Anyone come across 1 of these amps basically it’s a 4 channel Class AB Tip35 Tip 36 setup with class D sub
Anyway it’s a brand new amp but always had a fault on 1 of the 4 channels , best way i can describe it is it’s like connecting a 1.5 volt battery to a speaker and messing about with it , it can only be heard when the amp is very low and doesn’t affect the sound quality at all
I have e-mailed rang “midbass” whom are the parent company for advice / circuit diagram with no joy
Anyway it’s a brand new amp but always had a fault on 1 of the 4 channels , best way i can describe it is it’s like connecting a 1.5 volt battery to a speaker and messing about with it , it can only be heard when the amp is very low and doesn’t affect the sound quality at all
I have e-mailed rang “midbass” whom are the parent company for advice / circuit diagram with no joy
anyone familiar ........
IMG_2743.jpg Photo by semisheen | Photobucket
IMG_2742.jpg Photo by semisheen | Photobucket
IMG_2743.jpg Photo by semisheen | Photobucket
IMG_2742.jpg Photo by semisheen | Photobucket
IMG_2750_2.jpg Photo by semisheen | Photobucket
Thank you for your reply
I have uploaded a better picture of the Class AB part what’s got the problem (the rest of the amp is perfect)
The amplifier was crackling with NO preamp board connected, as i said earlier the base voltages or of the drivers the TIP 35 and TIP 36 were all over on the other 3 good amps they were something like 4 volts on the bad section there were between 4 and 19 volts in line with the crackling sound
The amp has since blown its drivers but i have also noticed R450 a 200 ohm resistor is measuring 140 ohms the capacitor i have removed C411 i cannot get any sort of reading from although i wouldn’t imagine it to be associated with the fault as all the other caps in that position i can’t get them to read anything either maybe they are less than 1Pf
Thank you for your reply
I have uploaded a better picture of the Class AB part what’s got the problem (the rest of the amp is perfect)
The amplifier was crackling with NO preamp board connected, as i said earlier the base voltages or of the drivers the TIP 35 and TIP 36 were all over on the other 3 good amps they were something like 4 volts on the bad section there were between 4 and 19 volts in line with the crackling sound
The amp has since blown its drivers but i have also noticed R450 a 200 ohm resistor is measuring 140 ohms the capacitor i have removed C411 i cannot get any sort of reading from although i wouldn’t imagine it to be associated with the fault as all the other caps in that position i can’t get them to read anything either maybe they are less than 1Pf
Replaced the parts on this amp ....still exactly the same 3 perfect channels 1 is still the same just constantly rustling hissing crackling , but very quiet, disconnected preamp board it’s still there , its NOT affected by the volume ie never gets louder and is drowned out by the volume , collector voltages are a constant 25 volts, base are floating so are voltages on the drivers , just can’t seem to isolate where it’s starting to go wrong , its puzzling me how the crackling and hissing is sooooo quiet & don’t increase with the volume , you would think with 3 identical amplifiers on the same bcb it would be easy to find but so far it’s been illusive , i can’t even see how i would find the fault with a signal injector or a scope any ideas anyone .....................its driving me mad
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