CurtPalme.com Home Theater Forum

[macgyver655]

39 is pretty low. I bet if you clipped the wire to pin 4 of cn90 it would stay running.

But like you said, you can just leave it disconnected.

[RayN999]

Testing out the other functions now. Since I don't have an exact remote, I have to reprogram one of the Harmony remotes for this receiver so I can get the OSD to display on a monitor for further function testing.

Appreciate your help & pointers, thanks!

Ray

[RayN999]

Looks like that's just a MAX3232 (3.3v version) transceiver with a set of 4 charge pump caps & a filter cap on power input. That's easy enough to shadetree engineer & I'm pretty sure I even have a chip around here somewhere. I can salvage the RS232 connector & the internal connector off that, put it on a small perfboard of my own, and rebuild it.

Will try lifting the ground (pin 4 on cn90) & see if that stops the shutdowns. Otherwise, there may be something else wrong with the 3.3v supply & that could be why it's shutting down in the first place.

Had a flash of inspiration at 4am, needed to get to the workbench to confirm my suspicions.

Now onto the next project, building the Parts Express Rump Thumper III subwoofer ( http://stories.parts-express.com/stories/2444-en_us/category/HomeSubwoofer/story/16517/redirect.htm ) from their DIY projects for the living room. We went & saw MI4 over the weekend, on the IMAX screen at local AMC theater & sat front row center. Probably were positioned right in front of the sub array behind the screen, but it had a total kick-a$$ feel in a few of the scenes. Said to wife, "I need to recreate that at home". All I got was an eye roll (I think, was dark in the theater).

[Sparky015]

So are you thinking the mechanical impact somehow shorted a trace on the comms board? The one downside of purchasing a bad piece of equipment is not knowing how it functioned before the issue occured. If you do go after the comms board, I am curious to hear what you find as the issue, board related or a component.

I love these threads!

[RayN999]

The 'comms board' is a small board, about 1.75" x 2.5", connected by a 4 pin ribbon cable, with one 9 pin RS232 port onboard that mounts to the back panel. Nothing physically looks wrong with the board, it has 5 small metal film capacitors and the max3232 chip onboard. That's it.

I don't know if any of it was mechanical related, it's possible it was faulty before, then returned to store/donated/junked at that point. The seller I got it from got it as part of a lot of other stuff he bought at auction.

Everything else looks quite well on the receiver except for the back panel where I removed the dent that was in it, and the top cover that has some dented areas. Will persuade those later today on the garage workbench with a hammer & chunk of scrap 2x4.

I've used the MAX232 (and related) chips before in some microcontroller apps, so I'm familiar with the layout & operation.

Ray

[macgyver655]

If that was a store return then you may want to check and see if that chip was mounted incorrectly (reversed 180 or straddling pins). Been there.....

[RayN999]

I moved receiver to living room for further testing. Audio side, everything seems to be performing top-notch.

Video, not so lucky....

the OSD menu system is supposed to be available on all 3 outputs, S-video, component, and HDMI. I have all 3 hooked to the TV, had used component & s-video on the old SR14EX because that receiver uses only s-video for the on-screen menu.

I have them all attached, hit the 'OSD' or 'Menu' button on remote, HDMI is blank, component video is blank, s-video is a pattern of white dots on black background. Looks like the TV tries to sync with it, but it can't quite lock on.

Looks like I get to troubleshoot the video subsystem a bit more, or I'll use it on my desk as an audio only receiver & go back to the SR14EX in the living room.