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I always think it is safer to have the AB installed in the machine particularly with the anode cap (big red wire) safely connected to the CRT with the earth cable connected. Too risky for amateurs to be playing around some of these deadly voltages. Safety first folks, safety first...

I fixed this on the weekend with the summary being : I think the Flyback caused the issue with Q2 (Q3 US) (as per above) being burned out. When I replaced Q2 as per above the temp was rising quickly on a few components. When I used a Flyback from another 512K AB the temps were again stable...

See this link with the underlying problem - https://68kmla.org/bb/index.php?threads/240v-power-circuit.38381/

Hi all, can I use a 157-0121 Flyback from a Macintosh Classic AB to replace a Flyback on a 512k AB ? Same screen Clinton 5144.

Yes I did and great work. I think my problem is back at Figure 2 of the original doc though re the horizontal sweep and high voltage circuit.

Yes I did and great work. I think my problem is back at Figure 2 of the original doc though re the horizontal sweep and high voltage circuit.

I have progressed this a bit in the background. I have tried the logic board from the 512 with a known working Mac Plus analog board and all ok, I have then tried the working Mac plus logicbaord with the problematic 512k analog board and has the same problem, no video. I then tried using an...

all fixed and yes these were the capacitors that needed replacing, did all 4.

Hi all, I am still trying to trace my no video issue on my 512k. Looks to me like the heater circuit on the CRT is not working as there is no glow when the unit has power. I can't find much information re how a CRT works but from what I can piece together the following pins on J2 are of...

Did you fix this ? I have the same problem with a recapped analog board and have tried to two working logic boards. I get a bong on startup and I know the logicbaords work ok in another CC.

Get work cheesestraws this will be very handy for all us non 120v'ers.

Found this for anyone interested. https://www.applefritter.com/content/apple-iie-list-capacitors

Do you mean (C9, C12, C7, C15) and/or (C10,C13, C18, C16) on the motherboard ? I can't see these referenced on the IIe Schematic but can see them on the board ? Interestingly on the IIe Schematics son page 2 it refers to the Power on LED being connected directly to the power source via a...

Hi all, anyone know much about the circuit of the Monitor IIe A2M2010P ? I have one which hasn't been powered on for about 20 years. On power up it has a well lit screen (nice green on full brightness) but doesn't display any of the characters being presented to it. I am suspecting caps need...

Potentially a silly question but how are people connecting their FloppyEMU to the Color Classics given the CC logic board doesn't have a DB19 connector exposed on the back ? I was going to connect the ribbon cable from the internal Floppy straight from the machine into the FloppyEMU after...

Thanks for the pointer Cheesestraws. I have replaced U2 as the NAND amplifier/inverter as a precaution, still no video. I have been through the trace with a scope and have attached the images of the scope from U2 through to the CRT neck. Seems ok to me but I might be missing something, I...

It has the -ve equivalents also. interesting though that it gives the voltages with no load and the same motherboard has the same result with a known working PSU. According to the schematic for J14 it should have Pin 1 - GND Pin 2 - GND Pin 3 - +5VDC Pin 4 - +12VDC Pin 5 - -12VDC Pin 6 -...

I replaced Q2 with a new BU406 and this fixed the flup flup flup and resulted in Avery nice loud and clear bong. Only problem is there is video display. I suspecting the Flyback. Is it feasible that the flyback may have blown or caused an issue that burned Q2 resulting in the problem. Should...

Hi, I have experience with the Compact Mac range so IIe's are a new venture for me. I have two both enhanced, I have had one for a years and it works fine, I have just acquired another which has been in a cupboard for about 30 years. I decided to recap the power supply before turning on...

Bibilit, I have already replaced U3 with no noticeable change.