Hello everyone,
I am having issues with 2 RCF HDL-20A amplifiers which fail to power on. Unfortunately the manufacturer does not provide any sort of schematics which makes this a very difficult repair for someone such as myself with medium level knowledge working with electronics.
Both of these amps had shorted mMosfets '6R190C6' as well as Driver IC 'S21531D' which have been replaced. Also replaced the 2 big electrolytic capacitors, the fuse, some burned SMD resistors (all on the power/hot side).
Checked remaining SMD resistors & transistors and the values match with those from a working amp.
A guy from another country told me to check voltage at the SMD capacitor shown in the pictures because it should get 14-15 volts otherwise the amp will not power on. When I measure a working amp the volts are indeed what he said but for the ones that do not power on the voltage is low and the cap is only getting 8.5 volts.
Problem is, I don't know where the SMD capacitor in question gets its voltage from or which component(s) are responsible for supplying the proper volts.
Anyone have any ideas? I labelled the main components on the power side of the main board on the first picture. The second picture zooms into the area with the capacitor in question. The third picture is a bit of a mess showing the path of continuity between the different components.
1 & 2: Big electrolytic caps. Have been replaced.
3: 1BW Transistor
4: SMD capacitor with the low voltage. Is it supposed to be 1μF?
5: S21531D: Driver IC. Has been replaced with IRS21531D.
6: LMC555CM: CMOS Timer.
7 & 8: 6R190C6 N-Channel Mosfets - Have been replaced with exact match.
9: 4702 SMD resistor = 47kΩ. On working system (still attached to the board) it reads 26.68kΩ vs. 40kΩ on faulty one.
10: U1JB: Ultrafast Rectifier Diode
There is a gentleman around in these forums who commented on another thread saying he has fixed tons of these so I am hoping he can chime in. He goes by Cresnet "cresnet.239809" but in reality any feedback will be much appreciated.
I am having issues with 2 RCF HDL-20A amplifiers which fail to power on. Unfortunately the manufacturer does not provide any sort of schematics which makes this a very difficult repair for someone such as myself with medium level knowledge working with electronics.
Both of these amps had shorted mMosfets '6R190C6' as well as Driver IC 'S21531D' which have been replaced. Also replaced the 2 big electrolytic capacitors, the fuse, some burned SMD resistors (all on the power/hot side).
Checked remaining SMD resistors & transistors and the values match with those from a working amp.
A guy from another country told me to check voltage at the SMD capacitor shown in the pictures because it should get 14-15 volts otherwise the amp will not power on. When I measure a working amp the volts are indeed what he said but for the ones that do not power on the voltage is low and the cap is only getting 8.5 volts.
Problem is, I don't know where the SMD capacitor in question gets its voltage from or which component(s) are responsible for supplying the proper volts.
Anyone have any ideas? I labelled the main components on the power side of the main board on the first picture. The second picture zooms into the area with the capacitor in question. The third picture is a bit of a mess showing the path of continuity between the different components.
1 & 2: Big electrolytic caps. Have been replaced.
3: 1BW Transistor
4: SMD capacitor with the low voltage. Is it supposed to be 1μF?
5: S21531D: Driver IC. Has been replaced with IRS21531D.
6: LMC555CM: CMOS Timer.
7 & 8: 6R190C6 N-Channel Mosfets - Have been replaced with exact match.
9: 4702 SMD resistor = 47kΩ. On working system (still attached to the board) it reads 26.68kΩ vs. 40kΩ on faulty one.
10: U1JB: Ultrafast Rectifier Diode
There is a gentleman around in these forums who commented on another thread saying he has fixed tons of these so I am hoping he can chime in. He goes by Cresnet "cresnet.239809" but in reality any feedback will be much appreciated.
Attachments
Issue resolved.
In one amplifier I had to change the SMD capacitor (1μF) to the right of the one mentioned above which was not receiving the 15VDCs and above the resistor marked 1089 plus the change of the 1BW transistor, driver IC S21531D and the 6R190C6 mosfets. The second one I had to change the same components except the SMD capacitor (1μF). Another issue is that the S21531D doesn't like to be soldered with hot air; I had to do it with a soldering iron.
In one amplifier I had to change the SMD capacitor (1μF) to the right of the one mentioned above which was not receiving the 15VDCs and above the resistor marked 1089 plus the change of the 1BW transistor, driver IC S21531D and the 6R190C6 mosfets. The second one I had to change the same components except the SMD capacitor (1μF). Another issue is that the S21531D doesn't like to be soldered with hot air; I had to do it with a soldering iron.