Need help...getting desperate

 

Bronze Member
Username: Taxman

Post Number: 35
Registered: Dec-03
I need major help from you guys. I have blown two receivers and need help before getting a replacement.

I have ceiling speakers (HTD) wired to a Hometech 150 volume control and then to my receiver. Each receiver (100 watt Sony) ran very hot in the first few minutes and both fried when I turned up the volume on the receiver. Does anyone have a clue what is causing this?

I have triple-checked all my connections and everything is correct. The setup worked fine until the volume on the receiver was raised a bit and boom...no receiver.

Any help is greatly appreciated.
 

Silver Member
Username: Project6

Post Number: 556
Registered: Dec-03
sounds like you are overtaxing the receivers. Check the resistance on your connections you should not get a reading less than 4 ohms.
 

Bronze Member
Username: Taxman

Post Number: 36
Registered: Dec-03
Would this be caused by the volume control (perhaps low quality)? The speakers have not been damaged and each receiver ran great for years.
 

J. B. Vigne
Unregistered guest
You are obviously over taxing the reciever, the question is how. Are the volume controls at the speaker turned down while you are trying to raise the volume at the reciever? That would make the amplifier try to slug its way through an enormous resistance and would make the amp run hot without going into protection. Has the ventilation to the reciever changed? Is there enough air flow? A small whisper fan might be the answer if this is the case. My next guess would be the wiring. Even though you have checked the connections the problem could exist within the walls were you can't see the wires. If this is a new installation a dry waller or electrician could have run through a wire just enough to create a short that the amplifier might tolerate at low volume but not as the demands of the system are increased. If it is an old install the wires could have cracked from heat or an animal could have chewed on them. Do you know how to use a VOM or a continuity meter?
 

J. Vigne
Unregistered guest
Also tell me how many speakers you have in the hook up, how many were you trying to drive when the system crashed, is there a speaker selector (what type) and have you tried just hooking the amp up to each pair of speakers directly without the volume controls and trying it with just the volume on the reciever? Are there any fuses anywhere in this system? Possibly inside the reciever or switch box? Did this problem start after you added the ceiling speakers or any change in the system?
 

Silver Member
Username: John_a

Post Number: 958
Registered: Dec-03
Taxman,

"Each receiver (100 watt Sony) ran very hot in the first few minutes and both fried".

If, by "fried", you mean "blown a fuse" then the first thing to do is probably to check the current rating of the replacement fuse has the correct value, in Amps. There are also other considerations for fuse specification, but that is the most important.
 

Bronze Member
Username: Taxman

Post Number: 37
Registered: Dec-03
I will try to answer the above as best I can:

1. I installed two high-end ceiling speakers from HTD (100W each, 8 ohms).
2. The speakers were prewired (new house) to a volume control casing and then on to the receiver location.
3. I purchased the Hometech 150 volume control from Best Buy (probably should have stuck with my local Paradigm dealer) and installed the control per the instructions.
4. Then, the wiring leads to a wall outlet where I installed a speaker connection faceplate.
5. I then ran 14 gauge speaker wire (Accoustic Research) from the speaker faceplate to my receiver (main speaker inputs).
6. Each Sony receiver was 100W and around 5 - 8 years old and have always worked great with all ther speakers I have used.
7. At low volumes, everything worked fine. When I turned the volume up on the receiver it went blank. The newer of the receives will power up, but no display or sound comes out. The older receiver does nothing.
8. I kept the volume control on a low setting (around 3 out of 12).
9. I have not tried to hook up speakers without the volume control yet. Of course, I am not going to experiment with my new $700 Yamaha.
10. One morning, a few days after installing the unit, the wife forgot to turn off the receiver and merely turned the volume to "off" on the volume control. When I got home the receiver was very hot and I could here soft radio music from the actual reciver (strange). However, the second receiver was only installed for a matter of minutes when it died.
11. I have no idea if each receiver blew a fuse or what. I have no experience working on the guts of receives.
12. There are no fuses that I know of.

I know this is a lot of info, but your expertise is greatly appreciated. I will be installing this same setup in two other rooms of my house and am scared to do anything until I find what the problem is.
 

Bronze Member
Username: Taxman

Post Number: 38
Registered: Dec-03
Forgot to add:

-both receivers were running at 8 ohms (same as speakers).
-by "high end" on the speakers, I am referring to the model from HTD's website. These speakers will never be confused with Speakercraft, etc.
 

Silver Member
Username: John_a

Post Number: 961
Registered: Dec-03
Taxman,

There are always an output fuses, one per channel, close to the speaker terminals, like small glass cylinders with metal collars at each end. When the fuse has blown, you can see the thin wire, connecting the two ends, inside the glass, has broken; is not continuous. You usually just pull the fuse out of two spring-clip retainers/connectors, one at each end. The spec for the correct replacement (where you should see that the the wire is continuous) ought to be printed near the retaining clips somewhere. No tools required, usually, once you have taken the cover off. Replacements are cheap. It is to protect the rest of the receiver (and more expensive components) from accidental short circuits in speakers, speaker connectors, etc. I do not understand the radio reception, however!
 

Bronze Member
Username: Taxman

Post Number: 39
Registered: Dec-03
John:

Thanks for the info. I will look for those fuses tonight and hope that is all it is since I don't like the idea of replacing both receivers. Like you, in all my years of homemade wiring, I have never heard sound coming from the receiver before.

The main question I have is if the volume control is at fault, how reliable can it really be if turning the master volume up on the reciever blows a fuse because the volume control is too low. Sounds like more headached than anything else. I may just try to wire the speakers without the volume control and see how that does it.
 

Silver Member
Username: John_a

Post Number: 962
Registered: Dec-03
Taxman,

I don't know the answer to that. Turning the volume control up on the receiver increases the current flowing out to the speaker, so it could still be the problem is the wrong fuse. I guess a "Sony Center" should be able advise you.
 

Bronze Member
Username: Taxman

Post Number: 40
Registered: Dec-03
Thanks John. If it is simply a matter of a blown fuse I can experiment a little bit with direct wiring and another volume control (since I need a couple more anyway). Very strange problem I have though.
 

Silver Member
Username: Kegger

MICHIGAN

Post Number: 255
Registered: Dec-03
have you tried the system without bypassing the
volume controls at the speaker? if not you should.

and if this works obviuosly it is a problem with
the volume controls.

if it does not work my guess would be a wire shorted going to the speakers.


 

Bronze Member
Username: Taxman

Post Number: 41
Registered: Dec-03
Kegger:

I havn't tried that yet, but I will as soon as I get an old receiver just in case.

I didn't know if anyone else has had similar problems or has used VCs without any trouble.
 

Vick
Unregistered guest
Please help!!!
I have an old RCA TV only one spot in the back to hook up anything, a sat receiver, vcr and dvd,right now it is all working - but I can not get the vcr to record when I am away from home.I have the vcr set to record but it doesn't do it. How can I hook this up to do a timed recording?
 

Bronze Member
Username: Mongo

Tucson, AZ USA

Post Number: 14
Registered: Apr-04
Taxman,
I deal with similar problems at work all the time. Sounds to me like your speaker volume control is wired backwards. These devices are typically configured as an L-Pad, which provides a constant impedance on the amplifier side, and variable impedance on the speaker side, which gives the control of speaker volume. If wired backwards and turned all the way down, it will give a dead short to the amplifier, causing it to "fry".
A less likely but more serious possibility is that your "prewired (new house)" speaker wires were incorrectly connected into the house AC power wiring. In which case, one of your lesser-used wall switches, when turned on, will connect 120VAC to your receiver amplifier outputs and fry them.
If you don't know how to use a DVM or multimeter to check for mis-wiring possibilities such as these, you need to find someone who can, maybe even hire an electrician. My less-likely scenario can have more serious consequences than a fried receiver, such as electrocution or a house fire.
 

Bronze Member
Username: Taxman

Post Number: 42
Registered: Dec-03
Mongo,
Thanks for the information. How does the VC get wired backwards? I assume you mean that the VC wire connections to the speakers should instead be connected to the amplifier wiring.

I am trying to locate replacement fuses for my "fried" amps (one takes 6 amp, 125V and the other 8 amp, 125V) with the hope that these can be salvaged. Any ideas or are both amps likely ruined?

Thanks.
 

J. Vigne
Unregistered guest
STOP!!! READ BEFORE YOU PROCEED!
Radio Shack should have replacement fuses, or most hardware stores. Those values seem high for either rail fuses or speaker protection. Are you getting this value from the fuse or the board under the fuse as John A. described? I'm guessing you have what is called a fast blow fuse that is not designed to tolerate a short circuit for more than hundreths of a second. If that is the case you cannot replace these with a standard fuse as you will be hard wiring your reciever to a short circuit situation and what you are looking at as problems now will be replaced in your mind with ... well, just don't do it! Get out your owner's manual or call Sony before you put a fuse in the amp.
If I'm understanding correctly this is a new house that was prewired when you got there. If that's correct, I would say the problem is in the wiring and would guess that a wire is shorted as I described above or as Mongo has suggested. You may have a wire strand (it only takes one) that is sitting across the opposite polarity wire on the plate you installed. If the first reciever worked at low volumes until it was asked to sit for hours producing power into a volume control that was turned off you may have even over heated the wiring and melted insulation which would be why the second reciever went down immediately. As for the phantom radio staion in the reciever you probably had the transformer moving and shaking trying to get away from the problem it was facing (if only life was that simple for any of us let alone a lowly Sony reciever). This caused an oscillation in a semi-conductor, probably a diode, and it was going at just the right frequency to create a very small signal. If anyone out there ever built a crystal radio from a kit you know it uses a diode that is trimmed to oscillate at a given frequency for tuning (you were just missing the trimming device) and without any amplification (oh,yeah, you were missing the amplifier, too) you can barely hear a signal if you put your ear to the circuit board. There's your lesson in audio history for the day. Hope it didn't cost you the price of two new recievers to learn something basic.
I don't believe you have told us whether you know how to operate a VOM and do you have an idea how to slowly work from the simplest connection to the most complex in a logical fashion. Please respond to this question. Because that is what will solve this problem. More often than not if you can go through the hookups in that fashion you will find the problem.
In my experience, the likelyhood of an equipment failure that would do this damage is slight. The chances of a mistake or carelessness in the installation is most common. Many times the guy who puts in the wiring and VC is working on a get paid by how many you do basis and knows he is not going to be the one to have to resolve a problem (resolve a problem, that's ridiculous, he can't even install it right in the first place). The drywaller is on the same schedule and the same aptitude level. If you paid attention the fault probably is not yours. If it is then you have to pay. If the builder hired these people and they are the ones who screwed it up then the builder has a responsiblity to make things right.
 

Bronze Member
Username: Taxman

Post Number: 43
Registered: Dec-03
Don't get me started on builders! I got the fuse information from the blown fuses themselves (that came standard on the receiver). Fortunately, I guess, I have been unable to find the fuses I described above. Radioshack has 6 amp and 8 amp fuses, but they are 250V rather than 125V. As for my electrical knowledge, it is very limited and I have never used a VOM before. However, I am willing to learn if it helps save another receiver.

To clarify, the second receiver worked fine until I raised the volume. I contacted Hometech (maker of the VC) and was basically told that I had the receiver volume too high and the VC setting too low which then strained the receiver. However, if this is the problem, then the VC is a piece of crap.

Thanks for your warning and advice, I will definitely do more tests or call in the installer before risking a fire situation.
 

Bronze Member
Username: Mongo

Tucson, AZ USA

Post Number: 18
Registered: Apr-04
I think you understand about how the VC can be backwards. A stereo speaker VC will have two sets of three contacts: three for left and three for right. For each speaker, there is a common terminal wired to (-) or BLACK on both the amplifier and the speaker. Then, there is a speaker terminal wired to (+) or RED on the speaker. Finally, there is an amplifier terminal wired to the (+) or RED on the amplifier. Swapping the speaker with the amplifier terminal on the VC could lead to amplifier damage.
BTW, the voltage rating on the fuse, 250V versus 125V, is irrelevant for speaker protection. The voltage rating would only be important if you are fusing AC line power in Europe (where they use 250VAC).
I am not sure how more advice from this forum can help you. Solving your problem will take more than verbal description. Visual inspections, diagrams, trials and measurements would be most helpful. For example, one trial you could perform is to hook up your receiver directly to speakers using short wires of adequate gauge (at least #18, preferably #16 or larger) and see if it works.
My point is that this will take forever if you try to check each step through this forum, whereas a technician on-the-spot could do this in a matter of hours.
 

Bronze Member
Username: Taxman

Post Number: 44
Registered: Dec-03
Thanks Mongo,

I will probably just bite the bullet and pay the company who did the wiring to come install a VC and verify that everything works. It may cost a little money, but it beats frying another receiver.

Thanks for everyone's help. If nothing else, you kept me from burning my new house down.
 

Bronze Member
Username: Ncavman

N.C.

Post Number: 71
Registered: Dec-03
Tax - That is a impedance issue if I have ever heard one. Get some Russound VCs or similar. I use them all over the house and they are reliable and accurate when put on the meter.
Also, as others have said, you can't say the Sony amps are running at 8-ohms. The speakers/load connected to an amp deterimines the impedance, not the amp itself. On a consumer level Sony you definitly don't want to use a load like 4 ohms and forget going lower than that. At low volume you may get away with it but as soon as you apply some power it will snap. You may be approaching a dead short situation with those VCs as Mongo said.

The VC's are obviosuly not showing 8 ohms to the receiver. I assume you only have one pair of speakers attached to the VCs, and they are 8 ohms. If they were good quality VCs, or even better, "impedance-matching" or "correcting" VC's it would not be an issue (matching types will also have jumpers or dip-switches on them to correct the dangerously low impedance, back to a safe Sony-friendly 8 ohms even when you add multiple pairs of speakers). If you bought the HVTC150, those are not high quality impedance matching VCs. Get ohm-correcting VCs or get a correcting speaker selector, one or the other. You can get Russounds online for under $40 a peice.

If you heard music coming out of the amp itself (real trebly sounding right??) you either have faulty VC's or wiring, causing a terrible strain on the amp, thus the fuse issue. You have been given good advice by the others. Good luck on getting it solved.

 

Bronze Member
Username: Taxman

Post Number: 45
Registered: Dec-03
Thanks NC AV. All this advice has led me to call in a pro. The bad part about it is that the VC cost $50 which is not exactly on the cheap side. We'll see if BestBuy gives me a credit for it. Thanks again.
 

J. Vigne
Unregistered guest
I would suggest you get your Paradigm dealer to look at the problem. The original installer is unlikely to admit to a problem that will cost them money.
 

Bronze Member
Username: Taxman

Post Number: 46
Registered: Dec-03
Vigne:

Good idea. Especially since I recently bought my entire main system (Paradigm with Yamaha receiver) from my local Paradigm dealer.
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