Adding AUX to 88-94 Stock Stereo

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TechNova

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I am willing to do a write up on fixing the 89 style radio box. I have read that it is a capacitor problem but do not know which is the correct part. Anyone know which it is from the pictures?
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df2x4

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I am willing to do a write up on fixing the 89 style radio box. I have read that it is a capacitor problem but do not know which is the correct part. Anyone know which it is from the pictures?
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I'm no help on the board specifics. Just a thought though... IMO if you're going to the trouble of replacing any capacitors in a 20+ year old piece of equipment, I would do them all. Chances are there's a few of them getting tired by this point. Regardless this is a cool project and I'd be interested to see the write up. One of my dad's old TBI trucks had this issue and he just dealt with it until he traded it in on the next one.
 

94burbk1500

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I am willing to do a write up on fixing the 89 style radio box. I have read that it is a capacitor problem but do not know which is the correct part. Anyone know which it is from the pictures?
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Like @df2x4 said, just replace all of the electrolytic capacitors, they don't age well.
 

DerekTheGreat

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Go for a later amp section too. Seems every year was different, later years are streamlined. The EQ one I pulled for my '89 from an '89 has just one board. This one looks to have multiple boards. Don't know if any years were better than others.

Looks like my antenna isn't seated all the way then, according to the pic.
 

DerekTheGreat

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One last update from me about this is you definitely want to make sure the brainbox/amp section is from a '92-'94 truck. I had one lying around that I decided to swap in as I troubleshooted my ignition noise. The verdict is the later ones do a better job handling the 2 ohm speakers. There is much less attenuation during heavier bass sequences and less of the radio dimming as it tries (& fails..) to handle the demand. It's a bit louder too.

Oh and the noise I was getting was from the thing not being properly grounded. Originally I only used two of the three fasteners to secure the amp section to the truck, as I didn't have the small bracket for the third one at the time of the install. Welp, put that bracket on the newer amp section and tightened all three fasteners and voila, no more ignition noise.
 

Donald Mitchell

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Nice job. I wish someone would write up the procedure for replacing the power supply capacitors in the stock amplifier unit (the part mounted above the accelerator pedal) which is what usually craps out in these radios. I went aftermarket and I really enjoy the bluetooth capability but restoration of the stock radio would be a good goal for someone attempting an authentic full restoration.25 year old capacitors WILL crap out, so if you go this route you should be prepared for it to happen.
Its not that hard. I just had mine apart. It was working ok so i just cleaned and looked it over for any components that looked like they may have been hot. After you pull the amp out you have to remove the top cover one of the screws is too close to the heatsink and I had too grind the heatsink a little to get it out. There are two tabs soldered to the top board that have to be unsoldered and bent away so you can lift it out. also the side bracket mounting bolt will have to push toward the back and come out. The top board plugs into the lower board with two sets of connectors. after you get the lower board out you will either have to grind or bend the fins on top of the heatsink to get to the 4 small screws in between. It has to come off to get to some of the capacitors better. The large filter cap at the rear Is a 4000uf 16 volt, Kinda oddball. A 3900uf is a bit more common and within 20% and less expensive and will work fine, Just make sure to get the same physical size as I don't think theres any extra room for that one. Most of the others are normal computer values and should be easy to find. There's also a few in the head unit. At 12-14 volts they are pretty reliable but age will eventually get everything. Sorry i didn't take any photos of the amp. Heres one of the head unit with three electrolytic caps.

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Eveready

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Good work, that will help. I have a head unit cluttering the garage and might delve into it. Some resistors MIGHT go high if they are handling voltage so if it doesn't work after re-capping replacing some resistors might be in order. Most likely though the caps will fix it.
 

Donald Mitchell

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Oh and if any of you are pulling out the wiring from the tape deck you might not be aware that theres a big wire retainer on top of the ashtray that ties it to the heat and ac wiring.

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