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Carvin BX500: Pt. 3
- Thread starter Chef
- Start date
No, definitely not under the 12 month warranty anymore... I've had it for about 15 months. Normally I have only played it for 1 to 2 hours at a time in cool weather, so this is the first time it has been stressed for 3+ hours in a warm room. It's possible the fan has never worked.
I guess I will call Carvin and see what they say.
It would help if anyone could comment on expected fan duty cycle for this amp. I just assumed that the fan rarely came on, so nothing was out of the ordinary. I have a different amp which has a fan that almost never comes on: GK 700RB-II.
I guess I will call Carvin and see what they say.
It would help if anyone could comment on expected fan duty cycle for this amp. I just assumed that the fan rarely came on, so nothing was out of the ordinary. I have a different amp which has a fan that almost never comes on: GK 700RB-II.
- Jan 17, 2002
- 1,249
- 23
- Disclosures
- I paid for all my gear myself. Well, me and MasterCard.
The fan is a pretty quiet one. If it's not spinning AT ALL, that's the cause of your problem. Inexpensive fans will die occasionally. Call Carvin and get a replacement. Swapping it out is simple.
My fan just Sh!t the bed too. It will run if I jump start it. Also, all the white goop that was on/under the heat sink cooked to a nice crispy flaky mess. Looking for a higher quality fan. I took mine apart and greased her and tried all sorts of fixes, but nothing. Can someone please post the specs on the fan??
I haven't had time to do much experimenting with the amp yet. I did e-mail Carvin, and a tech replied that he is very surprised that the amp would ever get that hot. He indicated that it should only get that hot when running at high volume under minimum impedance load (i.e., 2 ohms). In my case, I had a single 8-ohm GK 410MBX cabinet hooked up and I was running at half-master volume and half-input gain. So something is fishy there.
With respect to the fan, he said that the fan on the BX500 should engage only when the unit gets hot, which should not happen under light to normal operating conditions. In my case, it did not turn on at all even though the unit went into thermal protect mode, so clearly there is a problem with the fan or fan controller.
Rather than paying the (in my opinion completely outrageous) $225 service fee, the tech suggested that I could replace a resistor on the PCB to a different value, which should force the fan to turn on at startup. I'm not sure I want to do this just yet. I will first try to rule out whether the fan is simply broken or perhaps just has a bad connection.
I will also try the amp with a different cabinet and speakon cable to make sure the root cause of the heat isn't due to a low-impedance or short in my speaker load...
With respect to the fan, he said that the fan on the BX500 should engage only when the unit gets hot, which should not happen under light to normal operating conditions. In my case, it did not turn on at all even though the unit went into thermal protect mode, so clearly there is a problem with the fan or fan controller.
Rather than paying the (in my opinion completely outrageous) $225 service fee, the tech suggested that I could replace a resistor on the PCB to a different value, which should force the fan to turn on at startup. I'm not sure I want to do this just yet. I will first try to rule out whether the fan is simply broken or perhaps just has a bad connection.
I will also try the amp with a different cabinet and speakon cable to make sure the root cause of the heat isn't due to a low-impedance or short in my speaker load...
$225 to fix the fan is jacked
That's an "under an hour job," and should be a 1 hour minimum bench fee, or about $50 plus parts
IMO
That's an "under an hour job," and should be a 1 hour minimum bench fee, or about $50 plus parts
IMO
That's a discouraging level of customer service, IMO.
I'd ask to speak to the next guy up the food chain. Several times, if necessary.
Be polite, be firm.
I'd ask to speak to the next guy up the food chain. Several times, if necessary.
Be polite, be firm.
Before this explodes any further, I just want to emphasize/clarify that $225 was not a direct quote I received from Carvin. Rather, $225 is the published "flat rate" service fee advertised on Carvin's website for any non-warranty BX500 service. See the "bass amps" section at the bottom of the chart at:
Invalid Link Removed
Perhaps I misunderstand their service rates, but if so, they did not correct my understanding in our e-mail exchange. Has anyone else recently had a BX500 serviced out-of-warranty to say for certain?
I am willing to do some limited diagnostics myself; I can replace the fan myself by ordering a part if that is the extent of the problem. However, if the problem is a fan controller or bad thermal diode, I draw the line at modifying the PCB myself. So in that eventuality, I will push to get a real quote and let you know how it works out.
Yes, and I apologize for the confusion. In my original email to Carvin, I specifically mentioned that the $225 service fee advertised on their website seemed steep for what seemed like a fan issue in this case, and I was looking for alternative suggestions. In the tech's response, he did not respond directly to my service fee point, but he did suggest some do-it-yourself workarounds. So I don't want to read too far into the lack of response just yet. We'll see how it plays out.
In any case, thanks for the moral support as always!
Well, my trusty BX500 is starting to heat up too. Any solution to your problem, Troph?
I was playing a 3 hour gig yesterday in 90 degree heat and when I touched my amp after the first set, it was very hot. I don't think the fan came on at all. It never shut down, but I am definitely concerned at this point. I think I am within the 12-month warranty period, but I have no back up and I have gigs coming up.
I was playing a 3 hour gig yesterday in 90 degree heat and when I touched my amp after the first set, it was very hot. I don't think the fan came on at all. It never shut down, but I am definitely concerned at this point. I think I am within the 12-month warranty period, but I have no back up and I have gigs coming up.
My BX500 has been really great since last May (even survived a fall off a cabinet) but it recently started making a pop when turning it off. I called Carvin and the amp tech said he's aware of this issue and it's one little resistor that needs replacement with a new value. They're fixing it for free. I really like that amp - very flexible with a large tonal palette with plenty of features.
I used my Ampeg PF500 in similar conditions and that was happening. The thing was hot! It didn't shutdown though. I just don't think those little fans can cool the amp in those conditions. I had a fan blowing on me (required for hot outdoor gigs IMO) and just aimed it at the amp. Didn't have an issue at all for the gig (except sweat in my eyes!).
FWIW, I believe Carvin is on the 7th revision of the PC Board in the BX500. The current Board is stamped revision G. I don't know if this has a new/better resistor or not. I love my BX500 but it is only used as a back up due to fear of break downs. Old wiring at my old drummers house put my last 2 into permanent protection mode. I won't plug my 3rd one in without first checking the wiring. I use a cheap Home Depot tester that shows bad grounds, Open neutrals etc...
Good tip, I will have to start carrying a fan to gigs I guess!
I have encountered some questionable power situations, but never had any amp issues because of the power. I will have to check the board. Should I request the latest revision when I send it back or will they install in automatically?
I'm playing a BX500 through a Carvin 10.2 4 Ohm cab. It's killer with the blues trio I'm in. I've never needed more. I also have a Carvin B2000 head and a 10.4 4 Ohm cab that are overkill for anywhere we play, including outdoors.
I haven't had tons of playing time on it since the problem occurred: maybe 4 or 5 hours total. It hasn't overheated since then. I even tried playing through the exact same cabinet with the exact same settings and instrument for an hour, and it never got above room temperature. Maybe I wasn't playing the right songs to evoke the magic heat monster?
Anyway, at this point I have no clue what went wrong during that particular rehearsal, but sadly it's lowered my confidence in the amp.
When it overheated during the rehearsal and cut power down to 2% or whatever, I tried several things. I power cycled it, and it would typically work for a few seconds and then cut back out. I bypassed the input tube using the rear switch, same result. Then I unscrewed and removed the top and pointed an oscillating fan towards heatsink, and while I was at it I also re-connected the speakon cable. The unit was off for probably 5 or 10 minutes while I did this, while the band took a break. After this, I was able to continue with the rehearsal for another hour of equivalent playing without issue, and by the end the heatsink had cooled to the point where it was only slightly above room temperature.
To be honest, I don't think the problem was just the lack of fan; after I restarted the rehearsal, the heatsink just didn't seem to be producing as much heat as before. Whatever was producing the heat had stopped, for whatever reason.
This coincides with the Carvin tech, who basically indicated that the unit really shouldn't ever produce that much heat unless it's being asked to push a very low-impedance load. (In my case, it was just a single 8-ohm cabinet.)
So I suspect an internal short in the BX500, or perhaps an intermittent crossover problem in my cabinet. Without a repro, it's difficult to rule things out...
