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Message |
Dave40
Guest
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 Posted:
Fri Nov 04, 2005 5:43 am Post subject:
Help with a hafler p500 amp |
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I have been given a dead Hafler p500 amplifier, and I found that the
right channel had multiple output Mosfets, 1 zener,1 regular diode, and
Q13 were shorted.I changed all the outputs and have replaced them all
with exact parts. When I fired it up, the right channel overheated and
cut out with thermal protection within 2 minutes and the left channel,
as I turned up the input knob, the clip light lit up and the channel
cut out. I have found that Q3 and Q4, on the right channel, their HFE
doesn't match. Q3 is 154 and Q4 is 34. Their part number is 2n5550 and
I was wondering if I can sub in 2n5551 instead? I think that this is
the problem for the right channel but the left channel is a mystery.
Any help is greatly appreciated.
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David Carlstrom
Guest
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| Posted:
Sun Nov 06, 2005 8:54 pm Post subject:
Re: Help with a hafler p500 amp |
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2N5551 is very similar to 2N5550, so it may work. However, I doubt the HFE
difference is significant in this circuit. The simple answer for both
channels is that you did not find all the dead semiconductors. Troubleshoot
from the output toward the input. Check every semi until you find all of
them good. This is relatively easy with the schematic and nearly impossible
without.
"Dave40" <tablesncues@comcast.net> wrote in message
news:1131079445.515175.166690@o13g2000cwo.googlegroups.com...
| Quote: | I have been given a dead Hafler p500 amplifier, and I found that the
right channel had multiple output Mosfets, 1 zener,1 regular diode, and
Q13 were shorted.I changed all the outputs and have replaced them all
with exact parts. When I fired it up, the right channel overheated and
cut out with thermal protection within 2 minutes and the left channel,
as I turned up the input knob, the clip light lit up and the channel
cut out. I have found that Q3 and Q4, on the right channel, their HFE
doesn't match. Q3 is 154 and Q4 is 34. Their part number is 2n5550 and
I was wondering if I can sub in 2n5551 instead? I think that this is
the problem for the right channel but the left channel is a mystery.
Any help is greatly appreciated.
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Dave40
Guest
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| Posted:
Sun Nov 06, 2005 10:38 pm Post subject:
Re: Help with a hafler p500 amp |
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I have gone thru the 2 output boards with a diode check on my meter,
and haven't found anymore shorted or open semis or diodes. If I take
them out to check out of circuit, I may as well change them. The
channel that goes into clip, I was checking the rail voltage with the
fuses removed from the holders, and when I touched the meter to the
feed side of holder, (not the output board side), on that channel, the
clip light flickered each time I put the probe on it. The other channel
didn't do that. Is there something in the preamp that could be blown? I
have a full manual for this amp, and it shows alot of IC's in the
preamp. Thanks for the reply Dave.
David Carlstrom wrote:
| Quote: | 2N5551 is very similar to 2N5550, so it may work. However, I doubt the HFE
difference is significant in this circuit. The simple answer for both
channels is that you did not find all the dead semiconductors. Troubleshoot
from the output toward the input. Check every semi until you find all of
them good. This is relatively easy with the schematic and nearly impossible
without.
"Dave40" <tablesncues@comcast.net> wrote in message
news:1131079445.515175.166690@o13g2000cwo.googlegroups.com...
I have been given a dead Hafler p500 amplifier, and I found that the
right channel had multiple output Mosfets, 1 zener,1 regular diode, and
Q13 were shorted.I changed all the outputs and have replaced them all
with exact parts. When I fired it up, the right channel overheated and
cut out with thermal protection within 2 minutes and the left channel,
as I turned up the input knob, the clip light lit up and the channel
cut out. I have found that Q3 and Q4, on the right channel, their HFE
doesn't match. Q3 is 154 and Q4 is 34. Their part number is 2n5550 and
I was wondering if I can sub in 2n5551 instead? I think that this is
the problem for the right channel but the left channel is a mystery.
Any help is greatly appreciated.
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Michael Squires
Guest
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| Posted:
Mon Nov 07, 2005 3:26 am Post subject:
Re: Help with a hafler p500 amp |
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Not sure if these fit in this amp, but there are a number of sets of driver
cards for the 500, DH220, etc., for sale on eBay right now.
Mike Squires
--
Mike Squires (mikes at cs.indiana.edu) 317 233 9456 (w) 812 333 6564 (h)
mikes at siralan.org 546 N Park Ridge Rd., Bloomington, IN 47408 |
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David Carlstrom
Guest
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| Posted:
Mon Nov 07, 2005 3:32 am Post subject:
Re: Help with a hafler p500 amp |
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The semi's must be removed for testing.
"Dave40" <tablesncues@comcast.net> wrote in message
news:1131295121.084567.214790@g44g2000cwa.googlegroups.com...
| Quote: | I have gone thru the 2 output boards with a diode check on my meter,
and haven't found anymore shorted or open semis or diodes. If I take
them out to check out of circuit, I may as well change them. The
channel that goes into clip, I was checking the rail voltage with the
fuses removed from the holders, and when I touched the meter to the
feed side of holder, (not the output board side), on that channel, the
clip light flickered each time I put the probe on it. The other channel
didn't do that. Is there something in the preamp that could be blown? I
have a full manual for this amp, and it shows alot of IC's in the
preamp. Thanks for the reply Dave.
David Carlstrom wrote:
2N5551 is very similar to 2N5550, so it may work. However, I doubt the
HFE
difference is significant in this circuit. The simple answer for both
channels is that you did not find all the dead semiconductors.
Troubleshoot
from the output toward the input. Check every semi until you find all
of
them good. This is relatively easy with the schematic and nearly
impossible
without.
"Dave40" <tablesncues@comcast.net> wrote in message
news:1131079445.515175.166690@o13g2000cwo.googlegroups.com...
I have been given a dead Hafler p500 amplifier, and I found that the
right channel had multiple output Mosfets, 1 zener,1 regular diode,
and
Q13 were shorted.I changed all the outputs and have replaced them all
with exact parts. When I fired it up, the right channel overheated and
cut out with thermal protection within 2 minutes and the left channel,
as I turned up the input knob, the clip light lit up and the channel
cut out. I have found that Q3 and Q4, on the right channel, their HFE
doesn't match. Q3 is 154 and Q4 is 34. Their part number is 2n5550
and
I was wondering if I can sub in 2n5551 instead? I think that this is
the problem for the right channel but the left channel is a mystery.
Any help is greatly appreciated.
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Dave40
Guest
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| Posted:
Tue Nov 08, 2005 3:50 am Post subject:
Re: Help with a hafler p500 amp |
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I have ordered a batch of transistors and will pull all the semis to
test. I have seen the pairs of boards for sale on EBAY and am keeping
my eye on them. I am trying to keep the repair cost low as I already
have $125 invested in Mosfets and another $20 or so in misc. parts that
were blown up.
Thanks guy for the help,
Dave B
Michael Squires wrote:
| Quote: | Not sure if these fit in this amp, but there are a number of sets of driver
cards for the 500, DH220, etc., for sale on eBay right now.
Mike Squires
--
Mike Squires (mikes at cs.indiana.edu) 317 233 9456 (w) 812 333 6564 (h)
mikes at siralan.org 546 N Park Ridge Rd., Bloomington, IN 47408 |
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Arny Krueger
Guest
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| Posted:
Tue Nov 08, 2005 5:42 am Post subject:
Re: Help with a hafler p500 amp |
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"Dave40" <tablesncues@comcast.net> wrote in message
news:1131400217.058439.148290@g14g2000cwa.googlegroups.com
| Quote: | I have ordered a batch of transistors and will pull all
the semis to test. I have seen the pairs of boards for
sale on EBAY and am keeping my eye on them. I am trying
to keep the repair cost low as I already have $125
invested in Mosfets and another $20 or so in misc. parts
that were blown up.
|
The irony is that you're well into buying a modern amp with
similar ratings. |
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