| jakelm3075 |
Hi all. Newbe here. First I want to thank all who are helping me in another thread here.
I was just given a Dh-200 with a bad on\off switch. I went to radio shack and bought another 3 prong switch. Replaced the switch the excact same way the bad switch was. Plugged the amp in and blow the main fuse. The switch I bought is a 3 prong switch similar to the original, different look but same 3 prong. I'm lost as to what went wrong.
I did a search on this amp here and WOW, there are threads that last forever. But I patiently read through all of them and came up empty handed.
I also plan on bridging this amp for a sub amp. Is this a good idea? Does Hafler still make the bidgeing kit? Also, is there a way to bridge it without the kit?
I know i have alot of questions and I appreciate everyone's patients. Any help would be appreciated. |
|
|
| anatech |
Hi jakelm3075,
You may have damaged the new switch now.
There is a feed contact, a contact to the transformer and another that goes to the other side of the line (for the light). There is no standard way to hook them up. You need to look at the diagram for the new switch and change the wiring.
The DH 200 is a nice sounding amp, it should be "gone over". I am not a fan of bridging amplifiers. Do you have two subs or just one? Use one channel if you have only one.
You are lucky to have been given one of these. It's a nice classic.
-Chris |
|
|
| jakelm3075 |
I have one 12" MTX powered sub 4ohms with 100w plate amp. I'm rebuilding the box and changing the tuning FR. I was going to use the plate amp it came with, but not if the Hafler will do a better job at driving it. I read alot about bridgeing this amp with the kit. But it does seem like a big project, becides the fact that you have to spend more money on the big kit. But at 100w @ 8ohms in one channel. A 4ohm load on just one channel wont hurt it?. I would like to use all avaliable wattage the amp could provide, but like I said, it seems like a big project, unless I could bridge it out without buying a kit?
But first I need to fix that darn power switch. |
|
|
| BobEllis |
there may be a reason that the switch went bad - you might want to run it up on a variac or with a light bulb in series with the amp next time you turn it on. Hopefully nothing in the amp is blown.
for bridging see http://sound.westhost.com/project20.htm It's not the best way to bridge an amp, but suitable for subwoofer use.
:att'n: :att'n: WARNING! :att'n: :att'n: your four ohm sub will be seen by a bridged amp as a two ohm load. It probably won't like it much. You're better off using just one channel and/or adding another sub |
|
|
| jakelm3075 |
| Thanks Bob. So it would be better to just run the 4ohm sub off of one channel? Also, will I have a gain issue? Since I will be using my sub preout to the amp. Will I need an additional preamp to adjust sub volume? |
|
|
| anatech |
Hi jakelm3075,
See Bob's post above. If you want to use all the power, do get another speaker or just use one channel.
Other things happen when bridging, such as losing 1/2 of the damping factor. That and there is only 3dB difference (just audible) so why bother? With another speaker you will reduce the average voice coil temperature (you may then have the same power and more headroom) and also the excursson for each driver. SOunds like a win-win to me.
-Chris |
|
|
| jakelm3075 |
| Like I said I'm rebuilding the MTX sub system. I do have a PSW10 Polk Audio 10" powered sub that I can bypass the built in amp on there and run both subs. But I would rather run 4ohms into each channel then 8 ohm bridged. The reason for 8ohms bridged is because I will hook them up in series so I dont drop down to 2 ohms. I think 2ohms would cause alittle instability in the amp and have the amp run alittle too hot. |
|
|
| jakelm3075 |
| quote: | Originally posted by anatech
There is no standard way to hook them up. You need to look at the diagram for the new switch and change the wiring.
-Chris |
But Chris, excuse the ignorence. But isnt all 3 prong switches the same? I just disconnected one wire at a time and put it in the same place on the other switch. That should have worked right? Also, what is that little round resistor that connects the middle prong to the bottom prong? Could that have been damaged and cause the short? |
|
|
| BobEllis |
With solid state amps you do not select the 8 ohm or 4 ohm tap, you just hook up hte load and it is what it is.
With a single 4 ohm speaker as a load, use only one channel.
With 2 four ohm speakers, use each channel individually. Especially if they are not identical.
A bridged amp will see the load you connect as half of what it is. Because a bridged amp swings twice the voltage, the load draws twice the current. So an amp rated for a 4 ohm load should handle an 8 ohm load bridged. But it would not necessarily handle a 4 ohm load bridged, since the amp has to deliver current like the load was 2 ohms.
That round thing probably has a number like .005 on it and is a capacitor to limit the arcing that occurs when turning the amp off. That should not cause your problem |
|
|
| jakelm3075 |
| quote: | | That round thing probably has a number like .005 on it and is a capacitor to limit the arcing that occurs when turning the amp off. That should not cause your problem |
So I could accually remove that capacitor? I didnt knwo if it was to ajdust the voltage going to the light or what. Thanks for the input.
Back to the gain (volume) subject. Do any of you forsee a problem with this being I'm going straight from sub preout on receiver to amp? |
|
|
| BobEllis |
| You can remove the capacitor without killing the amp. You may cause interference with other electronics or even a speaker damaging pop when you turn your amp off without it. You will shorten the life of the switch. |
|
|
| jakelm3075 |
| That is a 5amp slow burn fuse right? |
|
|
| BobEllis |
In that case, it probably was a resistor used to limit the current through the lamp.
go back to Chris' comments about figuring out what each connection is. You probably got them mixed up and ended up placing the switch across the mains. Was there a diagram on the back of the Radio Shack package?
I don't have your manual handy, but 5A slow blow sounds about right. |
|
|
| anatech |
Hi jakelm3075,
Yes, it's a 5 A slow blow rated at at least 120VAC (not a 32V fuse!).
Different makes of switches may have their own terminal connections. This will be printed on the switch itself normally. Check the packaging. Leave the capacitor in. It protects the switch contacts as Bob pointed out.
-Chris |
|
|
| jakelm3075 |
Speaking if switches. Is there a right and wrong switch? If I picked up a 12v switch instead of a 125v switch or if the amps for the switch are 10amp instead of 30amp.
Knowing me I'll get home and redo the connection and blow the house up. I do not like 120 current. My wife will be sitting peicefully watching Survivor and pooof there go the lights. |
|
|
| GRollins |
Several points:
--One--give up on Radio Shack. The switch you need is Mouser part# 691-LTA201TRB/125N. They're about $3-4.00 or so. Don't pay the guy on ebay who wants $15. That's silly. For a nickel and a cup full of good wishes, I'd do a group buy on Hafler switches, get 100, and sell them for $5-6. $15 is highway robbery.
--Two--do not use those switches without the spark suppressor caps. The turn-on surge creates a millisecond arc that pits the contacts. Eventually they weld. The Hafler switches were notorious for giving up. We kept a box of replacements handy back when I sold Haflers.
--Three--personally, I'd recommend going to .01uF on the suppressor cap. Stock was (I think) .005uF, and it wasn't (in my opinion) enough. Ceramic disc caps are cheap. It's worth 10 cents of insurance to make the switch happy. Of course, part of the problem was that the older version of the switch was rated for 10A. The newer version is rated for 15A.
--Four--no, all switches aren't alike. Just because it's got three connections doesn't mean that it's the same pinout as another switch with three connections.
--Five--it's not a bad idea to put a cap across any power switch that will see a high-current surge. Again, cheap insurance, no matter who makes the switch or what the current ratings are.
There may have been other points raised, but I'm up to my rump in alligators at the moment and just tried to hit the high spots.
Grey |
|
|
| jakelm3075 |
Well Grey, Thanks big time for the info and time. Where would I go to purchase the switch you mentioned? And I will go to a .01uF disk.
You dont have, by any chance, some switches left?? |
|
|
| jakelm3075 |
Grey, what is your take on gain control in my situation? Running from sub preout directly to amp. Do you think I will have enough gain control? I dont like to run my gain over +1 or+2 on the reciever. I was told running gain too high on the reciever causes distorion and loss of sound quality.
Jake |
|
|
| BobEllis |
| quote: | Originally posted by GRollins
The switch you need is Mouser part# 691-LTA201TRB/125N. ...Grey |
Be sure to use a line rated cap, like Mouser part 75-125ld50 Or a higher capacitance version as grey mentioned.
sub out to amp is normally the way things run. If you are having trouble getting the sub loud enough, you may be able to set your receiver to attenuate the mains a bit. |
|
|
| choky |
from one of Hafler amps;
there you can see how switch is connected
little play with multimeter will tell ya how to connect switch
always use suppressor cap,as others tells ya already |
|
|
| slowhands |
| quote: | Originally posted by jakelm3075
...a Dh-200 with a bad on\off switch. I went to radio shack and bought another 3 prong switch. Replaced the switch the exact same way the bad switch was. Plugged the amp in and blow the main fuse. The switch I bought is a 3 prong switch similar to the original, different look but same 3 prong. I'm lost as to what went wrong.
.....
I also plan on bridging this amp for a sub amp. Is this a good idea? Does Hafler still make the bidgeing kit? Also, is there a way to bridge it without the kit?
|
There may be a reason the switch was burned out. The amp could have serious problems that cause it to draw lots of juice and blow the fuse. Or the cheapo switch from RS might not be able to handle the load. Or you might have hooked up the switch wrong. Switches are not standard in their pinouts, sorry to say.
You can tell if the amp is OK or not by just bypassing the switch, and seeing if the fuse blows again. People do this when the switch fails, and just plug and unplug the power cord instead. If fuses blow again, leave it for a tech, it's probably more than you can fix.
If not, figure out which two pins on the switch connect together when you close the switch. Those are the lugs to connect to. You should be able to figure out what two lugs to use by measuring the switch resistance with an ohmmeter as you move it on and off.
I have a hunch your RS switch can't take the load. It's a 15A rating demanded. I wrote up a fixit list for this amp two years ago here, and the first thing I mentioned is the switch is bad on most of the amps I see. Anyway, you need a beefy 15A switch, and it will still fail in a few years again, sorry about that. My patch for the switch is a thermistor, but I don't recommend you put this in unless you really know what you are doing.
Here is what I wrote about this in Feb 2004:
"First, here is my list of the most common failures in these amps, with causes. The power switch fails, due to excessive inrush currents (see fix below). The output transistors do burn out, probably due to insufficient cooling coupled with oversized fuses on power. The input pairs go leaky due to overdriven inputs. When the outputs fail, they generally take out drivers and possibly inputs, as you would expect. That's what I see most often, so those are the areas I check first.
There is not a lot you can do to hugely improve the sound of this amp, in my opinion. Here are some small mods that preserve the essential character of the design while adding reliability.
The first mod is simply an NTC thermistor (5 ohm cold) on the AC power. This is needed to prevent the switch from failing due to high inrush current. On most of the amps I see, the power switch is toast and has to be replaced, but it will just fail again unless you do this mod. If you do nothing else, do this mod!"
I don't know if your amp is seriously blown or just the switch is toast, you will have to do the switch bypass to see. If the fuses blow again, quit while you are ahead and turn this over to a tech. Probably the outputs MOSFETs are shorted, but there is no sense in you causing a fire trying to chase it down. You're dealing with a 30 year old amp that could have other issues, so walk softly.
As far as bridging this, once you get it working it's easy if you are a competent tech. A couple of wire pairs have to be connected in a particular way from each board to a new switch on the back. I do it all the time to the amps I modify. I put it in, and bingo, a monoblock is born. I get the feeling most people use these for subs, but they are still good amps in my book. Just no frills, which I like. Anyway, good luck! |
|
|
| jakelm3075 |
| Thanks slow. I'm trying another switch tonight. But if that doesn't work, what wires do I hook together to bypass the switch? There is a small wire from the fuse, a large black wire from the plug, another small black wire to the light and another blue wire from the right channel board. |
|
|
| jakelm3075 |
Well I just ordered the Carling rocker switch that was refered. 2nd day fedex. Picked up extra fuses as well.. Wish me luck..lol
Jake |
|
|
| slowhands |
| quote: | Originally posted by jakelm3075
Thanks slow. I'm trying another switch tonight. But if that doesn't work, what wires do I hook together to bypass the switch? There is a small wire from the fuse, a large black wire from the plug, another small black wire to the light and another blue wire from the right channel board. |
I will probably regret this, but...
To see if it is just the switch, connect the two wires together that do not go to the light. In other words, connect the wire from the fuse to the wire from the plug. This is just temporary. If it works, use the new switch when you get it.
If the fuse blows again, it's not just the switch. You have a big problem somewhere else. Quit while you are ahead and have a tech finish the job. |
|
|
| jakelm3075 |
| quote: | Originally posted by slowhands
I will probably regret this, but...
|
I will take full responsibility for my actions..
Lets hope the fuse blows before my house...lol |
|
|
| jakelm3075 |
| Another thing I think might have happened. The prongs on the switch are so close together, the current might have arced and blew the fuse. Not much I can do about thet though, unless my soldering skill was off abit. |
|
|
| jakelm3075 |
I do remember now that there was a unnormal hummm when I plugged the amp in the wall. Then fuse blew when I flipped the switch.
The amp was in perfect working order when I got it. It was just that the old switch was frozen in the on position. |
|
|
| Dick West |
You need to get up close and personal with the Hafler DH-200 schematic and wiring diagrams. You can get these at WWW.HAFLER.COM. Go to the Archive library and download the pdf file for your amp.
The switch has three prongs. Two are to switch the AC, the 3rd is to light the pilot light. The proper switch has the numbers 1, 2, 3 embossed on its back side. The Hafler wiring diagram shows the switch wiring complete with the numbers 1, 2, 3. If you study the diagrams and get the proper switch and match up the 1, 2, 3 connections installing the switch is as simple as "1, 2, 3." ;)
Install a ceramic cap across the AC connections and make it a .01 uF cap as previously suggested.
The other stuff you referred to, the resistor, etc., are part of a little circuit that makes the yellow indicator lamp blink if the amp overheats and one of the thermal switches opens up. Again, study the schematic and wiring diagrams and firgure it out. It is a simple circuit.
Don't even think about bridging the DH-200. Reports from those who did said the amp did not really like being bridged. To bridge it requires a special add on circuit card that no longer is available. Any amp channel has distortion and when you bridge an amp you add up the distortion from each channel together so the mono output has twice the normal amount of distortion. This, plus the impedance load limitations, make bridging a very poor solution. If you need more watts, get a larger amp.
When you get the Mouser switch, tell us about it. The Carling variety I purchase locally has the 1, 2, 3 numbers molded in. Does the Mouser switch have the numbers?
Good luck. :) |
|
|
| anatech |
Well, that seems to be at least three solid votes not to mess around bridging your amplifier. It takes a lack of understanding the technical issues at hand to think this is a good idea.
-Chris |
|
|
| jakelm3075 |
I do have the technical schematics manual for the amp. The amp seems to be a pretty easy design. I just want , with the help from you guys, to make sure I do things right, the first time (or second time in this case).
I take this project as the perfect oportunity to learn more about circuits and schematics. I am good at part changing but I do have alot to learn on how everything works. That was the main reason for joining up here. Hopefully I can learn alittle, then give my opinion to someone in the future who is in the same boat as I am right now.
I am more familiar with speaker design and audio\video calibration than actual hands on repairs. So I appreciate everyones patients and help.
Jake
P.s. I will let you know on the switch |
|
|
| anatech |
Hi Jake,
The last comment I made was not aimed at anyone, but rather intended to keep you from making an error. ;)
To test the amplifier, I have a real problem with just shorting the wires and juicing it up. At least use a variac or light bulb in series.
For a permanent inrush limiter, consider using a 2~4 ohm resistor in series that is shorted out by relay contacts, coil energized by the secondary DC supply. That will give you the best solution and lowest supply impedance in the "run" state. This method is used in many large amplifiers.
-Chris |
|
|
| GRollins |
I find it difficult to believe this thread has gone on this long. It's really a very simple fix.
Oh, well. I'm having a bad day so I'm grumpy. Ignore me if I fuss too much.
The Mouser part number I gave earlier is the Carling Mini-Tippette (or whatever they call the silly thing) direct replacement for the original switch, albeit with a 50% higher current rating than the early version of the switch. Jeez, guys, did you think I'd send you off on a wild goose chase? I've rebuilt four or five of these things in the past eight months or so and have yet another lying open on the floor behind my workbench, ready for Evil Experiments of a JFET nature. I also sold scads of the things back when I was in retail.
Yes, the switch will come in with the 1 2 3 connections stamped on the side. DO NOT IGNORE THE NUMBERS. Connect it as per the original Hafler schematic and you'll be fine.
If you want to upgrade the thing, go through and replace all the electrolytics with film caps. People did so for years. Then Hafler finally got smart and started a production version that did the same thing called the DH-220. It's relatively cheap (assuming that you don't use really, really expensive caps) and very effective, sound quality-wise. That said, the stock units still sound decent. As I detailed in another thread, they beat the pants off my la-di-dah Pioneer Elite receiver in my AV system, and that's without any updates, mods, increasing of bias, etc. Shameful, the sound that AV people think is acceptable, but there it is.
As I believe I mentioned earlier, the power switches in the DH-200 were prone to failure. They usually failed in the closed (i.e. "on") position, but every once in a while you'd get one that froze open. They don't like being hit, either. The red plastic rocker will break if you bump it against a table or shelf. The one booger is that you're going to be working in a tight space getting the new one put in. Be patient and it will work out okay. When doing repairs on these things I would sometimes use push-on connectors so as to make switch replacement faster and easier. The idea is worth what it cost you. If you get some bozo who has managed to kill three switches during the course of a year, it starts sounding like a good idea.
Regarding bridging:
--As I believe someone mentioned earlier, it's not a good idea to use a bridged DH-200 for low impedance loads. In this case, interpret low impedance as anything below 8 Ohms.
--The bridging boards may be unavailable, but that's not a problem. All the add-on board did was serve as a phase splitter. Nothing fancy. It was, as I recall, just a simple differential on a circuit board about an inch or two square. It's trivial to whip up something like that. Use, say, MPSA42s or ZTX453s. This would be a good time to use a current source, although a resistor will do nearly as well and be a lot simpler. Might even sound better. Something like a 15k 1/2W (or 1W if you want to be more conservative) would give you 2mA per side bias.
--For those who believe in opamps, it would be simple enough to use opamps to do the phase splitting, but remember that the Hafler rails are on the order of 60V. You're going to need to drop the voltage so that the opamp doesn't pop.
Regarding gain: There are far too many variables to guess about something like that. Try it. If it works, fine. If not, then we'll talk about possible solutions.
Grey |
|
|
| jakelm3075 |
| For the inrush limiter I picked up a small box of .01uF disk. I'm not too thrilled about "hard" wiring this amp either. I wont. I will just wait a couple of days for the Carling switch to come in. Tonight I'll go ahead and try my other switch again. If I blow a fuse, I blow a fuse. I looked at the switch again last night. Its not the switch I posted. That switch was for something else. The switch I bought from RS but is a much bigger toggle switch. The only difference in the switch I bought from RS and the Carling I bought was (becides the light) I believe the amps are different and the style. |
|
|
| anatech |
Hey Grey,
Yup, a bit touchy. You answered the question in your post #17 rather completely. Other concerns came up. The power switch thing should be in bed.
-Chris |
|
|
| choky |
| I have PCB pattern somewhere... |
|
|
| jakelm3075 |
| My dad had this amp driving 2pairs of Polk Monitor 7a's stacked. Which stacked dropped the ohms down to 3, this amp did a wonderfull job. Thats why I'm so excited to get it workign again. I have only one pair of Monitor 7b's I would love take them off of my Onkyo tx-502 and hook them up to the Hafler, use my onkyo as preamp. But for the long run, I am rebuilding two seperate subs and would use this amp to drive them. It has to be 10 times better than that little plate amp the subs came with. |
|
|
| jakelm3075 |
Choky I have this. But thanks.
Grey, Thanks for the input. I think of this more like a conversation rather than a botheration. If it offends you or anyone here I appologize for dragging this thread out so long. |
|
|
| GRollins |
Some conversations have more meat on their bones than others. Speaking purely for myself, unless we're due for tornadoes, hurricanes, and blizzards, all on the same day, I get bored with conversations about the weather. What's tomorrow's high going to be and is it going to rain? Mid-70s and 0% chance of rain. Conversation over. Move on to other things. Alcohol, naked ladies, you know...the usual. Given the choice, I prefer them 'nekkid' to 'nude.' As the humorist Lewis Grizzard used to say, "nude" is art--"nekkid" means you're up to something.
I regard inrush limiting as about the same sort of thing. You can use an active circuit, thermistors, relays, or lightbulbs, your choice. Will it make the switch last longer? Presumably. But my experience has been that the 15A version of the switch is pretty reliable as long as it's got the spark suppression caps on it and you don't bash it mechanically. Next topic.
The bridging thing is potentially more interesting, but to take it much further than "not lower than 6-8 Ohms or so" would get into questions of bias current, heatsinking, and whether the DH-200 power supply could handle that sort of thing. However, that seems to have been settled fairly efficiently and that's all to the good.
Jake, I'm not bothered by your posts. They're completely understandable--particularly when faced with some rather random and contradictory responses to your original questions. It's just that I wonder whether some of the posters in this thread really bothered to think about what they wrote, hence my somewhat less-than-cheerful tone (aside from the fact that I had a lousy afternoon, which is certainly not the fault of anyone here--those following the power JFET story will not be at all surprised to hear that I had another run-in with the USPS whilst trying to take care of some of our Canadian members).
Oh, and for the record, I'm not particularly wild about hot-wiring the power switch. Not necessarily for any reason that might first occur to anyone, though. My main objection is the spark you get when the plug first makes contact with the socket. It's an arc. It will pit the plug and the contacts in the socket, which will lead to poor contact in the future. That interface wasn't designed to handle a hot make/break current flow.
Me grumbly? Certainly. It's this unrequited wish to strangle certain nitwits at the post office that keeps bubbling over.
Grey |
|
|
| burnedfingers |
Grey and Chris are correct on the switch issues and about bridging. Thirty years ago when I was a pup I probably blew up more amplifiers than 1/4 of the population of people in my town own. Hell, when you can bridge a 8 ohm load why not throw caution to the wind and run her on a 4 ohm load. Heck, it will last a while. Funny thing about speakers is the impedance goes down with the frequency. What was an 8 ohm nominal speaker impedance may dip to 3 ohms at say 20 HZ. Another funny thing about amplifiers is that unless they are specifically designed to mono bridge your best bet is to leave them to hell alone. Example
An Altec model 9446 is a commercial amplifier that was designed to mono bridge. Note* Has bridging circuitry designed in. Unit will
run day in and day out bridged. The Mickey Mouse bridging adaptor is minimal at best and I could probably ramble on for a page about adequate heatsinking, DC offset, Bias circuit problems and a few other considerations.
Personally, I believe the amplifier in question has serious problems that need to be taken care of by a qualified individual.
Hook the thing up to a variac and run it up and test it. The it ran good belore answer won't cut it with some of us because we know that in the world of electronics something can work one minute and fail after that. It has age on it and **** happens. Rebuild it or send it down the road and move on. |
|
|
| GRollins |
If the poor thing needs a home, send it to me. I like the silly things.
Grey |
|
|
| jakelm3075 |
I admit, I get excited and ask question after question. My fault. I will give this amp a good home as soon as I bring it back to life. I'm waiting on the Carling switch I ordered. As soon as it comes in I'll install it and see what I'm working with. I'm not bridgeing it out. I figured at 8ohms I get a good 100watts, so at 4ohm I should get close to double that. Which should be all the "naked" juice I need. Hell, I might even invest in a good DVC sub and run both channels. But for now I'll just wait on the switch and try not to get too ahead of myself.
Jake |
|
|
| jakelm3075 |
| quote: | Originally posted by burnedfingers
The it ran good belore answer won't cut it with some of us because we know that in the world of electronics something can work one minute and fail after that. |
Oh I know Burn. Electronics are like cars. Just cause it started yesturday dont mean it will start today |
|
|
| GRollins |
I don't remember the DH-200 being biased heavily enough to double into 4 Ohms. Probably closer to 150W at a guess.
I've got a couple of the manuals around here somewhere. If I get a chance, I'll dredge one up and see what the 4 Ohm wattage was.
Grey |
|
|
| anatech |
Hi Jake,
I like these amps too. I don't want to see it die.
If you bridge it, the minimum impedance is 8 ohms total. You would be further ahead to run each woofer off it's own channel, non-bridged.
-Chris |
|
|
| jakelm3075 |
Ordered the switch yesturday morning. Still no comfirmation from Mouser. Almost 24 hours later. So aggrivating.
Jake |
|
|
| jakelm3075 |
What I read somewhere (might have been here at DIY) that the amp is 100wpc @ 8ohms. And that is was close to double wpc @ 4ohms. Still 150wpc @ 4ohms from a solid amp like this will blow away that cheep little MTX amp.
Jake |
|
|
| fab |
| From what I remember I have measured about 130W rms / 8 ohms and I think close to 180 W rms / 4 ohms before seeing clipping on the scope... |
|
|
| jakelm3075 |
| Then thats perfect for my little MTX. |
|
|
| jakelm3075 |
Well the new switch came in. Soldered all the wires in place......Plugged it in.....Flipped the switch...SPARKS flew everywhere!!....Plug caught on fire and fire was spreading....
Just kidding... switch worked perfectly. Plugged it in, flipped the switch on and the little red light in the switch lit up. Just like brand new.
I unhooked the plate amp in both the MTX and the Polk. Ran the sub pre out from the reciever and used the "Y" connection to go left and right on Hafler. Hooked left and right to both subs, set the gain on the Onkyo to "0" and popped in Animusic. I believe running a raw amp is a great improvement from the plate amps. The subs disapeared in my living room.
Being I have my beautiful vintage Polk 7's as front main, I set my reciever to 60hz. Now I know some of you might think that alittle low, but the Polks handle the rest beautifuly and blend everything in very well.
I just want to thank all of you for giving me such great help. And if there is anything I can help with , let me know.
I cant wait to dismantle those terrible manufacture sub boxes and use Win Isd to create bigger, better and lower tuned boxes for my 10" Polk and 12" MTX.
Jake |
|
|
| burnedfingers |
| Glad to hear that it worked. |
|
|
| jakelm3075 |
| It works great, burnedfingers. But I didnt realize how warm that amp ran. Is it safe to just leave it on? Or should I turn it off and on everytime I use it. The rest of my electronics stay on allways. I believe that leaving them on reduces moister that can currode connection. Am I right in leaving this particular amp on? |
|
|
| burnedfingers |
The purests would say to let all your gear run. In todays world with the increasing cost of electricity I would suggest turning on the equipment about 1/2 hour before listening to it. To answer your question I would not let it run. I would also check the bias to make sure it is tracking correctly and is set per factory specifications. As you know the sign of heat can sometimes mean the bias is a little heavy.
Actually I would turn off your gear. Turn it on 1/2 prior to using. I wouldn't worry about a moisture problem or corrosion. |
|
|
| jakelm3075 |
| The heat is not unusual heat (if that makes any since). As a matter of fact on my Onkyo reciever I can cook an egg (figuratively speaking), the Hafler isnt as warm as the Onkyo. |
|
|
| slowhands |
| quote: | Originally posted by jakelm3075
It works great, burnedfingers. But I didnt realize how warm that amp ran. Is it safe to just leave it on? Or should I turn it off and on everytime I use it. The rest of my electronics stay on allways. I believe that leaving them on reduces moister that can currode connection. Am I right in leaving this particular amp on? |
The bias might be set too high. It should run a little warm, but not extremely hot. Factory standard bias current is 200ma, which you measure by replacing one of the DC power fuses with an ammeter. Turn the P2 pot (in the center of the board) a little counter clockwise to turn it down a bit. The DC fuses are the pairs of fuses, two on each side of the transformer.
I'd leave the amp on all the time, because you don't want to burn out the switch again. It's days are numbered. |
|
|
| anatech |
Hi Jake,
I am solidly on the turn your gear off side. Many reasons to do so and very few weak arguments to leave it on.
Turn it all off and follow Joe's (burnedfingers) sage advice. You can easily add a soft start, or just replace the switch when needed.
-Chris |
|
|
| fab |
| I have already asked Hafler tech support and it says 260 ma for DC bias. |
|
|
| anatech |
To measure bias in fuse clips, use a 1 ohm resistor, I also have 0R1 ohm resistors for this purpose.
Remember to remove them before packing it up or running it hard. You will learn the hard way like I have a few times.
-Chris |
|
|
|
