Sorry to hear about the issues you're having. Since you've used a hot air gun on the board multiple times I would make sure that all of the pins on each chip on the board are fully soldered and haven't popped loose from all the temperature changes. Also, check very closely (with a microscope if you have one) all of the surface mount components, especially in areas you've been using hot air. It is possible for surface mount ceramic capacitors to crack or split in ways that are very hard to spot. I have seen this on a couple of video cards recently.

Have you tried removing the chip you soldered on?

Ozzuneoj wrote on 2025-12-22, 00:18:

Sorry to hear about the issues you're having. Since you've used a hot air gun on the board multiple times I would make sure that all of the pins on each chip on the board are fully soldered and haven't popped loose from all the temperature changes. Also, check very closely (with a microscope if you have one) all of the surface mount components, especially in areas you've been using hot air. It is possible for surface mount ceramic capacitors to crack or split in ways that are very hard to spot. I have seen this on a couple of video cards recently.

Many thanks - I've just looked up Necroware's video on reflowing and realised I clearly didn't use enough flux. I'll try his trick of running tweezers along to listen for loose pins.

The capacitors on this board do worry me a bit - all of the larger ones are rectangular tantalum types. I've seen these fail spectacularly in other contexts, but is there anything I should look for to indicate failure here?

bertrammatrix wrote on 2025-12-22, 03:11:

Have you tried removing the chip you soldered on?

Good point! I took the blog comment about their board working fine with the chip soldered but no EEPROM fitted as 'proof' it should be OK - I guess I shouldn't just trust this. I'll keep this as the last resort to test!

One other thing I noticed when examining closely, there is writing tucked under the battery "R45 for ES1868 ONLY; R46 for ES1869 ONLY". Although the SBC came with neither, the resistor is in the ES1868 position. I guess it will be worth moving this too! But might testing with it in the wrong position have caused damage?

Cool board and interesting how it seems to have progressively failed. Boots but slowly, then intermittent, then only beeps. One idea would be to look up the various supporting chips, e.g. the LM4863M and ADM485 and review their pinouts and check for the expected resistance, voltages, ground, etc. with a multimeter. Very low resistance for example could indicate a short or dead chip.

Setting up the EEPROM of course is another good step once you're able to flash one, if anything just to rule it out. And like you mentioned, as a last resort, removing the chips and trying to return the board to its original state will be a good bet for determining if it's the new chips or the installation that caused a problem. Good luck and hope you get it going!

I very carefully reflowed all of the pins of the VGA chip, VGA memory, and larger capacitors on the bottom side of the board (as the beep code was missing graphics card, and it was where they seemed to have the highest chance of having been knocked). I used plenty of flux and fresh solder, and checked very carefully with a monocle type magnifying lens. I also moved the ESS1868/1869 resistor, and removed another on the bottom that was marked ESS1868 "ONLY!". Alas, exactly the same behaviour.

I also checked the top side ICs with the Necroware "by sound" method, but couldn't find any obvious loose pins. I checked with the magnifying lens on the top too, which involved bringing my face very close to it. I'm sure I could smell a very slight residual burning type smell in the general region of the rather indistinct chip next to the second COM port header. I don't know if I'm imagining it, but might some of the capacitors below C4 look a little dodgy? M11 and the resistors below it also seem to look like they might have suffered when soldering the ESS chip?

Cosmic wrote on 2025-12-22, 20:33:

Cool board and interesting how it seems to have progressively failed. Boots but slowly, then intermittent, then only beeps. One idea would be to look up the various supporting chips, e.g. the LM4863M and ADM485 and review their pinouts and check for the expected resistance, voltages, ground, etc. with a multimeter. Very low resistance for example could indicate a short or dead chip.

The gradual failure is particularly worrying to me - certainly feels like something burning out, doesn't it? The LM4863M is a brand new chip installed along with the ESS chip. I guess no guarantee it is good! (I had assumed it just acted as an amplifier for sound?)

At this point I would just pull the ess chip. It could be defective and causing a bus conflict