Amp getting really hot and going into protect mode

[ashren315]

So my amp (RF800a4) gets really hot really quickly then after about 30 minutes of normal listening levels it goes into protect mode. After a minute of two it will come back on for a minute or two then shut back off and constantly repeats this process. It's in the trunk but mounted in open space and I have an RF600a4 back there as well that has no problems at all.

It's not an ohm load issue as I've checked all speakers attached. The rear channel is bridged running an 8ohm load and the front channels are running a 4 ohm load each. It's not a voltage issue as I've checked that and at the amp it never drops below 13 volts.

The gains are set at about 1/4 to 1/3 so it's not an overdriving issue. (It still happens even with the gains all the way down)

This amp does have one issue that I know of. The front side RCA inputs have a ground issue so I have that RCA ground shield being grounded to the RCA ground shield of the pass thru output on the amp. (I was getting a loud static like hiss through the front speakers attached to the amp prior to grounding the RCA outer shield)

For awhile, I just had the two rear channels running the sub with nothing going in the front channels and it never went into protect mode. It wasn't until recently when I hooked up the 2 speakers to the front output that it started going into protect mode.

I get that it's summer and it's hot as balls already. I just don't think that's what's going on here. I think this is something internal with the amp as the 600a4 only gets moderately warm. You can put your hand on it and leave it there no problem. On this 800a4 you can't even leave it for a few seconds. It's really hot. I just don't know enough about the internals of an amp to know what to look for if there really is something going on inside the amp. What parts of an amp could cause this?

Click to read more...

 

[shredder1 10+ year member]

This sounds strangely familiar... these guys had a new Skar RP 2000.1 and were running it at 1 ohm which it is supposed to be able to do... the thing was getting hot and would go to protection after 10 minutes from a cold start... he has NO issues with electrical... (god I wish I had his electrical)... but the amp would get so hot it was scary then shut down... nobody could come up with a solution... and there were at least 15 guys there... he had fans mounted at the amps but it did not help... just on a lark he took a stab in the dark... he decided to pull his subs... the 2 15's he had were playing just fine... he tested impedance while moving the cone to different positions and guess what?.. at ONE point the coil was shorting out... his impedance actually zeroed if he could hold the cone still enough... That's a reach I admit... I'm pretty sure you'll find an answer that's more common... but his amp got HOT and shut down after playing 10 minutes starting cold and even less when hot...

 

[Papermaker85 5,000+ posts]

Chances are it just needs better ventlation. Put a fan on it. They are cheapppp.

 

[hispls 5,000+ posts]

IMO about par for the course on those old A/B amps if you play them loud. Those old Foreman Grille fosgates are pretty good though.

I'm more surprised that you're not overheating the smaller one too. Have you tried just dialing back the gains or does it idle hot too? There's really nothing user serviceable in an amp and all but catastrophic failures of components will not be visible but will require knowledge of amp design and oscilloscope to detect.

 

[ashren315]

It does it with gains set all the way down and volume down all the way. I can pull the RCAs going to the front channel and it still got hot, but not this hot and never shuts itself down.

 

[BOOMINGRANDPA 5,000+ posts]

It does it with gains set all the way down and volume down all the way. I can pull the RCAs going to the front channel and it still got hot, but not this hot and never shuts itself down.

u check ground? make sure no paint or rust under it and is tight saw 1 guy said he did a few grounding spots before his problem stopped..

 

[ashren315]

u check ground? make sure no paint or rust under it and is tight saw 1 guy said he did a few grounding spots before his problem stopped..

Yep. Ground is good.

 

[shredder1 10+ year member]

If one of my Rockfords had a thermal problem at 8 ohm mono...even being run in 3 channel mode... I'd be furious... probably contacting the manufacturer or something... I ran a bunch of their equipment over the last 25 years and have had NO issues... and I live in Phoenix... at least yours plays BEFORE cutting out... this guy's did not... http://www.caraudio.com/forums/general-discussion/632739-amp-help.html

 

[ashren315]

It's an old amp (1999 model). Those things were built solid back then. I really didn't want to have to buy a new amp but if I can't figure this out of find someone locally who can, I guess I'm going to have to buy a new amp.

It's just funny that it plays fine and sounds good for about 30 to 40 minutes. It just extremely hot (literally burns if you touch it. I could probably cook an egg on it) and then starts going in and out of protection mode. What puzzles me even further is the fact that it never shut off when I only had it running the sub on the rear channels bridged.

I have an old 800a2 that I "technically" could use to drive these three speakers (sub and two midbass in kicks) but I'd lose the ability to do any fine tweaking between the left and right midbass speakers. I mean, it would work for now I guess. It would give me far more power running the 800a2 to each speaker so that would be a bright side.

 

[hispls 5,000+ posts]

It's an old amp (1999 model). Those things were built solid back then. I really didn't want to have to buy a new amp but if I can't figure this out of find someone locally who can, I guess I'm going to have to buy a new amp.
It's just funny that it plays fine and sounds good for about 30 to 40 minutes. It just extremely hot (literally burns if you touch it. I could probably cook an egg on it) and then starts going in and out of protection mode. What puzzles me even further is the fact that it never shut off when I only had it running the sub on the rear channels bridged.

I have an old 800a2 that I "technically" could use to drive these three speakers (sub and two midbass in kicks) but I'd lose the ability to do any fine tweaking between the left and right midbass speakers. I mean, it would work for now I guess. It would give me far more power running the 800a2 to each speaker so that would be a bright side.

You really are getting to the age where things wear out and you will need a professional to diagnose the problem. It should NOT be doing what you describe.

If you're happy with the output and footprint of that IMO it would be worth sending it out for restoration over buying a new amp. db-R in Texas or Zed Audio in southern California are both reliable and close to your region.

 

[ashren315]

You really are getting to the age where things wear out and you will need a professional to diagnose the problem. It should NOT be doing what you describe.
If you're happy with the output and footprint of that IMO it would be worth sending it out for restoration over buying a new amp. db-R in Texas or Zed Audio in southern California are both reliable and close to your region.

I'll check that out and see what they would charge me to repair it. If it's more than $100 though, I might as well get new. Amps today are so much cheaper than they were back then. Good quality amps can be had for a couple hundred dollars these days were as back then, the cheap brands cost you that much and the good stuff was all close to or over $1000.

 

[JonM]

I remember those days, I used to have a cheap urban audio setup in a 64' bug. Though was I was ******

 

[hispls 5,000+ posts]

I'll check that out and see what they would charge me to repair it. If it's more than $100 though, I might as well get new. Amps today are so much cheaper than they were back then. Good quality amps can be had for a couple hundred dollars these days were as back then, the cheap brands cost you that much and the good stuff was all close to or over $1000.

A lot of them are cheaper for a reason. I'd say if you can get it fixed for 100$ + shipping you'd do as well keeping it. Not sure what amp you'd buy for 100$+ shipping today that will go 20 years before it needs any repair.

 

[ashren315]

A lot of them are cheaper for a reason. I'd say if you can get it fixed for 100$ + shipping you'd do as well keeping it. Not sure what amp you'd buy for 100$+ shipping today that will go 20 years before it needs any repair.

I don't know about how long new amps last as I've not purchased one since I purchased all those Fosgates back in 99. I had the 600a4, the 800a4, and three 800a2s. All of them still work perfectly except this 800a4.

 

[hispls 5,000+ posts]

I don't know about how long new amps last as I've not purchased one since I purchased all those Fosgates back in 99. I had the 600a4, the 800a4, and three 800a2s. All of them still work perfectly except this 800a4.

20 years is about the life expectancy of electrolytic capacitors so amps failing after that point is not unusual. Build quality on new will vary. I strongly suspect most of the budget amps you'll buy today won't be playing 20 years from now though.