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Old 13th July 2006, 04:07 AM   #21
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Chris,
Perhaps I should explain my term "hi freq" since its really mid freq. My main load testing devices are some DIY "amplifier dynos" that have 2 frequency output settings: Lo freq (80hz) for car subwoofer amplifiers and Hi freq (1Khz) for all other amplifiers. The Cavers still seem to do well at 1Khz but I wouldn't want to go any higher.
Ok, more insults about my Fluke scopemeter. The photos were not current but I still use that same scope 99% of the time. Its really not the POS everyone thinks it is, this baby is the Crown Jewel of my work bench. The first scopemeter Fluke made, and everyone knows they cut corners on later models. I'm now just starting to break-in the Hi-Res LCD, thats why you can't see the "pip" on the old photos.
No luck in finding the thermal images I saved on CD. Give me a few days and I will scan another m400 cube and possibly another m1.5 and post the thermal image.
You seem to be one of the few Techs that really understand the Carver topology, I've picked up a few good tips from some of your past posts.
Photo is of the DIY "amp dyno" anybody want details?

Todd
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Old 13th July 2006, 12:34 PM   #22
anatech is offline anatech  Canada
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Hi Todd,
I'm sorry if you feel I was taking a shot of your scopemeter. I wasn't at all. I did work in a test instrument calibration facility at one time and have hands on experience with yours. I was being factual though.

As far as that class of portable LCD 'scopes are concerned, the Fluke scope meters were the best. They still do not offer the resolution of more expensive DSO products. An HP 54600 series 'scope was far better, and it's far behind these days. Your scopemeter may be enough for what you are doing. It's probably much better than what some other technicians are using. I do know it cost you a fair bit and that was money well spent if you needed portability.

Back to the Carver ....
The problem with high frequencies and this style amp is that the commutators turn on rapidly and stay on for a minimum period of time. Therefore as the frequency goes up, the commutator tends to stay turned on. It is "locked up". This has the effect of running the output stage at a far higher voltage than is was designed for. It will overheat as a result.

I could see the basic form of the "pips". It would be interesting to see what you can capture in the high res mode then.

Your amp dyno is a neat labour / time saving device. AC meter across built in dummy loads and calibrated in watts? Could be a 7106 based design.

-Chris
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Old 17th July 2006, 03:27 AM   #23
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Chris,
Its an old design I started about 10 years ago, all analog except for the LCD meter. This is the main circuit, not shown are the 400 watt resistors, a fan and LCD display. Lower right corner is the power supply: sg3525 pwm driving a torroid core trans that provides isolated voltages for the LCD, oscillator, precision diode, analog multiplier. Upper right corner is the oscillator: low distortion 80hz/1khz sine wave that is amplified and drives a transformer, the transformer also provides an inverted phase output for bridging a stereo amplifier. Lower right is the voltage/watts conversion: precision rectifier driving a AD633 analog multiplier, output is scaled to drive a lcd display with a maximum of 1999 watts displayed. The power supply is driven from battery power, above about 100 watts the power is pulled from the load resistors so it saves the battery power. A built in fan keeps everything cool, its power is also derived from the load resistors. By using a 24v wall wart power supply to feed the unit, an internal circuit will switch the fan and pwm power supply to use the 24v power only. Thus providing only resistive loads to the amplifier under test.
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Old 17th July 2006, 12:36 PM   #24
anatech is offline anatech  Canada
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Hey Todd,
That's a nice design, build quality is excellent. What's wrong with analog??

I'm sure it's saved you a ton of time over the years!

-Chris
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Old 5th September 2008, 01:32 AM   #25
jimr62 is offline jimr62  United States
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hi chris
new to diy audio
i have the carver reciever which was a gift from my wife many years ago and has sentimental value. i also have a carver m400 which has a nice small footplate to fit in a liftbox for my plasma screen. i have read many of your comments in many threads regarding carver amplifiers. i have found them to be informative ,responsive, and profoundly knowledgeable. from these and others i have deduced that i lack the ability to even attempt to repair these. i cannot find any local audio technicians to fix these and the only factory solution is in oregon usa. i live in western pennsylvania usa and was wondering if you know of a local or more regional interested and competent party able to help.thank you for your time. jim
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Old 26th November 2008, 02:57 AM   #26
anatech is offline anatech  Canada
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Hi Jim,
I hate being unable to answer that question for you.

In Canada, not many warranty shops could measure up. Just a couple were kept open. I had no contact with the US service network at all.

Having said that, shipping within the borders of the United States is not expensive, and it's pretty quick. Unless you know of a really good audio service shop, you should probably ship them off to Oregon for service. Be sure to call them first for an idea of charges. Make sure you have the serial numbers ready along with the model numbers.

What was the model number of your receiver?

-Chris
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Old 27th June 2009, 07:49 PM   #27
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Default PCB board drawing for PS capacitors

I am interested in obtaining at least two of the PCB boards for the replacement power supply capacitors shown in a photo by Toddyaudio above. I am a new member, so I am not able to send an e-mail yet. Please let me know how I might obtain some.
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Old 27th June 2009, 09:26 PM   #28
anatech is offline anatech  Canada
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Hi wrthissell,
Welcome to DiyAudio then!

All we can do is hope toddyaudio can see your post. He would then respond to you.

This all happened a while ago now in this thread. I am thinking that the project that toddyaudio built to test amplifiers would be a really nice project thread.

Now, with respect to replacing those capacitors .... It shouldn't be too difficult to remove the old caps. After this is done, place cardboard or paper on one side of the PCB and mark the location of the holes through the PCB onto that material. Then you only need to identify each connection. After that is done, you might want to make a copy of your terminal location guide. Now you are ready to select some capacitors and lay out where they will go, marking their terminals as well. Then, it's "connect the dots" time. Now you have a layout for a PCB. Select some blank PCB and cut it to the correct size, then use a copy of you layout to mark where the leads are going to go. Drill, clean and use a resist pen (I think it's bluing ink) to create your pads and traces. After the lacquer (or ink) dries, etch it in a bath of ferric chloride. That should only take about 15 minutes, faster if you warm it up and agitate the liquid a little. Rinse with water, remove the coating and assemble your adapter PCB.

Remember that capacitors can get pretty warm in operation, so allow space between and around them if you possibly can. Use the 105 types. If you can get these values in capacitors designed for switching power supplies, they may work better in this application.

Finally, there is a short moderation period for all new members. Yours will be over soon enough. Just post as you normally would until then.

I hope that helps you some. Let us know how you do.

-Chris
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Old 10th August 2010, 02:45 PM   #29
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Was wondering if anyone knows about Jensen 4 pole electrolytics. I'm trying to replace the 4 pole 2200uf power supply capacitors on the Carver M1.5t using the Jensens. Little confused on the wiring. The Computer Technology capacitors used originally were made with their circuit layout exactly as the circuit board dictates. Would I have to cross wire the Jensens (long leads, strink tube, etc) to match what I'd need for them to be used on the board?
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Old 8th June 2012, 09:08 PM   #30
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Hi, What did you end up doing on that?
I guess the thread was stopped.

or

did the thread move?

I"m having problems with an 1.5. Go figure.
I do have some notes with production problems
that need to be addressed with this amp.

I don't have the theory manul or the general op manual, are they available?

Cheers
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