Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 5, 2010 10:13:24 GMT
Liam You have long unshielded wires going from the internal RCA plugs to the volume control. These should use shielded cable, or at the least, tightly twisted together pairs of wires . If you have ever ripped apart a length of redundant 3 core mains lead to use for project wiring, you will notice that the wires are twisted together there too, but not so tightly. Even telephone cables as used at home, (as well as major cables in the street) have the wires of each pair twisted together to help reject hum from nearby mains appliances/wiring such as fluorescent table lamps etc. Also, try to keep those input leads well clear of the inductors L1 and L2. Alex
|
|
|
Post by binary01 on Feb 5, 2010 10:25:03 GMT
Thanks Alex, I'll give that a go and report back.
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Feb 5, 2010 10:42:58 GMT
Liam I gotta ask does it pick up 3LO ?
|
|
Spirit
Been here a while!
That's where I'm gonna go when I die
Posts: 1,107
|
Post by Spirit on Feb 5, 2010 11:42:49 GMT
Liam I gotta ask does it pick up 3LO ? I'm quite tempted to redo my wiring and see if I can't pick something up ;D
|
|
|
Post by binary01 on Feb 5, 2010 12:43:45 GMT
I thought I asked you to go easy on my handy work I'll try to move the wires around and see frequency I can get. Might become a dual purpose device. A little embarrased now.
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Feb 5, 2010 12:49:41 GMT
I thought I asked you to go easy on my handy work I'll try to move the wires around and see frequency I can get. Might become a dual purpose device. A little embarrased now. not at all you just need to learn some basic techniques and I'm sure you'll hear the difference when your finished,.. umm we're finished with ya
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Feb 5, 2010 13:05:03 GMT
first you'll need some shielded wire, now there are likely several outlets I use a screened cable from dick smith it's a miniature mic cable cat number escapes me but it reasonable actually quite good. DSE CAT # W2030 have a look at some of the offerings here rockgrotto.proboards.com/index.cgi?board=chitchat&action=display&thread=3729&page=1might even suggest a re-arrangement of the mains and PSU wiring. So how far did you want to go?
|
|
|
Post by binary01 on Feb 5, 2010 23:40:24 GMT
Initial investigation shows that my amp is indeed a radio reciever and/or theremin ;D I twisted them in pairs etc, but still have the noise, and it is very sensitive to moving the wires/putting my hand near them. Gonna pull them out and fit shielded wire. Thanks for the tips Alex and Rob.
How far do I want to go? Once I have this sorted, I'm going to attemp some of the RG recommended mods. One step at a time.
|
|
|
Post by PinkFloyd on Feb 5, 2010 23:55:28 GMT
When you have replaced the wiring you could also fit a class X2 470nF suppression cap across Live and Neutral and a class Y2 between live / earth, neutral / earth..... whilst your at it you could also fit a 275 MOV varistor across the line.....
Other little things are ferrite clamps around mains cables..... keep the wiring as sort as possible and keep all mains wiring away from the amp circuit board.
Mike.
|
|
|
Post by binary01 on Feb 7, 2010 7:56:47 GMT
Thanks guys, I replaced the input wiring and its all fixed. Mike, I'll keep your suggestions ready for the first round of modification just to be sure.
... now to try and squeeze a little extra gain out to more fully drive my cans. But thats for another thread.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 7, 2010 8:45:00 GMT
Liam I have sent you an email. Alex
|
|
|
Post by broovwa on Feb 8, 2010 9:09:17 GMT
Gday guys, still waiting on my alps blue to arrive in the post... should be here soon. Another question while im here though. This might be a stupid question, but i'm sure you understand already that im a complete novice with this stuff. If i were to hook a led up to the +5V output of the stock standard PSU, what specs would that led need? I've been looking at a few at altronics and jaycar and i cant find many with a rating of 5V
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 8, 2010 9:30:51 GMT
Brad You MUST use a series resistor with any LED that you use, or you will destroy it. That is why I ripped out the 7805 regulator in the mod shown in the "Tweaks"thread, and fitted a10K ohm resistor in place of the 5W 100 ohm resistor. That resulted in about 21V being fed through the 10K dropping resistor.The value of the series resistor needed will vary with the type of LED. In the modified PSU version, the 10K resistor is about right for Blue LEDs which are VERY bright. Other types of LEDs, especially those that don't have a clear encapsulation will need lower values. You could use the PSU as is from the 5V output, but you would then need to find a way to connect a resistor in series with the LED. There is an excellent Primer on the Jaycar website. Regards Alex www.jaycar.com.au/images_uploaded/Using%20LEDs%20-%20Its%20easy%20(JA).pdf
|
|
|
Post by broovwa on Feb 9, 2010 20:01:13 GMT
Thanks for the reply Alex. I'm pretty sure i understand the led situation a little better. Next time i'm at jaycar i'll pick up some resistors and a led and see how i go. I've found a few calculators on the net that tell me what resistor value i need, but they all state the wattage of the resistor should be low, like 0.125 W or lower. Is it ok to use a 0.25W resistor in this case?
Also, i just received my alps blue today, so i replaced my 2k resistors and wired the pot in. All is working perfectly at the moment. My only problem is that i could not earth the alps pot. the Altronics instruction say that if you are using a pot, you must earth the pot. I tried soldering the earth lead to the front panel of the pot (as the other 5 sides are plastic), but it just wouldnt stick. I tried scratching the surface to show a patch of fresh metal, but no luck, the solder still wouldnt hold.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 9, 2010 20:27:25 GMT
Thanks for the reply Alex. I'm pretty sure i understand the led situation a little better. Next time i'm at jaycar i'll pick up some resistors and a led and see how i go. I've found a few calculators on the net that tell me what resistor value i need, but they all state the wattage of the resistor should be low, like 0.125 W or lower. Is it ok to use a 0.25W resistor in this case? Also, i just received my alps blue today, so i replaced my 2k resistors and wired the pot in. All is working perfectly at the moment. My only problem is that i could not earth the alps pot. the Altronics instruction say that if you are using a pot, you must earth the pot. I tried soldering the earth lead to the front panel of the pot (as the other 5 sides are plastic), but it just wouldnt stick. I tried scratching the surface to show a patch of fresh metal, but no luck, the solder still wouldnt hold. Brad The Jaycar tutorial wil tell you how to work out resistor values. A .5 or .6W metal film resistor is O.K. too. Because I have some old larger RCA sockets. I connect an earth wire to the earth tag of one of those, snip the ring in one place so that I can open it a little further, then slip the ring over the shaft of the potentiometer. You could also cut a small piece of tinplate from a Milo lid etc.and drill a suitable size hole in it,then solder the earth lead to the tinplate and slip the shaft through it. Alex
|
|