SE/30 A/B issues

[CompuNurd]

Once I recapped one of my SE/30 boards, I popped it into the machine. When I turn it on, the screen turns on and off and you can hear a click each time. The screen stays on for about half a second then shuts off then back on. When the screen comes on, the fan speed decreases from the load of the CRT.

Seems like the caps in the PSU need replacing? I've never replaced caps in an SE/30's PSU, so I am not sure what the symptoms would be if it was failing.

 

[bibilit]

In your place i will remove the Molex connector from the hard drive and have a look at what kind of voltage the PSU is delivering.

 

[Elfen]

I would concur with Bibilit. Check the 5V and 12V coming from the hd power connector.

Q: Before the recapping, did the SE\30 turn on and light up as it should? If it did, then you should check your recapping work, you may have a short.

 

[CompuNurd]

5V line fluctuates between 3-4 volts, 12v line is 8-11 volts. This is without the board installed.

 

[Elfen]

Do it with the board installed. You need to have an electrical load when measuring voltages.

In truth, having the hard drive connected should be enough to measure the voltage. But you need to see how it going when connected to the logic board. As is, it sounds like a couple of caps in the SE\30's PSU maybe bad.

 

[bibilit]

As is, it sounds like a couple of caps in the SE\30's PSU maybe bad.

I agree, voltage is too low, even without load.

 

[techknight]

Because its ticking. tick tick tick. This is due to the power supply's inability to enter into proper regulation. 

Change the caps, and next the opto-isolator.