MaxTrac No audio

[70 cutlass 442]

Transmits fine, when I receive anything, its quiet... when I turn the radio on, I can hear just the slightest "beep" if i turn it up fast enough... Swapped speakers and still no luck, any input?

[Motoboy]

A few easy things to check would be to see if the jumper plug is installed in the back. You could also pull out your o-scope and check the signal level at the volume pot. If there is low/no audio at the volume pot, look toward the AFIC on the logic board...

[jackhackett]

Could be the audio power amp or the coupling capacitor from the amp to the speaker (the large 1000 uf cap near the accessory connector). There should be around 6.5 volts DC on the + lead of the capacitor (one towards the front of the radio), if it's much higher or lower you've got a problem in that area.

[70 cutlass 442]

Thanks for the replies... Do you know exactly where that cap may be? I will take a look this weekend. If that is indeed the issue, what is usually the culprit in this case?

[kc7gr]

One thing Maxtracs were notorious for, with this symptom, is: If they've ever been dropped, or sustained even a mild impact to the front panel, the volume pot's resistive element would fracture.

I would pay particular attention to said pot.

Happy tweaking.

[jackhackett]

The capacitor is hard to miss, it's the only large electrolytic. It's an axial lead so it's lying down lengthwise on the board. The lead you need to measure is easy to get at, but there's a metal chassis brace right next to it so be very careful not to short your probe to that while measuring.

Check the volume pot first, if that looks okay check the voltage on the cap.

Do you have an oscilloscope?

[AEC]

One other problem area to look at: Cold/bad solder joints on the transistor leads.

Looking at them will not reveal separation of the joints, except in cases where this is seen due to corrosion, but desolder the joints, and reflow fresh solder and check again.

I've had this problem on mor ethan a few, and it was difficult yo see with the eye, I used a 10X loupe, and then it became apparent.

[70 cutlass 442]

Well, i got the radio open the other day, and the lead coming into the capacitor reads .06 volts. Any idea where to go from here?

[Will]

I think you are measuring at the + side of the capacitor.

No volts there means the radio is programmed for the HANDSET which deactivates the speaker amplifier.

[70 cutlass 442]

I think you are measuring at the + side of the capacitor.

No volts there means the radio is programmed for the HANDSET which deactivates the speaker amplifier.

BINGO! Thank you all for the suggestions, Something as simple as an option in the RSS is all it was. Appears to work as expected now, thanks again.

[Bill_G]

Thanks Will. All these years and I never knew that. I've seen the check box, but never used it.