Dewalt DCR020 Power Board – No Power, Need Help Identifying ICs / Possible Replacement

[snipersquad100]

Hi all,

I’m working on a Dewalt DCR020 jobsite radio that won’t power on.
So far, I’ve checked the following:

• The mains is reaching the transformer
• Transformer outputs ~15-20 V AC
• Bridge rectifier outputs ~15-20 V DC
• All fuses test OK
• The on/off button signal reaches the PCB connector

Despite this, the unit does not power up at all.

Inside, I’ve identified some of the ICs:

• ST7317 (appears to be an LCD driver, not the main MCU)
• LM2937L (voltage regulator)Not putting out power, 0.5V on the input
• Markings like FS1235, unknown IC
• Board number: BG0260756A-T53

The on/off signal goes to pins 1 &2 of the ribbon cable opposite the red wire. It goes into the CD4011, where it goes in and out of 3 and gates, then disappears under the DAB daughter board, where I can not pick it back up.
Can't find an MCU


At this point, I’m wondering:

1. Does anyone have a schematic for the DCR020?
2. Can anyone help identify the above ICs (especially FS1235)?
3. Has anyone repaired one of these and found the common failure points?

Photos attached of the power board for reference.

Any advice or experience with these Dewalt radios would be greatly appreciated!

Thanks,
Snipersquad100

---

[madan1]

1. Can anyone help identify the above ICs (especially FS1235)? ------------------ The Kino 3 baseband processor is the latest generation of integrated system-on-chip,
   providing an optimised solution for WorldDMB Profile 1 DAB/DAB+/DMB-R and FM-RDS... https://www.electronicsdatasheets.co...d00.pdf?format

p.s. fun fact - According to this https://**************/dump/audio/ma.../73-1-0-100715 Makita dmr104 uses the same daughterboard/"brain".. unfortunately, still no schematics.
So I guess just start with the standard procedure - checking for shorts on caps and following the power rails.

I can't read the text on the eeprom, but according to the (censored) russian website above, it should be AT45DB041E. If so, when the unit is connected to power, there must be 1.65V - 3.6V on pins 6 and 7. I do not see any power converters on the daughter board (at least on top) so most likely all ICs on it use the same power rail.


And just found that http://www.df7sx.de/wp-content/uploads/2014/08/Verona_PB.pdf
board pinout - https://www.df7sx.de/wp-content/uploads/2014/08/radiowerkstatt_schema.pdf

[snipersquad100]

Thank you very much, I thought the daughter board was just a generic DAB radio module. Thank you for your help.

[stj]

dab radio's are a pain in the ass,
not only are there over a dozen modules, every radio uses different firmware to configure the display and controls.

[snipersquad100]

I need to know where the power on/off signal goes to see why it's not turning on. I need to desolder the daughter board so I can follow the track.

[madan1]

Just noticed that the link for the pinout is corrupted. Here it is https://www.df7sx.de/wp-content/uploads/2014/08/radiowerkstatt_schema.pdf
In this case for enable/stand_by is used pin 13 and it goes to transistor Q4 that enables mosfet Q3. Q3 switches on the power supply for the power amp.. so I guess the easiest way for you will be to follow back the power supply for the amp. TDA2009A gets power on pin9 so follow it from there.
Anyways, in order to have enable/st_by signal, the board must have power - 1.2V and 3.3 on pins 1 and 2. If you do not have those rails when the unit is plugged, do not expect to see any enable signal.