Having an issue with this thing.Unit powers up normally and relay closes.Draws about 1 amp and replaced the hip4080.Has no drive signal to output fets with 100hz drive signal.Rail voltage and +/- 15 is there as well.Have triangle wave on pin 6 and square wave on pin 7.Pin 5 only has 2.5 + vdc.Seems the 4080 isn't producing output and I dont know why.There's also a pic of the 4080 area where a 10R resistor is burnt and the film cap with red marks on it exploded and had to be replaced.
4080 pin voltages +vdc with ground as reference
1.13.1
2.13.5
3..054
4..063
5.2.5
6.6.7
7.7.0
8.5.2
9.5.2
10.13.1
11..067
12..067
13.13.5
14..063
15.13.4
16. 0? (Perhaps I wrote it down wrong,not sure if its important now)
17..051
18.13.5
19..073
20..066
4080 pin voltages +vdc with ground as reference
1.13.1
2.13.5
3..054
4..063
5.2.5
6.6.7
7.7.0
8.5.2
9.5.2
10.13.1
11..067
12..067
13.13.5
14..063
15.13.4
16. 0? (Perhaps I wrote it down wrong,not sure if its important now)
17..051
18.13.5
19..073
20..066
Attachments
Which LEDs are lit?
Solder a bridge between legs 1 and 2 on IC4C. What does that change on pins 5, 6 and 7?
Pins 15 and 16 are directly connected and both should have approximately 12v.
Solder a bridge between legs 1 and 2 on IC4C. What does that change on pins 5, 6 and 7?
Pins 15 and 16 are directly connected and both should have approximately 12v.
The green led lights up.No protection and relay clicks.This evening I'll bridge what you recommended.That film capacitor that's marked in the picture with the burnt resistor is for the output side of the 4080 correct?If so,any idea what caused it? I'm assuming just a bad 4080 because the original 4080 made the amp draw excessive current.There's no shorted output either.
The resistor and capacitor are in series and are connected to the output filter inductor.
If the capacitor shorted, that would have caused the resistor to overheat.
If the capacitor shorted, that would have caused the resistor to overheat.
I apologize.I only scoped pin 5 and checked voltages on 6,7. No,no square wave on pin 7(which is lm833 output I believe).To confirm,output on ic4c is straight DC voltage.
Pin5-2.6 vdc +
Pin6-6.7 vdc +
Pin7-6.9vdc+
Pin5-2.6 vdc +
Pin6-6.7 vdc +
Pin7-6.9vdc+
Does IC4C produce audio on pin 1?
If so, do you see modulation of the square wave on pin 5 of the 4080?
If so, do you see modulation of the square wave on pin 5 of the 4080?
There still bridged.Just straight dc voltage now.Before bridging there was square wave I believe on pin 1 and a not so perfect 100hz wave on pin 2.
Post the DC voltage on all terminals of IC4C with the jumper in place from 1-2. Also go back and confirm that you have the same voltage on pins 15 and 16.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Last edited:
1.6.9
2.6.9
3.6.9
4..084
5.6.6
6.6.6
7.6.9
8.13.5
15/16. .078 +vdc
I had several new 4080's and I've swapped them twice now out of curiosity.Perhaps there cheap junk ones.I've had them for quite a while and they may have came from china.This was before reading and understanding of counterfeit parts.Not 100% though.
2.6.9
3.6.9
4..084
5.6.6
6.6.6
7.6.9
8.13.5
15/16. .078 +vdc
I had several new 4080's and I've swapped them twice now out of curiosity.Perhaps there cheap junk ones.I've had them for quite a while and they may have came from china.This was before reading and understanding of counterfeit parts.Not 100% though.
I don't quite understand the 15/16...
15 and 16 have to be at or near 12v. If the voltage is intermittent there, you may have a problem with the regulator, although it looks OK by the numbers on the op-amp. If the regulator is OK, it's possible that there is a problem with the socket if 15 and/or 16 don't have 12v. I also checked to see if the 4080 will work without pin 16 powered. It seemed to work, at least at a basic level (outputs had rail-rail square wave).
I tested an amp here in protect mode (I know yours isn't in protect but the IC is acting like it's in protect mode) and the square wave on pin 1 of IC4C is OK. It's because it's not getting any feedback from the output stage. I wanted to confirm that IC4C was working OK (it appears OK) to eliminate that as the problem.
Do you have another 4080 based amp that you could try the ICs in?
15 and 16 have to be at or near 12v. If the voltage is intermittent there, you may have a problem with the regulator, although it looks OK by the numbers on the op-amp. If the regulator is OK, it's possible that there is a problem with the socket if 15 and/or 16 don't have 12v. I also checked to see if the 4080 will work without pin 16 powered. It seemed to work, at least at a basic level (outputs had rail-rail square wave).
I tested an amp here in protect mode (I know yours isn't in protect but the IC is acting like it's in protect mode) and the square wave on pin 1 of IC4C is OK. It's because it's not getting any feedback from the output stage. I wanted to confirm that IC4C was working OK (it appears OK) to eliminate that as the problem.
Do you have another 4080 based amp that you could try the ICs in?
The socket for this things about junk its way to narrow.I just changed it again and made triple sure about everything.All results are identical and there IS 13 vdc on 15/16.
I wish I had another 4080 based amp or even a different batch of 4080's.
Should I just order a few 4080's from digikey and try that? From what I understand(which isn't much lol) it should work.Everything seems well.
I wish I had another 4080 based amp or even a different batch of 4080's.
Should I just order a few 4080's from digikey and try that? From what I understand(which isn't much lol) it should work.Everything seems well.
Right. I don't see any problems. If none of the components around the IC are defective, I'd try a new 4080. Digi-key would be a reliable source.
Well,the 4080's must of been counterfeit.Have another issue.The picture with the burnt resistor on page 1 gets really hot instantly and its drawing over two amps of current.Any ideas?
No shorted outputs.
No shorted outputs.
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