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Old 9th January 2009, 09:30 PM   #1
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Default Hafler XL280-went kaput

I have a hafler xl280 whose beautiful sound I have listened to for many years...nothing comes out any more. I already checked the fuses. Is there anyone that does reasonable repairs? If not ...is there a modern amp with same quality at a reasonable price?
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Old 9th January 2009, 11:17 PM   #2
eyoung is offline eyoung  United States
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Hola Y,all,

Check out the Hafler dh200 Thread as your amp is an offspring of that design(the dh200,220,500,and xl280 are all similar design)

good luck, Elwood
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Old 10th January 2009, 12:55 AM   #3
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The XL-280 uses FETs in its front end and these devices are no longer available. Years ago Borbely used to sell a matched pair of them for around $30. Don't know if he still has any of them

I know of at least one person who threw out his XL-280 PCBs and installed a pair of boards from Musical Concepts, and is very happy.

Good luck.......
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Old 10th January 2009, 01:31 AM   #4
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It's more likely the output devices. There's a fellow on eBay who sells the parts (they're no longer in production). He bought all of Hafler's stock when they quit making them, so they're exactly the same part. Verify that it's the outputs before buying new parts so that you don't waste money.
Also possible: Dead power supply caps. This one--should it turn out to be the case--is real simple to fix. All you do is replace the caps with like-spec caps. Done.
Or you can send me the carcass. I use old Haflers to build things in. They're good for that.

Grey
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Old 10th January 2009, 04:05 AM   #5
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If the input FETs failed then lack of sound might be only in one channel. If both channels went dead at the same time the problem is probably in the power supply.

The XL-280 has a pair of large caps and diode bridge for each channel for the output devices; and, a separate smaller power supply with its own diode bridge and pair of small filter caps that runs the PCBs.

Some simple checking with a voltmeter could determine whether both power supplies are functioning.

The output lateral MOSFETs are rugged devices and fail much less often than parts on the PCBs.

The power to the outputs are fused. The power to the PCBs is not fused. The power transformer has an additional set of booster windings which provides the 70 VDC to the PCBs (five volts higher than the power to the output MOSFETs). The manual (with the schematic and parts list) is located at HAFLER.COM.

The heat sinks are drilled for 3 pairs of MOSFETs per channel. This, plus the dual voltage transformer, makes the chassis more valuable than a DH-200/220/P225 chassis.
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Old 10th January 2009, 03:59 PM   #6
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Default Thanks, guys

I am not versed in DIY....is there anyone in the Philadelphia area who can do repairs on this?
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Old 13th January 2009, 10:31 PM   #7
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Default update

Hi,

I just went to check this amp and the left channel is working perfectly, but nothing happens on the right...but when I reset the speaker cables I do get a loud crackling response from the right speakers, but no music...I am wondering if the problem is in the input jack for the right channel. I already tried reversing the input cables to no avail. I pupped the top cover and everything looks ok, what should I be looking for?
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Old 14th January 2009, 12:14 AM   #8
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I suspect your problem is with a component on the PCB. If you have a good meter and know how to work about potentially lethal voltages you could check the points on the diagram and see how close they come to those expected -- as shown on the diagram. These voltages are referenced to ground.

Remove the remaining sheet metal screws that hold the heat sink and fold it out, then remove the 3 small screws around the periphery of the PCB so you can get at its back side. This will allow you to check these voltages.

But, before doing this, you should first run a hot iron around all the traces and refresh the solder joints to the devices soldered to the board. Sometimes a solder joint develops a microscopic lesion and as it makes/breaks contact a popping sound occurs.

You could alternate heat and cold to the components on the board while listening for sounds. This might help identify which component is faulty.

And, you could try tapping each component with the plastic handle of a toothbrush to see if any spot makes the bad sounds.

Tricks of troubleshooting.

Good luck.
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Old 14th January 2009, 12:18 AM   #9
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And, you could try a spritz of TV contact cleaner on the switch on the back panel, the one to bridge the amp probably labeled "Stereo/Mono." If its contacts have corroded over the last 20 years you might get some bad sounds. Spray the switch's contacts and work it back and forth.
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