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Old 5th March 2005, 06:57 PM   #121
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Which particular caps do you want to swap out?

On the DH-200 schematic you can see caps C1, C5, C7 and C10. These are all electrolytic caps. Are these the ones you want to replace with newer ones?

It helps to know which item on the schematic you want to swap.
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Old 5th March 2005, 08:06 PM   #122
Bogie is offline Bogie  United States
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Oh, and while I'm at it...

Amp's back together. Nothing blew up. Thagyouvewwybuch.

Steely Dan sounds excellent.

Now what's this Hafler Trio stuff I see all over Ebay? Looks truly twisted.
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Old 5th March 2005, 08:27 PM   #123
Bogie is offline Bogie  United States
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Dick, I'm just gonna get basic... I figure that starting slow is probably best for me... These the ones with the screws... I figure I can worry about soldering after I learn a bit more theory...

Yup. Those big things that look like hand grenades with wires... This morning I replaced the Sangamos in my (already favorite) 200 with some new blue thangs, and the amp _does_ sound somewhat more alive. It already sounded good, and this seems to add a little to the low mids/lows...
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Old 5th March 2005, 08:31 PM   #124
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Quote:
Originally posted by Bogie
Oh, and while I'm at it...

Amp's back together. Nothing blew up. Thagyouvewwybuch.

Steely Dan sounds excellent.

Now what's this Hafler Trio stuff I see all over Ebay? Looks truly twisted.

The Hafler Trio is an extreme alternative, industrial, ambient group fully capable of releasing a 60 min CD comprised of nothing but a wavering 200Hz note in an incredibly elaborate package. In reality they can't be categorized.
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Old 6th March 2005, 05:26 AM   #125
fab is offline fab  Canada
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Default Big caps replace

Quote:
Originally posted by Bogie
Oh, and yet another stupid question - if I'm gonna swap out the caps in these other amps...

Just looked at Digikey's web site... And did a search on capacitor... Came up with >30,000 hits... Which do I pick?
Or how do I narrow the search?
On my side I have picked the Cornell Dubilier computer grade type series DCMC.... You have to be prepared that they are quite expensive.
In one amp, I have installed 4 x 14000 uF ( 2 x 14000 using 2 separate diodes bridge pack per channel).

In the other amp, 2 x 30000 uF.

You have to check for cap value, voltage of 75V nominal, size (2 inches diameter to fit into the dh-200 cap holders), low post terminal depending on height of cap (so it can fit into the amp with the cover closed).
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Old 6th March 2005, 06:35 AM   #126
Bogie is offline Bogie  United States
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Okayfine... Can't hardly be as gnarsty as blackgates... Or can they?

Some of that I understood... That may be an improvement. I dunno.

Does the cover have to be on the bugger?
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Old 6th March 2005, 04:31 PM   #127
fab is offline fab  Canada
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Default Big caps replace

Quote:
Originally posted by Bogie
Okayfine... Can't hardly be as gnarsty as blackgates... Or can they?

Some of that I understood... That may be an improvement. I dunno.

Does the cover have to be on the bugger?
I am not sure of the question but anyway:
Make sure that the cap height is lower than the height of the dh-200 chassis while the dh-200 chassis cover is installed. In my case, only as an optional precaution, I have added isolation tape on the dh-200 cover interior at the location of the caps screws to prevent any contact for any reason between the caps contacts screws and the metal cover.
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Old 5th April 2005, 04:53 AM   #128
fab is offline fab  Canada
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Default DH-200 New card Tests

Here are some news:
I have done some progress on the NO sym card for the DH-200/220 but I am not happy with the bench test results. I may continue later. By the way the Hafler SE-120 uses a NO sym card to drive lateral power mosfets too.

I decided to complete the already advanced SYM circuit that included my previously discussed mods. In additon there are some other mods that I could not do on the stock DH-200 card. A pcb is populated and bench tested with a +/- 28 Vdc power supply. Here are some results:

*THD at 1K Hz <= 0.02% (could be less but my home made meter is not that accurate) at Vac = Vdc -10V in 8 ohms (see scope screenshot)
* Rise time = 2 us (see scope screenshots at 10KHz Square wave)
* 8 ohms + 1 uF at 4 Vac (see scope screenshots at 10KHz Square wave)
* 8 ohms + 2.2 uF at 4 Vac (see scope screenshots at 10KHz Square wave)

Not installed in DH-200 yet so I have not listened to it.

I will post the scope screenshots on the next posts.
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Old 5th April 2005, 04:57 AM   #129
fab is offline fab  Canada
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Default DH-200 New card Tests

part 1
Attached Files
File Type: zip fab_sym_amp_revf.7c3_part_1.zip (90.2 KB, 326 views)
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Old 5th April 2005, 05:01 AM   #130
fab is offline fab  Canada
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Default DH-200 New card Tests

part 2
Attached Files
File Type: zip fab_sym_amp_revf.7c3_part_2.zip (77.4 KB, 158 views)
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