This is not a Ferrari controller, it is from an Alfa or Fiat. I have one (spare) exactly the same, two pins, like the one shown on your picture which I bought it on Ebay, advertised as from Fiat Coupe. The right of the two pins is the one for manual fan speed control. The left is connected to a temperature sensor. The missing pin is for some "electronic ground" which, together with the one connected to temp sensor, is used for automatic fan speed control (like varying the speed depending on the cabin temperature, going to full speed when you select "defrost" etc.). It will probably work (if it is still good) but you may lose parts of the automatic fan speed control. You can bench test it following the diagram (with a bulb) I posted earlier in this thread.
I have received Andrew's Blower Controller so the show begins. Perfect condition unit, like new outside (but not inside). First, open the thing. The back plastic plate is glued with epoxy at a few points only along its gap towards the body of the controller. I ran a blade a few times down the gap (you can feel when you come to the epoxied points) and I was then able to remove the plate. There is also a nice rubber gasket below. (Andrew, don't worry; not a scratch so far.) Image Unavailable, Please Login Image Unavailable, Please Login
A close look at the circuit board before removal. The marked points look a bit fried. I actually noticed an electrical burning smell coming from the controller even before I opened it. Image Unavailable, Please Login
Now is the time to get out your tin sucker. Remove the tin from the marked points (make sure that the pins are free inside their PC board holes) and you can then just pull out the board. Image Unavailable, Please Login
There are two power transistors, connected in parallel, controlling the fan speed. The left one is obviously blown (cracked); the right one looks fine outside but it is also blown. I believe that the right one does not have signs of burning because it died quickly - as the transistors are running in parallel (sharing the current to the fan), when one blows the other one gets overloaded and is killed instantly. Image Unavailable, Please Login Image Unavailable, Please Login
Other components on the board look fine. I will be off to Jalan Pasar tomorrow to get new transistors. Jalan Pasar (street) in Kuala Lumpur has about half a kilometer of electronics shops, near where I live. The story will continue... Image Unavailable, Please Login
Great pics and description, Miroljub! Looking forward to more and curious whether higher power replacement transistors are readily available. By the way, due to their nature would it not be prudent to replace the two electrolytic caps while you're in there?
The original transistors (TIP 142) are 10A 125W. I have identified a more powerful similar transistor, MJH 11018, 15A, 150W, and will see if I can get it tomorrow (otherwise Ebay or on0line companies) and check if it works fine with the circuit. The original transistors are "Darlington" type so it is not only their power to match but also the sensitivity (Hfe) which is very high in the case of Darlington transistors. I have a very good "Fluke" to test the capacitors (10u and 22u, 50V) and will probably replace them. But at these values, their longevity is not an issue (50 years?).
Amazing stuff Miro !!!! Thank you again for this. It is exciting stuff. A bit like watching an action packed movie. Never know what will come next.
Today I got new transistors, same as the original ones - TIP142 (a bit expensive, USD 1.50 a piece but what the hell). One tip: keep the old transistors with their pins undisturbed so that you can use them as a template to bend the pins of the new transistors in exactly the same way and they will be aligned with the PC board holes when the transistors is bolted in (with fresh heat transfer paste, of course). Bench tested the controller with the new transistors and it works perfectly (with my sweaty fingers). Andrew, I just "tack soldered" the new transistors for testing and have not yet completed the installation and assembly of the controller. At the same time, I have ordered two types of a bit more powerful transistors (could not get them in KL) which will probably work in the controller but I have yet to test them. I bought them on Ebay, basically for my own use/keeping, but, if you are interested in the experiment and the possibility of having your controller with somewhat more powerful transistors (about 20% higher power/robustness), let me know and I will hold assembly and sending of your controller until then. It will probably take about 10 days until these transistors arrive. If you are happy with the replacement transistors that are same as the original ones, I can send you back the controller next week (probably next Monday). Image Unavailable, Please Login
What a great thread!! And what a great fix!! I definitely know who I can trust to send mine to one day. Looking forward to seeing more, keep up the good work Miro.
Nice work Miroljub ! I've learned so much in this thread I'm hoping to fix the gremlins in my own 348. I have the same fan speed controller that needs work. Your skills are in short supply this side of the ocean. Thanks again for sharing your knowledge, JGW Victoria BC
G'Day Miro. I think given all the trouble you have gone through for me its only right that we make sure the fix is a long lasting one. I'm happy to wait the extra days if you feel it will be a benefit to do so. I think it would be well worth buying a few sets as I think you can expect more Fan Speed Controllers coming your way after this ! Of course what ever expenses your incurring even that $USD 1.50 (I'll get a bank loan to cover it) please make sure you list everything and we will sort it out through the PM. I must pay you something as well my friend for this so please keep that in mind
Great job. When I take a close look on both sides of the circuit board it seems to me that the previously mentioned "missing pin" has no connection to any circuit path. So it's existence is not mandatory. Can you confirm my observation since you dismantled it. If I am right we might have solved another puzzle.
Hi Andrew, It is good that you decided to wait - if the stronger transistors work, it will benefit you as well as many other members. These transistors are 160W (as compared to 125W of the original ones) and should last much longer. 160W is about the maximum in this transistor package. Otherwise, there are much more powerful transistors but in a bigger package (TO-3) - like the right one on the picture; the one to the left of it is the size of the transistors in the controller. In the TO-3 package, they go as high as 250W. Thomas, excellent observation; I did not pay attention to this as Ferrari say it is for something but, when I checked, I also found that it does nothing...I know - it's a spare pin; the manufacturer, knowing that the quality of the controller is lousy, included a spare so that you can move it over if one of the two working pins brakes. Mystery solved (endlich). Image Unavailable, Please Login
Ok then im happy to wait for the higher W transistors. Great to see we have solved the mystery of the 3 pin fan speed controller vs the 2 pin, both having the same part number. But looking at my wiring there is definately 3 wires, the 3rd pin being the black wire. (The plug is reversed in my pic). Is it just an earth? Why have it at all if it connects to nothing? Yes I know it is an Italian car after all. Ive owned Alfa's for years and nothing surprises me when it comes to italian car wiring 😆 Image Unavailable, Please Login
Received and tested the new more powerful transistors, MJH 6284 and MJH 11022. Both work very well but MJH 6284 is a bit more sensitive (more similar to the original transistor) and it is also more powerful than the MJH 11022. So, MJH 6284 is the best replacement, almost 30% more powerful (in Watts) than the original TIP 143. I bought both on Ebay - MJH 6284 at GBP10 and MJH 11022 at GBP6 per piece including shipping when you buy six transistors. Andrew, I will complete the re-assembly of your Controller (with MJH 6284-s) over the weekend and send it to you early next week (will contact you by email). Image Unavailable, Please Login
Great news Miro. Look forward to hearing from you. Cant wait to get it back the car and test the voltage range again.
No need to test the varying voltage. I have already bench tested it, not just using my wet fingers but also simulating the voltage variation using a manual potentiometer - the bulb brightness increases gradually from zero to near full and then the relay clicks at 4.7 V, same as what I recorded with the original transistors and when I earlier tested my own (still good) Controller. Just plug it.
Yes, same thing, only in housing TO-218. The MJH6284 I bought has just a bit different housing TO-247 (newer type) which looks bigger but it is not; it just has some additional plastic molded over the fixing tab. Performancewise, they are identical.
Installation of the new transistors: First, thermal (heat transfer) paste on the transistor seats. Then, screwed in the transistors with pre-bent pins. Amazingly, all eight pins found their holes when I put the PC board on. Soldered the points, put back the rubber gasket and the cover plate with spot-epoxy as what was originally done and it's ready to go back to Australia. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
