Defender reset problem

MacPac80

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My Defender played great for years but recently would not boot up sometimes. Now it won't go past the "rug" start up screen. No led's are on on the RAM board...the power supply board seems ok and I've switched out all the RAM's with no difference. Is this a ROM problem?

Mark
 
I've tried to different power supplies and they both have the same effect. I have another that works good so I'll try it and see if I get the same results.
 
My Defender played great for years but recently would not boot up sometimes. Now it won't go past the "rug" start up screen. No led's are on on the RAM board...the power supply board seems ok and I've switched out all the RAM's with no difference. Is this a ROM problem?

Mark

There are no LEDs on the MPU board (the large board with the RAM on it).

There are 4 LEDs on the power supply board (board with aluminum heat sink fins on it mounted next to the transformer) and there are 4 LEDs on the ROM board (small board right of MPU board, above smallest board (I/O board)). So how many LEDs are not lit, so we can tell which board you are talking about?

ken
 
There are no LEDs on the MPU board (the large board with the RAM on it).

There are 3 LEDs on the power supply board (board with aluminum heat sink fins on it mounted next to the transformer) and there are 4 LEDs on the ROM board (small board right of MPU board, above smallest board (I/O board)). So how many LEDs are not lit, so we can tell which board you are talking about?

ken

fixed it for ya Ken
 
We've had a couple of them that were resetting. The first one was caused by a crapped out connection on the power board. One of the connectors had corroded a little and fried a bit.

The other one that has reset a couple of times (and paused at the rug) is bad sockets on the decoder proms. Make sure everything is seated really well and try to get past the rug screen again.
 
Ok, I stated the wrong board earlier. The 3 led's on each of my power supply boards light up and I have resoldered the connector points. They seem to work like they should. The Led's on the ROM board had the 1st, 2nd, and 4th ones lighting up which should state that ROM 5 is bad....only problem, there is no ROM 5. I messed with the machine for 5 hours yesterday and seated/reseated every chip that ws in a socket on all the boards. Plus I swapped out all the chips with another set I had. After doing all that, it wasn't lighting up any LED's on the ROM board. I just now plugged it in and the 1st and 2nd lights were lighting up every 30 seconds or so. I guess that mean ROM #4 is bad? Of course, that chip is missing from my 2nd set of boards.
 
Funny you should post this, I am having the same problem, I cant get past the repating rug, I have the same LEDs on power board all 3, and every boot has different rom leds lit as previously mentioned. I dont have batteries on my board, does this matter to boot up, and to help the OP, as well as myself, where are the test points to see if the corect voltages on the power supply are working, and what should they read? If all 3 LEDs on the PS board are good, does this equate to proper voltage?
 
The best place to test the voltages is actually on the RAM chips. The voltages on the corner legs of the RAM chips should be +5V, +12V, -5V and Ground.

The LEDs on the power supply basically indicate that the voltages are at a minimum voltage, they could very easily be much higher.

ken
 
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