Recapping Hafler DH200 and\or Hafler DH500 amps

[oldvinyldude]

I want to recap each of these amps. I have the instruction\assembly instructions, but was wondering if anyone has a cap list?, as I only want to replace the likely faulty\out of spec devices.

I plan on skipping any small value disk types, and the main filter caps (if they test ok).

I am new to recapping, but have done some recapping recently (successfully-yay!), and I get the impression that some caps rarely fail, while others (electrolytic) should all replaced, unless expensive and tested good (like main filter caps).

I want to do the driver boards, and test the filter caps.

Suggestions or a list are appreciated.

Thanks

 

[Blue Shadow]

Caps in the DH-200 manual are identified as to kind, skip the ceramics and the films do the electrolytics and use a film for the input cap.

Since you are new to this, why don't you dive in to the 200 with the manual and build a cap list and post it for vetting. More learning than just buying a cap list and soldering.

There is a lot more you can do to the 200 as detailed in the 200-page thread on this amp over on DIY. Might want to take a look and see.

 

[zebulon1]

Totally concur.
The DH200 has about eight electrolytic’s. A few are Bipolar.
Not to much to mess up.

 

[nerdorama]

I just did all the small electrolytic caps in a dh500 last week. Replacing the relay later today. I bought the caps from Mouser.

Might be a good idea to replace the thermal compound on the outputs, too. I haven't done this yet.

 

[rcs16]

I have two DH-200's on my bench for implementing a new design, DH-220C.

The old boards are PC-6A, there are 4 ecaps,
1) 10uF/16V BP, use a Nichicon UES
2) 470uF/6.3V BP, use a Nichicon UES
3) 2 of 100uF/80V polarized, use a Nichicon UPW
Do not know if they are bad or if they would have needed replacing as I did not measure them.

They also used PC-19 pcbs as well in these designs.

I agree the thermal paste should be replaced as the ones I have, the paste was dried out, applied un-evenly and insufficient.

Watch out for those fibre washers/spacers between the pcb and the heatsink ears.

 

[oldvinyldude]

1) 10uF/16V BP, use a Nichicon UES
2) 470uF/6.3V BP, use a Nichicon UES
3) 2 of 100uF/80V polarized, use a Nichicon UPW

This what I see as well-using the assembly manual-I looked them up prior to me reading your post-so thanks for the confirmation.

use a film for the input cap.

Not understanding which cap this is-but I am away from the amp. Is it actually on the imput jack rears?

200-page thread on this amp over on DIY

Maybe I am not using the search correctly-I searched DH200 as thread title in DIY and don't see it. Not that I doubt it exists-after all, this is a very popular amp!

 

[Blue Shadow]

Oh, DIYaudio and it is only 169 pages: https://www.diyaudio.com/forums/solid-state/31131-hafler-dh-200-220-mods.html

Input cap is the first one listed above. I think DIY talks about it being one you can lower the capacitance of to get one that will fit. It is the DC blocking cap on the input.

 

[Blue Shadow]

I put together a page or two from the DIYaudio thread and am about half done doing the upgrades. I went with the star ground, a bit honking copper wire between the two big caps and new RCA jacks both wired the same. A few other things, thinking I bypassed the input cap with a film cap.

There are more changes you can do. The signal leaves the board goes to the rear panel speaker fuses and back to the board. Why? who knows, some just go from the board to the outputs and skip the fuses and 10+" of internal wiring.

I did not change the dual binding posts as I hate those clear plastic yellow colored metal pieces of crap coming from China on all kinds of gear an installed by many here because they think they look fancy. If I change em, I'll go with Pomona as they make a quality product. Of course, the Cardas binding posts are nice, put them on a pair of L-07M amps recently, but all metal, easier to short so no for me.

 

[eickmewg]

I have had several instances where internal (driver transistor failure) and external (a turn-on transient from a tube preamp) factors blew the 2-amp speaker protection fuses. I think my speakers were thankful. I would not remove the speaker fuses from my DH-200; they are there for a very good purpose. The original RCA inputs and speaker outputs generally could use replacement. In addition, I've recapped the driver boards, renewed the power caps, renewed the semiconductors on the right channel board, and replaced the power switch on mine.

 

[sunvalleylaw]

Hi! I have a Hafler P225 that I love, and that I understand is very similar to the 200/220. Mine is stock, and I wonder about going through it like this at some point.

To be clear, people in this thread are just talking about recapping in essentially stock lay out, and not talking about the mods that can be done, either by collecting the parts yourself, or by getting the upgrade kits such as by musical concepts including a new board AND recapping stuff and other changes.

How many have been pleased with just recapping and keeping it stock, vs. the upgrade? At some point, I want to do the recapping, and at the same time I guess would consider the upgraded board. But think I would attempt to save some dough and buy the caps and such not as part of a kit.

 

[Mike Stehr]

I just did all the small electrolytic caps in a dh500 last week. Replacing the relay later today. I bought the caps from Mouser.

A friend up north of Spokane has a couple of DH-500s, with one getting the full rebuild.
A week ago, I listened to his fully rebuilt DH-220 with a homebrew grounded grid preamplifier, through a pair of Tannoy DMT 12 studio monitors.

Now that was an impressive sound...

He bought driver boards from eBay that have the upgrades, which IIRC, changes all the pre and driver transistors to Jfet.

 

[Blue Shadow]

How many have been pleased with just recapping and keeping it stock,

I have kept mine stock with some of the DIYAudio mods as I have other amps that are better sounding. The cost to make mine better sounding from some of the folks that were building these amps when new are more than I paid for my amps. Then the Musical Concepts are similarly more than I paid. but both are considered to be very nice upgrades moving the amp to a much higher performance level. Unfortunately these are mods that usually can't be recovered when sold but heck I've had mine since 1980. I have not bypassed the speaker fuses something that isn't really a problem for me as the speaker have fuses. But I got them refreshed and working properly with the star ground and the RCA inputs wired the same and some bypass caps added.

oops DP

You can use the delete option on your thread since you are a subscriber. Easier than an edit usually. Not that it really matters just want you to get all you paid for with that 25 buck outlay.

 

[Mike Stehr]

You can use the delete option on your thread since you are a subscriber. Easier than an edit usually. Not that it really matters just want you to get all you paid for with that 25 buck outlay.

Thanks. I hadn't paid attention to the "delete" option.

 

[rcs16]

How many have been pleased with just recapping and keeping it stock, vs. the upgrade?

I have just upgraded the two DH-200 that I have in my possession with a new design that I have been working on with Bob Cordell, he calls the design DH-220C.
Bob presented this design at a BAF2016 meeting. Here is a link to the documents and more discussions on DH200/220 mods.
https://www.diyaudio.com/forums/clubs-and-events/289409-burning-amp-2016-a-25.html
the design is also covered in Bob's second edition of his power amp design book.

I asked around and made a deal with the owner of these two DH-200's, in that I would mod one in exchange for the other.
The two had issues, the 4 channels that I measured, before the mods, 3 channels had high distortions, one channel showed oscillations. I did not investigate the reasons why, since I was pulling the boards.
The mods sound good and measure really well as measured by Bob, since I gave him an assembled pcb so he could test out in his DH-220.
I measured mine, with an Amber 3501 audio test set, it measures at residual level, <100dB, good enough for me. Bob did thorough measurements on his unit, with very good results.

The idea is to sell blank pcb's and probably the jfets too, since they are expensive to ship. Will provide a link to a Mouser shopping cart for parts except the jfets and set up a google drive with the documentation, showing pics of assembly etc.
Once Bob says "good to go" I will proceed. Here are a few pics of the DH-200 mods for your enjoyment.
As for the DH-500, that is still in the works for qualification at the +/-90V supply V.

1) 10uF/16V BP, use a Nichicon UES

This is the input coupling ecap, not much room in there to fit a 10uF film.

Anyone have a schematic (complete service manual) of the P225/230?, we know it uses the PC-19c pcb, so assumptions are it is the exact same as the DH-220.

 

[nutpecker]

Subscribing...I just got a "working" DH-200 today.

 

[sunvalleylaw]

I have kept mine stock with some of the DIYAudio mods as I have other amps that are better sounding. The cost to make mine better sounding from some of the folks that were building these amps when new are more than I paid for my amps. Then the Musical Concepts are similarly more than I paid. but both are considered to be very nice upgrades moving the amp to a much higher performance level. Unfortunately these are mods that usually can't be recovered when sold but heck I've had mine since 1980. I have not bypassed the speaker fuses something that isn't really a problem for me as the speaker have fuses. But I got them refreshed and working properly with the star ground and the RCA inputs wired the same and some bypass caps added.

You can use the delete option on your thread since you are a subscriber. Easier than an edit usually. Not that it really matters just want you to get all you paid for with that 25 buck outlay.

I have just upgraded the two DH-200 that I have in my possession with a new design that I have been working on with Bob Cordell, he calls the design DH-220C.
Bob presented this design at a BAF2016 meeting. Here is a link to the documents and more discussions on DH200/220 mods.
https://www.diyaudio.com/forums/clubs-and-events/289409-burning-amp-2016-a-25.html
the design is also covered in Bob's second edition of his power amp design book.

I asked around and made a deal with the owner of these two DH-200's, in that I would mod one in exchange for the other.
The two had issues, the 4 channels that I measured, before the mods, 3 channels had high distortions, one channel showed oscillations. I did not investigate the reasons why, since I was pulling the boards.
The mods sound good and measure really well as measured by Bob, since I gave him an assembled pcb so he could test out in his DH-220.
I measured mine, with an Amber 3501 audio test set, it measures at residual level, <100dB, good enough for me. Bob did thorough measurements on his unit, with very good results.

The idea is to sell blank pcb's and probably the jfets too, since they are expensive to ship. Will provide a link to a Mouser shopping cart for parts except the jfets and set up a google drive with the documentation, showing pics of assembly etc.
Once Bob says "good to go" I will proceed. Here are a few pics of the DH-200 mods for your enjoyment.
As for the DH-500, that is still in the works for qualification at the +/-90V supply V.

This is the input coupling ecap, not much room in there to fit a 10uF film.

Anyone have a schematic (complete service manual) of the P225/230?, we know it uses the PC-19c pcb, so assumptions are it is the exact same as the DH-220.

Thanks! While I think my old P-225 sounds pretty good now, I would like at some point to take it out of service for a bit, and do some of these mods, hopefully by getting the parts and doing it myself. I have a friend in town building various amps (mostly tube stuff) and I think he might help me. I can do some soldering, but am not very good at it. Mine has mostly been to replace guitar pickups, switches and the like. Fine work on a board is not my strong suit. I don't think I would spend a grand or so plus shipping to send in my amp to Musical Concepts and have it done. But I think the project would be fun, when I have some time to do take it on. Will keep an eye on this!

 

[rickl]

The idea is to sell blank pcb's and probably the jfets too

Once Bob says "good to go" I will proceed. Here are a few pics of the DH-200 mods for your enjoyment.

Will you post the 'good to go' on this thread, DIY forum or some other AK place? I'm interested in boards (saw them on DIYaudio) and will watch this thread for updates.

 

[rcs16]

Will you post the 'good to go' on this thread

Probably not, but if I remember, I might. It will be posted in the DIYAudio threads, for sure since we have established those threads as a place to converse about these designs in more details.
Will also sell using eBay, since it is the easiest way for me to sell boards and advertise. If I ever get a web site set up, there too. Probably could email/PM me as well and save a few $ on those fees.
Thanks for your interest in this upgrade. Bob did a fine job in its design and we are very fortunate that he spent much of his time evaluating the prototypes.

I don't think I would spend a grand or so plus shipping to send in my amp to Musical Concepts and have it done.

Yeah, that is pretty expensive, if anything, I might sell assembled/tested boards but even that jacks up the costs because it takes a fair amount of time. The idea is DIY after all.

If you are doing some minor mods like changing ecaps, putting new thermal compound on the devices, most should be able to do this but it does require that you have some understanding, proper tools and at least a DMM, probably a DBT to be on the safe side too.

Cheers Rick