Oh-oh! Did I Fry My Pre Amp?

[Atomic Turtle]

I feel so stupid, I'm not even going to bother making up any lies about what I did. It was just so dumb, I deserve to look like an idiot.

Long story short, I had to move my equipment. The lighting was terrible, I had to reconnect mostly by touch because of poor access, and somehow - incredible as it sounds - when i reconnected the speaker wires, I managed to reverse the polarity. Hooked up the positive wires to the negative posts and vice versa. On both speakers. The flashlight I was using was so dim, I seriously could not tell the difference between the colors of the wires.

OK, the speakers still work fine, because I connected them to an old receiver. But now either my Carver M-500 amp or my C-1 pre amp (hopefully it's only one or the other) are not putting out any signal at all. I can't tell which one is dead, all I know is that there is no sound and the VU meters on the amp are not showing any signal. I haven't touched either one (other than to totally disconnect them) since I saw what I had done. Has anyone got any ideas on what sort of damage I've done, and what I ought to do next? Obligatory smartass remarks are entirely appropropriate under the circumstances, but an occasional pertinent response amid the deafening chorus of derision would be greatly welcomed.

[Face]

I don't see how reversing the polarity could have caused any problems other than poor sounding music.

Are you sure the + and - didn't touch? Did you check all fuses, etc...? Are you sure a breaker didn't trip? :D

[Atomic Turtle]

The positive and negative didn't touch while the power was on, because I'd powered off completely while I moved everything. Didn't power up again until everything was hooked up. I can't verify the fuse on the amp because it's opaque; doesn't show whether it's blown or not. Apparently the only way to check it is to test it, and I don't have the equipment. The fuse on the pre must be internal, because I can't see anything on the outside. No, the breaker in my house didn't trip, so that's not it. The amp and the pre both power up - they just don't put out any signal.

One thing I just noticed, though... the ground wire for the amp is disconnected from the post on the back, and it just happens to be dangling in the general area of the RCA input jacks. It's a bit of a stretch, but it's at least theoretically possible that the bare end of the ground fell across both the right and left input jacks while the system was powered. Like I say, seems like a long shot, but anything's possible at this point. I can't rule it out.

[HB27]

You're not the first one to do this or something very similar.
DON'T DO IT AGAIN!!!
Unplug your equipment and start over making sure all the connections are correct. Inverting the phase on the speakers shouldn't have done any damage.
You possibly could have blown a fuse but I'm betting the lighting is still bad and the connections are wrong. You're probably not feeding signal and no meter activity. It's worth a shot.
If that's not the problem, pull the covers and check for fused protection. Check continuity with a VOM on fuses.
Other than that you might have blown your output transistors and a diode or two. Not too expensive.
These are just guesses without me being "hands on" but it's worth considering.
I've also seen guys plug their equipment on switched outlets and not have power to them without "flipping" the switch.
HB

[HB27]

You might want to make sure you are in the "correct" mode. I've done it before just because I hit a button or switch by accident.
It's probably something simple like a wrong connection. Then again, Bob Carver has made some wild designs.
hb

[Atomic Turtle]

I've triple-checked the connections, and there is definitely signal going into the pre, because the same signal works fine when I feed it into a receiver. I can't tell whether the pre is putting out any signal to the amp; all i know for sure is that the amp and pre put out no sound and the VU meters on the amp show no signal. And again, both units power up fine, so that's not the issue. More and more, I suspect that damned ground wire may have fallen across the input jacks on the amp while the system was powered. That could do it, couldn't it?

I'll pop the hood on the pre tomorrow and see if there's a fuse inside. I'm about out of other ideas at the moment; way past my normal bedtime. Too tired to troubleshoot anymore tonight. Thanks for the replies thus far, guys.

[Face]

Are you 100% sure your interconnects to your amps are plugged in the correct spots? Not CD in or something? :)

[HB27]

Go to Ratshack or similar and pick up a VOM for less than $20. The output jacks on the outside are the grounds. Unless it's the speaker outputs. Shouldn't have done any damage that way.
Fresh brain may find something very simple.
Best of luck and hoping it's not any damage other than a tired "brain fart".
HB

[Atomic Turtle]

Are you 100% sure your interconnects to your amps are plugged in the correct spots? Not CD in or something? :)

Absolutely. No question about that one. The amp only has one input, and I didn't disconnect any of the outputs on the pre. In fact, I never touched the pre until after the problem began; I only moved the amp. It has to have something to do with the way I hooked up the speakers, or that ground wire making a short between the right and left channels on the input jack.

[danger boy]

be sure it's not in mute or a secondary pair of speaker connectors on your amp.. it should not have fried your gear... i think it's a wrong setting some where.

replace your interconnect. tear it all down and start over.. where you can see what is being plugged in where.

Open that amp up. .. they have internal fuses too.. sometimes several fuses.. like 4 or more of them hidden away

good luck bro..

[venomclan]

Best of luck, we have all been there.

[strider]

Did you check the fuse on the back of the amp? I know there is one on the back of the M-500, IIRC on the right hand side as you're looking at the back.

[Atomic Turtle]

OK, I didn't get a whole lot of sleep, but I've narrowed it down a bit. It's definitely not the interconnects or any other connection issue, because every time I unplug the connections and plug them into the back of the receiver, they work fine. It doesn't appear to be the amp, because I hooked another amp up to the pre and it doesn't work either. It's not likely I could blown two amps.

At this point, I'd have to say it's got to be something to do with the pre amp. When I get home from work, I'll do a thorough check to make sure there isn't any sort of obscure setting I could have changed on the pre, but based on the troubleshooting I did this morning I don't think that's the case. If i can't find some magic setting, I guess there's not much to do but find a local repair shop that works on Carvers. :(

[Atomic Turtle]

Did you check the fuse on the back of the amp? I know there is one on the back of the M-500, IIRC on the right hand side as you're looking at the back.

Yup, but I can't tell if it's blown because it's ceramic, not glass. Either way, I swapped out the fuse with the one from my new M-500t (the one I was trying to hook up when this whole nightmare began), and also swapped out the amps. Same result with both fuses and both amps.

[strider]

If i can't find some magic setting, I guess there's not much to do but find a local repair shop that works on Carvers. :(

Do you post on the Carver Audio forum? From what I've heard, it's down right now, but I know they have a handle on who does good work on Carvers. There's a couple members here that post over there regularly, maybe they'll chime in with the name.

[Atomic Turtle]

Do you post on the Carver Audio forum? From what I've heard, it's down right now, but I know they have a handle on who does good work on Carvers. There's a couple members here that post over there regularly, maybe they'll chime in with the name.

Yeah, I'm a member there too, and yeah - it's down alright. Just as well; they'd probably laugh me out of the place. The standard recommendation there is to send it to Roland at Hi Tech, and I'll probably give him a call today and talk to him about the matter. But I don't think this really warrants the expense and the 2-month turnaround time required to send it off to him; I think it's probably a relatively simple matter for someone who knows what they're doing.

[GV#27]

One thing I just noticed, though... the ground wire for the amp is disconnected from the post on the back, and it just happens to be dangling in the general area of the RCA input jacks. It's a bit of a stretch, but it's at least theoretically possible that the bare end of the ground fell across both the right and left input jacks while the system was powered. Like I say, seems like a long shot, but anything's possible at this point. I can't rule it out.Doudtful this would cause any harm as it would likely just touch the ground section of the input connector.


By chance did you engage a tape monitor switch?

[jakelm]

Pics....

[HB27]

Well,
What's the status? I'm curious as to what's happening with your gear.
HB

[Atomic Turtle]

Well,
What's the status? I'm curious as to what's happening with your gear.
HB

Me too, and unfortunately I don't seem to be any closer to having the answer than I was 48 hours ago. I tried every switch and reconnected every interconnect I could find, and still no go. I'm sure it's the pre, so I'll send it in for repair next week sometime. Thanks for all the advice and sympathy, guys. When i get it back from Roland, I promise to revive the thread and let everyone know what the issue was.

Ah, well. The gear's getting pretty old anyway. I'll have the C-1 completely recapped and refurbished for 185 bucks, and it'll probably last me the rest of my life. It's something i would almost certainly have wound up doing at some point in the future anyway, so i might as well do it now. But damn, that sweet-sounding system sure sounds underpowered with just my little old Panasonic XA-55 driving it! :(

[HB27]

I wish it had been something simple. Keep us informed on the issue with it. Something else must have happened to it you didn't notice OR reversing the polarity on the Carver did damage it. Or, it may just have been time to refresh it and a little "misuse" finished it off. OR..., just let us know.
HB

[engtaz]

Carver site is up now.

engtaz

[HB27]

How's the preamp and amp? Any word yet?
HB

[dcmeigs]

There is no way connecting speakers out of phase can do any harm. If so about 25% of the equipment would be shot. You need to separate the components and check them out one by one.

You need to set the equipment out on the table or bench in good lighting so you can see what you are doing. Get some head phones and jack up a source and see if the preamp is working without connecting the amp. Play with that until you get it working.

You can check the amp by dragging it over to a buds house with some cables and jack up to the preouts on his receiver, or you can use your computer headphone jacks and send that signal to your amp using the computers volume control to keep things under control. You can get some RCA x miniplug at the rat shack.

Once you figure out which component is working, you can concentrate your efforts on the other one. Chances are it's something simple and real em-bare-ass-ing.