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Dewalt DC012 radio - No sound

H2814D

Nov 4, 2017
214
Joined
Nov 4, 2017
Messages
214
Does anybody have a schematic of this board? I have the same failure issue with all caps checking OK, and good voltages everywhere...8, 12, 14, 16, etc.., just really really low volume sound. There's got to be something simple but critical in the audio amplifier input path that affects both channels of audio somehow. The board is too small to visually track audio path. Need schematic. The three pin B1336 heat sink is warm, the 78M08 volt reg is warm and correct in and out voltages, 12 and 8, but the Audio IC501 is cool and with a heat sink fin should feel warm. So I think the problem is here. The output 1000uF capacitors to the speakers are also both good. Any ideas? This common failure has to be a common reason. What a shame, the whole rest of the unit works perfectly, display, buttons, knobs (tuner needed a little electronic spray but that's normal). What the heck here.
You should check that the speaker(s) is working properly then. Sometimes they stop moving as they should. You can disconnect the speaker leads and put another radio amplifier on them to test them. Make sure you pay attention to the ohm rating and wattage for the speaker you are using and start out with a very low volume. Just to make sure it works. Let us know what you find.
 

H2814D

Nov 4, 2017
214
Joined
Nov 4, 2017
Messages
214
Does anybody have a schematic of this board? I have the same failure issue with all caps checking OK, and good voltages everywhere...8, 12, 14, 16, etc.., just really really low volume sound. There's got to be something simple but critical in the audio amplifier input path that affects both channels of audio somehow. The board is too small to visually track audio path. Need schematic. The three pin B1336 heat sink is warm, the 78M08 volt reg is warm and correct in and out voltages, 12 and 8, but the Audio IC501 is cool and with a heat sink fin should feel warm. So I think the problem is here. The output 1000uF capacitors to the speakers are also both good. Any ideas? This common failure has to be a common reason. What a shame, the whole rest of the unit works perfectly, display, buttons, knobs (tuner needed a little electronic spray but that's normal). What the heck here.
Take clear pictures of the front and back sides of your board, the same as the previous posters have done. I may have a fix for you. I can let you know more after seeing the pics. For now, though, don't mess with anything else.
 

DocOfRock2000

Feb 23, 2024
3
Joined
Feb 23, 2024
Messages
3
You should check that the speaker(s) is working properly then. Sometimes they stop moving as they should. You can disconnect the speaker leads and put another radio amplifier on them to test them. Make sure you pay attention to the ohm rating and wattage for the speaker you are using and start out with a very low volume. Just to make sure it works. Let us know what you find.
Thank you very much for the suggestion. Unfortunately both 6ohm speakers are fine. As suspected it’s something in the audio path but since dewalt has been ABSOLUTELY no help with technical information—-it’s proprietary they say—-, it’s a throw away item. So no fix, no buy Dewalt anymore. How’s that for customer service feedback? All in all you know what, can’t use NiCd or NiMHydride batteries anymore either as they’re way too expensive to replace and drain themselves even without using the tools. Lesson: buy the best cheapest tool you won’t mind tossing in two to three years. Don’t care it, rather wear it out in two years so you get your money’s worth when it’s 90% dead instead of when it’s 10% dead but still unusable. Too bad really.
 

H2814D

Nov 4, 2017
214
Joined
Nov 4, 2017
Messages
214
Thank you very much for the suggestion. Unfortunately both 6ohm speakers are fine. As suspected it’s something in the audio path but since dewalt has been ABSOLUTELY no help with technical information—-it’s proprietary they say—-, it’s a throw away item. So no fix, no buy Dewalt anymore. How’s that for customer service feedback? All in all you know what, can’t use NiCd or NiMHydride batteries anymore either as they’re way too expensive to replace and drain themselves even without using the tools. Lesson: buy the best cheapest tool you won’t mind tossing in two to three years. Don’t care it, rather wear it out in two years so you get your money’s worth when it’s 90% dead instead of when it’s 10% dead but still unusable. Too bad really.
Before you toss this, can you take clear pictures of the front and back side of the printed circuit board like others have done. I just repaired one of these for a neighbor. If yours is similar, there may be a fix.
 

DocOfRock2000

Feb 23, 2024
3
Joined
Feb 23, 2024
Messages
3
Before you toss this, can you take clear pictures of the front and back side of the printed circuit board like others have done. I just repaired one of these for a neighbor. If yours is similar, there may be a fix.
I know 8V reg is messy as I took it out and put it back in. 12V in and 8V out ok. Vss on the TA8227P audio chip on pins 1 and 12 is about 13V. And both heat sinks get warm on this and the B1366 TO220 3 pin. Please let me know what you think. I believe it’s something simple but critical as I call it. The output 1000uF caps to speakers are good too I want to say ~6VDC on the chip side pins 2 & 11, and 0DC on speaker side as would be normal. Attached a data sheet page too for you. Thanks!
 

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H2814D

Nov 4, 2017
214
Joined
Nov 4, 2017
Messages
214
I know 8V reg is messy as I took it out and put it back in. 12V in and 8V out ok. Vss on the TA8227P audio chip on pins 1 and 12 is about 13V. And both heat sinks get warm on this and the B1366 TO220 3 pin. Please let me know what you think. I believe it’s something simple but critical as I call it. The output 1000uF caps to speakers are good too I want to say ~6VDC on the chip side pins 2 & 11, and 0DC on speaker side as would be normal. Attached a data sheet page too for you. Thanks!
Well I will just tell you what I did to fix the other one. On the component side, C1, a 220uF 16V capacitor had gone bad. This prevented the smd voltage regulator (IC1) on the other side of the board from turning on. I replaced the capacitor (C1) and the regulator worked afterward, as did the rest of the radio. You might want to give it a try.

It looks like you did something to IC1 already. You should check your solder connections there, because looking at it closer, it doesn't appear as if the lower right leg is soldered to the pad sufficiently. Actually, both lower legs should be redone. Keep the heat on the pin, the solder, and the pad a bit longer, until you see the solder melt and flow onto the pad. Flux helps. After replacing C1, let us know what happens.
 
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