Carvin HT1000 repair. AKA: Jim is a hero.

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Carvin HT1000 repair. AKA: Jim is a hero.

Postby Ken Baker » Tue Nov 18, 2008 3:48 pm

This is from my post in "Wanted"

I was maybe looking for a power amp to replace a Carvin HT1000 that was intermittently dropping out on channel 2.

Ken Baker wrote:Allow me to expand on "intermittent"... (edited)

With the level set to half power, channel 2 operates for a few seconds then cuts out for a few minutes. Then it starts up again and cuts out again. Lather, rinse, repeat. Has the feel of a thermal issue, which has the feel of a semiconductor issue. If I knew it was the power transistors I'd replace 'em all, but there are a lot of chips squeezed onto the heatsinks besides just the big guys and they're not getting stressed. The thing ought to be loafing at half power. I've given the boards inside a good look-see and nothing looks as if it had been overheated. Caps all appear to be in good condition (no swelling or discoloration). The various plugs & cables are snug. There's no audible distortion or scratchiness when it drops out - it just stops. That's what makes me lean toward a thermal shutdown issue.

Ken...


spideyjg wrote:Didja use some DeOxit on the internal connectors?

Recently scored a DCM 150 and 4 PM-5s and the DCM was wonky on one channel. Busted it open and disconnected all harnesses, sprayed them and the pots with DeOxit and reinserted. Fixed it right up.

May want to call Carvin and ask the scoop. I thing the HT sereis was right before the DCM and parts may be interchangeable.

Jim


Took the thing apart as much as possible, which isn't as much as I'd like but will have to do. Carvin glues a lot of stuff in place in addition to nuts & bolts. I was able to get the power amp board out once I defeated the freakin' tacked-down fish paper. The power supply and control boards were easy - just sitting on machine screws. I was not able to remove the I/O board in the back for unknown reasons.

There are huge Molex connectors in there routing DC power to various boards. This includes a cable harness and board-level sockets. These were all disconnected and shot liberally with Caig ProGold G5 (Now DeOxit Gold). I also spread open the split male contacts of the connectors for a better physical connection.

There are a couple low-power/low-level ribbon cables connecting signal around as well. These utilize PC mount keyed stake connectors. These also got a liberal shot of cleaner.

All miscellaneous push-on connectors were checked, cleaned, and re-seated.

The controls were shot, rotated, shot, & rotated.

I shot cleaner into the I/O board as best I could, hoping to get at least a little of it into the pushbutton switches back there. Best I could do short of probably destroying something.

Buttoned the whole thing back up, reduced the controls to zero, and fired up. No smoke (that's a good thing). Hooked up the BMAX, a speaker, and a bass; and it works. Then I connected a small mixer to channel 1, paralleled the inputs, connected the speaker to channel 2, and routed an MP3 player to drive it for an extended period. It's been going strong for the past half hour.

Jim, you were right. Lunch is on me at the next BB hookup.

Ken...
...at least the doctors find me fascinating...
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Ken Baker
"Turn the darned thing down!!"
 
Location: Orange County, CA

Re: Carvin HT1000 repair. AKA: Jim is a hero.

Postby spideyjg » Tue Nov 18, 2008 9:24 pm

No sweat Ken,
A can of DeOxit is a fair cheaper bet than a new amp ain't it? [smilie=icon_biggrin.gif]

Cleaning and reseating connectors often clears intermittent faults. Back in the Navy days I used to always have an eraser and alcohol handy to remedy edge connector issues. DeOxit is a must have tool bag item for a tech IMO.

The mo' connectors, the mo' fault possibilities.

I was kinda surprised the number of connectors in the DCM 150 but Carvin claims the modular design expidites repairs.

I often wondered how the DCM 150 handled heat dissipation and what they have internally is about a 1/4" thick metal plate on the bottom to which the power module is affixed. There is plenty of that plate that is bare metal throughout the chassis to act as a heat sink sans fan or fins. Pretty slick.

Jim
Silverbass wrote:gawd damn the pusher man
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spideyjg
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Re: Carvin HT1000 repair. AKA: Jim is a hero.

Postby Ken Baker » Tue Nov 18, 2008 11:19 pm

spideyjg wrote:No sweat Ken,
A can of DeOxit is a fair cheaper bet than a new amp ain't it? [smilie=icon_biggrin.gif]

Cleaning and reseating connectors often clears intermittent faults.


What's funny is that I went through the amp shortly after I got it and reseated everything I could get my hands on. Didn't spray it at the time, but did make sure I had good mechanical connections. So much for that.

I was kinda surprised the number of connectors in the DCM 150 but Carvin claims the modular design expidites repairs.


I'm sure it does. Find faulty board & replace it, then get the unit back to the customer. Component-level repairs can happen later, and possibly offshore.

I often wondered how the DCM 150 handled heat dissipation and what they have internally is about a 1/4" thick metal plate on the bottom to which the power module is affixed. There is plenty of that plate that is bare metal throughout the chassis to act as a heat sink sans fan or fins. Pretty slick.


Look at your old 400RB. The power transistors are mounted to a plate that bolts to the back panel and the heatsink is bolted to that. Nothing but mechanical connections and no fan. A whole load of aluminum though.

The HT1000 has a surprisingly small heatsink for the power it develops. There are 3 complimentary pairs of 16 amp transistors per channel bolted to the thing, plus a bunch of smaller TO-220 modules. Busy as Hell and only one low RPM fan.

Ken...
...at least the doctors find me fascinating...
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Ken Baker
"Turn the darned thing down!!"
 
Location: Orange County, CA

Re: Carvin HT1000 repair. AKA: Jim is a hero.

Postby Ben Esparza » Thu May 28, 2009 10:47 am

I'm resurrecting this old thread because I had my Carvin DCM600 take a dump on me on Monday. I was using it to power up some passive EON's, playing an Ipod through a Behringer UB1202 (thanks, Ken). One side was not coming through and when I tried to troubleshoot it, the other side crapped out. Wound up plugging the Ipod into my daughter's computer speakers. Anyway, I remembered this thread because it raised a flag for me since Ken bought that Carvin HT1000 from me. I did exactly what Ken did by taking things apart, separating connectors for better contact, using DeOxit on every connector that can be unplugged, on the pots, etc. I even plugged and unplugged each connector after the DeOxit to kind of sand any film or corrosion off each connector. Had a stuck Limiter button and I sprayed it and worked the button until it pressed in and out freely.

After all was done I connected and played a CD Walkman into a Raven Labs PHA-1, then into one side of the amp, and then out into a speaker cab. Tested both sides side using a 1/4" input from the Raven Labs to the amplifier. I then got a 1/4" TRS to XLR cord and went from the Raven Labs to each side in its XLR input. EVERYTHING WORKED FINE! A whole lot cheaper and much more satifying than paying an amp tech for 1-2 hours of labor to do the same thing.
"You can talk about virtuosity all you want, but what it comes down to is you're supposed to back up the other guys. They're not supposed to notice you until you stop."
- Keith Ferguson
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Ben Esparza
 
Location: Pico Rivera, CA

Re: Carvin HT1000 repair. AKA: Jim is a hero.

Postby Ken Baker » Fri May 29, 2009 8:06 pm

Ben Esparza wrote:After all was done I connected and played a CD Walkman into a Raven Labs PHA-1, then into one side of the amp, and then out into a speaker cab. Tested both sides side using a 1/4" input from the Raven Labs to the amplifier. I then got a 1/4" TRS to XLR cord and went from the Raven Labs to each side in its XLR input. EVERYTHING WORKED FINE! A whole lot cheaper and much more satifying than paying an amp tech for 1-2 hours of labor to do the same thing.


Yup, that is indeed pretty cool. Kinda make a guy want to take everything apart and give it a blast of Deoxit.

Glad to hear that little mixer is working well for you.

Ken...
...at least the doctors find me fascinating...
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Ken Baker
"Turn the darned thing down!!"
 
Location: Orange County, CA

Re: Carvin HT1000 repair. AKA: Jim is a hero.

Postby spideyjg » Fri May 29, 2009 8:46 pm

Ken Baker wrote:
Yup, that is indeed pretty cool. Kinda make a guy want to take everything apart and give it a blast of Deoxit.


That stuff is indispensable. Everybody should have a can in the tool box. [smilie=music-smiley-005.gif]

Jim
Silverbass wrote:gawd damn the pusher man
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spideyjg
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Location: San Diego


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