[pelvicthrustman]

I’ve done some more testing and realized I made a mistake – I forgot to restore the DTV 480p setting after initially setting it (I realize that’s what profiles are for, I just forgot after turning the OSSC on and off, new owner mistake). This led me to discover the reason I didn’t notice the problem on the first day I got the OSSC. The problem occurs only when 480p in Sampler is set to either Auto or VESA. The device heat seems to have no effect on signal stability in DTV mode, while changing the sampler setting instantly destabilized the signal after a long operating period. I ran the Dreamcast for 90 minutes @ 480p in DTV mode with no issues, flipping sampler back to VESA or Auto after operating for this long caused the LED to flash red and the LCD to show the strange 525p/525i/1050i output you can see in the pictures from my previous post.
Setting sampler back to DTV 480p returned the signal stability immediately.

@BuckoA51 I’m sorry I didn’t realize the above sooner, did you test the OSSC 1.6 in DTV mode?

I understand that DTV 480p mode is the recommended setting for the Dreamcast but I assume Auto/VESA still shouldn’t exhibit this kind of problem, right?

[pelvicthrustman]

@marqs – I will try to get a different source to test with, though I don’t currently have another on hand

I did some additional testing with the Dreamcast @ 480p today, letting the OSSC stay on longer and in a slightly more enclosed space (which accelerated the onset of problems). While the signal was going in and out at one point I noticed the LED flashing red quickly (it usually stays solid green, even when the signal is problematic). As this was happening the LCD began wildly switching between 525p @ 59.94Hz, 525i @ 119.88Hz and 1050i @ 59.94Hz, this lasted for about 30 seconds before the LED and LCD display stabilized back to 525p @ 59.94Hz (although the HDMI signal did not return).

Pictures: https://imgur.com/a/jRRkY

[pelvicthrustman]

I’ve done a few hours of follow up testing:

576p, 480p and 480i via AV2 (PS2) tested 45 mins to one hour each with no issue.
480i and 240p signals via AV1 (PS1) for over an hour no issue.
AV3 (Dreamcast) 480i and 240p over an hour no issue.

While the OSSC was experiencing signal loss due to overheating using 480p on the Dreamcast via AV3 I also tried turning off the console, flipping the VGA switch to 15Khz and booting up a game with no issues after 30 minutes. Rebooting the console and flipping the VGA switch back to 480p caused the issue to return immediately. I repeated this a couple of times and found the results to be consistent.

From what I can tell the issue is isolated to AV3 RGBHV @ 480p.

[pelvicthrustman]

I’m using the defaults other than setting DTV mode. My TV (Sony KDL55BX520, circa 2011) reports a 640×480 signal.

[pelvicthrustman]

Just got my OSSC 1.6 and can confirm this issue is still present. Same symptoms described by the OP. Everything is perfect, then intermittent black screens and eventually no signal. I was playing Phantasy Star Online on the Dreamcast at the time for about 15 minutes before the issue presented itself. I am using the recommended DTV setting and a Kuro VGA box with a brand new VGA cable. I’ll try to reproduce the issue and see if I notice anything else. Does anyone know if there is anything I should try or anything helpful to look for?

Update:
I just tested the same scenario (PSO on DC via VGA) and I am quite sure that the problem is in fact thermal.
Here is the timeline of my testing:

– 15 minutes in game –
First loss of HDMI signal

– 21 minutes –
Second loss of signal event

– 22 minutes –
Third event, signal becomes intermittent at this point, occasionally recovering for up to a minute

– 26 minutes –
TV reports unsupported signal (audio stutters through for a second or two every minute or so but no picture)

– 30 minutes –
No change in 4 minutes, I restart the OSSC by toggling the on/off switch, the test pattern appears, I set AV3 input, everything works, a few seconds later the signal drops again, and returns intermittently

– 32 minutes –
Once again total loss of signal, I turn off the OSSC and leave it off for 30 seconds, once set back to AV3 the signal is back and stable

– 35 minutes –
Signal drops again

– 36 minutes –
Constant signal drops, I turn the OSSC off and leave it off for one minute

– 37 minutes –
Back on, signal stable

– 40 minutes –
First signal drop

– 43 minutes –
Total loss of signal, I blow onto the small copper heat-sink visible through the hole for the power switch for 15 seconds, the picture returns and is stable for several minutes

I repeated the last procedure a few times for sanity’s sake: Wait for the signal to stop completely (not intermittently dropping) and then restore the signal simply by blowing on the heat-sink. For reference, the room was around 20 degrees Celsius.

It seems that either my heat-sink was seated improperly at the factory or that the heat-sink itself is of insufficient size (albeit barely – the tiny amount of heat build up removed by blowing on the heat-sink shows that it is very close to being able to dissipate the necessary thermals).

Not sure what to do about this, but hopefully this helps someone, I really don’t want to return this thing to the UK (I’m in the USA), but I also don’t really feel like installing a new heat-sink – although that seems like the best course of action at this point – assuming I can find a bigger one that will fit.

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