A different CDTi fan problem - Page 7

RayH · 26th July 2015, 23:47

Quote:

Originally Posted by Jules

The PWM PCB's are susceptible to damage when removing them from the relays.
No matter how careful and gradually they are removed from the tight fitting relay terminals odd faults can occur after refitting.

My guess is that the delicate surface mount components can get cracked or a solder joint broken.

The other theory is that one of the IC's is actually static sensitive and unless full SSD procedures are carried out, the board will be damaged just by touching it

This is why we don't recommend diesel owners change the relays until a reliable source of spare PCB's is found.

The 100 or so boards I had from Longbridge have all been used up so they are like hens teeth now.

You may well be right although I went over my old board with a jewellers loupe and found nothing obvious.
Also the static damage theory would not explain why the original board failed in the first place.

Perhaps French Mike can throw some light on it when he has examined my old board. It's probably held up in some French port as we speak

Jules · 26th July 2015, 23:54

Apart from wear & tear of course.
Any electronics can fail at anytime with no notice especially in harsh environments such as in automobiles !

RayH · 26th July 2015, 23:58

Quote:

Originally Posted by Jules

Apart from wear & tear of course.
Any electronics can fail at anytime with no notice especially in harsh environments such as in automobiles !

Absolutely and don't we know it!
In fact just replace "electronics" with "thing" in that statement

A bit OT (but it's my thread so I can

) did you sort out that pollution previously discussed?

Jules · 27th July 2015, 00:20

Not yet Ray

Union Wheels · 27th July 2015, 12:17

Very interesting read and well done for seeing the problem solved.

My own experience of the P.C board was after a bird strike which broke the fan blades.

Before I refitted the fan assembly I tested the relays by putting 12 volts across their coils, and then refitted the fan assembly, only to find that the slow speed did not work.

Upon further investigation one of the relay coil switching transistors had failed (surface mount PNP device had gone base/emitter short circuit). I had a quantity of BC327 transistors laying around and mounted one of these in place of the surface mount device. This solved the problem.

I think that testing the relays while still in circuit damaged this transistor due to the back EMF of the coil, and point this out as warning to anybody testing the relays in this way

Cheers, Pete.

Jules · 27th July 2015, 13:42

My sentiments entirely Pete.
Don't test relays in circuit.

BC327's yum used plenty of those back in my TV repair days

FrenchMike · 31st July 2015, 11:40

Hi All,

I have received the PCB that RayH kindly has sent to me and i have learnt
a lot of things i would like to share..

Thread coming soon

Mike

Arctic · 31st July 2015, 11:48

Quote:

Originally Posted by FrenchMike

Hi All,

I have received the PCB that RayH kindly has sent to me and i have learnt
a lot of things i want to share..

Thread coming soon

Mike

Hi Mike.
I /we will look forward to a good read then

Arctic

FrenchMike · 31st July 2015, 14:09

Quote:

Originally Posted by Arctic

Hi Mike.
I /we will look forward to a good read then

Arctic

HERE IT IS:

http://www.the75andztclub.co.uk/foru...d.php?t=222452

All comments are welcome

Mike

26th July 2015, 23:54	#62
Jules This is my second home ZT 260 SE Twilight and 10 other 75 ZT's :O Join Date: Jan 2007 Location: Conwy NORTH WALES Posts: 11,094 Thanks: 512 Thanked 1,116 Times in 763 Posts	Apart from wear & tear of course. Any electronics can fail at anytime with no notice especially in harsh environments such as in automobiles ! __________________ [SIGPIC][/SIGPIC] Newbies do now!! 1. Plenum drains..all 3 or 4 year dependent 2. Cooling fan..All speeds functioning 3. Bonnet cable divider block

27th July 2015, 00:20	#64
Jules This is my second home ZT 260 SE Twilight and 10 other 75 ZT's :O Join Date: Jan 2007 Location: Conwy NORTH WALES Posts: 11,094 Thanks: 512 Thanked 1,116 Times in 763 Posts	Not yet Ray __________________ [SIGPIC][/SIGPIC] Newbies do now!! 1. Plenum drains..all 3 or 4 year dependent 2. Cooling fan..All speeds functioning 3. Bonnet cable divider block

27th July 2015, 12:17	#65
Union Wheels Loves to post Honda Accord Tourer i dtec Join Date: Jul 2011 Location: Wakefield Posts: 331 Thanks: 56 Thanked 90 Times in 75 Posts	Very interesting read and well done for seeing the problem solved. My own experience of the P.C board was after a bird strike which broke the fan blades. Before I refitted the fan assembly I tested the relays by putting 12 volts across their coils, and then refitted the fan assembly, only to find that the slow speed did not work. Upon further investigation one of the relay coil switching transistors had failed (surface mount PNP device had gone base/emitter short circuit). I had a quantity of BC327 transistors laying around and mounted one of these in place of the surface mount device. This solved the problem. I think that testing the relays while still in circuit damaged this transistor due to the back EMF of the coil, and point this out as warning to anybody testing the relays in this way Cheers, Pete. __________________ [SIGPIC][/SIGPIC] How to Retrofit Diesel Cruise Control + Loom http://www.the75andztclub.co.uk/foru...87&postcount=1 How to Modify a 3 Speed Fan for CDT & V6 into a 2 Speed with a Resistor. http://www.the75andztclub.co.uk/foru...d.php?t=209920 CDT now gone to new owner, but still on forum

27th July 2015, 13:42	#66
Jules This is my second home ZT 260 SE Twilight and 10 other 75 ZT's :O Join Date: Jan 2007 Location: Conwy NORTH WALES Posts: 11,094 Thanks: 512 Thanked 1,116 Times in 763 Posts	My sentiments entirely Pete. Don't test relays in circuit. BC327's yum used plenty of those back in my TV repair days __________________ [SIGPIC][/SIGPIC] Newbies do now!! 1. Plenum drains..all 3 or 4 year dependent 2. Cooling fan..All speeds functioning 3. Bonnet cable divider block

31st July 2015, 11:40	#67
FrenchMike This is my second home Rover 75 Saloon Join Date: Aug 2007 Location: Avignon Posts: 4,466 Thanks: 94 Thanked 661 Times in 554 Posts	Hi All, I have received the PCB that RayH kindly has sent to me and i have learnt a lot of things i would like to share.. Thread coming soon Mike Last edited by FrenchMike; 31st July 2015 at 11:48..