TAM black screen

[ninjafist1]

Hey everyone, got my second TAM recently and it was getting a black screen on boot, chime but no picture.  While troubleshooting I unfortunately knocked it over and cracked the screen.  Horrible moment in time!  Anyway, I just replaced the screen with one from a 3400c that was tested and working...Just booted it and same thing, good chime, but then no display, just black.  also, and possibly related, I can't tell if HDD is spinning up or not.  I have also reset the cuda a few times to no avail.  Any help appreciated! Thanks everyone

 

[Alexlfm]

Did you try starting the machine without any HDD connected? If the drive is borderline bad the machine will attempt to read the drive and doesn't start up the screen because it isn't able to read the drive. Make sure the drive is disconnected and then try booting again. This worked for me. With the drive disconnected you can boot any other media like normal.

 

[Byrd]

Clean all the connectors, especially the umbilical plug, disconnect PRAM battery, take it down to one known good stick of RAM and nothing else.  Also remove the heatsink and replace whatever grease might be left, if at all

 

[Alexlfm]

While I agree with the heatsink (really on all of these old machines it's a good idea), it wouldn't be likely to be causing a black screen situation (I have never once seen a machine not show the startup screen with a thermal issue. The most important things to look at first are the memory, hdd and battery. Cleaning the connectors going to the sub may not be a bad idea as a generality, however if you are getting a tone, it is unlikely to be an issue there, at least not one which cleaning would be liable to fix. Your best bet as Byrd said is to narrow down known good parts (thankfully you have another machine so you can swap parts from the broken into the good one), then check power rails for voltage, and if still nothing, move on to the logic board. Make sure to put the pieces into the GOOD TAM to test since a power issue could destroy parts on the non working one.

 

[pb3623]

Dumb question but how long did you wait? I now have two TAMs that sometimes <shrug> will take up to a 45 seconds or so before the green power LED and display come on (right before Happy Mac). Both happen to have Sonnet G3 accelerators but I didn't try to replicate with them pulled.

 

[Byrd]

The TAM is my most enjoyed, yet picky computer I own.  Mine usually comes up with the green LED immediately at power on, LCD ~ 20 seconds later, yet be either quick or slow to get to the Happy Mac to boot Mac OS, ranging in time from 20 seconds - 2 minutes.

 

[Alexlfm]

Both happen to have Sonnet G3 accelerators but I didn't try to replicate with them pulled.

The sonnet accelerator is to blame for the longer times. I have one in mine and it does the exact same thing (although not consistently) and when removed it boots considerably faster. Although my sonnet card is unstable in general so that could have something to do with it as well, but then I don't think I've ever used a sonnet upgrade that was perfectly stable. Either I have terrible luck or they're just buggy.