Phipli
Well-known member
Previously I've had someone (sorry, I can't find the old posts, I can't remember who it was) tell me that fitting an LED to the "desktop" LED footprint will change a Quadra 800 into a Quadra 650, which caused confusion because that contradicts how my Centris 650 behaves (if I jumper the J25 tower (Frigidaire) LED header and have the desktop LED, DS1 fitted, my machine reports as a Quadra 800, even though the DS1 is fitted).
Looking at the schematic, I can see there is faint pen markup correcting the labels for the two LEDs. This markup corrects phrasing from the assumption that the 650 is a desktop at 25MHz, and the 800 is a tower at 33MHz, to just that the 650 is a desktop and the 800 is a tower.
I considered if perhaps the ROM revision changes behaviour, but looking at the schematic, this can't be the case. "LED_Pwr" is jst a test point to check that the LED is getting power, so there is no way in this circuit to detect if DS1 is fitted or not. On the other hand, a jumper included in the tower LED cable causes "CPU_ID_ext3" to be pulled down (overpowering the built in pullup) and sends a signal indicating that the tower LED is fitted... i.e. this is a Quadra 800.
In the following, "For 33MHz" and "For 25MHz" have been crossed out and an almost illegible notes written. 33MHz has been replaced with "Frigidaire", the 800 case. I can't read the other, but it probably says "Lego", the name of the 650 case.
Has anyone else seen their machine gestalt change from modifying DS1? If would only make sense if the circuit design was modified, I'm really confused by the suggestion.
Looking at the schematic, I can see there is faint pen markup correcting the labels for the two LEDs. This markup corrects phrasing from the assumption that the 650 is a desktop at 25MHz, and the 800 is a tower at 33MHz, to just that the 650 is a desktop and the 800 is a tower.
I considered if perhaps the ROM revision changes behaviour, but looking at the schematic, this can't be the case. "LED_Pwr" is jst a test point to check that the LED is getting power, so there is no way in this circuit to detect if DS1 is fitted or not. On the other hand, a jumper included in the tower LED cable causes "CPU_ID_ext3" to be pulled down (overpowering the built in pullup) and sends a signal indicating that the tower LED is fitted... i.e. this is a Quadra 800.
In the following, "For 33MHz" and "For 25MHz" have been crossed out and an almost illegible notes written. 33MHz has been replaced with "Frigidaire", the 800 case. I can't read the other, but it probably says "Lego", the name of the 650 case.
Has anyone else seen their machine gestalt change from modifying DS1? If would only make sense if the circuit design was modified, I'm really confused by the suggestion.
Last edited: