| Author | Message | ||
| Bill White (Nc_newbie)
New member Username: Nc_newbie Post Number: 43 Registered: 2-2003 |
Thanks for the offer Jeff but we both have the diagrams. This board is shown as a "box" on the diagrams that would require ferrari part replacement. I was trying to explain how to repair the board without replacement. Bill | ||
| Jeff Howe (Ferrari_uk)
Junior Member Username: Ferrari_uk Post Number: 160 Registered: 12-2002 |
Mikehuber - We have USA Spec wiring diagrams in stock for Mondial QV & Cab, 1983. Part nbr is 95990823 and they are about $24.73. If you like, if it would help I could fax some of it over .....dunno how well it would come out though....    | ||
| Bill White (Nc_newbie)
New member Username: Nc_newbie Post Number: 35 Registered: 2-2003 |
Let's take this offline since it is now electronics rather than Ferrari specific. I'll send you an email explaining the testing. Bill | ||
| Peter Connolly (Mondial_32_aus)
Junior Member Username: Mondial_32_aus Post Number: 111 Registered: 8-2001 |
Nice one. So, presumably I would attach my multi meter to 12V and then use the other probe to look for a voltage out of the transistor (labelled Output)? Sorry to be so ignorant but the trannsistor has 3 legs, right? Is it the case that these transistors are configured EBC when looking at the flat side of the transistor. As per the attached diag. PC  | ||
| Bill White (Nc_newbie)
New member Username: Nc_newbie Post Number: 32 Registered: 2-2003 |
I've attached the amount of the dimmer board I reverse engineered until I found my problem (CR237). You can check the voltage for change as you turn the dimmer at the base of CR237 and that will tell you if it is one of the output transistors.  | ||
| Peter Connolly (Mondial_32_aus)
Junior Member Username: Mondial_32_aus Post Number: 110 Registered: 8-2001 |
Amazing! My 87 Mondial has problems with instrument lights, rheostat & fog light switch too! Do you reckon we could take out a class action against those italian bastards who made this?;^) Actually, my trouble began when I bought the car, the fogs worked, dash lisghts worked and the dimmer worked too. I noticed that my main cigarette lighter didn't work so I removed the centre tunnel console and found it was not plugged in! So, as you do, I plugged the ciggy lighter socket in, next thing there is a column of smoke rising from the socket! No fuses blew! I quickly unplugged it but from that day my dash light dimmer never worked again, the dash lights were ok but not dimmerable. Recently pressing the fog light switch caused the dash lights/fog lights fuse # 17 to blow! Aaarggh! I took it to Ferrari Sydney who claimed the fog light switch was faulty but open circuit! How could that do anything when pressed in? They then wired my fog lights to my hi beam, great.NOT. But the dash lights still worked. I recently sent the car to a local auto electrician, they confirmed a open circuit fog light switch. Any clues on what to look for in the dimmer/speedo board? I have measured the reostat and it seems to vary when turned. I have it out at present and have a multimeter ready to go and a Mondial 3.2 electrical circuit diagram but am a little clueless on what to do next. PC | ||
| michaelthuber (Mikehuber)
New member Username: Mikehuber Post Number: 5 Registered: 3-2003 |
Bill and Jeff, With a few more hours of troubleshooting I have isolated the problem and am pretty confident I found the real source of the failure. The problem is definitely in the card as Bill suggested. I haven't located the offending component yet, BUT, when I jumpered to the dash light circuit I got the dash lights to work. I then went about checking that everything in the dash worked. When I got to the fog light switch and turned it on I thought I smelled something getting hot. I quickly turned off the battery switch. I felt the two Pink wires on the fog light switch (the infeed and the switched leg for the fog lights) and they were hot to the touch. I turned the switch off and turned the battery switch back on. I got the switch out where I could see the back of it. I then pushed the fog light switch on and saw a bright arc from the switched leg of the fog circuit to the YELLOW terminal that is in the dash light circuit. Sure enough the wires starting heating up. I took the switch out and found that the riveted lug on the switched side of the fog light switch was loose. Instead of making contact through the lug into the fog light wire it was jumping to the dash light wire terminal. I believe this is what caused the card to burn out. I soldered the lug back in place, and insulated the dash light lug with silicone sealer, but I think I am going to invest in a new fog light switch. I thought you might find this discovery interesting. Mike | ||
| jeff ryerson (Atheyg)
Junior Member Username: Atheyg Post Number: 184 Registered: 8-2002 |
My 328 has had a similar problem fixed 2x by a dealer I had my complete circuit board apart etc it turns out a connector to the main board was a little too far apart and causing this problem Id check your connectors and get some di-electric grease and cleaner and clean them | ||
| michaelthuber (Mikehuber)
New member Username: Mikehuber Post Number: 4 Registered: 3-2003 |
Bill, Thanks. I think I'll at least try to see if I can find a bad transistor and if not I'll use the jumper. Mike | ||
| Bill White (Nc_newbie)
New member Username: Nc_newbie Post Number: 30 Registered: 2-2003 |
I am not sure I follow your post but it sounds like you are jumpering 12V from the headlight circuit to the dash lights. One of the outputs of the board is to the dash lights. You can jumper 12V on that from the headlight switch and it will work fine and be bright but you will not have any dimmer control. Bottom line is you can bypass the board with 12V or you can put an inline resistor to drop the voltage slightly to dim the lights a little. No down side except for no dimmer control and shorter bulb life with a higher voltage or you can fix the board. Bill | ||
| michaelthuber (Mikehuber)
New member Username: Mikehuber Post Number: 3 Registered: 3-2003 |
Thanks Bill. Your fix sounds like a good one. I have a meter so I can test the transistors. If I understand you correctly if the transistor is bad it cuts off all power at that point. I have read alot of archive stuff about how weak the dash lights are if you go through the board. I saw that many folks have eliminated the rheostat board from their circuits to get brighter lights. Let me try this out on you. If I just jumper from the headlight switch into the circuit, I can get bright lights and it doesn't blow any fuses since with the circuit open with whatever failure I currently have I am not feeding from two different fused circuits. If I just leave it jumpered, do you see a problem? The Jumper wire I have has an in-line fuse in it(5A). I am jumpering from the blue/red striped wire from the headlight switch and I am feeding the yellow wire circuit that goes into all of the lights. Thanks for your response. | ||
| Bill White (Nc_newbie)
New member Username: Nc_newbie Post Number: 28 Registered: 2-2003 |
I had the exact same problem on my '86 mondial. I went ahead and did some board level trouble shooting on the board with the reostat. It turned out one of the final drive transistors was blown. You can test the output transisors with an ohm meter set on about a 2K ohm scale since they are all bipolar rather than mosfets. The part that was bad on mine was the next to the last output transistor which was a CR237. I replaced it with a 2222 and my dash lisghts are brighter now due to the higher gain of the 2222. If this is beyond your electronic skills, check and see how much a new board is and I might help you for a small price if it is really expensive part since that was my fear and the reason I spent the time to do the board level repair. Bill | ||
| michaelthuber (Mikehuber)
New member Username: Mikehuber Post Number: 2 Registered: 3-2003 |
My dash lights don't work at all on my 85 Mondail QV Cab. I have the whole instrument cluster, including the "card" with the "rehostat" on it apart. I have checked every fuse in the box and all are ok. In any normal circuit you have a "hot" wire and a ground wire, BUT, when I check continuity between the yellow wire on the ring around the base of the Speedo light and the black wire around the ring of the Speedo light I get continuity. I found two wires going into the rheostat card that have power, but I cannot get any power when testing any of the soldered lugs of the rheostat to ground. I think this card also does something with the speedo. I can get a difference in resistance between two of the rheostat poles by turning the stem on the rheostat. That tells me the rheostat is working. I know that the bulbs are good because I tested them out of their sockets with a 12v source and they lit. There are three blue wires that jump between the two bulbs on the speedo and three more that jump between the two bulbs on the tach. All of tyhe other "feed" wires into the bulbs for the rest of the instruments and switches are yellow. I am reluctant to jumper 12v onto the yellow wire because I am afraid of a dead short. I have a 328 wiring diagram, but it does not match precisely. I am totally baffled. Can anyone help? I have spent the last three nights going through the archive posts but didn't find this condition in any of them. |