Atari 400 no red light .. pwb issues?

[Bikerbob]

Hey all, I was having trouble getting power to my 400. I think because I know the adapter is good.. and there is the separate PWB board. That I have an issue there.

 

I am going to replace the voltage regulators as per this article. https://retrorepairsandrefurbs.com/2023/02/04/1982-atari-400-repair-restoration

 

But if you have had to trouble shoot this before.. I would love some tips??

 

James

[Beeblebrox]

2 hours ago, Bikerbob said:

Hey all, I was having trouble getting power to my 400. I think because I know the adapter is good.. and there is the separate PWB board. That I have an issue there.

 

I am going to replace the voltage regulators as per this article. https://retrorepairsandrefurbs.com/2023/02/04/1982-atari-400-repair-restoration

 

But if you have had to trouble shoot this before.. I would love some tips??

 

James

first port of call is to check the cart bay door switch is engaging. it won't power up if not. 

[Bikerbob]

17 minutes ago, Beeblebrox said:

first port of call is to check the cart bay door switch is engaging. it won't power up if not. 

yep.. did that.. I can hear a very faint squeel.. and prior to no power it was taking 2-3 attempts to get a clean boot.  I suppose I could try and quickly power it up, see if I am getting +12 and -5v as per the manual. just wonder if I do any damage without a load on it.

 

[ClausB]

You will need some load on +5V to get a good voltage reading. I use a 25 Ohms 10 Watts power resistor (although 5V across 25 Ohms is only 1 Watt).