Troubleshooting GLUE, C32M, and C16M

[obsolete]

I know this isn't unique to compact Macs because early Mac IIs also used GLUE, but I'm putting it in the Compact Mac subforum because it's related to my SE/30 reloaded build.

My reloaded board isn't working; no bong, no video. In my troubleshooting so far, I've confirmed that the reset circuit works, but I have no C16M, so the processor isn't running. Based on what I've read, the GLUE is supposed to generate C16M from C32M. I've verified that the GLUE has good 5V and GND, and I see C32M going into the the GLUE, but no C16M coming out. C32M looks the same as my working SE/30 board. I can post some pictures later.

So, does the GLUE need anything other than 5V, GND, and C32M in order to generate C16M? I am starting to worry that my GLUE is bad. I had it in an 84-pin PLCC socket, but as soon as I found this problem, I removed the socket and soldered the chip directly to the board, but unfortunately that did not improve anything.

 

[codevonlux]

By reading the schematic. It seems to me that C16M is generated by UI6 on pin 17

 

[croissantking]

By reading the schematic. It seems to me that C16M is generated by UI6 on pin 17

Yes I was thinking the same thing yesterday, that one of the PAL chips does this.

 

[Bolle]

By reading the schematic. It seems to me that C16M is generated by UI6 on pin 17

That's right, UI6 is just acting as a driver for the clock signal though and it needs the 16MHz input signal on pin 2 to generate it. And that input is fed by C16G which originates from the GLUE.

 

[obsolete]

Thanks all, sorry for the confusion. On the schematic, pin 18 on the GLUE is labeled C16M, but the net is called C16G, which as Bolle said is fed into UI6 on pin 2. UI6 pin 17 drives a 16MHz clock on the net labeled C16M, which is the main 16MHz clock for the board. So I am actually talking about C16G; I would edit the original post if I could. I see C32M on pin 17 of the GLUE, but I do not see C16G on pin 18 of the GLUE.

I have tried swapping UI6s with my working board and it works there, so the PAL is good.

 

[obsolete]

Been thinking about this problem again lately, and I did a little experiment. I pulled the GLUE off the board and soldered wires onto pins 1 and 84 for GND and +5V, and pins 17 and 18 for C32M and C16G.

Taking GND and +5V off the PDS slot, and C32M off pin 1 of UI6, behold, there's C16G on pin 18 of the GLUE.

So, what would cause it to work off the board, but not on the board? Maybe I need to take another look at the RESET circuit.

 

[macmike]

Hi, while i am building my reloaded board i find out that it is very sensitive to what kind of surface it is on when testing. Good isolated surface is recommended. Also find out the 65c22 from WDT (Mouser) did not work.

 

[obsolete]

Hi, while i am building my reloaded board i find out that it is very sensitive to what kind of surface it is on when testing. Good isolated surface is recommended. Also find out the 65c22 from WDT (Mouser) did not work.

Thanks for the info. You are using the W65C22N? I know that other reloaded board builders have had success with it; yours is the first report I've heard of it not working. What kind of problems did you have?

 

[macmike]

Hi, it pulls down the 1Hz Output from the RTC. After exchange with the originals from the doner board everything is OK.

 

[obsolete]

Hi, it pulls down the 1Hz Output from the RTC. After exchange with the originals from the doner board everything is OK.

Interesting. The machine should still boot in that condition though, shouldn't it? Seems to me that the time just wouldn't advance.