John, Jaycar in Newcastle Street have a good range of transistors.
BX dash ventilation fans stopped dead!
- Thread starter JohnW
- Start date
JohnW said:
This is a 1905cc petrol right? The oil pressure sender is on the front of the block, centre left. If you look behind, and under the intake manifold, you will find it. It's a bugger to get at!!! john s
tomsheppard said:
Thanks Tom,
I went to my local electronics shop today - they only have an NPN3055 which poses the obvious question!! Are you sure it is PNP not NPN.
Don't you love it!!
Ta
JohnW
Stuey said:
I wish I'd discovered them years ago. Very dangerous shop!!!! They can't help me however, as they haven't the BX one listed in anything. "Have you googled?" was their response.
So I'm googling. It does exist and has been replaced I think - but there is one digit missing at the end of the Puegeot one compared with the BX one.
Sigh. I'll persist now that the car is dismantled..... It's easier than I expected - have to get over this "Citroen intimidation" factor!
Cheers
JohnW
smiffy1071 said:
Thanks John!!! I've two gauges not working and am steadily sorting out a few other things - pulled off the central locking control unit and refitted it and some (not all!) of the door open warning lights now work. But not all..... Still it's an improvement.
Cheers
JohnW
Sorry I can't remember where the oil level sender is, if you need any other info, let me know, as I have a 1905 XU engine sat in the shed at work, and my mate can answer virtually any BX question, as he's had 35 of the bloody things! (mostly to scrap, so he knows where everything is!) john sJohnW said:
tomsheppard said:
Tom,
All fascinating stuff! My advice seem to be that the direct replacement for the FW26025A1 is an MJ2955 (both labelled "Malaysia") and available here for A$2.50.
I've had the "offending" device checked and it is fine!!!! However, the earth return through to the circuit board via the brass rivets is very burned and may have lost high current capacity through the insulating properties of oxide. So I'm about to solder up a proper connection and test the fans. Then if they don't work, I'll go to the dashboard and check out the board and wiper resistor, having found your old Andyspares posting on that subject. Not that I had anything else to do..............
More will undoubtedly follow. A friend did some research and found the following "I've done a bit of research. The 2N3055 is an NPN device. Its PNP complement is a 2N2955 (or MJE2955)". So you may have been mistaken with that PNP3055 as the 2955 is independently identified as the successor to the 26025. I'm suitably confused, personally.
Thanks again to all for the wonderful input.
Cheers
JohnW
Well it's fixed. Total cost: two small brass nuts and bolts and 5 minutes with a soldering iron. Oh, and 6 hours' research, many bits of welcome advice, two hours scouring electronic shops, two unnecessary $2.50 transistors to avoid the hassle of an unparkable shop in North Perth, 3 hours' dismantling and re-assembly!!
The total problem was loose and old rivets holding the power transistor to its circuit board inside the left hand fan duct. Overheating increased the resistance and the metal film on the circuit board burned somewhat - 8-10 ohms' resistance between case and circuit board. Drilled out rivets, replaced with clean brass nuts and bolts and washers, soldered across everything on the circuit board side and voila!!!!
Very instructive and I sincerely thank all who helped!
Now the best shop by miles in Perth of those that I found was
RS Components at 26 Walters Drive, Herdsman (5 minutes from home but the last visited of course!!). They tested the transistor (90 seconds), said "it's all right mate" and then observed that the replacement transistor would be a something or other (no-one else could even find an equivalent and these guys knew immediately, recognising its functionality). They agreed I should replace the rivets holding it in (which I'd concluded already but at that time I didn't know the transistor was working OK). So there we are.
Now we have air in large lumps. For how long? A long time I suspect, now that the circuit is robust.
Now for the CX starter.....
Cheers
JohnW
The total problem was loose and old rivets holding the power transistor to its circuit board inside the left hand fan duct. Overheating increased the resistance and the metal film on the circuit board burned somewhat - 8-10 ohms' resistance between case and circuit board. Drilled out rivets, replaced with clean brass nuts and bolts and washers, soldered across everything on the circuit board side and voila!!!!
Very instructive and I sincerely thank all who helped!
Now the best shop by miles in Perth of those that I found was
RS Components at 26 Walters Drive, Herdsman (5 minutes from home but the last visited of course!!). They tested the transistor (90 seconds), said "it's all right mate" and then observed that the replacement transistor would be a something or other (no-one else could even find an equivalent and these guys knew immediately, recognising its functionality). They agreed I should replace the rivets holding it in (which I'd concluded already but at that time I didn't know the transistor was working OK). So there we are.
Now we have air in large lumps. For how long? A long time I suspect, now that the circuit is robust.
Now for the CX starter.....
Cheers
JohnW
Glad to hear it! wish that CXs were so easy to flow air in! The rear washer switch is unlikely to be your problem. Do not attempt to dismantle it. YOU WILL NOT GET CLEAR IN TIME! The operation of the switch is one of those silly half press functions that mean that you never know for sure if it is working or not but the motor wiring gets shabby and could usually do with a clean (High resistances - you may have come across 'em before 
) I would take a good look at the map and put in a push button across the existing contacts if it really is a switch fault. THey really do seldom fail, even in this land of rain. . If you get stuck, there's always a spare over here and it won't cost a bomb to send.
) I would take a good look at the map and put in a push button across the existing contacts if it really is a switch fault. THey really do seldom fail, even in this land of rain. . If you get stuck, there's always a spare over here and it won't cost a bomb to send.Thanks for that address, John. Are they general electronics component suppliers? (I'm installing a relay on my Mi starter and want a diode that can handle more than 6 amps - the maximum that Jaycar can supply - to protect the contacts in the relay. Otherwise it'll be three in parallel.)JohnW said:
Oh, and don't you get satisfaction out of that result? I would!
Cheers
Stuey
Stuey said:
Hi Stuey,
3 diodes in parallel isn't really a good answer. You may find due to manufacturing differences one diode can carry signifigantly more power than the other two. If it burns out, you then have two diodes carrying the power so they will also rapidly burn out.
1 big diode sounds like the best option.
seeya,
Shane L.
Stuey said:
They're pretty good Stuey, and very helpful. The power transistors I bought in anticipation will handle much more than 6 amps.
If you go there, we are 5 minutes to the west!! Come and have a cuppa or a Coopers.
Cheers
John
I have joined this discussion very late but I just tried out the modification to engage the max speed relay.
The bad news for me is that it has not worked and I know that max speed works as I have tested it with relay without a cover that I manipulate manualy. The opperation of the rest of the circuit board appears fine.
I only tried it becasue I appear to only have two fan speeds. two questions does the max speed relay go through the speed control transistor? or could my problem be somewhere else?
Bill
The bad news for me is that it has not worked and I know that max speed works as I have tested it with relay without a cover that I manipulate manualy. The opperation of the rest of the circuit board appears fine.
I only tried it becasue I appear to only have two fan speeds. two questions does the max speed relay go through the speed control transistor? or could my problem be somewhere else?
Bill
Our lesson this week comes from the book of Haynes#908 P.417
The full speed relay (745)shorts the fan to ground and disconnects the transistor,(658). The pictures you need to verify the correct mod are at tomshepdotcodotuk. There is one link to be cut and a wire to put in. Ensure that you have the same board(278) layout, there are 2 types. My board was marked "Chausson" in the lower right corner.
You have two speeds. The correct operation is to have variable speed all the way up and then click into the full speed setting so, some detective work. If the track was busted, then the fan would only work once you had connected into the unbroken bit so multimeter both ends of the resistive track and ensure that you don't have an open circuit. Using the multimeter again, from earth to the connection on the far left of the board, you should see a falling voltage as you rotate clockwise. That you get some speed with the relay off suggests that the transistor is conducting and this check is verifying the control voltage. When you get to full speed, this falling voltage on the left hand connection rises again and the terminal to its right should go from 12v to 0V as the wiper of the rheostat connects it to earth which is what operates the relay. IF it remains at 0V throughout, then your relay is #1 suspect.
The full speed relay (745)shorts the fan to ground and disconnects the transistor,(658). The pictures you need to verify the correct mod are at tomshepdotcodotuk. There is one link to be cut and a wire to put in. Ensure that you have the same board(278) layout, there are 2 types. My board was marked "Chausson" in the lower right corner.
You have two speeds. The correct operation is to have variable speed all the way up and then click into the full speed setting so, some detective work. If the track was busted, then the fan would only work once you had connected into the unbroken bit so multimeter both ends of the resistive track and ensure that you don't have an open circuit. Using the multimeter again, from earth to the connection on the far left of the board, you should see a falling voltage as you rotate clockwise. That you get some speed with the relay off suggests that the transistor is conducting and this check is verifying the control voltage. When you get to full speed, this falling voltage on the left hand connection rises again and the terminal to its right should go from 12v to 0V as the wiper of the rheostat connects it to earth which is what operates the relay. IF it remains at 0V throughout, then your relay is #1 suspect.
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Sorry about the sub-thread emergence here, John.DoubleChevron said:
Thanks Shane - I'm an electronics novice. I contacted RS Components and they sell diodes that can handle up to 15,000V and 400 AMPS! So no worries about using one diode.....
(Shane, I've started a thread under the Tech section - could you have a look for me please, mate? I've picked up that you know a bit about electronics/electrics over time!)
Cheers
Stuey
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Tom,
just cut the track and no change so I then repaced the full speed relay still no change and then finaly tried it with out the relay pluged in and even stranger no fans at all.
Is there any explanation for this? It looks like I am only getting fan speed through this relay?
On another matter I also discovered that the vetilation flaps are not working. There is power to the switch and the flaps work when bypassed. Only leaves the switch ? Oh and for me to test if there is power to the flaps. Can anyone explain how the switch works?
just cut the track and no change
so I then repaced the full speed relay still no change and then finaly tried it with out the relay pluged in and even stranger no fans at all. Is there any explanation for this? It looks like I am only getting fan speed through this relay?
On another matter I also discovered that the vetilation flaps are not working. There is power to the switch and the flaps work when bypassed. Only leaves the switch ? Oh and for me to test if there is power to the flaps. Can anyone explain how the switch works?
Bill B said:Tom,
just cut the track and no change
Is there any explanation for this? It looks like I am only getting fan speed through this relay?
On another matter I also discovered that the vetilation flaps are not working. There is power to the switch and the flaps work when bypassed. Only leaves the switch ? Oh and for me to test if there is power to the flaps. Can anyone explain how the switch works?
Hi Bill - I can't help with that at all I'm afraid. I haven't chased the full speed relay business at all as I've plenty of air now my transistor is earthed properly so have left well alone.
The only movement of ventilation flaps that I'm aware of (with switching, that is), is going from fresh air to recirculation with the slider switch, and then the two flaps with externally geared motors in the plenum chamber rotate. Is this what you are asking about?
Cheers
JohnW
Right, then. Remote repairs at 12,000 miles distance. This should be easy :roflmao:
Put the relay back! all feeds to the fan come through this. You have tested the feed to the negative side of the fan thus. Replace it and it will run.
Assuming that you have correctly modified the board, (Send me a digipic and I'll mark you out of ten. tomattomshepdotcodotuk) then replacing the relay should at least give you full speed, if you pull the second terminal from the left on the board to earth.
What follows is a diagram of sorts, outlining the board, viewed in place in the car. Left is 5 right is 1.
1 I must be at earth. I'm the panel light return.
2 I'm the variable + from the light dimmer.
3 I must be at earth always. I'm the rheostat wiper.
4 Earth me for full speed. I'm the relay coil contact.
5Variable voltage to drive transistor.
So start by metering 1 and 3 to earth. if one is not at earth, run in a wire and recheck.
3 is the control that pulls 4 down at full speed. Short these two for full speed
If you get full speed then the wiper of the rheostat may not be making contact.
Go away and do that, Then I'll have some data to help you with.
Put the relay back! all feeds to the fan come through this. You have tested the feed to the negative side of the fan thus. Replace it and it will run.
Assuming that you have correctly modified the board, (Send me a digipic and I'll mark you out of ten. tomattomshepdotcodotuk) then replacing the relay should at least give you full speed, if you pull the second terminal from the left on the board to earth.
What follows is a diagram of sorts, outlining the board, viewed in place in the car. Left is 5 right is 1.
1 I must be at earth. I'm the panel light return.
2 I'm the variable + from the light dimmer.
3 I must be at earth always. I'm the rheostat wiper.
4 Earth me for full speed. I'm the relay coil contact.
5Variable voltage to drive transistor.
So start by metering 1 and 3 to earth. if one is not at earth, run in a wire and recheck.
3 is the control that pulls 4 down at full speed. Short these two for full speed
If you get full speed then the wiper of the rheostat may not be making contact.
Go away and do that, Then I'll have some data to help you with.
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