Problems with stereo audio on Extron Crosspoint 450 Plus

[lordairivis]

I recently picked up a 12x8 Extron Crosspoint 450 Plus from eBay listed for parts/repair. The seller said their customer said it "wasn't working properly" but couldn't confirm anything besides the fact that it powered on, so I made an offer and picked it up for pretty cheap with the intention of reviving it.

When I received it, I found that it would not send any video through from any input to any output but all the front panel lights and buttons seemed to work correctly. Upon opening it up I found a bunch of bulging capacitors in various places on all the boards inside (front panel PCB, audio PCB, and video PCB). I replaced them all with brand new Nichicons of equal capacitance/voltage and was able to restore video. Checking the output voltages from the power supply confirmed the -15v and 15v rails are present so the power supply seems to be working fine. There doesn't appear to be any visible damage otherwise to any of the boards or components (no scorching, no broken traces/pads, no weird smells, no heat issues that I can feel).

The problem I am running into now is that I am only getting the left channel of the stereo audio out of the device, and absolutely nothing from the right channel on any combination of inputs or outputs. I tested this by panning the audio to the left and right with the audio test in the Genesis 240p test suite. Stereo works correctly if I directly attach the audio out from the Genesis to my speakers, so I know the audio is going into the Crosspoint correctly.

I'm using these adapter boards (RCA jack version) to connect stereo audio to the Phoenix connectors on the input and output sides, using the correct output board on the output side of things. I've tried probing around on the audio board inside the Crosspoint with my multimeter but I'm not extremely well versed at troubleshooting these kinds of things. I'm not exactly sure what I should be looking for and it doesn't seem like there are schematics available anywhere. I replaced a linear voltage regulator (markings on the part say 7912CT, replaced with this part from Digikey) on the audio PCB that didn't seem to be putting the right voltage out, but I am getting the same results from the new one so I'm not certain if this is the root of the problem or if it's even the right part. Input voltage for the LVR looks correct. I've tried several different output boards and several different input boards to try to eliminate the possibility of a bad adapter board.

Has anyone run into this or a similar issue and can maybe point me in the right direction?

[lordairivis]

Here's some pictures of the board, I'm not sure if that will help anyone. It looks like there are some places where there are unpopulated components, not sure if there's supposed to be something installed on the pads or what those components might be.

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[NewSchoolBoxer]

Good work replacing the capacitors and restoring video! Sorry you haven't gotten a response. I'm not so qualified to weigh in having never used or studied an Extron device but I wanted to give perspective.

15 year old or so complex device has wear and tear. That L audio works and R does not suggests the central audio processor chip has a break on its trace. Can use the continuity test on a multimeter. Lift the pin on the R audio in to confirm that the signal is getting that far. If not then the chip needs to be replaced.

Note that L channel is (L+R) and R channel is (L-R) to be backwards compatible with Mono audio systems. Like most all PVMs. L is all you need for audio, though naturally losing the stereo effect. I don't think I notice playing SNES games. Maybe most aren't coded for stereo anyway.

Really, this problem is very manageable. I would bypass the audio inputs and outputs on Crosspoints altogether and save money on Phoenix connectors. Copying from the internet:

2.5mm, 3.5mm (also called headphone cables), and ¼” audio cables have a maximum distance of 150' on average. Off-the-shelf, standard audio cables will be rated with 150' in mind.

[Konsolkongen]

Really, this problem is very manageable. I would bypass the audio inputs and outputs on Crosspoints altogether and save money on Phoenix connectors. Copying from the internet:

2.5mm, 3.5mm (also called headphone cables), and ¼” audio cables have a maximum distance of 150' on average. Off-the-shelf, standard audio cables will be rated with 150' in mind.

I'm not really sure what you mean by your quote. I think it would be a hassle to manually swap cables or use a separate audio switcher. Some Extron crosspoints also have adjustable gain control which is especially handy.

[NewSchoolBoxer]

I was just saying that audio cables are rated for very long distances so bypassing the Extra audio input and output is easy enough. Yes, you give up the switching with video. It's hard for me to think of a use case that needs a matrix or switcher for more than two displays on the output. If you have 3+ televisions or monitors all hooked up, I'd like to see the setup!

I surprisingly get used to Mono sound on my PVM when I have a stereo set just sitting around. That your matrix works with L channel, you're still in a good position.

[Star1]

If you have 3+ televisions or monitors all hooked up, I'd like to see the setup!

Hey, there are dozens of us! https://www.youtube.com/watch?v=bEdmCnq ... e=youtu.be xD

[Konsolkongen]

I use three of the four outputs for RGB, Component and VGA on the OSSC. I used to have outputs hooked up to various scalers other too. It’s very convenient to route everything through the Extron especially because I run all audio from output 1 directly to my AVR.

[lordairivis]

Good work replacing the capacitors and restoring video! Sorry you haven't gotten a response. I'm not so qualified to weigh in having never used or studied an Extron device but I wanted to give perspective.

15 year old or so complex device has wear and tear. That L audio works and R does not suggests the central audio processor chip has a break on its trace. Can use the continuity test on a multimeter. Lift the pin on the R audio in to confirm that the signal is getting that far. If not then the chip needs to be replaced.

...

Really, this problem is very manageable. I would bypass the audio inputs and outputs on Crosspoints altogether and save money on Phoenix connectors.

Thanks for the response. I can do some continuity testing to look for a broken trace, and more recent behavior of my Crosspoint suggests there is some sort of partially-failed component inside on the audio board. If all else fails, I can always simply add an audio switcher to handle the stereo audio.

I reconnected the switch to play around with it some more and left it plugged in for a couple days out of laziness thinking I would get back to it later and sent an email to Extron technical support for advice. When I came back to look at the Crosspoint again after receiving an email back from Extron a day or two later, I tried the audio again and suddenly the right channel popped in. Not sure what happened, the device hasn't moved from where I left it other than to spin it around to connect and disconnect cables. So, at least for the time being, everything seems to be working correctly. Extron quoted me $375 to repair/replace the Crosspoint so I will definitely want to get this fixed on my own if it's something as simple as an off-the-shelf part replacement.