hafler psu caps

dcgold2000 · 20th December 2009, 02:53 AM

Anybody know how to determine the relative "goodness" of the original Hafler 10K caps or must we assume they need replacement.

planet10 · 20th December 2009, 03:20 AM

how old is the amp?

dave

jleaman · 20th December 2009, 03:53 AM

when in doubt change em out

dcgold2000 · 20th December 2009, 02:19 PM

Quote:

Originally Posted by planet10

how old is the amp?

dave

Not sure. It's a dh-200. The manual was copyrighted in 1980. I got several of these from ebay for my HT. They seem to work OK. When I hang the scope on the caps I see a pretty typical sawtooth. It would be nice to have a simple go/no go test.
Dennis

WithTarragon · 20th December 2009, 06:05 PM

Well, they are at least 20 to 30 years old.

Go ahead and replace them. While you are at it, here are some fairly inexpensive upgrades for a DH200.
1. Attach some thermistors on the Power supply (the start up is hard on the Hafler switch)
2. fabricate a heavier bus on the PS caps (rather than the small wire that is currently there).
3. Attach (parallel) small bypass caps on the PS caps.

These are all documented on this forum - do a search.

If you are more adventurous, then,
4. there a few other caps that can be upgraded and bypassed. Again, search the threads. Also check the bias and re-set to factory specs.

These are fairly simple and will clean up the bass a bit (#3) and make the mids a bit clearer (#4).

My suggestions are quite affordable.
Good luck.

samsagaz · 20th December 2009, 07:52 PM

wich capacitors recommend for an upgrade like that?
wich brand, model?

dcgold2000 · 20th December 2009, 09:24 PM

Some how I knew replacement would be the consensus. For those who might be interested, I found a guy on ebay selling 18K Hafler replacement caps for $50 a pair. I found a capacitor upgrade kit for the pc board as well. Just search Hafler in electronics. Thanks for the other tips. I will look them up.
Dennis

CharleyW · 21st December 2009, 01:19 AM

The DH-200 was out of production no later than the 3rd quarter of 1982.

Damon Hill · 21st December 2009, 03:11 AM

Sounds like your main power supply caps are still usable; determining the quality of the smaller decoupling caps is a little harder. In my experience, these fail at least as often as the big caps, depending on the temperatures they were exposed to. At this point, I'd buy up a supply of suitable caps (including bipolar caps for the feedback network and any input coupling) and replace them at your leisure, saving the big caps for last and follow some of the upgrading procedures recommended here.

After that, if you're still motivated, the resistors are probably good candidates for replacement; they were probably carbon film and maybe some composition. Quality metal films might be installed in the feedback network and that's what I'd recommend for the rest of the amplifier, starting with the input section.

20th December 2009, 02:53 AM	#1
dcgold2000 diyAudio Member Join Date: Dec 2009	hafler psu caps Anybody know how to determine the relative "goodness" of the original Hafler 10K caps or must we assume they need replacement.

20th December 2009, 03:20 AM	#2
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	how old is the amp? dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

21st December 2009, 01:19 AM	#8
CharleyW diyAudio Member Join Date: Aug 2002 Location: Arlington, TX	The DH-200 was out of production no later than the 3rd quarter of 1982. __________________ Hey is for horses.

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20th December 2009, 03:53 AM	#3
jleaman Banned Join Date: Apr 2002	when in doubt change em out

20th December 2009, 06:05 PM	#5
WithTarragon diyAudio Member Join Date: Jun 2007	Well, they are at least 20 to 30 years old. Go ahead and replace them. While you are at it, here are some fairly inexpensive upgrades for a DH200. 1. Attach some thermistors on the Power supply (the start up is hard on the Hafler switch) 2. fabricate a heavier bus on the PS caps (rather than the small wire that is currently there). 3. Attach (parallel) small bypass caps on the PS caps. These are all documented on this forum - do a search. If you are more adventurous, then, 4. there a few other caps that can be upgraded and bypassed. Again, search the threads. Also check the bias and re-set to factory specs. These are fairly simple and will clean up the bass a bit (#3) and make the mids a bit clearer (#4). My suggestions are quite affordable. Good luck.

20th December 2009, 07:52 PM	#6
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	wich capacitors recommend for an upgrade like that? wich brand, model?

20th December 2009, 09:24 PM	#7
dcgold2000 diyAudio Member Join Date: Dec 2009	Some how I knew replacement would be the consensus. For those who might be interested, I found a guy on ebay selling 18K Hafler replacement caps for $50 a pair. I found a capacitor upgrade kit for the pc board as well. Just search Hafler in electronics. Thanks for the other tips. I will look them up. Dennis

21st December 2009, 03:11 AM	#9
Damon Hill diyAudio Member Join Date: Mar 2001 Location: Auburn, WA (somewhere between Seattle and Tacoma) Blog Entries: 1	Sounds like your main power supply caps are still usable; determining the quality of the smaller decoupling caps is a little harder. In my experience, these fail at least as often as the big caps, depending on the temperatures they were exposed to. At this point, I'd buy up a supply of suitable caps (including bipolar caps for the feedback network and any input coupling) and replace them at your leisure, saving the big caps for last and follow some of the upgrading procedures recommended here. After that, if you're still motivated, the resistors are probably good candidates for replacement; they were probably carbon film and maybe some composition. Quality metal films might be installed in the feedback network and that's what I'd recommend for the rest of the amplifier, starting with the input section.

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