airikka Posted August 21, 2011 Report Share Posted August 21, 2011 Hi, I'm a lucky sammichSID owner. I have just assembled it and it works! But... it has one strange behavior... maybe you can help me out? When the sammichSID has been unplugged a while, it takes about 5-10 minutes (and serveral power on/off) before I get it working. When I measure voltage on J2, it starts at about 2.5V and then it is constantly climbing. When it comes to about 4.5V, it starts working. Any suggestions? Br, airikka Quote Link to comment Share on other sites More sharing options...
Wilba Posted August 22, 2011 Report Share Posted August 22, 2011 I'm a bit confused about how that can happen. The red LCDs are "high-powered" so you should use a shunt in JR4 and JBL set to "12V" (i.e. input power) and set brightness pot to half-way. Can you tell me what happens if you set the brightness pot to minimum? I suspect the problem is related to current, perhaps your PSU cannot deliver enough current when the brightness is maximum. Also tell me what happens if you remove the SIDs. Describe what kind of SIDs and PSU you are using, the voltage, current rating, regulated or unregulated, etc. I would like to "blame" the PSU for this behaviour, but it could be just that the sammichSID is drawing too much current for the PSU. Quote Link to comment Share on other sites More sharing options...
airikka Posted August 22, 2011 Author Report Share Posted August 22, 2011 Also tell me what happens if you remove the SIDs. Describe what kind of SIDs and PSU you are using, the voltage, current rating, regulated or unregulated, etc. I would like to "blame" the PSU for this behaviour, but it could be just that the sammichSID is drawing too much current for the PSU. I use a SA30-12U as PSU: http://www.b2badapter.com/switching-power-supply/SA130B.htm First I thought that this unit was an ordinary unregulated PSU, but is it? Can this be the cause? When I tried without 6582A, then it worked directly. But with one or two (tested both slots), it takes some time before it comes up.... I forgot to check how it works with LCD unlit. Br, airikka Quote Link to comment Share on other sites More sharing options...
airikka Posted August 22, 2011 Author Report Share Posted August 22, 2011 It was the PSU's fault. I tried another and it worked directly. But still I want to learn something from this. Why didn't it work with the first one? Is it possible to use the first one if I do something with the base board? Br, airikka Quote Link to comment Share on other sites More sharing options...
technobreath Posted August 23, 2011 Report Share Posted August 23, 2011 That psu is a switcher, it probably works ok with a switcher, not owning a sammichsid, I can't tell u for sure, but I see no reason why it shouldn't work other than the sound may be a bit contaminated by switch noise if its low enough frequency... This psu is regulated yes. I may be out on deep water here, but what u describe here sounds like the psu doesn't deliver 12v at once but for some reason is softstarting itself. Maybe because the sammichsid is drawing too much for it during startup aka charging the caps. I mean, maybe it can't for some reason deliver all that current at once... This may also be a defect in the psu... Tried it with another load connected? If u connect it to another thing that u have wich fits the psu specs and measure the voltage at the psu output when u turn on. Does it start slow now too? I can't imagine that 30w @ 12v should be insufficient for the sammichsid either... But these are just thoughts, I've worked with linear psu only wich is a totally different type, so I'm sure wilba can do this much better than me hehe... Quote Link to comment Share on other sites More sharing options...
airikka Posted August 24, 2011 Author Report Share Posted August 24, 2011 This may also be a defect in the psu... Yes, it may be. That is probably the most resonable theory for this problem. I have not tried that PSU with other devices. Quote Link to comment Share on other sites More sharing options...
Wilba Posted August 25, 2011 Report Share Posted August 25, 2011 I can't explain why that PSU doesn't work. Some switchmode PSUs I've tried work OK but are noisy. I've only found one that works without noise, looks like the one you have, but it takes a 3-pin power plug (like on a PC) and since tip is positive, I use the shunts in JBP to bypass the bridge rectifier so negative of the PSU is also ground of the sammichSID. This might explain why there's no noise - it's even less noisy than a regulated linear (transformer) plugpack. Quote Link to comment Share on other sites More sharing options...
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