Rog--

ATX fuses are like the standard ATO's used in the cars, but in a bigger package with larger blades and therefore more area for the connections. Other car manufacturers use them commonly in high-current circuits and feeders to the smaller panels for local distribution. You can buy ATX-sized fuseholders at higher-quality car audio places, since they are often used for high-power amp feeders for instance.

 

Dr Bob,
I am surrounded by the best 928 brains in the World, you and Alan and I have Doc Mirror here in the office.
We googled ATX so I see what you mean.
Roger

 

how about solder the self resetting circuit breaker to the back of the CE panel?

 

Wouldn't need to solder. The CB has studs, so use ring terminals on the existing wiring.

 

Roger - in the picture of my battery box I posted a few replies back there is a large ATX fuseholder at the top (a really good one) that I use for a fused feeder to my audio amps and decoupling capacitor. Its a 50A with a massive 4AWG feeder - much more than you need for fans - but an example.

Below that is the ATC fuse panel that I use for my fan feeders - its a good quality ATC/ATO box with big triple claw connectors to the fuses blades. More than twice as much terminal area as the Porsche ones.

I got that one at Waytek Wire - I expored many options before I found one that good... I've never seen better - though better designs should certainly be possible..

ATO fuse blocks at Waytek: http://order.waytekwire.com/productd...20%204%20FUSE/

See also modular ATX offerings: http://order.waytekwire.com/productd...LOCK%20HOLDER/

Alan

 

This problem sounds like an opportunity/excuse to re-wire the whole mess that is the Porsche 928 CE panel. Was the CE panel out-sourced to Turkish day-laborers?

 

Amazingly, the CE panel in the 928 was teh start of a trend at Porsche, a trend that only years later managed to flow to the 911 cars. It is a very robust design, and only seems to suffer when something else causes tinkle-down problems with corrosion or overheating of wiring. You'll be very hard pressed to get as many connections and devices in the same space as you try to re-engineer what's there.

Moving on, remember that the individual wire connectors that snap into the panel are available as separate parts from the VW/Audi parts guys. Last time I needed similar pieces (not for my 928 though), the VW dealer parts counter had a big box of all the different little spade terminals for the fuses and relays. In that rework/repair project, I replaced the wiring and the connections on both ends of the affected conductors, and used an AMP crimp tool made specifically for those terminals. They are berylium-copper so they ave some spring to them, and don't take that well to the heat of soldering. Mine did get heat-shrinked though.

 

The one fuse that melted also melted/damaged the socket on the CE panel so I replaced that section with a good unit. Next is to install a Deutsche 2 wire connector for both fans. What is the gauge thickness for the wire fans?

 

i had a similar issue with the fan fuse in which the block melted around the fuse . On closer inspection I noticed that my fuse link in the block where dirty/coroded. The cause was the seal that holds the intake for the HVAC blower; anytime it rained the water would run down to the CE Panel.

 

4mm^2, which puts it between 8ga and 10ga (very close to 10ga) in AWG sizing.

 

I appreciate it Dr Bob.

 

This chart was shared here a few years ago. Credit for finding goes to someone else in this group whose name I've forgotten.

 

Fuses 28 and 29 (ea 30A), protects the driver stage for the fans. Fuses do not become hot unless there is excessive contact resistance in their sockets. Provided that there are no short circuits to ground in the connections between the driver stage and the fans, you likely have a damaged driver stage, e g a short circuit inside the stage.

Proceed as follows to find out exactly where the failure is located:
- Disconnect both fans from the driver stage
- Measure the resistance between the two terminals of each fan. Since the fuse rating is 30A the resistance shall be <0.45 ohm but not 0. Alternatively; connect B+ and GND to each fan to verify that they are working properly.
- Verify that R between each fan lead and GND is Mohms. If not; there is a short circuit which needs to be found and removed.
- Remove fuses 28 and 29
- With fans still disconnected; verify that R between the driver stage side of the fuse holder and GND is >10 kohms. If not, the driver stage is faulty.
A driver stage can be repaired by replacing the power transistors.

 

This is ancient history - But I have a new favorite ATX fuse holder - it is honestly the best I have ever seen - looks good, has good sealing has nice wire connectors and the best blade terminal spring contact patch. If you need high current these are excellent: a pair of these in the battery box intercepting the 2 fan feeders would allow you to bypass each of the fuses on the fan feeders on the CE panel (connect fuse in to fuse out wire on each on the back of the panel) - soldering and heat shrinking them would be best. See:
Alan

 

Nice! Hands-on review I trust?