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.
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.
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
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
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.
But first I need to fix that darn power switch.
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.
WARNING! 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
for bridging see http://sound.westhost.com/project20.htm It's not the best way to bridge an amp, but suitable for subwoofer use.
WARNING! 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
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
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
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.
anatech said:
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?
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
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
If memory serves me right. This is the switch I bought http://www.radioshack.com/product/index.jsp?productId=2103602&cp=&pg=2&kw=switches&parentPage=search
Accept it was a 125v switch
Accept it was a 125v switch
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.
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.
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
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
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.
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.
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
--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
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
Jake
GRollins said:
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.