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Post by vibroverbus on Feb 3, 2019 9:13:46 GMT -5
Recently after noticing that my surround was not what it should be, and trying to check speaker levels "test tones" , I was found that the right surround speaker was fizzy and low volume... not good...
After a quick left/right cable swap test, pretty much could immediately narrow it down to the UMC-200 output (i.e. not an issue w/ speaker, speaker cable, or the big ol' rock solid XPR-5...)
This made me kind of harken back and note that the other day I was doing house chores w/ the radio on and the system shutdown... at the time I thought the dog laid on the remote on the couch (I now sounds ridiculous but has happened before) but now it sure looks like a failure mode.
Now I also have an 8100 which has been PS repaired twice, so I'm well familiar with that situation and possibility, although this looks different, because aside from the shutdown the only symptom is this one channel... (the PS failure normally manifests as initially intermittent symptoms ceasing to pass through a signal, ceasing to respond to remote inputs, which get worse and worse until eventually possibily the system entirely hanging up at boot time...) So my thinking is this is more like some other channel-related-failure and maybe that time the system went into a protection shutdown due to voltage detection?
Unit is WAY out of warranty, and I know the cost of shipping + repair will be cost-prohibitive, so I'm going to open her up and have a look at the notorious PS capacitors...
Bottom line - my question for the Emotiva crowd is...
Anybody ever have single-channel issues with these? Tends to sound to me a little like a different problem - either a driver IC or coupling cap or something on one channel... I found one picture of the internal board that seems to show a big line of electrolytics that correspond 1 to each analog output... wondering if one of those may have pooped it much like the PS caps... I'll be looking further into it today but if there's any BTDT to share would greatly appreciate...
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Post by vibroverbus on Feb 3, 2019 10:46:46 GMT -5
Hmmm. Very short-cycle update here obviously. That didn't take long. This is amusing. Pulled unit to do some quick checks, see if there was DC on any output or floating voltage on the chassis anything obvious like that (there wasn't). Opened it up just to have an eyeball and...  LOL. Now this unit has NEVER EVER been open. For sure. So that, my friends, is a Genuine OEM Factory Issue Chinese Toothpick. Ha! At first I had a thought it was maybe perhaps maybe intentional and wedged in there to keep space between those inductors as a sneaky workaround cheat to a layout problem or something crazy like that. But immediately upon touching the thing, it was apparent the pick is just loose and rattling around in there. But - hey maybe its a special Audiophile Toothpick like those "Brilliant Pebbles"! Maybe I've just destroyed my soundstage imaging ambiance atmospheric enhancement by removing it!!!! It probably performs EMI absorptive re-harmonization of odd-order THD artifacts captured through organic-material-resonance which then is shunted into a kinetic energy flux buffer in order to create improved clarity and definition!!! Seriously. It is now removed. I doubt it was the cause of any problems honestly. However I did get a handle on the internal construction. Two boards, top appears to be the Inputs + Main Processing nitty gritty main dude, and the bottom seems to be an "output" board. Full disassembly looks straight forward but not super quick as the inputs and outputs are all very nicely well secured to the rear panel with copious screws (to handle the load of plugging/unplugging) and because of that getting to the bottom board will take a little more time with the ol' mini-driver, which I wasn't prepared for today... So... as an analog-audio repair-geek from way back, I looked for some good ol' quicky tricks to try. The main board appears to feed the lower output board via a wide ribbon cable on the far right side. All the audio channels are labeled on the PCB for this ribbon cable, so its clear what it is, and mine had a bit of a foldy/kink in it, as well as being just a hair crooked, so, I pulled the ribbon and reseated it firmly, and tidied up its placement a little. Threw some Deoxit on the output jacks for good measure, then slapped it back together. Well how do you do, guess what, and voila.... All is well with Right Surround Channel again. Must have been the Toothpick-ectomy! OK that's highly doubtful... (its either the ribbon cable, or Deoxit, or just general bumping around an intermittent issue that might come back to haunt me later) but who knows really... So. Back in the game for now... If I do have a recurrence then I will get the thing apart, and I'm going to order the C7 / C18 / C19 caps now just to have on hand in case this guy needs them. If it comes to that, I need to get my old UMC-1 out of storage to toss into interim duty which is one reason I didn't go further today, but, serendipity seems to indicate it was a good thing the UMC-1 wasn't around here as then I'd probably have wasted a bunch of time pulling that bottom board out and setting up the UMC-1 etc. etc. .... |
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Post by vibroverbus on Feb 4, 2019 20:36:50 GMT -5
Another update. The whole audio output sounds much improved on multiple channels. Suspect that ribbon cable connection was dodgy. Couldn't be happier.
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Post by vibroverbus on Feb 15, 2019 8:57:42 GMT -5
OK further update. After running for a little bit the symptoms came back. This time I was getting static burst on big audio hits - ex: a surround sound film explosion etc. - and a different channel was now sending the XPR-5 into protection. Same channel each time in this case, would sound fine for a while but then on some crescendo or transient: "ZAP!" and the amp would be shut down (love the XPR for that tho!). There would also be a little noise sometimes on switching (sources and/or formats) but then I began to wonder if it'd been doing that a little for a while and we kinda hadn't noticed....OK... time to get serious... So I pulled it apart properly, did the power supply capacitor service, and pulled the top input/video board so that I could also clean and reset the other side of that ribbon cable. Well well interesting underneath there is one IC that has a bunch of nasty flux and crap on it, clearly came filthy from the factory but then probably dirt blowing in / rattling around in there piled up around the pins. Checking the datasheet thats a volume/tone/output control chip, so, probably important. Here's a pic, I had smeared around the flux a little already to be sure it was soft but hadn't fully cleaned it, so it was a little dirtier than this when I found it.  So... I cleaned that up all shiny, reset the ribbon cable (which indeed was at a janky-angle, from the factory its routing wasn't really that great...), finished the power supply service (and I 'upgraded' the replacement caps a little with higher voltage ratings and a wee bump in value, made sure they were low ESR per Emotiva instructions...) Put her back together, and.... Success so far. Audio sounds great, no dropouts all channels working great, no issues on transients or switching... Have been trying to stress test with loud music and 'big' surround movies for about a week now, and it all seems good. Lets hope its a permanent fix! The only downer is that one of my front speakers got whacked by one of the transients I'm afraid, and started rattling on really big hits. Pulled it and perhaps the voice coil former warped a little, it is clearly making contact on big bass excursions. Cone didn't look 100% centered, so was able to better center the pole by gently tapping on the phase plug, but, I further protected it by changing setup from "Full range" to a 55hz crossover on the front speakers, and that seems to have taken care of that. It was probably a mistake to try to drive these guys that hard with surround LF content in the first place. Summary:- Symptoms: Discovered one surround channel was fizzy and low output. Confirmed not input/amp/speaker related.
- Repair 1: Attempted minor cleaning, discovered loose Chinese toothpick inside.
- Results: Fixed that channel but then another was misbehaving, system creating noise bursts on switching and large transients and causing amp to go into protection
- Repair 2: Discovered significant contamination on output controller chip pins, performed further cleaning, and then performed power supply cap service per Emotiva
- Results: Strong clear audio, no symptoms at this time
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KeithL
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Post by KeithL on Feb 15, 2019 11:55:07 GMT -5
Actually the messy flux is probably not important..... In the old days electronic components were soldered using chemically active flux - which really had to be cleaned or it would eventually cause corrosion. Nowadays, the majority of the components on most PCBs are machine-soldered, and subjected to the equivalent of a car wash afterwards. Then, after that, the few components that aren't machine friendly are soldered by hand... Likewise, if bad parts or bad solder connections are found during production testing, they are also soldered by hand... But, by this time, the board also contains other parts which aren't safe to simply "run through the washing machine"...
Because of this, nowadays, a lot of hand soldering is done with "no clean flux"... This sort of flux is chemically inert except at the high temperatures used when soldering - and simply becomes an inert insulator at normal temperatures... (So you aren't expected to clean it, you don't have to clean it, and it won't hurt anything to NOT clean it.)
Most of those long rows of capacitors are audio coupling capacitors... If one were to fail, it could cause a channel to drop out, but would be more likely to cause DC or a pop on that channel... However, because coupling caps on solid state equipment tend to operate at relatively low voltages, they are MUCH less likely to fail than caps in a power supply... (Coupling caps in tube equipment were very prone to failure because they often operated at very high voltages.)
Those particular caps in the power supply that fail so often are under a lot of stress... (they are subjected to high ripple current at high frequencies). That's why they really want to be "low ESR" "high temperature" caps.
OK further update. After running for a little bit the symptoms came back. This time I was getting static burst on big audio hits - ex: a surround sound film explosion etc. - and a different channel was now sending the XPR-5 into protection. Same channel each time in this case, would sound fine for a while but then on some crescendo or transient: "ZAP!" and the amp would be shut down (love the XPR for that tho!). There would also be a little noise sometimes on switching (sources and/or formats) but then I began to wonder if it'd been doing that a little for a while and we kinda hadn't noticed....OK... time to get serious... So I pulled it apart properly, did the power supply capacitor service, and pulled the top input/video board so that I could also clean and reset the other side of that ribbon cable. Well well interesting underneath there is one IC that has a bunch of nasty flux and crap on it, clearly came filthy from the factory but then probably dirt blowing in / rattling around in there piled up around the pins. Checking the datasheet thats a volume/tone/output control chip, so, probably important. Here's a pic, I had smeared around the flux a little already to be sure it was soft but hadn't fully cleaned it, so it was a little dirtier than this when I found it. So... I cleaned that up all shiny, reset the ribbon cable (which indeed was at a janky-angle, from the factory its routing wasn't really that great...), finished the power supply service (and I 'upgraded' the replacement caps a little with higher voltage ratings and a wee bump in value, made sure they were low ESR per Emotiva instructions...) Put her back together, and.... Success so far. Audio sounds great, no dropouts all channels working great, no issues on transients or switching... Have been trying to stress test with loud music and 'big' surround movies for about a week now, and it all seems good. Lets hope its a permanent fix! The only downer is that one of my front speakers got whacked by one of the transients I'm afraid, and started rattling on really big hits. Pulled it and perhaps the voice coil former warped a little, it is clearly making contact on big bass excursions. Cone didn't look 100% centered, so was able to better center the pole by gently tapping on the phase plug, but, I further protected it by changing setup from "Full range" to a 55hz crossover on the front speakers, and that seems to have taken care of that. It was probably a mistake to try to drive these guys that hard with surround LF content in the first place. Summary:- Symptoms: Discovered one surround channel was fizzy and low output. Confirmed not input/amp/speaker related.
- Repair 1: Attempted minor cleaning, discovered loose Chinese toothpick inside.
- Results: Fixed that channel but then another was misbehaving, system creating noise bursts on switching and large transients and causing amp to go into protection
- Repair 2: Discovered significant contamination on output controller chip pins, performed further cleaning, and then performed power supply cap service per Emotiva
- Results: Strong clear audio, no symptoms at this time
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Post by Gary Cook on Feb 15, 2019 14:52:02 GMT -5
For a few locals I replaced the caps on early UMC-200 power supplies, which all worked out OK and still do as far as I know. Mine unfortunately only lasted a few months with the replacement caps and so Emotiva sent me a new power supply board which is still working. There obviously was some change in the components on the later board which resolved the caps issue. Later UMC-200’s didn’t seem to have any issues with their power supplies.
Cheers
Gary
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Post by geeqner on Feb 15, 2019 14:52:53 GMT -5
You know - modern solder CAN be a bit "whierd" --
I work for a small manufacturer, and a few years ago, we switched to a ROHS-compliant solder (european agency, lead-free, vapors etc safer for our Production people)
The stuff flows like crap compared to the "good old, dangerous-for-long-term-use Lead-based stuff.
The flux that it uses is water-soluble, and we found that it can be a bit "hydrophyllic" (absorbs water in a humid environment and becomes "semi-conductive" when wet / damp).
This IS NOT saying that Emotiva and/or their board manufacturer uses the same stuff - just sayin' that cleaning key junctions COULD potentially make a difference...
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