working on a kenwood 9102d amp it doesnt do anything doesnt power up no output checked all the power supply transistors and checked outputs they are all fine just wondering it has a coil on the amp or maybe its a transformer in the power supply could that have gone bad?? how do i tell if thats the problem or what else do i check??
As with any amp that will not power up, you need to check the voltage on the pins of the power supply driver IC (TLx94, SG352x...). This will tell you if the amp is in protection, or if the IC isn't getting the required voltage/inputs to allow the power supply to operate.
If you don't know what you're supposed to have on the various pins, post the part number of the IC and the voltage on each pin. Set your meter to DC volts. Place the black meter lead on the amp's ground terminal for all readings. The amp should have +B and remote applied. Be careful not to let the meter's probe slip and short between terminals.
If you don't know what you're supposed to have on the various pins, post the part number of the IC and the voltage on each pin. Set your meter to DC volts. Place the black meter lead on the amp's ground terminal for all readings. The amp should have +B and remote applied. Be careful not to let the meter's probe slip and short between terminals.
driver kenwood
the part is tl4941 working right to left if the chip is in front of u bottom row pin 1 is 0 pin 2=.05 pin3=.05 pin4=.19 pin5=1.19 pin6=3.00 pin7=0 pin8=5.32 top row pin1=0 pin2=4.38 pin3=4.38 pin4=4.38 pin5= 5.28 pin6 =5.28 pin7=2.20 pin8=2.20
wondering if this chip is bad or what please help me out and let me know i appericate all the help
the part is tl4941 working right to left if the chip is in front of u bottom row pin 1 is 0 pin 2=.05 pin3=.05 pin4=.19 pin5=1.19 pin6=3.00 pin7=0 pin8=5.32 top row pin1=0 pin2=4.38 pin3=4.38 pin4=4.38 pin5= 5.28 pin6 =5.28 pin7=2.20 pin8=2.20
wondering if this chip is bad or what please help me out and let me know i appericate all the help
Download this and notice how the pins are numbered.
http://focus.ti.com/lit/ds/symlink/tl494.pdf
There is insufficient voltage on pins 8, 11 and 12. The IC seems to be working and the amp would likely power up if you restore the voltage supply to those pins. The voltage is likely supplied by a PNP transistor. If so, the 'input' of the transistor will on pin 1 (emitter). The output to the IC will be on pin 2 (collector). This assumes that the transistor is in a to-92 style case (or similar).
http://focus.ti.com/lit/ds/symlink/tl494.pdf
There is insufficient voltage on pins 8, 11 and 12. The IC seems to be working and the amp would likely power up if you restore the voltage supply to those pins. The voltage is likely supplied by a PNP transistor. If so, the 'input' of the transistor will on pin 1 (emitter). The output to the IC will be on pin 2 (collector). This assumes that the transistor is in a to-92 style case (or similar).
kenwood amp
it looks like the transistors that supply voltage to pins 1 and 2 are like the mmbt3906 but there is no marking on theese transistors and no board locations just wondering what i might be able to do to find out what parts to buy to replace theese because when i check them i get no reading at all on the 2 transistors
it looks like the transistors that supply voltage to pins 1 and 2 are like the mmbt3906 but there is no marking on theese transistors and no board locations just wondering what i might be able to do to find out what parts to buy to replace theese because when i check them i get no reading at all on the 2 transistors
If all else fails, you can order a service manual for the amp. It will have the part numbers.
The transistor in question would supply voltage to pins 8, 11 and 12. Not pins 1 and 2 of the IC.
Kenwood uses 'digital' transistors that have built in biasing resistors. These can be difficult to check. The transistor that's going to be used to supply voltage to the 494 is going to be a standard transistor which should be easy to check (although you may have to remove it from the board to do so definitively).
Are you sure that there are no markings?
Use a lighted magnifying glass to be sure. You can also apply a tiny bit of heatsink compound to the top of the transistor then wipe it off. It will remain in the etched markings and will make it easier to read the numbers.
The transistor in question would supply voltage to pins 8, 11 and 12. Not pins 1 and 2 of the IC.
Kenwood uses 'digital' transistors that have built in biasing resistors. These can be difficult to check. The transistor that's going to be used to supply voltage to the 494 is going to be a standard transistor which should be easy to check (although you may have to remove it from the board to do so definitively).
Are you sure that there are no markings?
Use a lighted magnifying glass to be sure. You can also apply a tiny bit of heatsink compound to the top of the transistor then wipe it off. It will remain in the etched markings and will make it easier to read the numbers.
mike49504:
Measure the DC voltage on the pins of Q3. Black meter lead on the ground terminal of the amp.
With power and remote applied to the amp, pin 1 of Q3 should have the same voltage as the B+ terminal.
The middle pin should have approximately 0.1 v less than pin 1.
Pin 3 of Q3 should have ~0.6 volts less than pin 1 of Q3.
docfin:
Thanks for the quick delivery.
Measure the DC voltage on the pins of Q3. Black meter lead on the ground terminal of the amp.
With power and remote applied to the amp, pin 1 of Q3 should have the same voltage as the B+ terminal.
The middle pin should have approximately 0.1 v less than pin 1.
Pin 3 of Q3 should have ~0.6 volts less than pin 1 of Q3.
docfin:
Thanks for the quick delivery.
Which transistor failed? It may help lead to other problems.
Do you have both positive and negative rail voltage?
What about + and - regulated voltage on the op-amps?
Do you have all of the boards plugged in?
Are the cables between the boards properly seated?
If you have to trace the signal, you'll either need a scope or something like the radio shack mini amplifier. The former is best. the latter is OK but only for low level audio.
RS Catalog #: 277-1008
If you buy one, you'll need a cable to plug into the input of the RS MA. The other end of the cable will be cut off. You'll either solder test leads or alligator clips to it.
If you continue to do this type of work, you'll need to buy AND use a scope (I know several people who purchased scopes but refuse to learn to use them).
Do you have both positive and negative rail voltage?
What about + and - regulated voltage on the op-amps?
Do you have all of the boards plugged in?
Are the cables between the boards properly seated?
If you have to trace the signal, you'll either need a scope or something like the radio shack mini amplifier. The former is best. the latter is OK but only for low level audio.
RS Catalog #: 277-1008
If you buy one, you'll need a cable to plug into the input of the RS MA. The other end of the cable will be cut off. You'll either solder test leads or alligator clips to it.
If you continue to do this type of work, you'll need to buy AND use a scope (I know several people who purchased scopes but refuse to learn to use them).
where the diodes and big transistors are right behing them a transistor was bad c1845 replaced it and amp came on but no output u said op amps im a idiot i dont know where the are on the amp or what there labled just wondering how do i check thoose and what else do i check i have no scope but im gonna buy one in a few weeks all i have is a multimeter
The transistor you changed has nothing to do with the voltage feeding the TLx94 IC. What did you do to get the voltage to the TLx94 back to 12 volts (on pins 8, 11 and 12)?
The transistor you changed is part of the 15v regulator.
Download the datasheets for the op-amps. This is one of them. Checking these alone should tell you if the regs are working properly.
http://www.njr.co.jp/pdf/ae/ae04056.pdf
I think too many people avoid datasheets because they're too technical. You don't have to understand everything on it. All you need is the pin-out configuration.
Make sure that you have both positive and negative voltage on the output transistors.
The transistor you changed is part of the 15v regulator.
Download the datasheets for the op-amps. This is one of them. Checking these alone should tell you if the regs are working properly.
http://www.njr.co.jp/pdf/ae/ae04056.pdf
I think too many people avoid datasheets because they're too technical. You don't have to understand everything on it. All you need is the pin-out configuration.
Make sure that you have both positive and negative voltage on the output transistors.
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