just measured the outputs ,ps fets and fen/p16 diodes
-------------------------------
outputs/emitter resistors
37 vdc for positive rail
-37 vdc for negative rail
all measure the same
-------------------------------
ps fets/gate resistors
1.79 vdc
all measure the same
-----------------------------
for the fen/p16 diodes
the negative diode is at 0.002 for the middle leg and 9.9 for both outer legs.
positive diode is at 19.9 middle leg, and 9.9 for both outer legs
is this normal?
ps...make sure you read my other post before this one in case you missed it...
-------------------------------
outputs/emitter resistors
37 vdc for positive rail
-37 vdc for negative rail
all measure the same
-------------------------------
ps fets/gate resistors
1.79 vdc
all measure the same
-----------------------------
for the fen/p16 diodes
the negative diode is at 0.002 for the middle leg and 9.9 for both outer legs.
positive diode is at 19.9 middle leg, and 9.9 for both outer legs
is this normal?
ps...make sure you read my other post before this one in case you missed it...
Using the 2n transistors should make no difference in performance.
They will not drive the outputs any harder.
They will run slightly cooler than the U07/57 because they have ore surface area. If you want it to look better, mount them under the board like the large rectifiers. Use short pieces of wire to connect them to the board. If you're lucky, you may be able to get the collector and base legs to go directly into the board. Then you'd only have to hard wire the emitter.
They will last as long as or longer than the U07/57s.
Those voltages look OK except for the negative rectifier. I would expect it to have -20v (approximately) on the center leg.
To determine if you ammeter is correct, connect the power resistor in series with the main power wire and measure the voltage across it. Using Ohm's law, you can determine the current flow.
If you find that the amp is actually drawing 10 amps of current, it could be due to a short in the negative rectifier circuit. If the ammeter is not accurate and there is no excessive current draw, the rectifier may be open.
They will not drive the outputs any harder.
They will run slightly cooler than the U07/57 because they have ore surface area. If you want it to look better, mount them under the board like the large rectifiers. Use short pieces of wire to connect them to the board. If you're lucky, you may be able to get the collector and base legs to go directly into the board. Then you'd only have to hard wire the emitter.
They will last as long as or longer than the U07/57s.
Those voltages look OK except for the negative rectifier. I would expect it to have -20v (approximately) on the center leg.
To determine if you ammeter is correct, connect the power resistor in series with the main power wire and measure the voltage across it. Using Ohm's law, you can determine the current flow.
If you find that the amp is actually drawing 10 amps of current, it could be due to a short in the negative rectifier circuit. If the ammeter is not accurate and there is no excessive current draw, the rectifier may be open.
alright im gonna go for it and put in the 2NE's....hope it works out
about the negative rectifier, i think i measured it wrong...i put the black lead on the B- and the red lead on the middle leg.
so i tried putting the red lead on B+ and put the black lead on the middle lead...14 vdc .....is this the right way to measure it?
just wondering, if you have a transistor that checks out ok, but is 10 years old, will the output still be the same as it were new?
because these 2NE's i plan on using are oem orion from other amps i pulled them from...my other alternative are the BD911/912's....which i have been using in place of the 2NE's.
well , i'll let you know how the modification goes...and Thanx!!!
about the negative rectifier, i think i measured it wrong...i put the black lead on the B- and the red lead on the middle leg.
so i tried putting the red lead on B+ and put the black lead on the middle lead...14 vdc .....is this the right way to measure it?
just wondering, if you have a transistor that checks out ok, but is 10 years old, will the output still be the same as it were new?
because these 2NE's i plan on using are oem orion from other amps i pulled them from...my other alternative are the BD911/912's....which i have been using in place of the 2NE's.
well , i'll let you know how the modification goes...and Thanx!!!
Use the secondary center tap or the RCA shield ground on the amp for the reference point (black meter lead). The red lead would go to the center leg of the negative rectifier. The voltage should be approximately the same as on the positive rectifier but with the opposite polarity.
10 year old transistors may still meet spec in some ways (Hfe, threshold voltage, leakage...) but if driven hard, they may be more likely to fail. I'd strongly suggest using new transistors. Although I don't have any experience with them, the BD911/912 should work as well as the 2N6488/91.
If your used transistors were in parallel with a transistor that failed, I'd suggest against using them for any repair. If one transistor of the set was subjected to a load that destroyed it, the others may be weakened or otherwise damaged. Transistors are cheap. If one fails, it can take out many more. You should always use new parts.
10 year old transistors may still meet spec in some ways (Hfe, threshold voltage, leakage...) but if driven hard, they may be more likely to fail. I'd strongly suggest using new transistors. Although I don't have any experience with them, the BD911/912 should work as well as the 2N6488/91.
If your used transistors were in parallel with a transistor that failed, I'd suggest against using them for any repair. If one transistor of the set was subjected to a load that destroyed it, the others may be weakened or otherwise damaged. Transistors are cheap. If one fails, it can take out many more. You should always use new parts.
im stumped on the negative rectifier, i checked the fen/p16 as well as the fen/p30 underneath ... check the a0/56 drive transistors as well... all were good.
how is it that the output transistors are still getting a negative rail voltage as well as a positive rail? if that rectifier isnt giving a
-20vdc voltage reading?
TL494 defective?
how is it that the output transistors are still getting a negative rail voltage as well as a positive rail? if that rectifier isnt giving a
-20vdc voltage reading?
TL494 defective?
Now you've done it! You made me learn something new.
The two FEx16 rectifiers are used to generate a 20 volt supply that's used to generate a secondary voltage source for the power supply drive circuit. This is similar to the circuit in the punch amps but much more complex.
I believe they use this type of circuit to insure that the drive voltage never drops too low even if the B+ voltage drops.
The center leg of the negative rectifier is grounded. The outer legs are connected to the extra, isolated winding of the power transformer (near the negative rectifier).
In operation, the negative rectifier simply prevents the voltage on the winding from going significantly below ground (sort of the same function as in a voltage doubler circuit -- the type using diodes and capacitors).
The center leg of the negative rectifier should be at 0v.
The large rectifiers under the board supply the rail voltage.
The 494 is OK.
The two FEx16 rectifiers are used to generate a 20 volt supply that's used to generate a secondary voltage source for the power supply drive circuit. This is similar to the circuit in the punch amps but much more complex.
I believe they use this type of circuit to insure that the drive voltage never drops too low even if the B+ voltage drops.
The center leg of the negative rectifier is grounded. The outer legs are connected to the extra, isolated winding of the power transformer (near the negative rectifier).
In operation, the negative rectifier simply prevents the voltage on the winding from going significantly below ground (sort of the same function as in a voltage doubler circuit -- the type using diodes and capacitors).
The center leg of the negative rectifier should be at 0v.
The large rectifiers under the board supply the rail voltage.
The 494 is OK.
***Clipped smacks himself on forehead*** 
hey man, you had me scared with that first sentence...
i was wondering what those wires were for by the neg rectifier, i thought they were just there to confuse me .
a power supply for the power supply.... sure dont make em like they use to...
speaking of 'punch' i have an oldschool punch 75 with a ps problem, i turned those pots and poooffffff.... i smell another post coming on .
will start bending 2NE legs tomorrow...
hey man, you had me scared with that first sentence...
i was wondering what those wires were for by the neg rectifier, i thought they were just there to confuse me .
a power supply for the power supply.... sure dont make em like they use to...
speaking of 'punch' i have an oldschool punch 75 with a ps problem, i turned those pots and poooffffff.... i smell another post coming on .
will start bending 2NE legs tomorrow...
Dear Clipped,
I have not notticed the pin order like Perry Barbin. All my suggestions based on normal pin numbers. But, I saw you are measuring true things on TL494 and it is not defective. I want to get you repairing PS(power supply) at first. So, I again suggest you to remove the FEP/N16 diodes. Then make sure your amp(PS) does not exceeds 1 or 2 amps(20 amps is still much more).But, I am feeling, you have a defective part on your circuit's (amp section) negative rail. Because you should read same voltage readings for positive and negative rails. The defective part probably one of output transistor. I do not know your circuit. All my suggestions based on experience on repairing/building car amps.(because all of them have similar circuits)
Regards
I have not notticed the pin order like Perry Barbin. All my suggestions based on normal pin numbers. But, I saw you are measuring true things on TL494 and it is not defective. I want to get you repairing PS(power supply) at first. So, I again suggest you to remove the FEP/N16 diodes. Then make sure your amp(PS) does not exceeds 1 or 2 amps(20 amps is still much more).But, I am feeling, you have a defective part on your circuit's (amp section) negative rail. Because you should read same voltage readings for positive and negative rails. The defective part probably one of output transistor. I do not know your circuit. All my suggestions based on experience on repairing/building car amps.(because all of them have similar circuits)
Regards
Connect the resistor in series with the B+ line (one end to the DC power supply and the other end to the amp's B+ wire).
Meter set to DC volts.
One lead on each end of the resistor.
Apply remote voltage to power up the amp.
Read the DC voltage across the resistor.
V=I*R rearanged to I=V/R
V = voltage across the resistor.
R is the resistors value (ohms).
I = current passing through the resistor into the amp.
Compare the ammeter reading to the calculated current.
Meter set to DC volts.
One lead on each end of the resistor.
Apply remote voltage to power up the amp.
Read the DC voltage across the resistor.
V=I*R rearanged to I=V/R
V = voltage across the resistor.
R is the resistors value (ohms).
I = current passing through the resistor into the amp.
Compare the ammeter reading to the calculated current.
0.722 ? i use this number? i wasnt so sure because it looks so low.
so I=V/R
would be
I=0.722/0.8
I= 0.9025
seriously , it couldnt be that low coud it? well assuming the signal drivers arent in place...maybe?
this is with voltage at approx 13.1 vdc measured before the resistor
so I=V/R
would be
I=0.722/0.8
I= 0.9025
An externally hosted image should be here but it was not working when we last tested it.
seriously , it couldnt be that low coud it? well assuming the signal drivers arent in place...maybe?
this is with voltage at approx 13.1 vdc measured before the resistor
Hi Clipped,
Kocaeli is a city from Turkey. Perry Barbin more experienced on your amp and his suggestions are correct. Any way, most of car amplifiers could draw only a few amps while working without sound input/output. For eg. I am using a 12V 1A (can give 5A peak)DC power supply to test if an amp is working or not. If it is not working with this power then usually i am firstly checking the power supply section and then the output transistors. This is a safety way not to blow the pcb traces. When all the repair finish, I am testing it with 14.4V 40A SMPS which is made by me.
Kind regards
Kocaeli is a city from Turkey. Perry Barbin more experienced on your amp and his suggestions are correct. Any way, most of car amplifiers could draw only a few amps while working without sound input/output. For eg. I am using a 12V 1A (can give 5A peak)DC power supply to test if an amp is working or not. If it is not working with this power then usually i am firstly checking the power supply section and then the output transistors. This is a safety way not to blow the pcb traces. When all the repair finish, I am testing it with 14.4V 40A SMPS which is made by me.
Kind regards
well.....put the 2NE's in .... and it went back to maxing out the ammeter at 100 amps again.... i did this after , putting the capacitor inline, becuse i thought something was fishy 
........ ............ 
.........
the orange channel is putting out -7 vdc
the yellow channel is putting out .035 to .045vac
checked the rest of the Ao6/A56....all were good but changed them anyway...
im gonna go get drunk now...
........ ............ ......... the orange channel is putting out -7 vdc
the yellow channel is putting out .035 to .045vac
checked the rest of the Ao6/A56....all were good but changed them anyway...
im gonna go get drunk now...
With the series resistor in line, your meter set to DC volts and the amp on, measure the voltage across EACH emitter resistor in the channel producing DC.
Do they all have approximately the same voltage?
What's the voltage across them (assuming they're all the same)?
Are you 100% sure you have the replacements wired correctly AND have the replacements in the correct locations (NPN/PNP)?
Have you cleaned the flux from the solder connections so you could see if there are any solder bridges?
If not, have you checked for solder bridges or shorted components with your ohm meter?
Have you measured the base-emitter voltage for all of the output transistors?
Compare the B-E voltage of the good channel to the bad channel.
Post the B-E voltages for the NPN and PNP output transistors of both channels (4 voltages) if the all of the NPNs and all of the PNPs in each channel match (±10%).
Do they all have approximately the same voltage?
What's the voltage across them (assuming they're all the same)?
Are you 100% sure you have the replacements wired correctly AND have the replacements in the correct locations (NPN/PNP)?
Have you cleaned the flux from the solder connections so you could see if there are any solder bridges?
If not, have you checked for solder bridges or shorted components with your ohm meter?
Have you measured the base-emitter voltage for all of the output transistors?
Compare the B-E voltage of the good channel to the bad channel.
Post the B-E voltages for the NPN and PNP output transistors of both channels (4 voltages) if the all of the NPNs and all of the PNPs in each channel match (±10%).
orange channel
emitter= 7.38 and -7.34
base = 6.99 and -6.85
yellow channel
emitter = 7.47 and -7.41
base = 7.46 and -7.40
this is how the drivers were oriented when i got the amp:
im gonna pull out a pair of 2nes at a time, to see if i can find a problem pair.
emitter= 7.38 and -7.34
base = 6.99 and -6.85
yellow channel
emitter = 7.47 and -7.41
base = 7.46 and -7.40
this is how the drivers were oriented when i got the amp:
An externally hosted image should be here but it was not working when we last tested it.
im gonna pull out a pair of 2nes at a time, to see if i can find a problem pair.
when i take this pair out, the emitter goes to +/-37 volts as well as the base.
after taking out that pair the orange channel is still getting
-6.3vdc on the speaker outputs
the ammeter doesnt jump up after taking that pair out.
and the power LED doesnt come on.
looking at this pic, i cant really seem to determine the orientation of the orange channel drivers , but it looks like the adjacent pair is backwards. (cant tell)
after taking out that pair the orange channel is still getting
-6.3vdc on the speaker outputs
the ammeter doesnt jump up after taking that pair out.
and the power LED doesnt come on.
An externally hosted image should be here but it was not working when we last tested it.
looking at this pic, i cant really seem to determine the orientation of the orange channel drivers , but it looks like the adjacent pair is backwards. (cant tell)
An externally hosted image should be here but it was not working when we last tested it.
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