A couple years ago, a guy who worked for me gave me a Hafler DH-220 power amp and a DH-110 pre-amp. I’m just getting around to trying them out. Haven’t tried the power amp yet, but the pre-amp seems to have a problem. The right output is about half as loud as the left, and sounds subdued, or muted. I tried swapping the inputs from the source and the right channel is still the problem. I tried swapping the outputs to the power amp and the problem moves to the left speaker. I tried this with the source in both AUX and Tuner modes. Any ideas?
I don't know much about electronics, I'd just like this thing to work.
Appreciate any help I can get.
Thanks,
grym
I don't know much about electronics, I'd just like this thing to work.
Appreciate any help I can get.
Thanks,
grym
Hi grym,
That is a really nice sounding combination. It is well worth keeping in top shape. Unless you are an audio tech, I would recommend you visit a good one. There are things the amplifier needs to have done, and the same goes for the preamp.
Most DIY attempts end with wrecked PC boards and equipment that is rough even repaired. In addition to capacitors, there are transistors that need replacing with matched pairs. The difference in sound quality is worth while. This is detail work that only good, professional audio techs do, and advanced hobbyists. It can be difficult to sort them out from the hackers because everyone thinks they are "great"!
Stay away from shops that specialize in modifications. They are the most harmful breed that destroys more equipment every year than any other cause.
-Chris
That is a really nice sounding combination. It is well worth keeping in top shape. Unless you are an audio tech, I would recommend you visit a good one. There are things the amplifier needs to have done, and the same goes for the preamp.
Most DIY attempts end with wrecked PC boards and equipment that is rough even repaired. In addition to capacitors, there are transistors that need replacing with matched pairs. The difference in sound quality is worth while. This is detail work that only good, professional audio techs do, and advanced hobbyists. It can be difficult to sort them out from the hackers because everyone thinks they are "great"!
Stay away from shops that specialize in modifications. They are the most harmful breed that destroys more equipment every year than any other cause.
-Chris
Probably it's a bad part that will require an electronics tech to find and fix.
Any local friends that can look at it?
Sounds like I can either pay a bunch to have someone fix this thing, or wreck it by attempting the repairs myself! .... or shove it back into the basement and worry about it some other day.
I did just fire up the 220 and so far so good! I just have it on low volume now, letting it run. I'll crank it up later when Mrs. Grymster goes shopping, see if my tired old ears can distinguish the sound from the Onkyo amp I have in that system.
I did just fire up the 220 and so far so good! I just have it on low volume now, letting it run. I'll crank it up later when Mrs. Grymster goes shopping, see if my tired old ears can distinguish the sound from the Onkyo amp I have in that system.
Hi grym,
You haven't heard anything yet. Once gone over, your Hafler equipment will be a joy to listen to. I have serviced many over the years, and each of my customers have been extremely happy with both the price and the equipment.
It's not cheap to have a good job done, but cheaper than having a bad job done. These will last a very, very long time. Once you hear these things in fighting form, you will understand. Right now, they aren't anything to write home about. All you need is an honest tech who services audio only. I hope you can find one close to where you live.
-Chris
You haven't heard anything yet. Once gone over, your Hafler equipment will be a joy to listen to. I have serviced many over the years, and each of my customers have been extremely happy with both the price and the equipment.
It's not cheap to have a good job done, but cheaper than having a bad job done. These will last a very, very long time. Once you hear these things in fighting form, you will understand. Right now, they aren't anything to write home about. All you need is an honest tech who services audio only. I hope you can find one close to where you live.
-Chris
Thanks Chris!
There doesn't seem to be much locally. Seems most people I know these days have some 5.1 or 7.1 home theater system and don't much care about old school, two channel stuff. And if something breaks, they seem to just toss it and go buy another one.
There is a place in Alameda (about 50 miles from me). Not sure that I'll want to mess around with this at this time, but at least you've kept me from digging into the preamp with my less than stellar electronics skills! I suppose if I do take it to someone I could ask what they recommend, then run that by you folks before committing?
grym
There doesn't seem to be much locally. Seems most people I know these days have some 5.1 or 7.1 home theater system and don't much care about old school, two channel stuff. And if something breaks, they seem to just toss it and go buy another one.
There is a place in Alameda (about 50 miles from me). Not sure that I'll want to mess around with this at this time, but at least you've kept me from digging into the preamp with my less than stellar electronics skills! I suppose if I do take it to someone I could ask what they recommend, then run that by you folks before committing?
grym
Hi grym,
By all means, we would love to help. Too bad I don't live down there. I actually enjoy rebuilding these little amplifiers, and the preamp is the same for me.
The best techs these days are probably working from home, like myself now. They will be in their 50's (the young ones), and have a pretty nice bench. I find that the guys who know the most are generally pretty helpful people. Many are members here, so possibly one may catch your thread and respond. The cranky old guys are a minority, but they exist too.
-Chris
By all means, we would love to help. Too bad I don't live down there. I actually enjoy rebuilding these little amplifiers, and the preamp is the same for me.
The best techs these days are probably working from home, like myself now. They will be in their 50's (the young ones), and have a pretty nice bench. I find that the guys who know the most are generally pretty helpful people. Many are members here, so possibly one may catch your thread and respond. The cranky old guys are a minority, but they exist too.
-Chris
So first thing to do with the 110 is to get a can of Caig laboratories "deoxIT" and clean all the switches. As for the differing levels problem, there is a JFET in each channel that performs a de thumping mute function on power up. you need to replace both of them. When I repaired these under warranty this was the most common problem ( actually about the only problem) I have simply just removed the JFETS in a number of 110's and have not had any thumping issues at all. Due to the age of these units a replacement of power supply caps is in order here with larger uf values preferred . The 110 has electrolytic output coupling caps bypassed with a small film type a polypropylene cap of your prefferred flavor here makes a dramatic upgrade , you will need to mount them offboard as there is not much room.
As for the DH220 there is a wealth of upgades and advice out there ( and in diyaudio.com) The 110 got some bad press in the beginning as being coarse sounding and the switches are an issue - way too many contacts in the signal path. but with very little work they can be great! have fun!
As for the DH220 there is a wealth of upgades and advice out there ( and in diyaudio.com) The 110 got some bad press in the beginning as being coarse sounding and the switches are an issue - way too many contacts in the signal path. but with very little work they can be great! have fun!
Hi amp_guy,
What are your thoughts about replacing the muting JFets with relay contacts to signal ground?
-Chris
What are your thoughts about replacing the muting JFets with relay contacts to signal ground?
-Chris
Thanks amp_guy!
As I said before, I don’t know a whole bunch about electronics (I was a mechanical manufacturing guy before I retired), but I do have some experience. A couple years ago, I almost completed a tube amp from a kit. Was actually two mono amps from S5. I’ve also soldered a number of other kits together (little amplifies and power supplies and such), and built a pair of Overnight Sensation speakers. We put the house on the market before I finished the tube amp, and while the speakers work great, I didn't get to finishing the boxes, so all that stuff is still packed away in the basement.
Replacing a couple of JFETs sounds like something I could do though. My problem will be identifying the components that I need to replace. For instance, the muting JFETs you mentioned are not completely obvious to me. The “component values” list in the 110 manual lists 15 transistors, but only one is designated a FET (J112).
As I said before, I don’t know a whole bunch about electronics (I was a mechanical manufacturing guy before I retired), but I do have some experience. A couple years ago, I almost completed a tube amp from a kit. Was actually two mono amps from S5. I’ve also soldered a number of other kits together (little amplifies and power supplies and such), and built a pair of Overnight Sensation speakers. We put the house on the market before I finished the tube amp, and while the speakers work great, I didn't get to finishing the boxes, so all that stuff is still packed away in the basement.
Replacing a couple of JFETs sounds like something I could do though. My problem will be identifying the components that I need to replace. For instance, the muting JFETs you mentioned are not completely obvious to me. The “component values” list in the 110 manual lists 15 transistors, but only one is designated a FET (J112).
So despite anatech’s probably very sound advice, I think I might want to try and fix the preamp myself. I really don’t want to screw it up, but I’m out only my time and the cost of a few components if I do.
I think I found the JFETs and new ones are $.51 from Mouser…. Plus about $7 to ship them. Wondering if I should throw some capacitors into that order, get more shipping bang for my buck.
I think I located the power supply caps (1000mfd, 50v) and I'm pretty sure I could remove and replace them without too much trouble. amp_guy says to up the capacitance some, so any recommendations for brand/capacitance for them would be nice.
Not sure, but I think the output coupling caps are 470 nF, 50 volt units. Any recommendations for those?
amp_guy also says “The 110 has electrolytic output coupling caps bypassed with a small film type a polypropylene cap of your prefferred flavor here makes a dramatic upgrade , you will need to mount them offboard as there is not much room.”
Not sure exactly what that entails, but any recommendations for these would be greatly appreciated also.
Thanks,
grym
I think I found the JFETs and new ones are $.51 from Mouser…. Plus about $7 to ship them. Wondering if I should throw some capacitors into that order, get more shipping bang for my buck.
I think I located the power supply caps (1000mfd, 50v) and I'm pretty sure I could remove and replace them without too much trouble. amp_guy says to up the capacitance some, so any recommendations for brand/capacitance for them would be nice.
Not sure, but I think the output coupling caps are 470 nF, 50 volt units. Any recommendations for those?
amp_guy also says “The 110 has electrolytic output coupling caps bypassed with a small film type a polypropylene cap of your prefferred flavor here makes a dramatic upgrade , you will need to mount them offboard as there is not much room.”
Not sure exactly what that entails, but any recommendations for these would be greatly appreciated also.
Thanks,
grym
Hi grym,
Since you do have experience in working on equipment, I don't see any problems with you doing some service work yourself. Just take you time and do a neat job. Never forget that the most expensive component is / are the PC board(s). Do you have a large desoldering tool? Its usually blue and has a little recoil when it operates. If not, please get one. These take the heat out with the solder. This is a two-hand operated solder sucker for priming it, not the little wee useless ones. Temperature controlled soldering stations are available for $90 ~ $110 here in Canada. These are really excellent stations and may have various brand names on them. Mine is over 20 years old and has been rebuilt once. The brand name I have is Solomon and has a digital temperature display that you can check your set and actual temperatures on. Highly recommended. Get a large and small "screwdriver tip" when you buy it. I always buy extra tips with a station.
The JFETs you found sound like the correct ones. If you just remove them and try the unit, you can tell if the JFETs where bad or not as far as causing distortion is coincerned. They tend t check good, even when they have a problem.
Main filter caps are often just fine. You can certainly replace them, but do not increase their size in capacitance. If you do, only a little bit. Increasing these capacitors will not improve anything, and may actually cause more diode noise. There is a happy spot when sizing filter capacitors. The same goes for "high speed" or any other special rectifier diodes or bridges. There is a good reason why industry uses "standard rectifiers". They have been carefully developed for the job they do.
The capacitors that need replacement most often are the smaller ones. Use a good, normal brand for these. If the capacitor body is too big for the mounting location, DO NOT USE IT. If the lead wires are much larger than the original ones, do not use them. This is all very basic common sense stuff.
Why do I care about this? I am very tired of cleaning up other people's messes. I can tell you from talking to other good service techs that they are too. Now, the most difficult thing to do for you will be to stop if you go beyond your skill level. No good service tech will fault you for being honest and up front with them, and it will save you money.
I'm all for you doing this yourself. Just as long as you have the skills to do the work, and it sounds as if you shouldn't have any problems. Don't forget to take some digital pictures of the board from all angles so you have a record of things like transistor orientation and capacitor polarity. I do it, and before digital cameras I used to draw rough pictures by hand. They can save your life! 🙂
-Chris
Since you do have experience in working on equipment, I don't see any problems with you doing some service work yourself. Just take you time and do a neat job. Never forget that the most expensive component is / are the PC board(s). Do you have a large desoldering tool? Its usually blue and has a little recoil when it operates. If not, please get one. These take the heat out with the solder. This is a two-hand operated solder sucker for priming it, not the little wee useless ones. Temperature controlled soldering stations are available for $90 ~ $110 here in Canada. These are really excellent stations and may have various brand names on them. Mine is over 20 years old and has been rebuilt once. The brand name I have is Solomon and has a digital temperature display that you can check your set and actual temperatures on. Highly recommended. Get a large and small "screwdriver tip" when you buy it. I always buy extra tips with a station.
The JFETs you found sound like the correct ones. If you just remove them and try the unit, you can tell if the JFETs where bad or not as far as causing distortion is coincerned. They tend t check good, even when they have a problem.
Main filter caps are often just fine. You can certainly replace them, but do not increase their size in capacitance. If you do, only a little bit. Increasing these capacitors will not improve anything, and may actually cause more diode noise. There is a happy spot when sizing filter capacitors. The same goes for "high speed" or any other special rectifier diodes or bridges. There is a good reason why industry uses "standard rectifiers". They have been carefully developed for the job they do.
The capacitors that need replacement most often are the smaller ones. Use a good, normal brand for these. If the capacitor body is too big for the mounting location, DO NOT USE IT. If the lead wires are much larger than the original ones, do not use them. This is all very basic common sense stuff.
Why do I care about this? I am very tired of cleaning up other people's messes. I can tell you from talking to other good service techs that they are too. Now, the most difficult thing to do for you will be to stop if you go beyond your skill level. No good service tech will fault you for being honest and up front with them, and it will save you money.
I'm all for you doing this yourself. Just as long as you have the skills to do the work, and it sounds as if you shouldn't have any problems. Don't forget to take some digital pictures of the board from all angles so you have a record of things like transistor orientation and capacitor polarity. I do it, and before digital cameras I used to draw rough pictures by hand. They can save your life! 🙂
-Chris
Thanks for the response, Chris!
I did buy the JFETs and a bunch of the caps recommended by HaflerFreak in his thread titled refurbishing-hafler-dh-110-how-haflerfreak-got-his-groove-back. I couldn’t find all the ones he recommended, and so substituted a few with similar ones. I also bought one of those desoldering tools, and yep…. I got a “little wee useless one”🙂. Will try to fix that problem when I get a decent soldering setup like you recommend. Although I find many desoldering pumps on Amazon, I’m not sure which would be a good one.
Life gets in the way every now and then, and I have some health issues to resolve before I will be able to work much on this any time soon, but I really appreciate the help!
grym
I did buy the JFETs and a bunch of the caps recommended by HaflerFreak in his thread titled refurbishing-hafler-dh-110-how-haflerfreak-got-his-groove-back. I couldn’t find all the ones he recommended, and so substituted a few with similar ones. I also bought one of those desoldering tools, and yep…. I got a “little wee useless one”🙂. Will try to fix that problem when I get a decent soldering setup like you recommend. Although I find many desoldering pumps on Amazon, I’m not sure which would be a good one.
Life gets in the way every now and then, and I have some health issues to resolve before I will be able to work much on this any time soon, but I really appreciate the help!
grym
Hi grym,
I understand the health problem thing all to well.
The good solder pumps cost about $20 to $30+. Edsyn is the best, and no. The look alike units are not the same, not even close. I have tried them. The return spring usually fails quickly, as does the trigger. Don't waste your $$ on cheap units.
-Chris
I understand the health problem thing all to well.
The good solder pumps cost about $20 to $30+. Edsyn is the best, and no. The look alike units are not the same, not even close. I have tried them. The return spring usually fails quickly, as does the trigger. Don't waste your $$ on cheap units.
-Chris
So I used my useless little solder sucker, and while it was a pain, I did get the old JFETs out, soldered in the new ones and....... wait for it..... SILENCE! Nothing. No sound at all!
Checked all the connections, looked at every component on the board for visible signs... nothing. Removed the board again and took out the new JFETs...... and..... YES, I think it works fine now. Gunna put it all back together soon and hook it up to my main system in the house. Think I'm going to like this preamp.
Thanks for all your help to a noob here!
Checked all the connections, looked at every component on the board for visible signs... nothing. Removed the board again and took out the new JFETs...... and..... YES, I think it works fine now. Gunna put it all back together soon and hook it up to my main system in the house. Think I'm going to like this preamp.
Thanks for all your help to a noob here!
Hi grym,
No problem. Here is hoping for your success. You really have to get a real solder sucker. You know, the ones with recoil. 🙂
Let us know how this turns out for you, Chris
No problem. Here is hoping for your success. You really have to get a real solder sucker. You know, the ones with recoil. 🙂
Let us know how this turns out for you, Chris
OK, will find a solder sucker with a shoulder stock! 🙂
Actually, I have an Edsyn Deluxe Soldapullt, Heavy Duty, High Vacuum unit in my Amazon cart, but hadn't pulled the trigger on it yet. If I can, I try and get a few things shipped together, so Mrs. Grymster doesn't see so many boxes hit the porch. 😉
Actually, I have an Edsyn Deluxe Soldapullt, Heavy Duty, High Vacuum unit in my Amazon cart, but hadn't pulled the trigger on it yet. If I can, I try and get a few things shipped together, so Mrs. Grymster doesn't see so many boxes hit the porch. 😉
Hi grym,
-Chris
Perfect!
This is the one to get. Buy a couple extra tips for it while you are at it.
Understand completely! I have to do the same thing.
-Chris
Put it back together tonight. Didn't swap out for any of the new caps I have. Just no energy for that. Will bring it upstairs and hook to main systems when I get a chance. If it sounds good, I'll leave it as is, if not, maybe new caps.
Mrs. Grymster took a look and said "You have children older than this thing. Why do you bother?" 🙂
Mrs. Grymster took a look and said "You have children older than this thing. Why do you bother?" 🙂