[mythtvnz] Help troubleshooting signal interference

[Matt Poff]

It's fairly grunty - a RaidMax 380 Watt unit:

http://www.tigerdirect.com/applications/searchtools/item-Details.asp?EdpNo=1648607&sku=R456-1002

Not near the machine currently so can't try disabling the additional  
SATA. Here are the system specs of the box:

AMD Athlon 64 X2 Dual Core 3800+ Socket AM2 Processor
Geforce 7600GS 256MB DDR3 Graphics card
1G DDR2 667 RAM
320GB SATA2 7200rpm HDD
18x DVD-R/+R, Dual Layer DVD writer
500W Raidmax Power supply
MSI K9N Neo-F Motherboard, Socket AM2 Motherboard
Silverstone Lascala SST-LC16S-MR ATX Home Theatre Case, Silver (has 2  
built-in fans).

Not convinced it's an under-powering issue though as I wouldn't expect  
to see the interference still occurring on the TV video-input when the  
Myth box is powered down (but still plugged in with the main power  
switch on).

Noticed a few posts on the web where people were reporting electrical  
leakage into ATI graphics cards affecting outputs. I'm wondering if an  
earth from a case screw onto the RCA-connector (plugged into the S- 
Video->Composite converter that came with the Gfx card) might be worth  
a try. Still - it's run fine for a year and a half so can't understand  
why it's a problem now.

Will take a DVI monitor home and see if that outputs signal OK -  
perhaps the aforementioned converter is faulty?

Matt


On 7/02/2009, at 11:30 AM, Douglas Pearless wrote:

> Are you running near the limits of the power supply? (What size is it?
> If it only requires a 4 pin extra power plug for the motherboard,  
> then I
> have a spare you could borrow to troubleshoot).
>
> If you remove the extra sata drive, does this fix it?
>
> Douglas.
>
> Matt Poff wrote:
>> Over the last couple of weeks my MythBox has developed some weird
>> signal interference which obliterates the picture feed to the TV.
>> There have been no electrical wiring changes in the house or new
>> appliances plugged in so it's a mystery. I unplugged every other
>> device from the mains running off the same dual socket except the TV
>> and Myth box and unplugged everything else (audio jack, DVB-S feeds
>> etc.) from the box but the interference persists even when the Myth
>> box is not running.  I even grabbed an extension cord and fed the TV
>> and Myth Box of completely different loops with no effect. Only  
>> when I
>> actually turn off the power switch at the back does the interference
>> stop.
>>
>> I opened the box up to check whether there were any loose cables etc
>> but couldn't find any. The only change I've made recently was adding
>> another SATA drive to the rig.
>>
>> I'm assuming the problem stems from the power supply but not sure how
>> to fix it? Do I need to ground the box in some way? It's a purpose-
>> built PVR case (Silverstone LC16M) so should be fit-for-purpose.
>>
>> The actual supply of power is fine and the system runs but the feed
>> out to the TV is borked. Turning the RCA jack  (good quality video
>> gold-plated) in the Video-In socket sometimes improves the picture
>> fleetingly. If the system is unplugged from the mains and left for 10
>> minutes or so the signal is usually OK on the next restart for half  
>> an
>> hour or so before the interference kicks in.
>>
>> Any ideas how to fix or further troubleshoot this?
>>
>> Cheers,
>> Matt
>>
>>
>>
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>
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