - or go open circuit & the clock works erratically. I've replaced these poor batteries, with Button Ni-mh 1.2v 80mah, with complete success.
2 for £5 on Ebay - but of course, they would rather people paid £100 or so, for a new time switch !

 

[bobmeades]

No, not very green at all ! These nearly all suffer from the same problem, the original Ni-cads, either short out & stop the clock - or go open circuit & the clock works erratically. I've replaced these poor batteries, with Button Ni-mh 1.2v 80mah, with complete success.
2 for £5 on Ebay - but of course, they would rather people paid £100 or so, for a new time switch !

Further - later models were fitted with a 320mah ni-mh - which can also fail - difficult to find an exact replacement which does give a very long backup time.