Eberspacher Control unit and cooked Diode.

L

Lee_D

Guest

• Feb 27, 2006

• #1

Right the exorcisiom of the Eber seemed to reveal a cooked diode in the
control unit so,

1. Any one got one off a scrapped just in case?
2. If I can replace the diode should I be concerned? As in is this a case of
"They all do that" or is the Diode being interfered with by strange radio
waves or creatures from another dimension. I've mastered basic electronics
several years ago so there are a few cobwebs on the old grey matter... is it
fair to have a diode just give up after 30 years of just hanging around?

Lee D

--
www.lrproject.com

 

P

puffernutter

Guest

• Feb 27, 2006

• #2

Lee_D wrote:
> Right the exorcisiom of the Eber seemed to reveal a cooked diode in the
> control unit so,
>
> 1. Any one got one off a scrapped just in case?
> 2. If I can replace the diode should I be concerned? As in is this a case of
>
<snip>>
>
Lee D
>
> --
> www.lrproject.com#

In the best of engineering traditions, replace it and see what else
blows up!
(and yes, diodes do have a finite life)

Cheers

Peter

 

S

Steve Taylor

Guest

• Feb 27, 2006

• #3

puffernutter wrote:

> (and yes, diodes do have a finite life)
bollocks.
;-)
Only a VERY VERY poorly specced diode has a finite life.
Steve

 

B

beamendsltd

Guest

• Feb 27, 2006

• #4

In message <[email protected]>
Steve Taylor <[email protected]> wrote:

> puffernutter wrote:
>
> > (and yes, diodes do have a finite life)
> bollocks.
> ;-)
> Only a VERY VERY poorly specced diode has a finite life.
> Steve

Or, more accurately, they are specced *to* have a optimal lifetime
aginst cost, the good old "bathtub" curve for component reliability.

Richard
--
www.beamends-lrspares.co.uk [email protected]
Running a business in a Microsoft free environment - it can be done
Powered by Risc-OS - you won't get a virus from us!!
Boycott the Yorkshire Dales - No Play, No Pay

 

P

puffernutter

Guest

• Feb 27, 2006

• #5

Steve Taylor wrote:
> puffernutter wrote:
>
> > (and yes, diodes do have a finite life)
> bollocks.
> ;-)
> Only a VERY VERY poorly specced diode has a finite life.
> Steve

Whilst they have no moving parts, they are still subject to wear and
tear from a variety of sources.

They can fail due any number of reasons and it's not just a poor
specification. It could be a manufacturing defect, spikes (EMI),
reverse voltages, temperature (heating cooling etc.), humidity,
vibration (especially in a LR!)

If you look at Mil HDBK 217F you will find a mean time between failures
for diodes. It may be high, but it is finite!

Cheers

Peter

 

L

Lee_D

Guest

• Feb 27, 2006

• #6

Steve Taylor <[email protected]> uttered summat worrerz
funny about:
> puffernutter wrote:
>
>> (and yes, diodes do have a finite life)
> bollocks.
> ;-)
> Only a VERY VERY poorly specced diode has a finite life.
> Steve

Lucky me! looks like I got several poorly speced items and now looking out
for a control unit.

When plugged back in the fuel pump kicked in straight away, then I thought
what the hell and switched it all on.. Fired up a treat and got nice and
toasty. The themo stat worked I could see the relay operating to shut the
cuircut down or at least the petrol side.. the heater carried on heating
regardless. I switched it all off and if still carried on regardless. I
disconnected it (last resort!) and it stopped.. now ideal as they should run
to burn off any fuel

So renewed appeal to liberate any old B4L controllers sat on a shelf
anywhere.

:-(

Lee D

 

P

puffernutter

Guest

• Feb 27, 2006

• #7

Steve Taylor wrote:
> puffernutter wrote:
>
> > (and yes, diodes do have a finite life)
> bollocks.
> ;-)
> Only a VERY VERY poorly specced diode has a finite life.
> Steve

Whilst they have no moving parts, they are still subject to wear and
tear from a variety of sources.

They can fail due any number of reasons and it's not just a poor
specification. It could be a manufacturing defect, spikes (EMI),
reverse voltages, temperature (heating cooling etc.), humidity,
vibration (especially in a LR!)

If you look at Mil HDBK 217F you will find a mean time between failures
for diodes. It may be high, but it is finite!

Cheers

Peter

 

S

Steve Taylor

Guest

• Feb 27, 2006

• #8

puffernutter wrote:

> They can fail due any number of reasons and it's not just a poor
> specification. It could be a manufacturing defect, spikes (EMI),
> reverse voltages, temperature (heating cooling etc.), humidity,
> vibration (especially in a LR!)
>

Oh sure, if you abuse them they fail, which gives anything a finite
life. You imply that they fail by some internal mechanism, like a lead
acid battery HAS a finite life, however you treat it. Kept within specs,
diodes won't fail.

Steve

 

S

Steve Taylor

Guest

• Feb 27, 2006

• #9

Lee_D wrote:
The themo stat worked I could see the relay operating to shut the
> cuircut down or at least the petrol side.. the heater carried on heating
> regardless. I switched it all off and if still carried on regardless. I
> disconnected it (last resort!) and it stopped.. now ideal as they should run
> to burn off any fuel
>

So, did the fuel pump cut out or not ! It sounds like the relay contacts
have welded - I have seen cases where the armatures move, fooling you
into thinking the contacts are following it.

Bung it up here and I'll take a look at it for you, unless some kind
soul has spares.

Steve

 

L

Lee_D

Guest

• Feb 27, 2006

• #10

Steve Taylor <[email protected]> uttered summat worrerz
funny about:
> Lee_D wrote:
> The themo stat worked I could see the relay operating to shut the
>> cuircut down or at least the petrol side.. the heater carried on
>> heating regardless. I switched it all off and if still carried on
>> regardless. I disconnected it (last resort!) and it stopped.. now
>> ideal as they should run to burn off any fuel
>>
>
> So, did the fuel pump cut out or not ! It sounds like the relay
> contacts have welded - I have seen cases where the armatures move,
> fooling you into thinking the contacts are following it.
>
> Bung it up here and I'll take a look at it for you, unless some kind
> soul has spares.
>
> Steve

Fuel pump wasn't having issues before the Diode replacement, the issue was
no hot air at all and the cool fan coming on when it liked... even when away
from the truck.

I replaced the diode with what the local chap sold me, same part number etc
and inserted the right way.

Now as soon as it's plugged in the fuel pump kicked in. The metering pump
fired up as it is supposed to when the switch was pulled to position II.
When the switch is pushed back in both the fuel and metering pumps carry on
until the leads are pulled from the unit.

I suspect theres more to it than just the diode, the new one is getting hot
too so no doubt summat else is duff but it's all a bit over my current level
of understanding.

The heater worked fine until recently. I suspect the moisture in the cabin
from the leaking roof has reaked havoc with the circuit. Leak is now fixed,
thats about as positive as it gets. I'll explore some more options but may
yet drop it off for you to prod. Does your heater work? Just wondering how
you would bench test it.

Lee

 

L

Lee_D

Guest

• Feb 27, 2006

• #11

Lee_D <[email protected]> uttered summat worrerz
funny about:
> Lee

oh yep knew there was summat else, the relays seem to be moving ok and not
welded.

dammed frustrating.

Lee

 

S

Steve Taylor

Guest

• Feb 27, 2006

• #12

Lee_D wrote:

>
> The heater worked fine until recently. I suspect the moisture in the cabin
> from the leaking roof has reaked havoc with the circuit. Leak is now fixed,
> thats about as positive as it gets. I'll explore some more options but may
> yet drop it off for you to prod. Does your heater work? Just wondering how
> you would bench test it.

Simulate all the pumps and sensors on the bench. Don't know if my
hairyscratcher works or not.

Steve