hi,
Need help. Can anyone help me find the SMD part number of Q32 and Q33, as shown encircled red in the image of Sound MAgus DK1800 amp, They are blown as it is impossible for me to see the part number. Thanks a lot brothers in advance.
Need help. Can anyone help me find the SMD part number of Q32 and Q33, as shown encircled red in the image of Sound MAgus DK1800 amp, They are blown as it is impossible for me to see the part number. Thanks a lot brothers in advance.
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These are not critical. If the circuit fits the following diagram, there are a lot of options. One is an NPN, the other a PNP. I use the MMBTA06 and MMBTA56.
http://www.bcae1.com/temp/SLA1500.pdf
http://www.bcae1.com/temp/SLA1500.pdf
Good day. So i came back repairing the Sound Magus mono amp, it had a blown power supply Fets STP60NF06, i replaced 6 of them. I replaced also 4 blown buffer transistors as replacement values from Perry MABTA56 and MMBTA06 and the driver chip TL494. At power on i got the blue light and drive square wave gate signal from pin 9 and 10 of the chip TL494. But then suddenly the signal from pin 10 went out, thinking of a bad solder i resoldered it again but when i applied power with Rem the output signal became just spikes from pin 9 and 10. I suspectedt that i damaged the chip, so i replaced it with new one, but now i don't get anymore drive signal from the chip. I got the TL494 from Aliexpress, are they reliable chips from China? I had checked again the chip Vcc ,buffer transistors , resistors in the drive circuit and they are all good. Please advice why i don't get signal, by the way i replaced it 3 times already.
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Post the DC voltage on all terminals of the 494. Copy and paste the following list and fill in the blanks.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:
TL 494 pin voltage with respect to ground: the amp in Protect mode
Pin 1: 0 vdc
Pin 2: 4.98
Pin 3: 4.74
Pin 4: 0
Pin 5: 1.482
Pin 6: 3.61
Pin 7: 0
Pin 8: 12.66
Pin 9: 0.143
Pin 10: 0.122
Pin 11: 12.66
Pin 12: 12.66
Pin 13: 4.98
Pin 14: 4.98
Pin 15: 2.044
Pin 16: 4.18
Pin 1: 0 vdc
Pin 2: 4.98
Pin 3: 4.74
Pin 4: 0
Pin 5: 1.482
Pin 6: 3.61
Pin 7: 0
Pin 8: 12.66
Pin 9: 0.143
Pin 10: 0.122
Pin 11: 12.66
Pin 12: 12.66
Pin 13: 4.98
Pin 14: 4.98
Pin 15: 2.044
Pin 16: 4.18
I don't have the exact diagram for this amp. Do you have a Q14 that has its collector connected to pin 16 of the 494?
If so, lift it to see if the amp will power up.
If so, lift it to see if the amp will power up.
I don't find one, but sorry i found their was a shorted transistor BCX52-10 of its collector connected to pin 11 & 12. I missed checking it maybe. I removed it but amp won't power up because pin 12 is the Vcc pin right? I don't have the part at the moment. Let me get back to you once i got it. Thanks you so much as always Perry.
If you can, post photos of various areas of the board in good enough quality that I can read the part markings and the circuit board designations.
Yes. Pin 12 is the 12v supply pin. If it's the switching transistor between B+ and pin 12, you can jump it collector to emitter. If the transistor was shorted c-e, it was nothing more than a jumper.
Yes. Pin 12 is the 12v supply pin. If it's the switching transistor between B+ and pin 12, you can jump it collector to emitter. If the transistor was shorted c-e, it was nothing more than a jumper.
Actually b-c-e of the transistor was shorted. Emitter is directly connected to 12v supply. I pulled out the transistor and jumped C-E and it powers but on protect mode. Is the chip be damaged again because of the transistor earlier shorted? I will try to send clear photos of the supply side. Thanks.
Good day bro. Can you please provide the value of the capacitor connected to Pin # 5 of TL494, this is providing the saw tooth signal to pin #5. A bad day for me , some frustrations in my recent repairs maybe, I accidentally broke it while cleaning the carbon traces. I ordered some 494 also from Rs Electronics, still waiting for them just to removed my doubts of the chips i ordered from AliAxpress. Let me see the outcome.Anyway, i hope you can provide me the capacitance value bro. Thanks
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OK thanks bro. Let me replace it , with the new 494 from RsElectronics i ordered and recheck the Vdc of each pins &post it.
Just want to close my thread jus a tip for those who had the same problem. Amp now working in perfect condition. Replaced TL 494 driver chip and 2 driver transistors MABTA56 and MMBTA06 in each bank of the power supply , one capacitor 2200pf for the saw tooth signal on Pin 5. Replaced new power FETS as well . Just took time because of broken traces on the board. But mind you this amp will be in protect mode if the output FETs are not installed so make sure drive signals are all present in each bank before installing new Fets. Again, Thank you Perry for the timely guidance.