TCI bad?

I fixed my TCI for about 30 CAN including the shipping from DigiKey.com. Sometimes you can identify "burnt" areas on a board but the transistors are the most likely culprit. I did go through my TCI checking for bad diodes and resistors and found no other issues. I never got around to checking the zeners as it seemed easier just to try my fix without it.

 

sorry - double post.

 

I know the component modules for the military radios were filled with some sort of gunk, although I kinda doubt it was "impenetrable". At any rate, the modules for the Viragos very well may have been sealed... I honestly don't know. I can, however, personally attest that the ones for the 750 Maxims can be surgically operated on.

 

Conformal coating is a common method of sealing circuit cards against moisture and it's corrosive effects. It can be made up of RTV, epoxy, or a small number of useful and annoying materials. I prefer LPS conformal but you can use clear acrylic, polyurethane, or lacquer as a coating. Most should clean off with agressive use of alcohol (as in the case of our TCIs) or a slight over-curing with a heat-gun on low and a spatula (use a wooden dowel or plastic rod beveled on the end to make a chisel) to scrape the material off. Use care and don't go overboard, slow and easy is the best way to achieve good results.

 

Hiya guys and gals i have a 81 XJ550 FORFREE!! i have narrowed my ignition issues down to the TCi box i see that fixing these seems to be well worth the effort. i have a smoked transistor on the heatsink plate i can tell this is the case by the transistor guts hanging out lol. I replaced the coils with some used ones that i got from E-bay that OHM out right on spec. the old 1-4 coil was ZeroOHMs thus the exploded transistor.

Now i went onto DigiKey.com and my eyes glazed over with the sheer number of diffrent choices. Fraps could you hook me up with the PN# that are needed to fix this thing. it has 1X 50V 2.2uf, 3X 25V 10uf, and 2X 50V .47uf caps and the markings on the Transistors say 121 EDT41-035 . Help a Electro NOOB out!

This bike has been in my Uncles Garage since i was a kid i remember when it was new it has not ran in like 5 years he gave it to me hoping that i would be able to keep it running and have a bike for my wife to ride!! This website has been a great resource!!! thanks in advance... Ryan

 

RPCVFR
Type in CAP 2.2UF 50V into the Digikey search engine. You will want Electrolytic Aluminum caps. You need to measure the lead pitch (distance between the component leads) to get the best match for replacement. Use the same details for each of your other caps. Once you have the search narrowed, any one (I pick the cheapest) should work.
I ran your Transistor numbers on FindChips.com and got no hits. Any chance you could photograph the chip info? A manufacturer mark might help narrow the field down a bit.

 

p/n ETD41-035 transistor

Replace with MJE5740 Darlington Transistor
can buy at digikey.

 

Sweet Thankyou HUGE! at $1.82 i got 3 just incase i mess it up or get a defective one. Friend hooked me up with some caps, and helped me redo all the other joints we installed some generic NPN Transistor he had laying around and the beast fired up on all 4 today woohoo... Will replace with the ones i ordered when they get here.

On a side note we also noticed that the system voltage was only 12.6V at the battery when running. But the voltage at the fuse was 14.2 found the stock main 20A fuse holder was cooked and fell apart when we touched the voltmeter leads to it. Yeah i would say all the posts about the fuse blocks hit the nail on the head. Now if i could get the weather to get up above 30F lol...

 

Ok, so how do you crack the case on an 85 xj700? There arent any screws to take out. Just wondering when i get my electrical project done, and it does turn out to be the TCI, then how to rip her open.