Radio works only when cold

ID Status Date Year Make Model Transmission Type A/C Controls Public/Private
#16925 In Progress 1999 Chevy 1500 Silverado public

The radio hasn’t worked 5 or so years. It’s the stock non-theftlock 1.5 din radio/cassette on a 1999 Silverado base model. I don’t know if the cassette player works. Never used it. But all other features on the unit work all the time. It just won’t play any stations.

Just a couple weeks ago I discovered that on cool mornings, I’m able to get the radio to play by giving it thwack with my knuckles. The station will come in clearly, but static starts after a few minutes and completely peters out as if loosing reception. It will not play any more that day. I imagine there is a crack in a solder joint that looses continuity as the crack widens with warming temperature. However I’ve no idea really. A few years ago I bought an identical used one off ebay that didn’t play either.

Sparky

Oxidation on the connector terminals, loose or poor antenna, faulty amplifier or like you said possible a failing solder joint internally. It would be kind of strange to by a replacement with the identical concern.

Thanks for the reply.

The ebay unit was identical in terms of features etc. IIRC, it was the identical part number. It didn’t play at all, but at that time, I had not yet discovered that thwacking on the face just above the controls would get my original unit to play for a few minutes when cold.

The antenna is not connected to the back of the unit, but thwacking the unit gives clear reception on a local AM station. Budging the connector or wires doesn’t do anything.

I just dug out the other radio. Neither play any stations correctly, They are not the same models. The original is 09367685 and the ebay is 16194545. I thought I had the original installed, but didn’t. So it is the ebay unit plays when cold & thwacked.

The original worked flawlessly for 250,000 miles, but now only plays when I press upward on the radio jack, which being in the corner, puts a slight twist in the upper circuit board. There are three somewhat odd solder joints near where the jack is mounted to the circuit board.

Sparky

There were a couple of different sized antenna jacks back then.  They may not be fitting together properly or the internal leads in the antenna cable could be broken. If you happen to have an old antenna lead laying around your garage I would try that first. You can always just use a piece of regular wire too. Just have to be careful where you touch it to the radio.

Also could you upload a picture of the questionable solder joints?

I wedged a tooth pick to keep the jack ‘pressed up’. Not sure why that makes it work nor how long that fix will last.

Sorry, I didn’t see you had replied. Also, when I wrote above about AM stations, I meant FM stations. When either unit succeeds in playing FM stations, they do so whether or not the antenna cable is plugged in. Have not tried AM stations.

I have the original radio unit back in the truck, with the toothpick wedging up the antenna jack … so the original is working 100% correctly right now.

Not sure about the ebay radio, which would play when cold and give a knuckle rap. IIRC, the ebay seller was a parts yard and said it was working when pulled.

I’ve attached a photo. The 3 solders labeled A hold the antenna jack bracket to the pcb. The 3 solders labeled 1,2,3 look odd to me, 2 and 3 look cold, and 1 looks messy. The tooth pick is visible in the lower left. It puts a twist in the entire circuit board.

two more photos

There is another circuit board about 1″ below this one. The wires and ribbon cable that connect one to the other are soldered in place on both boards, and are only ~2″ long, so it is difficult to identify the what components are where.

Sparky

Solder joints 1,2 & 3 in the second image definitely look like someone has attempted to resolder and not necessarily succeeded.

Thanks. It is the radio that came with truck when I bought it new in 1999. Never been worked on since new. With the toothpick wedging up the antenna jack, it is working 100% now If/when the hack fails, I’ll try re-flowing the solder joints. Any advice on good technique for that?

I found FM reception degrades rapidly as I get farther into the countryside, so I have the antenna cable plugged in now, and am getting really good reception everywhere so far. If I can find the antenna mast, I’ll screw that back in.

Sparky

Hard to  what would be the better technique to attempt to reflow the solder work. Speed wise, using a hot air reflow station would be best but there are some beefier joints there that would require the heat of a good soldering iron to reflow them.  Very time consuming but I would probably reflow each joint with a good soldering iron.

At this point I would agree with leaving well enough alone.

Reflowing may happen sooner rather than later. The toothpick is not stable enough as a wedge. I’ll try something thicker and broader.

Do you know how I can test the antenna cable and mast?

A bit of an update. With the toothpick shim wedged under the jack bracket, the fm station reception would cut in an out.

So in the same place I removed the toothpick then wedge a plastic shim that was thicker than the toothpick. Reception became stable for several days, but there were blurts of scratchy-ness happening seemingly randomly, about once or twice per second. Apart from that, fm reception was good.

After a few days with the the plastic shim in place, I removed the shim, removed the radio, removed the top plate, used a soldering pencil to melt the 5 solder joints in the above photo, put the top plate back on and reinstalled the radio (without any shims). The reception now is the same as before with the plastic shim — stable but sporadically scratchy.

I found the antenna mast that I removed some 5 years ago, and screwed it back on. It didn’t help. In fact, reception is the same with or without the antenna cable plugged into the back of the radio.

Sparky

Check continuity on the center lead and then check continuity on the outer shell terminals. Don’t know exactly what the resistance should be but I think it would be fairly low.  5 to 40 ohms. Also there should be no continuity between the inner and outer leads.

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