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Class D Switching Power Amplifiers and Power D/A conversion

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Old 4th January 2012, 03:43 PM   #1951
nertia is offline nertia  Scotland
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Quote:
Originally Posted by damarfi View Post
When I get it, will post my experience... I just don't see reason why Mean Well has to be reference in SMPS production in country of 1.4 billion people ? There are other companies as well which has good products and export around the world.
If specs are true, seems that one is better, no fan, better ripple and noise (150 mWp-p vs. 250 mWp-p), better efficiency (85% vs. 83%).
I bought a Meanwell clone a year ago to power a T2 amp. The ebay description even used the Meanwell performance graphs, but at 27 delivered to the U.K. I knew it was a clone.

When it arrived I opened it up to inspect it as I have seen some really dodgy soldering jobs on cheap ATX computer supplies, but it looked pretty clean so I hooked it up.

Yesterday on powering it up there was a loud pop and a flash and that was the end of my MW clone. I have no idea what happened but the IEC input fuse blew and inside the unit one of the large capacitors seems to have either bulged and shorted to the case or blown as a result of the fault.

I am sure there are Chinese manufacturers that make excellent SMPS and I will be replacing my clone with a Connexelectronic supply, but if you can afford it, buy something with a known pedigree. At the time I couldn't afford a better supply, took the risk and paid for it.
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Old 5th January 2012, 02:26 PM   #1952
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Originally Posted by sst4270 View Post
Hi,

I'm looking for guidance. I purchased a T1 board last year (V1.2) and power supply from Hifimediy and just got around to hooking it up. No modifications to the board. The only thing I did out of the ordinary was to connect L & R INPUTS (not outputs) together. I wouldn't think that would have any negative impact on the amp.

Anyways the amp started smoking. I immediately cut power (27VDC measured BTW). Disconnected input. Separated inputs. Turned power back on and no smoke, but the output is much lower than I would expect.
I feel like something is blown, but I have no idea where to start looking (SMT components are small even with a magnifying glass).

I read through this thread and noticed some issues with caps on the underside (page 83). I'm not sure if this could be my problem. Maybe I got one of the boards from that batch.

I was playing the amp through an 8-ohm highly efficient speaker (98db). I was expecting it to play much louder than 'bedroom level'.

Hi res pictures attached. As you can see no modifications and no glaring discolored components.

Any suggestions?

Thanks so much in advance.

Steve
Hi, I'm sorry for that.
If you can power on without smoke now, I suggest first to check the power supply ( main DC supply after relay or on the 2x big FC caps, and 5V power supply from the SMT chip U5) if you can.
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Old 5th January 2012, 02:30 PM   #1953
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Another possible problem is C32 (270uF/16V) cap damaged, that also make 5V power supply on board not normal, may lead to some problem. Change this cap will repair.
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Old 5th January 2012, 02:59 PM   #1954
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Quote:
Originally Posted by sst4270 View Post
Hi,

I'm looking for guidance. I purchased a T1 board last year (V1.2) and power supply from Hifimediy and just got around to hooking it up. No modifications to the board. The only thing I did out of the ordinary was to connect L & R INPUTS (not outputs) together. I wouldn't think that would have any negative impact on the amp.

Anyways the amp started smoking. I immediately cut power (27VDC measured BTW). Disconnected input. Separated inputs. Turned power back on and no smoke, but the output is much lower than I would expect.
I feel like something is blown, but I have no idea where to start looking (SMT components are small even with a magnifying glass).

I read through this thread and noticed some issues with caps on the underside (page 83). I'm not sure if this could be my problem. Maybe I got one of the boards from that batch.

I was playing the amp through an 8-ohm highly efficient speaker (98db). I was expecting it to play much louder than 'bedroom level'.

Hi res pictures attached. As you can see no modifications and no glaring discolored components.

Any suggestions?

Thanks so much in advance.

Steve
This situation happened to me too, with T4! But in 1 second I cut the power and I cannot listen to any modification in sound. I accidentally shorted LR channels on the pot...and some smoke came out from something between heatsink and output terminals, if I remember well. These amps cannot definitely work as mono amp.
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Old 5th January 2012, 05:23 PM   #1955
lovro is offline lovro  Croatia
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Hi, guys
I have two t1 boards (I am making an emerald physics cs3 inspired system), and I seems I have a problem. I have been able to set the DC offset to ~0mV on three of the four channels.
On the last one the minimal offset I am able to set by turning the pot all the way counterclockwise is 65mV. That seems too much.

Anybody had the same problem?

Thnx, Lovro
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Old 6th January 2012, 03:49 AM   #1956
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Quote:
Originally Posted by Centvrion View Post
This situation happened to me too, with T4! But in 1 second I cut the power and I cannot listen to any modification in sound. I accidentally shorted LR channels on the pot...and some smoke came out from something between heatsink and output terminals, if I remember well. These amps cannot definitely work as mono amp.
I never tried that before, so your experience could be a lesson to us.
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Old 6th January 2012, 03:54 AM   #1957
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Quote:
Originally Posted by lovro View Post
Hi, guys
I have two t1 boards (I am making an emerald physics cs3 inspired system), and I seems I have a problem. I have been able to set the DC offset to ~0mV on three of the four channels.
On the last one the minimal offset I am able to set by turning the pot all the way counterclockwise is 65mV. That seems too much.

Anybody had the same problem?

Thnx, Lovro
Hi, if the channel has no problem to play music, we can say the trimmer(R22/R23) or resistor RP1 on the bottom side is down/bad soldered.
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Old 6th January 2012, 03:30 PM   #1958
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Shorting inputs with smoke as a result sounds serious.
Please get back to us with the result from the testing.

In another question. What would the idle power for a T1 STA510A at 32V be?
I have plans to drive one with a 32V 1A regulated supply, expecting no more then about 10W channel of course. The upshot is that I can use the PSU to it's full potential without getting over 60% where class-t amps supposedly start to sound worse with volume.
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Old 6th January 2012, 04:00 PM   #1959
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Originally Posted by David_Web View Post

In another question. What would the idle power for a T1 STA510A at 32V be?
I have plans to drive one with a 32V 1A regulated supply, expecting no more then about 10W channel of course. The upshot is that I can use the PSU to it's full potential without getting over 60% where class-t amps supposedly start to sound worse with volume.
T1 sta508 version was 0.1A @24V at idle. T2 was around 0.18A if I remember correctly.
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Old 6th January 2012, 05:57 PM   #1960
sst4270 is offline sst4270  United States
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Default Shorting Inputs

Pardon my ignorance, but why can't the inputs be shorted? (re: hifimediy T1 amp)

Nick or Steinar, care to respond?

Regards,

Steve
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