UMC-200 center channel gain has a mind of its own

[themg]

A strange thing has been happening with my UMC-200. I'm not sure when it started, could have been a while, but I started noticing it a few months ago.

Randomly the center channel, which I normally have set to 0dB (in the "test tones" section of the speaker setup menu), will suddenly jump up to +8dB. I'll set it back to 0dB and it will stay at that until the next time I turn the UMC-200 off/on. But it doesn't happen all the time, sometimes I'll turn it on and it will be at 0dB other times I'll find it's jumped up to +8dB again.

It doesn't seem to matter which input I have selected at the time either, and I can't pinpoint a specific usage pattern which causes this to occur. Seems almost totally random.

All the other channel gains are staying right where I set them. Only the center channel changes.

UMC-200 is running the latest firmware version (52).

Anyone seen this before? Some kind of weird bug or sign of a bigger problem?

[405x5]

age related hardware issue....sure sounds like.....unfortunately.

[lynnmass603]

are you bumping the center channel button on the bottom of the remote unintentionally i believe that has a up and down level

[will95]

I'm having a similar problem with my UMC-200. Last year I noticed that speaker level changes were not sticking after a power cycle and levels on some channels (e.g. Subwoofer, left surround) would be at some unexpected setting after startup. I contacted Emotiva and learned that there is no out of warranty service. They sent me info on the Power Supply voltages to check and capacitors to change as a possibility. I was hoping that would fix the issue. I replaced the power supply capacitors yesterday and afterwards re-flashed the firmware. Unfortunately, this did not result in a fix for the random speaker level settings at start-up issue. HDMI switching and other functions seem to work ok. Must manually set volume and speaker levels each time after power on to correct for the phantom changes. Don't know if this is related, but EMO-Q also started doing a poor job with room EQ around the same time as the phantom speaker level issue started. I was searching for info on this issue when I came across your post. This does not appear to be a common issue that's been reported on.

[themg]

Well, last week my UMC-200 started misbehaving badly. Frequently needed to power cycle it 2-3 times to get any output on the HDMI, and it even would occasionally lock up at the firmware version screen.

So I did what I should have done a long time ago... opened it up and checked all the capacitors with a capacitance/ESR meter. Found a filter capacitor (220uF 16V) on the 5V output of the power supply that was pretty much completely toast. I replaced it, and have not had any problems since, even the center channel level has not randomly changed anymore.

I assume what was happening is that on power-up the 5V supply was unstable during the time the microcontroller is reading the settings from EEPROM, resulting in the incorrect level occasionally being set. Why this was only affecting the center channel level and no other settings is a bit of a mystery, but I know from experience that unstable power supplies can cause all sorts of very strange faults.

[bolle]

That´s the classic fix for 99% of the UMC-200 problems - just replace C18 and C19. Use a part with higher voltage tolerance and you should never have that problem again.