i found an old kenwood head unit and got it all hooked up. i didn't even know i had it.
now when i play it there is a constant audible static. and if i connect shield and chassis there is a fairly loud buzzing sound.
it makes no difference if it's bridged or each channel.
if i have the speaker connected to the front channels and i turn the gain knob for the rear channels it will affect the front output and vice versa.
now when i play it there is a constant audible static. and if i connect shield and chassis there is a fairly loud buzzing sound.
it makes no difference if it's bridged or each channel.
if i have the speaker connected to the front channels and i turn the gain knob for the rear channels it will affect the front output and vice versa.
That's a bit higher than I'd expect and may cause some problems. Ground the shields to the case of the head unit with a jumper (preferably fused at 3A or less).
If it's still distorted. Play a sine wave through the amp and post a photo of the distorted signal.
If it's still distorted. Play a sine wave through the amp and post a photo of the distorted signal.
i was measuring the shield/chassis resistance with one probe on the output rca jacks from my switcher box and the othe probes on the case of the head unit whitch gave me ~48 ohms.
when i measure shield/chassis resistance directly on the back of the radio i get ~1 ohm.
it must be the various components in the switcher box causing the resistance.
when i measure shield/chassis resistance directly on the back of the radio i get ~1 ohm.
it must be the various components in the switcher box causing the resistance.
There are resistors in the switcher that are there to protect the head unit. They rarely cause any problems. A few of the MTX amps are the only ones that I can remember having issues with the resistance.
For this amp, plug the head unit directly in to eliminate that as a possible problem.
If it's still distorted, post a photo of the distorted waveform.
For this amp, plug the head unit directly in to eliminate that as a possible problem.
If it's still distorted, post a photo of the distorted waveform.
with the rca's directly from the head unit to the amp it appears to work perfectly in every configuration hp/lp/fp, high vol, low vol, ect...
Some amps are sensitive to resistance in the shield line. This must be one of them.
The resistors in the switcher are required to protect the source unit shield ground from amps that have shorted transformers or for times when the signal lines may come in contact with the 12v power line on the bench. I'd suggest that you leave the circuit as is but if it's confusing to you, you can do a couple of things. You can wire a momentary switch to short across the resistors to temporarily bypass them. You could also replace the resistors with an 1156 brake lamp. The cold resistance of the lamp's filament will be much lower than that of the resistors.
The resistors in the switcher are required to protect the source unit shield ground from amps that have shorted transformers or for times when the signal lines may come in contact with the 12v power line on the bench. I'd suggest that you leave the circuit as is but if it's confusing to you, you can do a couple of things. You can wire a momentary switch to short across the resistors to temporarily bypass them. You could also replace the resistors with an 1156 brake lamp. The cold resistance of the lamp's filament will be much lower than that of the resistors.
i'll just leave it as is. i've been so busy that i just started using my switcher box and i just need to get familiar with it.
hi i know this is a old post but i have this same amp but all it does is flash the led then it trips my power supply when i try to power it on. im guessing this is because there is a short in one of the power mosfets??? and the amp has no fuse so it shuts my power off??idk but i was just wondering if there is a way to check the rectifiers and mosfets in the circuit because they appear to have some type of thermal management system board they are connected to and i really dont want risk me messing up the solder jobs but if i have to i will. or does anyone have a suggestion on what components to check first?i can post pics if it helps thanks
You need to test all of the output FET's first. You probably have one or more shorted.
Set your meter to ohms and tell me the reading you get from gate to source on all the output FET's.
Set your meter to ohms and tell me the reading you get from gate to source on all the output FET's.
im getting .56 for the buz21 and buz272 from gate to source are these the output fets? 50N06V im getting 9.59, then i have a u1620r and u1620 and a 317t and 337t not sure how to test those. also those measurements were in circuit.
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im getting .56 for the buz21 and buz272 from gate to source are these the output fets?
Did you try reversing the leads on gate to source to see if the reading changes?
Is your meter on ohms and if so what range are you in or is it in auto detect mode?
Make sure not to use diode check for this test.
Those readings are not what I would expect.
Did you try reversing the leads on gate to source to see if the reading changes?
Is your meter on ohms and if so what range are you in or is it in auto detect mode?
Make sure not to use diode check for this test.
Those readings are not what I would expect.
that was in ohms on the 20k position.in the 2000 position they all ranged from 567 to 571 on one side and the other side matched?not sure if that makes since but im guessing they are all bad? i know how to remove them from the circuit board but they look like they are glued or possibly soldered to a mehsa board?
539 and 582 with reverse leads on one side and 538 with 585 reverse leads on the other side for the 50N06V power fets and forgive me and please correct me if im wrong or not testing something right im just trying to learn and thanks for all your help i really appreciate it
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Post a good photo of the board close-up.
All those readings seem to be ok for now.
What are you using for a power supply?
All those readings seem to be ok for now.
What are you using for a power supply?
there's only one place on the board that looks messed up (red circle around it) but i checked the trace and it is connected. im using a computer power supply but i know the power supply works because i can hook my kicker amp up and it works fine. if the pictures arent close enough let me know please and thanks
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Have you tried hooking it up with a car battery with a 10 amp fuse inline with the positive lead?
Just want to rule out the supply as it may work fine for some amps but not others.
Just want to rule out the supply as it may work fine for some amps but not others.
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