[[email protected]]

Hi

Has any one had a problem with Honeywell programmers for h/w and c/h
where first there was not enough oomph to hold on two relays and now it
does not have the strengths to hold on one.

Symptoms - time comes to turn on and the LED changes colour slightly
(as it receives voltage) but the relay does not click.

As mentioned it started happening just with the heating relay but now
with both - its as though there is not enough oomph to turn on the
relays when required.

I am capable of checking voltages and replacing components - but am
always a bit wary of these types of unit which somehow scales down the
voltage without a transformer.

The model number is ST6400

Francis

[raden]

In message .com,
writes
Hi

Has any one had a problem with Honeywell programmers for h/w and c/h
where first there was not enough oomph to hold on two relays and now it
does not have the strengths to hold on one.

Symptoms - time comes to turn on and the LED changes colour slightly
(as it receives voltage) but the relay does not click.

As mentioned it started happening just with the heating relay but now
with both - its as though there is not enough oomph to turn on the
relays when required.

I am capable of checking voltages and replacing components - but am
always a bit wary of these types of unit which somehow scales down the
voltage without a transformer.

The model number is ST6400

There are a couple of things which could be causing this

an electrolytic having dried out or a zener diode going down

the ST 6400 is mainly surface mount inside

you're probably as well off just replacing it as messing around with it

--
geoff

[[email protected]]

Geoff

thanks - done a bit of messing about - when one relay is asked to close
volatage across coil is 28v approx (and sometimes closes) - when the
two are asked to close - the voltage across the coils drops to 17 and
neither close

but thanks for the advice anyway

Francis

[Clint Sharp]

In message , raden
writes
There are a couple of things which could be causing this

an electrolytic having dried out or a zener diode going down
Electrolytic going down would be my guess as well but high value
resistors have a habit of going higher as well

the ST 6400 is mainly surface mount inside

you're probably as well off just replacing it as messing around with it

My thoughts exactly.
--
Clint Sharp

[Jonathan Schneider]

writes:

Geoff

thanks - done a bit of messing about - when one relay is asked to close
volatage across coil is 28v approx (and sometimes closes) - when the
two are asked to close - the voltage across the coils drops to 17 and
neither close

And the voltage of the electronics power supply ? I agree with the
poster about electrolytics. The components in question cost pence of
course. Where are you Francis ?

Jon

[Jonathan Schneider]

Jonathan Schneider writes:

I should just add that I have had a couple of very cold christmases
thanks to Honeywell gas valves whose solenoids run hot by design to
the extent that I have two failed ones.

Jon

[raden]

In message . com,
writes
Geoff

thanks - done a bit of messing about - when one relay is asked to close
volatage across coil is 28v approx (and sometimes closes) - when the
two are asked to close - the voltage across the coils drops to 17 and
neither close

but thanks for the advice anyway

If you're anywhere near Watford, I prolly have a few 6400s lying around
or bits thereof


--
geoff

[raden]

In message , Clint Sharp
writes
In message , raden
writes
There are a couple of things which could be causing this

an electrolytic having dried out or a zener diode going down
Electrolytic going down would be my guess as well but high value
resistors have a habit of going higher as well

Nope, never come across it in this case


the ST 6400 is mainly surface mount inside

you're probably as well off just replacing it as messing around with it

My thoughts exactly.

--
geoff