Hi all, i need a little guidance....i bought a pair of very mint pioneer gm-h120 car amps...they are mint inside and outside...the guy said they turn on but no sound...he was right...all output mosfets tested good. With speakers hooked up to them dead air on noise can be heard from the speakers...what could it be? What is also odd is that it seems to be the same thing for both amps...is there a common thing that goes bad on these old amps? Any help would be muchly appreciated
Thanks!
Tyson
Thanks!
Tyson
Just a guess: don't such amps have a enable/ ~head power (12VDC) input? The "system control terminal". Note that 12V comes from 3 places, the battery, the dash and the radio head.
Connecting When Combined With A Car Stereo With Rca Pin Jacks - Pioneer GM-H120 Service Manual [Page 16]
Connecting When Combined With A Car Stereo With Rca Pin Jacks - Pioneer GM-H120 Service Manual [Page 16]
Yes i have the remote turn on hooked up...amp powers up fine, just no sound....recapped the small sound board with gain pots, swapped out ic chips still nothing
Perry i get one click from the relay when it turns on...i know there is two relays, am i supposed to get two clicks? Tim what yellow black wire are you refering to? My Remote turn on clip has a red and a blue wire. Both are jumped together to the remote turn on wire to my deck...
I was too quick and careless reading steveu's link.
Older Pioneer GM series amplifiers with DIN connections required a current draw rather than a remote-on voltage to turn on, I thought the yellow wire was related to that.
Perry may have more info on this one, but to be sure- I would connect the red wire to the accessory power that runs the head unit. It may need to be powered up before the remote lead.
I was a teenager the last time I saw one of the older ones (GMA120) but IIRC, it was important to connect the battery power lead last.
Older Pioneer GM series amplifiers with DIN connections required a current draw rather than a remote-on voltage to turn on, I thought the yellow wire was related to that.
Perry may have more info on this one, but to be sure- I would connect the red wire to the accessory power that runs the head unit. It may need to be powered up before the remote lead.
I was a teenager the last time I saw one of the older ones (GMA120) but IIRC, it was important to connect the battery power lead last.
Post #7:
The relays will click at the same time so it may be difficult to hear them both click.
You stated that you heard 'dead air'. I'm assuming that you're referring to hiss. Do you hear this only after the relays click?
Do you have a scope?
Post #8:
http://www.bcae1.com/temp/pioneer - gm-h100 gm-h50.pdf
The relays will click at the same time so it may be difficult to hear them both click.
You stated that you heard 'dead air'. I'm assuming that you're referring to hiss. Do you hear this only after the relays click?
Do you have a scope?
Post #8:
http://www.bcae1.com/temp/pioneer - gm-h100 gm-h50.pdf
Perry thanks, yes i have a scope, its just a cheap one but nontheless its a scope..lol. Yes the "hiss" comes on after the click...i still find it strange why i have two doing the exact same thing, plus i have a gm-h100 doing the same thing minus the hiss when it clicks...
I'm sorry. I grabbed the wrong file.
http://www.bcae1.com/temp/pioneer - GM-H120 -- GM-3400.pdf
Is the shield of your signal source grounded? (it should be)
http://www.bcae1.com/temp/pioneer - GM-H120 -- GM-3400.pdf
Is the shield of your signal source grounded? (it should be)
Everything is hooked up correct....it has to be somthing stupid and small as you can hear the faint hiss through the speakers, and you can hear it shut off through the speakers when turned off...
That doesn't answer the question. Is the signal source grounded to the 12v power supply so that the shield is at ground (0v DC)?
What's the resistance from the RCA shield on the amp (with the signal source plugged in) to the main ground terminal?
What's the DC voltage between those two points with the amp on?
What's the DC voltage between those two points with the amp on?
Ok perry so i just did those checks and what i am gettting on both amps is: 12.2v ground to shield, and 135 ohms ground to shield
I don't think that these amps will work with a floating shield and yours is floating. What is your signal source?
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