Hi All, i have a Mosconi AS 200.4, channel 2 is very quiet compared to the others, around 3-4 db. I have checked and swapped everything to make sure the fault doesnt follow and fault stays the same - ch 2 only. Any ideas? thank you in advance.
Have you tried operating all of the pots and switches through their entire range with a signal source connected and a speaker connected to the weak channel to see if the channel ever improved?
Measure the actual output voltage of the good channel and the weak channel and post the exact AC voltage on each. Drive the good channel up to 10v.
Measure the actual output voltage of the good channel and the weak channel and post the exact AC voltage on each. Drive the good channel up to 10v.
Thankyou, i have not tried any of that as i am very much trying to learn and unsure of componentry. I have the diagram of the board but trying to identify each component
Hi again.
Have operated all pots and switches, no change to either channel, tried all combinations of rca/left/right/single input switch etc. No change. I have tested the AC voltage on both channels, left 0.5v, right 4v tested at 10v, same volume setting. I double checked the output on both channels while checking ac voltage and confirmed there is no change. Thank you.
Have operated all pots and switches, no change to either channel, tried all combinations of rca/left/right/single input switch etc. No change. I have tested the AC voltage on both channels, left 0.5v, right 4v tested at 10v, same volume setting. I double checked the output on both channels while checking ac voltage and confirmed there is no change. Thank you.
I'm confused. If you set the good channel to read 10v, how did you read 4v?
Which of the 4 op-amps near the output section is associated with the weak channel? IC1? IC2?...
Which of the 4 op-amps near the output section is associated with the weak channel? IC1? IC2?...
Set the DCV to somewhere between 12 and 14v.
Do this again.
You said the controls made no difference. I assume that you meant that the difference in the output, weak channel to the normal channel, never improved. All crossover and gain functions changed the output of the amp, correct?
Do this again.
You said the controls made no difference. I assume that you meant that the difference in the output, weak channel to the normal channel, never improved. All crossover and gain functions changed the output of the amp, correct?
Ok, dc supply 14.5, gain halfway, ch1 6v, ch2 12v. Gain full, ch1 10v, ch2 16.
crossovers etc all functional, fault unchanged.
crossovers etc all functional, fault unchanged.
Which of the 4 op-amps near the output section is associated with the weak channel? IC1? IC2?...
Hello again,
I have the following information:
14v supply, source volume half, 500hz tone.
CH1 12V
CH2 6v
When swapping RCA inputs left/right, no change.
CH1 and 2 bridged 12v
CH3 12v
CH4 12v
When testing voltages i found:
CH3pos-ch1pos 12v
CH3pos-CH2neg 6v
CH4pos-CH1pos-12v
CH4neg-CH1pos-12v
CH3neg-CH1pos 12
CH3neg-CH1neg-12v
CH4pos-CH2neg-6v
CH4neg-CH2neg-6v
The op amps are marked CH2,3,4,5, I assume IC4 would be CH4?
I have the following information:
14v supply, source volume half, 500hz tone.
CH1 12V
CH2 6v
When swapping RCA inputs left/right, no change.
CH1 and 2 bridged 12v
CH3 12v
CH4 12v
When testing voltages i found:
CH3pos-ch1pos 12v
CH3pos-CH2neg 6v
CH4pos-CH1pos-12v
CH4neg-CH1pos-12v
CH3neg-CH1pos 12
CH3neg-CH1neg-12v
CH4pos-CH2neg-6v
CH4neg-CH2neg-6v
The op amps are marked CH2,3,4,5, I assume IC4 would be CH4?
The op amps are marked 2,3,4,5, I assume IC4 would be CH4? - sorry i meant i assume CH2 will be IC3
There is a 1uF 50v cap feeding each of those final op-amps. Confirm that the AC voltage on each side of those 4 capacitors is equal.