mj1pate

Surely we have double-E professionals in this forum. Some of the relays with solid state components are quite expensive as new. Has anyone mapped out the parts necessary to rebuild some of them? Is it possible to replace worm out contacts? Do the coil components ever fail?

Mike

dr bob

Many moon ago I temped a fuel pump relay together for a similar VW Jetta duty. I used a little perfboard and a few Radio Shack components, and glued the little board to the side of a standard relay can. I used the new relay's internals foir the on-off switching duty. It was for my poor brother's car. Would I do it again? Um, no. The replacement lasted to the end of the car's days OK, but you have no reason to believe that one you build/modify/whatever will last until you get home. And that's really what your goal is-- getting home, right?

The other 'interesting' relay is probably the combo lamp relay. Inside that baby you find 3 primary contactors for the lights themselves, plus the solid-state smarts to run the contactors as well as operate the motor up/down.


Different year-models have different variations and flavors of the relays, so there is no real magic duz-it-all solid-state relay device that works for everything.

Alan

Even allowing for the reliability issues Dr Bob notes... there is no way the economics of this works unless the retail relays are many hundreds of $$..

If you get engineering talent that's cheap enough to build these in low quanities for even the current retail relay prices - you probably wouldn't want to use them...!

The only thing that would be nice & possibly economically practical is a generic relay that could be switched to take over any of the single base relay functions - not so much as a cost reduction but as a really good spare to carry around - I'd pay $100 for one of those! Still doesn't solve the dual base issue though..

Alan

JP Rodkey

I actually toyed with that idea some time ago. Those things are produced with high quality components and tested under load to verify specs. Sure, a person can source high(er) quality components and perform reliability tests given enough time, money, and resources. It's really amazing how reliable these things are considering use of discreet components, IC's, and 100% reliability over a temp range from - 30F (?) up to at least +125F ambient. In the case of a fuel pump relay, where reliability is foremost if we want to get home, many of these relays function for a very long time with degraded conductors, poor connections, and failing pumps that can draw enormous current. I decided it better to go with mass produced relays.

mj1pate

Yes...I agree with your experience. I'm with you in that I spent my days breadboarding/fixing Triumph and Alfa relays, when money was very tight 25 years ago... and money is tight again with boys in College. The 86.5 (and more recent) uses the common $12 (141 951 253 B) relay for most critical functions. It makes all the sense in the world to just replace ~5 critical relays in a newly purchased car with unknown relay replacement history, which is what I'm doing. $60 bucks for factory equivalent parts is welcome, cheap insurance.

On the other hand, I was thinking of alternatives to "non-critical" relay replacement. For example, I'll want to spend more time looking into exactly what some including the interior lighting time delay relay (928.618.225.01) are doing aside from the delay function, and if a non-delay relay substitute can produce interior light (without delay of course), for less than ~ $135.00. On the surface I would think that a capacitor, couple of resistors, and a transistor might could be soldered into the factory unit for less. But....The carefully reading schematics may illustrate that there's more than I would initially assume, and mods/fixes of course must be ellegant. I need to do more homework.

Regards;
Mike

Alan

There is indeed more... the schematics don't show the connections for any but the most basic extra function relays - e.g. those with series diodes in the coil line.

Example - The interior lighting delay relay has an ignition input that turns the light off immediately and a lock input that does the same - in some years unlocking also turns the lights on with usual delay... some years use the interior lights off (NC relay position) to enable central locking features.

Lots of variations of features... doable but lots of work

AND for all but the basic relay base - you'd need to cannibalize a Porsche relay in order to have enough pins to plug into the socket.

These bases are not generally available - Sharkskin & I were discussing this recently - you just can't buy empty relays enclosures - not even the standard Bosch SPDT footprint types.

Alan

mj1pate

I see... Oh Well. I can still be grateful for the cheap 141 951 253 B types ! ;-)

Regards;

Mike

Tom928

Repairing relays is not really practical. Many parts are one of a kind while others do not lend themselves to replacement without completely replacing the entire assembly.

For the cost (even though it may be high), you are getting a good reliable part that should give hours of trouble free operation and meets all the specs.

For all the "EE's" out there - remember you can't say GEEK without the double e

Cheers,

RngTrtl

I agree with all above. I am an EE and I would only do it just to see if I could do it, there is no way that I would want to be responsible for burning up someones board, or stranding them on the side of the road.