Usual Webasto stuff!

[storminmike]

[quote="Stevejspm"]
I'm throwing this info in on every Webo post on here!....

http://www.the75andztclub.co.uk/forum/s ... Frenchmike

Followed his guide & replaced 1 capacitor & 1 resistor on the PCB, fitted to the car & it fired up! I'm chuffed to bits. 80pence in components & it's running. Mine had the symptoms of every time a door was opened etc the air fan would fire up but nothing else.
Fortunately I completed an apprenticeship in electronic engineering so can follow my way round a PCB quite well.
I'm happy to help anyone down to component level if anyone wishes
[/quote]

I've got the circuit board out of mine here....same thing. I found French Mike 2 weeks ago via that board but have yet to send him it. He sent me a couple of emails with his address....in France )

I'd have a go but my eyesight is bobbins at circuit level. My circuit tester is cheap too so finding the duff one if that's what it is might prove tricky

I saw the 3 resistors in that pic but don't recall anything about a duff capacitor?

[Stevejspm]

I think there is only 1 mention of the capacitor where another chap mentions it's value at 100pf, he had also put a link to the 'K Bus' chip (which is near said dodgy components) data sheet, the data sheet also mentions this 100pf capacitor being connected to one of the chips terminations. This 100pf capacitor is very close to the right hand (big blue) capacitor & has no markings, looks like one of the resistors,  so to identify it you have to look very carefully at 'FRENCHMIKES' photos.
I only had to replace one other component being the 4.7k resistor near the left hand (big blue) capacitor, all other mentioned resistors tested fine.

I fitted the Maplin RF remote today with timer function & can confirm the Webasto behaves exactly as it should, happy days!

[Stevejspm]

One other thing........would you like me to take a look at your PCB? I couldn't be held responsible for any damage in transit or otherwise though. I could probably repair it if it involves the components mentioned in FRENCHMIKES post though but any other components I'd struggle due to not having a circuit diagram for the PCB & therefore no actual component values.

[smg916]

Stevejspm - I know that wasn't aimed at me, but I'd take up your offer if you were willing to help; and would happily supply you with the necessary beer tokens for your time. I also accept the risks that go with this – it’s scrap already so far as I’m concerned. Is it OK to drop you a PM?

[Stevejspm]

Hi smg916, yes drop me a PM, no problem

[storminmike]

[quote="Stevejspm"]
One other thing........would you like me to take a look at your PCB? I couldn't be held responsible for any damage in transit or otherwise though. I could probably repair it if it involves the components mentioned in FRENCHMIKES post though but any other components I'd struggle due to not having a circuit diagram for the PCB & therefore no actual component values.
[/quote]

Hi Stevejspm

I can wrap it well but that's my look out. I'll PM you if you don't mind?

[nujon]

[quote="Stevejspm"]
I'm throwing this info in on every Webo post on here!....

http://www.the75andztclub.co.uk/forum/s ... Frenchmike

Followed his guide & replaced 1 capacitor & 1 resistor on the PCB, fitted to the car & it fired up! I'm chuffed to bits. 80pence in components & it's running. Mine had the symptoms of every time a door was opened etc the air fan would fire up but nothing else.
Fortunately I completed an apprenticeship in electronic engineering so can follow my way round a PCB quite well.
I'm happy to help anyone down to component level if anyone wishes
[/quote]

Fascinating stuff - inspired me to look at the PCB on my Webasto (which has never worked!) Removed the gunge from the PCB and found the following:-

- adjacent to central electrolytic capacitor - both 10k and 4.75k resistors (formally under the gunge ) showing infinite resistance/open circuit - goosed!

- around the RHS electrolytic capacitor and formally under the gunge  - nominal 1 Ohm resistor reading 1.1 Ohm - presume OK, 49.9 K Ohm resistor reading 50.1 K Ohm - presume OK. Capacitor connecting to Kbus chip dead (not charging/discharging) - lower capacitor charging/discharging so maybe OK

Anyone know where I can get replacement components from - and find which way (polarity) a replacement for my failed capacitor should be installed (e.g. is the broad PCB track -ve ? )   

[Stevejspm]

Go to Maplins & ask for the lowest wattage resistors they do. Their still too wide across the body so you'd have to stand them on end (with one leg bent downwards to run parallel with the up stood body). The capacitor is not polarity sensitive & is a ceramic disc 100pf value (marked 101 on its body).

[X5Sport]

RS Components ( uk.rs-online.com ) may offer a better range in terms of parts.  Your resistor figures look to  within meter tolerance so they are OK.

Can you read the resistor colour codes to get the wattage? 

As above, usually only electrolytics need to be correctly polarised.  They tend to fizz and smoke if connected backwards.....

Richard

[nujon]

[quote="Stevejspm"]
Go to Maplins & ask for the lowest wattage resistors they do. Their still too wide across the body so you'd have to stand them on end (with one leg bent downwards to run parallel with the up stood body). The capacitor is not polarity sensitive & is a ceramic disc 100pf value (marked 101 on its body).
[/quote]

Thanks very much for that - thought the SMRs had no legs? - have you used ordinary wire-tailed resistors?

The capacitor has no marking, - just a mid-brown colour

Have still to work out a technique for unsoldering / re-soldering - I have done PCB repairs on high-end quartz watches before - using slivers of masking tape to cover contacts you don't want to solder, 0.25mm flux-cored solder wire - and a cone-pointed gas-heated micro iron

[nujon]

[quote="X5Sport"]
RS Components ( uk.rs-online.com ) may offer a better range in terms of parts.  Your resistor figures look to  within meter tolerance so they are OK.

Can you read the resistor colour codes to get the wattage? 

As above, usually only electrolytics need to be correctly polarised.  They tend to fizz and smoke if connected backwards.....

Richard
[/quote]

Thanks Richard - the resistors are not band-coded but numerical (value, value, value + power of 10) - the numbers can be clearly read so no probs re. R value - don't know the wattage to go for though! (Guess the physical size of the resistor (L x W) may be a clue ? - the body colour is black in all cases so no help there!)

[X5Sport]

Probably +/- 10% then.  Can't imagine them needing to be more accurate than that.

Is this of any use?  There's a section towards the bottom on SMD types and how to read them too.....

[nujon]

[quote="X5Sport"]
Probably +/- 10% then.  Can't imagine them needing to be more accurate than that.

Is this of any use?  There's a section towards the bottom on SMD types and how to read them too.....
[/quote]

Thanks Richard - that's useful. On RS, I can find SMRs of the required Ohms - and of the same appearance and size; they are described as 'chip' resistors and are rated between 0.1 - 0.125 Watts - think they will do?

RS also list 100pF ceramic capacitors of same appearance and size - noting the voltage limits on the BUS input to the ELMOS chip (+25 / -25) I am thinking of going for a 50v capacitor rating

[X5Sport]

Most likely be fine.  SMR components are not designed to have lots of current as they tend to turn black and smoke otherwise!  I came out of third line maint just as SM Tech was going mainstream.

Shame the cap is naked as 50V is probably just fine given the +/- 25V showing.  It allows for enough of a surge.

I wish we could get hold of circuit diagrams!!

R

[nujon]

[quote="X5Sport"]
Most likely be fine.  SMR components are not designed to have lots of current as they tend to turn black and smoke otherwise!  I came out of third line maint just as SM Tech was going mainstream.

Shame the cap is naked as 50V is probably just fine given the +/- 25V showing.  It allows for enough of a surge.

I wish we could get hold of circuit diagrams!!

R
[/quote]

Thanks - appreciated your views