| chazzmani |
Hi everyone. I just purchased a used PPI 4400 (4 channel) amp and when I hook up the power and the remote turn-on lead, it just turns on and off continually. According to the manual, it says that if a short is detected in the system (like a miswired speaker, etc), the amp will do this. But I haven't even connected any speakers yet!
So just for arguments sake, I then went ahead and hooked up all of the speakers and the same thing happens: on/off repeatedly.
I have another 4400 amp with two bad channels and I hooked it up and it stayed on just fine so I am inclined to believe this newer amp has an internal short. Could I be missing something obvious... could this amp be fine and the error be mine somehow?
I would appreciate any input. Thanks in advance. |
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| justonemoreamp |
It sounds like your internal protection circuitry is engaging and shuting your amp down. It then recycles and tries again to start back up and operate, and then shuts down again, over and over.
I would have someone qualified look at it if possible. I'm qualified but not local to you. there are others here that are qualified also, TO-3, Perry Babin, etc...
Your amps problem can be caused by a number of issues, like a shorted power supply, a failed low voltage rail, a blown channel or two, etc...
Let us know your intentions so some of the excellent technical folks here can step up and be of help.
as always I hope this is found helpful :) :) :) |
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| TO-3 |
| quote: | Originally posted by chazzmani
Hi everyone. I just purchased a used PPI 4400 (4 channel) amp and when I hook up the power and the remote turn-on lead, it just turns on and off continually. According to the manual, it says that if a short is detected in the system (like a miswired speaker, etc), the amp will do this. But I haven't even connected any speakers yet!
So just for arguments sake, I then went ahead and hooked up all of the speakers and the same thing happens: on/off repeatedly.
I have another 4400 amp with two bad channels and I hooked it up and it stayed on just fine so I am inclined to believe this newer amp has an internal short. Could I be missing something obvious... could this amp be fine and the error be mine somehow?
I would appreciate any input. Thanks in advance. |
Right off the bat I would say it may be a shorted output. But possibly the protection circuitry is to blame. You should measure the outputs of all of the channels and see if you can find a short. I can tell you how to deactivate the protection circuit later. Just make sure you have a current-limited power supply, or a fuse. |
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| chazzmani |
| quote: | Originally posted by TO-3
Right off the bat I would say it may be a shorted output. But possibly the protection circuitry is to blame. You should measure the outputs of all of the channels and see if you can find a short. I can tell you how to deactivate the protection circuit later. Just make sure you have a current-limited power supply, or a fuse. |
Thanks everyone for the replies. Yes, the line supplying power to my amps are fused. One thing strange I have found is that the gain controls on this amp spin infinitely. On my other 4400, the gain controls spin counterclockwise and clockwise to a stop (so you know where min and max are). These gain controls never stop... they just keep spinning. Dunno if that provides any info. |
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| TO-3 |
| quote: | Originally posted by chazzmani
Thanks everyone for the replies. Yes, the line supplying power to my amps are fused. One thing strange I have found is that the gain controls on this amp spin infinitely. On my other 4400, the gain controls spin counterclockwise and clockwise to a stop (so you know where min and max are). These gain controls never stop... they just keep spinning. Dunno if that provides any info. |
Find R92. I don't know the value, but one side should be connected to the collector of Q36 and the other should be connected to the collector of Q35. Pull up one side of the resistor and that will disable the DC offset protection on the channels and allow you to troubleshoot.
You should replace the gainpot. |
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| chazzmani |
| Wow... you guys have infinitely more knowledge than I have. I don't even know what components you are referring to. I think I better take my lumps and either have this repaired by someone who knows how or beat the seller to a pulp for telling me this worked fine. |
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| TO-3 |
| quote: | Originally posted by chazzmani
Wow... you guys have infinitely more knowledge than I have. I don't even know what components you are referring to. I think I better take my lumps and either have this repaired by someone who knows how or beat the seller to a pulp for telling me this worked fine. |
.....or fix it yourself! That's what we do around here. There is plenty of knowledge to go around. |
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| justonemoreamp |
E-bay huh ? another perfect working amplifier lol lol I have gotten a few of those over the years.:bigeyes: :bigeyes: :bigeyes: :bawling:
File with Pay-pal for not as described by the seller. They got my money back for me, and others everyday.
Your seller thinks its the wild wild west and the internet can hide his criminal activities. At least E-bay & Pay-pal will try and help you out on this one as the seller was shady.
Please post his e-bay ID here so we can all avoid his criminal selling.
And TO-3 is correct we fix ours here, and are glad to help others. Hope it all works out in your best interests:) :) :) :) |
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| mike49504 |
| if the gain pots are bad the amp will shut off and turn on and shut off like that i had a crossfire that did the same thing i replaced the pots and amp works fine |
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| chazzmani |
| I clearly don't have a fraction of the technical knowledge that you guys have. What's a pot? and how would I test or replace them? |
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| justonemoreamp |
The pot is that gain control that spins 360 when its supposed to stop at 270 degrees. Pot is short for Potentiometer :) :) :)
If your looking at getting it fixed then you might PM someone for more direct help, just a thought, as it might be your best bet on restoration of your amp :) Especially if your lecking time on the bench doing restorations and repairs.:) |
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| chazzmani |
| quote: | Originally posted by justonemoreamp
The pot is that gain control that spins 360 when its supposed to stop at 270 degrees. Pot is short for Potentiometer :) :) :)
If your looking at getting it fixed then you might PM someone for more direct help, just a thought, as it might be your best bet on restoration of your amp :) Especially if your lecking time on the bench doing restorations and repairs.:) |
Ahhh, OK... I had wondered why the pots were spinning continually instead of stopping at min & max. I am comfortable opening up the unit and tinkering with it, but i am not comfortable with soldering and I imagine the pots are ultimately soldered in. Please tell me if i am wrong though -- if tey are just screwed in or otherwise attached whereby I don't need to solder them, I'm game to try this. Thanks! |
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| justonemoreamp |
You must learn to solder to work on any electronics, and on the newer stuff you will need to learn how to use a rework station to be able to repair them properly.
Its just part of the job for a full time tech, and it goes with the territory so to speak:)
Soory to bear the bad news but all electronics is soldered together just like stain glass windows, only alot finer detail.
You might just ask some of the guys here if they can do your repair for you if their not too busy. I'm sure you will get treated right by these guys ;) |
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| TO-3 |
| justonemoreamp is right. That amplifier is too nice of an amp to be kept out of commision. Your amp has just a minor problem. It can definately be repaired. |
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| Dan2 |
| pots aren't too bad to unsolder - they are pretty big and only 3 legs- just make sure you keep soldering as neat as possible ;) |
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| chazzmani |
This definitely isn't a project I want to have as my first. Too much to risk.
If anyone can suggest someone on these forums who does repairs for other people (and charges fair prices), please let me know.
I see people advertising on eBay for $55 - 75 per repair. |
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| justonemoreamp |
Yeah I see those guys too, want pics of there work:bigeyes:
Becareful, they are not as they seem, and I have customers to prove it.
Perhaps TO-3 if he has time. he has my vote of confidence. Or maybe Perry he seems to know his business also. |
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