Pioneer VSX-1123 Receiver - weird voltage problem

[pulper111]

Hello. My receiver "seems" to be working fine. It functions as it should. the receiver is the Pioneer vsx-1123. However, while doing some work in the house, I noticed that my HDMI cable from the receiver was registering as "hot" using my fluke non-contact voltage tester.

I've done some troubleshooting to try to narrow down the problem, and all wires (speaker/hdmi/subwoofer) coming from the receiver, whether it's powered on or stand-by, register as "hot". none of my other receivers are experiencing this issue, so it doesn't seem to be an issue with the tester.

for further testing, i've removed all the wires, yet even placing the tester near the chassis registers as hot, as does the speaker and hdmi terminals. i've tested the receiver using different outlets - same response.

When I set my multimeter to A/C, and with the unit on standby, I place one probe in the grounded outlet of a three prong outlet. Then I touch the other probe to the HDMI port or speaker port. it registers approximately 55 volts. The chassis on the top registers about 3.5 volts, but closer to the outlets goes up to about 30 volts.

the user manual for this receiver does indicate that the speaker terminals do contain hazardous amounts of voltage, but this seems hi to me.

any ideas as to what is happening here? again, this receiver has been working just fine but i'm concerned that it could impact other components (or that it's on its way out).

Thank you for your time.

[petehall347]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

is the mains plug reversible ?

[pulper111]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

is the mains plug reversible ?

No. One wider than the other.

[budm]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

It is two-prong plug with no ground, correct?

[pulper111]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

hello - yes it is a 2 prong outlet with no ground.

[budm]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

hello - yes it is a 2 prong outlet with no ground.

See my post #4 update on how to test.
Make sure nothing else is connected to this receiver when doing the test.

[pulper111]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

See my post #4 update on how to test.
Make sure nothing else is connected to this receiver when doing the test.

Thank you for taking the time to reply to my issue. Before your reply, I actually was looking at a section called "checking for a hot chassis" in the book How to Test Almost Everything Electronic. It actually suggested the test that I performed (multimeter on A/C, one connector to ground, other to chassis) in order to check for a hot chassis, and indicates that the results that I received were indicative of a "mechanical short somewhere in the equipment being tested".

Now, as you can probably tell from my post, I am really a beginner. I do not own a leak current tester, and I do not have the recommended resistor and capacitor needed for the other test (AFAIK - I have collected some stuff over time but it would take some time to find it).

Is there an added benefit to doing either of the suggested tests to confirm a short rather than what I've done? If so, then I'd look at continuing testing. However, it would seem (PLEASE correct me if I'm wrong) that I've already confirmed that there is a mechanical short.

Also before your post, based on what I read, I started taking apart the receiver. I've run into two types of items that I am having problems removing, without being in danger of destroying the connection (I did try to pull on one and unfortunately I'll have to resolder the connection afterwards).

Can anyone offer help on how to remove these items? One of the items is a board to board connector (CN607) and the other item is a white wire connector that appears as though there should be some lock but I can't find it. And as mentioned previously, I'm now wary of simply pulling up on it.

I really appreciate any help. Thank you.

[budm]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

1) If you do have mechanical short from LINE (HOT) to chassis, you can test by checking the resistance between chassis against each prong of the AC plug. Another test will be hooking up night lights between chassis and EARTH/Safety Ground then plug the AC cord into GFCI outlet to see if it will trip the GFCI outlet.

2) The unit has 'Y' capacitors connected between Chassis and LINE (HOT), Chassis and Neutral so when you test between Ground and chassis you will see AC Voltage present.

3) If you perform the same test with other product that has two prong AC plug, what Voltage do you see when perform the same test (no other products connected to the unit)?

4) 'How to Test Almost Everything Electronic' any link to see exactly what it says?

5) If you are not sure what you are doing and do not have proper way to test then you need to take it to professional repair shop to them perform the safety test on the unit.

[pulper111]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

I've attached pics of the pages from the book. Hopefully readable.

I tested my Denon AVR-2803 the same way as the Pioneer in question. Nothing attached. Registered 0.5 Volts. Compared to 55 Volts with the Pioneer.

I agree with your point 5 but my post indicated that I'd continue testing if I needed to purchase, for example, the leak current tester to perform one of the two suggested tests. What I read indicated that I did not, but being a beginner, I wanted to confirm.

I'm surprised that there are components (such as the "y" capacitor that you indicate) within a receiver that would cause a chassis of a perfectly working and safe receiver to register 55 volts between the chassis and ground. Again, this shows how little I know. But, I try to never stop learning.

Any suggestions (anyone) on how to disconnect the items in my previous post? Thank you.

[petehall347]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

its the current that matters more than voltage .

[budm]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

I've attached pics of the pages from the book. Hopefully readable.

I tested my Denon AVR-2803 the same way as the Pioneer in question. Nothing attached. Registered 0.5 Volts. Compared to 55 Volts with the Pioneer.

I agree with your point 5 but my post indicated that I'd continue testing if I needed to purchase, for example, the leak current tester to perform one of the two suggested tests. What I read indicated that I did not, but being a beginner, I wanted to confirm.

I'm surprised that there are components (such as the "y" capacitor that you indicate) within a receiver that would cause a chassis of a perfectly working and safe receiver to register 55 volts between the chassis and ground. Again, this shows how little I know. But, I try to never stop learning.

Any suggestions (anyone) on how to disconnect the items in my previous post? Thank you.

Can the Denon AC be plugged into the AC outlet either way?

[redwire]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

It's normal to have small AC leakage current from a two-prong powered stereo or TV, DVD player, laptop brick, wall wart, phone charger etc. You'll commonly measure around 60VAC with a multimeter between the chassis and earth ground.

But if the TV is connected to cable TV (which is earth-grounded) and the TV is HDMI connected to the stereo, you will no longer see leakage current on either because it's all flowing to ground via that path.

[pulper111]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

Can the Denon AC be plugged into the AC outlet either way?

Sorry - I should have included that in my response. The Denon plug can only go in one way.

[pulper111]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

ok - i was able to get a couple of the connectors open. may have wrecked them a bit but we'll see later. :-)

what i've decided to do now is some continuity testing between the chassis and the internal parts. i figure that since the chassis is hot, something is connected to it that shouldn't be.

i found a couple of things that may or may not be meaningful that i'd like to run by you guys before i delve deeper into them.

first of all, i found some capacitors that have seem to be grounded to the chassis. i'm not sure if this is what budm was referring to with "y" capacitors, but i thought i'd see if this is meaningful for diagnosing my problem.

two examples of these capacitors are items C496 and C353+. I've attached schematics with those two items with the hopes that this might be helpful. if something seems wrong, i'd really appreciate your input. if you need more info, please feel free to ask. The numbers in the schematics are highlighted in yellow.

second, some of the metal screws on the front assembly are grounded to the chassis, while some are not. I haven't taken this part off yet but thought that this was odd. I have attached an image of the front with labels of the screws that are grounded to the chassis and ones that are not. Grounded/not grounded labels refers to whether it is grounded to the chassis.

if i am or am not on the right track here, it would be great to hear your input. thank you for your time! I apologize in advance if I've got some of the terminology wrong here.

[petehall347]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

you need to simply measure the leakage current rather than tearing it apart and breaking things ..

[budm]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

Why not do simple test as suggested instead of causing damage to the unit?
And don't you have GFCI outlet?

My post #8:

1) If you do have mechanical short from LINE (HOT) to chassis, you can test by checking the resistance between chassis against each prong of the AC plug. Another test will be hooking up night lights between chassis and EARTH/Safety Ground then plug the AC cord into GFCI outlet to see if it will trip the GFCI outlet.

Y caps are in the HOT side of the circuit, I do not know why you look in the cold side of the circuit.

Cold side circuit ground is tided to chassis.

[pulper111]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

i had previously checked the continuity between each of the two prongs of the plug and the chassis and there was no beep.

in a previous post, I had been asked to reference the book that indicated how to test for a hot chassis using the test that I used. I did that. I also was requested to test another receiver for comparison and, having done that, received substantially different values using this test. After posting the page(s) from the book, I have not heard why the test that it suggested would not confirm a mechanical short so I thought that it was confirmed. Given that it registered approximately 55 volts, and that the comparison model only registered about 0.5 volts, again I thought that there was a mechanical short. Nothing since has indicated otherwise.

Since there was no continuity between the prongs of the plug and the chassis (which i neglected to indicate), i figured that there must be something conductive in physical contact with both the circuitry and the chassis. That's why I've gone searching as indicated in my previous post.

I'm a little sensitive by nature, but perhaps I've upset some on this forum, and that sincerely has not been my intention. I've asked for help and also searched on my own at the same time. While waiting for answers, i read in a book that i'm to "watch out" if the test they suggest for a hot chassis is positive. I am not sure why I should be still testing to see if there is a hot chassis rather than searching for the cause. If there is something wrong with the book reference that I posted, please let me know.

[R_J]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

The continuity "BEEP" is meaningless unless there was resistance between 0Ω and around 150Ω. You likely have more of a phantom voltage, If there is a IE: 1meg resistor from line to chassis, you will likely measure 55vac, with no current draw there will be no voltage drop. As soon as the hdmi cable is connected the voltage will likely disapear.
There are two capacitors, C131 & C133 (0.01µf) that are connected from the a/c line to the chassis, so the one connected to the line side will likely cause the phantom voltage between ground and the receiver chassis.

If there "was" a "short" from line to chassis, connecting an incandescent lamp between ground and chassis would light at half brightness, but if you tried this you would likely find that 55vac would disapear.

[budm]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

My post #8: Simple test
Another test will be hooking up night lights between chassis and EARTH/Safety Ground then plug the AC cord into GFCI outlet to see if it will trip the GFCI outlet.
The DENON may not have any Y cap connected to chassis.
You also can have what they called stray capacitance.
The resistance test between the AC plug and the chassis also show no direct connection of the Line or Neutral to the chassis.

If you look at the schematic of your service manual, you will see Y caps connected to the chassis.

[pulper111]

Re: Pioneer VSX-1123 Receiver - weird voltage problem

Ok. I've attached three pictures. First, a sincere apology. If I'm not misreading what happened here, then you guys were right and the book was wrong.

To confirm I've tested this correctly, I've attached one pictures which shows my setup of the GFCI (in my kitchen - it was either this or the bathroom). Red clip attached to one prong of nightlight with other end to the chassis. Black clip attached to other prong of nightlight with other end to the grounding part of the outlet. I confirmed that this outlet is properly grounded prior to testing.

With this connected and the receiver plugged in, there was no tripping. Also, the nightlight did not shine.

Based on another comment by a reader here, I then tested the voltage of the chassis using the multimeter, one probe attached to chassis and other to ground. I did this both with and without the nightlight's black clip attached to the ground. When the nightlight was not attached to ground, the reading was 52.9 volts. When I attached the nightlight to ground, the reading was 0.8 Volts. I've attached the pics of these readings.

So, my understanding here is that the chassis is hot, but if one of the wires (hdmi, speaker, subwoofer, etc) goes to an earth ground, then it will no longer be hot (as suggested previously by another helpful poster here). Let me know if I'm wrong in this.

A very important question though. How come the hdmi cable showed up as hot when connected from the receiver to the TV? Also, speaker cables and the subwoofer cable also were hot. This is what got me started on this "learning experience" for lack of a better term. Since there's no grounding prong on the outlet, then that leads me to believe that there is a grounding failure elsewhere (perhaps the TV plug). However, I've checked both the receiver outlet and the tv outlet (separate rooms) and both show up as grounded. I test using the following:
https://www.hunker.com/12601223/how-...et-is-grounded
Any thoughts on this? Also, please feel free to correct any of my stuff above. Thanks again!