Amp heats up and shuts off - Help!!

[jeskibuff]

there are crossovers involved which add impedance and capacitance to the mix.

Oops...I meant "...inductance and capacitance...". Impedance is actually a measure of resistance, capacitance, inductance and other factors that resists or "impedes" electrical current flow.

Next time i go to Delhi - i sure will arrange for a stereo adapter for the Y cables.

Before you do that, you need to tell us what you've got. If you get a stereo adapter but the "Y" cables are mono, it still won't work right.

But i must say Jeskibuff and F1 seem to be on the path to clairvoyance - peeping into my head to check out all things stupid that i could have done.

Well, it helps that we've probably both done such "stupid" things many times in our lives. So, we're not clairvoyant...just "experienced"! Of course, when we "normal" people make mistakes, we just take our damaged electronics in to the repair shop. When you doctors use a mono heart bypass valve instead of a stereo valve, it has much more dire consequences!

[msrance]

If you get a stereo adapter but the "Y" cables are mono, it still won't work right.

Yes, Jeskibuff, you could trust me to make these silly mistakes - but then the same can be said for the chap who assembelled the Y cables for me. The adapter is stereo - the one with two black bands - but the Y cables maybe mono. How do you check out if the Y cables are mono? except for the fact that they run only one speaker - how else do you get to that diagnosis?

Well, it helps that we've probably both done such "stupid" things many times in our lives. So, we're not clairvoyant...just "experienced"! Of course, when we "normal" people make mistakes, we just take our damaged electronics in to the repair shop. When you doctors use a mono heart bypass valve instead of a stereo valve, it has much more dire consequences!

First of all friend, let me clarify that its not that we docs are "abnormal" - we are about as normal as anyone else! Thank God for small mercies - there are no stereo heart valves. But I was just thinking - if the Y cables of such a valve were to short circuit - what would be the side effect to the individual's hair !!

[jeskibuff]

...the same can be said for the chap who assembelled the Y cables for me.

Ah...if I'm right, I think we may have located the problem. These are homemade cables? Are the connectors hand soldered to the wires? So far this looks like it may be the culprit and the source of the hum. Can you describe this cable? Does it have a stereo or mono mini-phono jack?

How do you check out if the Y cables are mono?

I assume that you don't have a volt-ohm meter on hand. You can build a little continuity tester pretty easily from devices like battery-powered flashlights, remote controls and some wire. Let me know what you have on hand and I'll walk you through it. You need about a 2-foot section of flexible wiring such as cheap speaker cable. Lamp cord will work, but it will be harder to work with. A flashlight will work, but one where the flashlight will still work with the battery compartment opened. A battery-powered toy might be another good possibility, like a toy car.

[F1]

Yes, Jeskibuff, you could trust me to make these silly mistakes - but then the same can be said for the chap who assembelled the Y cables for me. The adapter is stereo - the one with two black bands - but the Y cables maybe mono. How do you check out if the Y cables are mono? except for the fact that they run only one speaker - how else do you get to that diagnosis?

Strange, you have stereo mini plug but getting mono sound. Did you plug it in to the soundcard all the way in? Basically if you have connector something like this
http://www.radioshack.com/product.as...5Fid=274%2D883
or
http://www.partsexpress.com/pe/showd..._ID=4885&DID=7
(ok wrong size in the part from Partsexpress, but this type) you just need to connect one end to soundcard and the other end to normal RCA cable to amplifier.
Try also to connect to different input on the amplifier: aux, tape or else, and see if you have the same problem.

[msrance]

Strange, you have stereo mini plug but getting mono sound. Did you plug it in to the soundcard all the way in? Basically if you have connector something like this
http://www.partsexpress.com/pe/showd..._ID=4885&DID=7 you just need to connect one end to soundcard and the other end to normal RCA cable to amplifier. Try also to connect to different input on the amplifier: aux, tape or else, and see if you have the same problem.

Yes, my friend F1, You've hit it bang on again. This looks like the partsexpress cable. It is plugged all the way in. I tried connecting it with variuos inputs - but thats the best it ever does. The problem is with the Y cable that has a stereo adapter at one end and has connectors for connecting to Amp input. ( This chap calls them the Banana Plugs ).

Ah...if I'm right, I think we may have located the problem. These are homemade cables? Are the connectors hand soldered to the wires? So far this looks like it may be the culprit and the source of the hum. Can you describe this cable? Does it have a stereo or mono mini-phono jack?

Yes, Jeskibuff they are home made cables. The connectors are hand soldered to the wires. This cable has a mini phono jack at one end - from here two pairs of flimsy wires are soldered which at the other end are soldered to a pair of ?RCA connectors (the above mentioned ones- Banana Plugs)

I assume that you don't have a volt-ohm meter on hand. You can build a little continuity tester pretty easily from devices like battery-powered flashlights, remote controls and some wire. Let me know what you have on hand and I'll walk you through it. You need about a 2-foot section of flexible wiring such as cheap speaker cable. Lamp cord will work, but it will be harder to work with. A flashlight will work, but one where the flashlight will still work with the battery compartment opened. A battery-powered toy might be another good possibility, like a toy car.

Correct Assumption, friend. I indeed dont have a volt-ohm meter. I guess I could get it tested from some small time electronics repair chap. I dont think I could ever build such a thing even if I had all those things.

Did I ever tell you that I'd got admitted to an engineering college by sheer chance ? ( electric engineering - at that ). I flunked my 1st semester exam in 'Applied Mechanics'. Now thats what I call - undying interest in a subject. Not that I was dumb enough to not pass - I could complete my medicine without any hurdles along the way later - but i failed in engineering coz I just plain hated Physics, Electricity and the whole gamut of such insanities! The thought of making something brings back all the painful memories of failure!

Anyways, I do have a thin, copper lamp wire, a flashlight but not the kind that could work when open. I guess the TV repair chap would be a cheaper bet on this one. No toys - I am too old for them and no kids (actually no wife too) - so the whole thing might be a bit too expensive for a screening test. What's to be checked in this whole assembly?

[jeskibuff]

No toys - I am too old for them and no kids (actually no wife too) - so the whole thing might be a bit too expensive for a screening test.

Okay...so you're too old for toys and don't have any kids, but maybe you have some old materials left over from medical school.

Perhaps you have on hand Milton Bradley's "Operation"


Of all the toys out there, this is nothing more but an entertaining continuity tester! But if you don't have one on hand, just forget it. The problem is most likely in that homemade cable. Get a store-bought one and I'm sure your hum & no-left-channel problem will go away.

[msrance]

The problem is most likely in that homemade cable. Get a store-bought one and I'm sure your hum & no-left-channel problem will go away.

I guess so, The Y cable should be the culprit. I will get myself a better Y cable when I go to a city. Thanks Jeskibuff.

But still do you feel - getting this one tested out - or getting a new one made from some local small time electronics repair chap will not be of any help for the time being - till i can get something better?

Or did I paint too pessimistic a picture of myself?

[jeskibuff]

But still do you feel - getting this one tested out - or getting a new one made from some local small time electronics repair chap will not be of any help for the time being - till i can get something better?

The way you describe it (flimsy and homemade) tells me that it's most likely at fault. It's difficult to do a good job soldering such connectors. A precision manufacturing facility will do a much better job, ensuring solid electrical connections, sturdy construction and adequate insulation. Rather than getting another "Y" cable, get one of these type connectors that F1 linked to:

This should last a lifetime and is virtually indestructible. Cables are much more vulnerable to damage (pinching, failure due to flexing, etc.), so if a "Y" cable fails, you have to search for another one. With the connector pictured above, a common RCA cable is the weak point, and they're relatively easy to find in a variety of lengths and quality.

did I paint too pessimistic a picture of myself?

Not at all. I trust that my little "normal people" and "medical school tools" comments were taken as just funning with you!

Incidentally, there's ONE test that you can make pretty easily. Just flip the RCA connectors going into your Yamaha (left/right). Instead of the left channel humming, I bet the right channel will hum. All that will prove is that the Yamaha is NOT at fault. The problem still could be with the "Y" cable or the adapter. Swapping the connections won't give a definitive answer over which is faulty, but it eliminates one possibility.