Help! Hafler DH102

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
B

baldrick

Member
Joined 2008
I've had the good fortune to come across a PCB for the ever elusive DH102 head amp that mounts inside the DH101.

Problem is that the circuit diagram and the parts layouts on these boards just don't exist anywhere.

My PCB is empty, and I'd love to build it up and run it.

Any DH102 owners out there that could provide a parts list and layout?

Thanks in advance!
 
M

mmerig

Member
Joined 2005
I could post what I have on the forum, as this would benefit more people; my only concern is Hafler's intellectual propoerty rights. The last time I checked, including an email to them, Hafler had nothing on the DH102. The DH102 is old, and Hafler has lots of schematics etc. on their website for other DH vintage products, but I leave it to a moderator to advise me before I post what I have on the forum which is:

1) Hafler's operating and installation instructions for the DH102 for installation in the DH101

2) A schematic and stuffing guide I derived from the board (not included in above)

3) A scan of the non-component side of the board

The schematic follows the board layout, and it could probably be simplified.

There is a muting circuit on the DH102, but I did not complete this on the schematic (I put my DH102 in the DH110, which has its own muting). I could complete the muting circuit, but it will be a week or so before I get to it.
 
B

baldrick

Member
Joined 2008
Considering its age and the fact that the parent company:

a) does not support it any more
b) has no data on it
c) doesn't seem to care that dozens of people are selling copies of documents they freely give away on their site

It should be considered public domain, IMHO.
 
Zen Mod

Zen Mod

Official Court Jester
Joined 2003
zenmod.in.rs/
Paid Member
sch
 

Attachments

  • schmtcsw.jpg
    schmtcsw.jpg
    59.5 KB · Views: 594
M

mmerig

Member
Joined 2005
It appears at first glance that the DH102 DH111 and DH112 are pretty much the same thing.
Click to expand...

Assuming Zen Mod's drawings were from the DH112, then the DH102 looks the same to me at a quick glance too. The Hafler manual for the DH110 states that the DH111 and DH112 "differ in electrical and mechanical configuration" but who knows, it may just be metal film resistors in the newer versions instead what looks like carbon film in the DH102.

I went to some trouble to make a power supply to match the DH102 (18 V each rail) to the DH110 which had 23V taps for the DH111 and DH112 power supply, but the transitors are the same in Zen Mod's drawing as in the DH102.


Zen Mod, are your drawings from the DH112?


The DH102 has a thick (about 3 mm) steel housing around it, an dthe installation instructions mention some wire re-roting to reduce hum. It may be worth shielding the head amp to reduce noise.

Baldric, let me know if you need the installation instructions for the DH102. Attached are a scan of the copper reversed so it matches the component side, and my circuit trace and list which should overlap the copper scan. The values for the bypass caps may be off; I had a hard time reading the stamps and I did not get consistent readings from the caps themselves.
 

Attachments

  • dh102 circuit.jpg
    dh102 circuit.jpg
    92.1 KB · Views: 406
B

baldrick

Member
Joined 2008
I'm off to the races with this information. Installing it is pretty simple if you know where the power taps are and the signal points.

I've been lucky lately. I've come across a complete functioning DH112 since this thread started. It appears that the blank PCB for the DH102 I got is identical.

BTW this is a pretty darn fine headamp coupled with the internal phono section of the DH110 preamp. It makes a pretty kick*ss combination, especially with my P3-RB300-ATOC9 setup.

Now I'm set to work on my so-called DH102 board. It'll be a DH112 in no time. Thanks guys.

This is a great opportunity for those of us with DH110 preamps to upgrade to an internal Hafler Moving Coil stepup. There is a vendor on ebay selling blank DH102 boards.
 
L

Lesco

Member
Joined 2009
Baldrick,
Hopefully you have the Hafler up and running by now but if not, both cap & transistor upgrade kits are available on ebay. They're not expensive and include parts for both the main pcb and power supply. I updated all the components in my DH101 and it sounds better than ever. By the way, I've owned the DH101 & DH200 since new and have all the documentation for both if I can be of assistance.
Les
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom