Car radio stopped working

[eccerr0r]

Re: Car radio stopped working

find two cheap single channel pots, use a rubber band to gang them? =\

[eccerr0r]

Re: Car radio stopped working

speaking of balance controls, I have one line powered desktop radio that solved the balance for debug solution by ganging two pots, one for left and one for right, by default (friction) but you can rotate the two pots separately for debug or if the broadcast/tape was sourcing weird...
interesting if not unconventional, though this unit is ancient, probably 40 year old design.

[stj]

Re: Car radio stopped working

you could actually use a rotary encoder and a couple of digital-pot chips.
i use those chips sometimes - they are very interesting.

[eccerr0r]

Re: Car radio stopped working

That'd infinitely increase the cost of the radio/repair!

Then again I probably already did so already by putting in a 220Ω ⅛W resistor to fix that one nonfunctional channel... fortunately it was a salvage resistor so maybe not so bad.

[jimku4aa]

Re: Car radio stopped working

eccerr0r,

I had found your thread while cruising the net for some info on the Temic FM tuner module. Since the last post was only 5 weeks ago, I thought I might ask: Are you still working on your car radio (not given up on it)?

I might be able to help with a donor unit that I have as a spare.
Jim

[eccerr0r]

Re: Car radio stopped working

Thanks, I'm good with it now, I found a "parts unit" radio that had apparently has a good TEMIC module in it. I ended up repairing the "parts unit" as the original unit needing repairs had been severely damaged from the accident. Still no cassette player, but the radio/amplifier works fine and that's good enough for now.

Not sure why but I'm still holding onto the old tape mechanism... unfortunately cannot use with the "parts unit" radio.

Old unit:
busted TEMIC module
busted volume control (due to accidental fall)
tape player works (with bad caps...)

Parts unit:
TEMIC module along with the rest of the broadcast receiver electronics works
Bad tape player (tape player is completely jammed)
one audio channel broken (I was able to fix it, tracked down one teeny surface mount resistor)
doesn't totally fit (jury rigged it to fit)

[jimku4aa]

Re: Car radio stopped working

Ok. I have a Chrysler "RAS" original factory radio from a 1994 Dodge Dakota that is fully functional, for which I have absolutely no use. It's an AM/FM unit with cassette. Price is right, too: $0.

I worked for Chrysler Huntsville Electronics from 1985 to 2001, originally in automotive tester section but moved over to component test in 1998. I was assigned to work up a test program on the automated test equipment to verify the Temic FM tuner units. Seemed that the Temics had a very high failure rate and was probably the #1 failure item on the late 90's Huntsville radios. Big important project, I was told. But before I could begin implementation of the test program, I received my pink slip (at my 15-1/2 year anniversary, to the day! ). I'm now drawing my pension from Chrysler, but kinda wished that I could have tackled that Temic project. Looked quite interesting, especially since I'm now doing a lot of RF stuff at home.

Best wishes for your success on your ongoing radio project!

[eccerr0r]

Re: Car radio stopped working

Ah cool yeah, I had to dumpster dive that "parts unit" pretty much. I spied a craigslist ad with something that looked similar to what I had and went ahead to snap it up. I guess it just costed gas.

That's pretty awful, seems those TEMIC units are just awful. If only you had remained to find a way to weed out those bad units! Then again I can only be about 80% sure that it was my TEMIC unit that failed due to the lack of documentation, alas I think the cursory spec sheets were just about sufficient (I did not detect the OSC or MPX output on my Tek2465 though I think I did detect the control voltage IIRC.)

I still sort of wonder what specifically failed - was it diebond or the COB itself or something else... without further information about the guts of the module it's kind of hard to get much further. That and the special sauce part numbers that car manufacturers like to put on their ICs to baffle the DIY repairers.

What made you search for TEMIC information? Sounds like you know a lot more of these things than us mere mortals...

[jimku4aa]

Re: Car radio stopped working

I was looking for some odd RF parts to play with to kill some time in my garage/workshop. Pulled that RAS radio out of a bin with other car radios I had. Opened the radio then realized that it was a unit with the Temic FM tuner and a TDK (?) AM tuner. Not much RF fun there.

I might have been the Temic guru at Chrysler had I stayed on and completed the test program. That was 20 years ago, and I pitched any documents that I might have retained long ago. I've got some double-balanced mixers coming in next week from Ebay, but that's next week! The Temic unit is basically a black box you put signals and power in and get audio out. No fun for an experimenter.

[eccerr0r]

Re: Car radio stopped working

Yes very true, alas it makes thing a lot easier in terms of shielding and its sensitivity/selectivity is fairly good compared to any homemade devices. Before I acquired the parts radio, I put in another car radio, was only a 1DIN instead of a 1.5DIN. This radio on the other hand was more of a discrete receiver - has components everywhere. Didn't spend the time investigating it but was nothing like the TEMIC - more like my old Heathkit AR-1219's design - though it should be PLL based (it has digital tuning after all) like the TEMIC/Chrysler radio, and not an open loop drifty LO like the Heathkit.

Alas that radio's sensitivity (and selectivity) is nowhere near the TEMIC. There are stations it can't pick up as well as the TEMIC and can even hear bleedover from nearby stations. Ugh. Well the main reason why I despised this interim receiver was that it was 1DIN and didn't really fit, not to mention it was a single ended versus the Chrysler radio that had a higher power bridged output.

[jimku4aa]

Re: Car radio stopped working

No doubt about it, the OEM Chrysler radios were top-of-the-line for sensitivity, selectivity, and audio. I was quite proud of the radios we built in Huntsville. Only reason I pulled the OEM radio in my '03 Dodge Dakota was to gain the hands-free features of a Bluetooth radio. Took out the 1.5 DIN, put in a double-DIN. Now THAT was a job!