Apple IIe Platinum seems dead - help!

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Apple IIe Platinum seems dead - help!

I was recently "gifted" an Apple IIe Platinum -- with a dead power supply, and every single slot empty. 

The power supply had significant damage to it (likely from whoever owned it previously replacing the fuse on the AC side with a piece of 14-gauge wire) and had the 6-pin motherboard power plug clipped off. 

I was able to cobble together a power supply to test the power to the board. Initial tests indicated that the board was doing positively nothing outside of the power and keyboard LEDs until I discovered that pin 1 of the 65C02 processor had been clipped off completely. Pin 2 had also been folded back underneath the chip socket. 

I replaced the 65C02, and now, so long as the keyboard is plugged in and I do not have a monitor plugged in, I get a beep. But if I plug a monitor into the composite out, I get no beep and scrambled video (just lines, not characters). 

If I leave the monitor unplugged, the keyboard doesn't appear to do anything (if I type, I get no response).

I've got very little idea of where to start with troubleshooting from here. Can anyone help with this?

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Are you sure that you
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Are you sure that you

Are you sure that you duplicated every signal and voltage? The //e PSU is dampened, so perhaps voltage loss is to blame.

 

First thing that I suggest is the Reactive Micro PSU kit, as this will net you a proper PSU, not a guessathon power supply.

 

Short of that, I have one window opening for restoration next month.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Timelord wrote:Are you sure
Timelord wrote:

Are you sure that you duplicated every signal and voltage? The //e PSU is dampened, so perhaps voltage loss is to blame.

 

First thing that I suggest is the Reactive Micro PSU kit, as this will net you a proper PSU, not a guessathon power supply.

 

Short of that, I have one window opening for restoration next month.

When you say "dampened," what do you mean there? The power supply I used is a reclaimed ATX power supply, with a +12, -12, +5, and -5V rail. 

Would it potentially be a current thing? The stock IIe PSU could put out 4A on the +5 line, but the one I have can only deliver 2A -- do you think it's simply underpowered?

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2A on the 5V line should be

2A on the 5V line should be sufficient wth no external devices connected.

If you're getting a beep with no video that's a good sign - it means that the CPU is getting its reset signal and executing sufficient ROM code to get to the "BEEP" routine in ROM.

 

However, connecting a monitor to the composite video port causing the computer to fail is weird.  Even if the video pin were shorted to ground if shouldn't cause the computer to fail.

Scrambled video could also mean a poor connection to the video out connector.  Does wiggling the cable at the back of the IIe do anything visually?

Can you show a pic of what your video pattern is?

 

Have you tried starting up with the "option" key pressed, to force it to run the self-diagnostic?

 

 

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baldrick wrote:2A on the 5V
baldrick wrote:

2A on the 5V line should be sufficient wth no external devices connected.

If you're getting a beep with no video that's a good sign - it means that the CPU is getting its reset signal and executing sufficient ROM code to get to the "BEEP" routine in ROM.

However, connecting a monitor to the composite video port causing the computer to fail is weird.  Even if the video pin were shorted to ground if shouldn't cause the computer to fail.

Scrambled video could also mean a poor connection to the video out connector.  Does wiggling the cable at the back of the IIe do anything visually?

Can you show a pic of what your video pattern is?

Have you tried starting up with the "option" key pressed, to force it to run the self-diagnostic?

 

I've attached images of the video I got. The Apple monitor would simply display very faint garbled signals similar to what you see here, and when the output was probed with a scope, the signal would drop from about 1V P-P with the monitor unconnected to about 0.5V P-P with it attached.

One thing I thought about is that if the Apple monitor is a 75-ohm connection, it might be loading things down to the point where they don't operate, so I tried a different monitor with a high-impedance switch on the back and it would beep with that monitor attached, and that monitor provided the resultant photos.

Without the Option key pressed, I get the first picture. Portions of it blink.

With the Option key pressed, I get the second picture -- and it seems to fail to sync to the signal as there's some pretty serious horizontal rolling. Could this be a PAL board and I don't know it?

 

 

 

<--- Normal boot. Option NOT pressed.

 

 

 

 

 

 

 

 

 

<--- Diagnostics mode. Option IS pressed.

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Can you check the voltages

Can you check the voltages WHILE the computer is running? That should rule out a PSU issue.

 

With no monitor, can you power up, then press CTRL-RESET to get to the prompt and then press CTRL-G to trigger the BEEP manually? If you hear the BEEP, the computer is probably working fine, just you cannot see the picture.

 

It's indeed weird that a monitor causes that. Maybe it's a silly idea but are both the PC and the monitor properly grounded?

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Dumb question but does that

Dumb question but does that monitor work when connected to another computer?

Or the video out of an old VCR or DVD player?

 

Have you got another monitor?

 

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mabalmer wrote:until I
mabalmer wrote:
until I discovered that pin 1 of the 65C02 processor had been clipped off completely

Well, what kind of 65C02 was the CPU? Maybe a W65C02S? This is the latest 6502 made by WDC.

The original 6502 had two ground pins: pins 1 and pin 21 were both ground. Since a duplicated ground connection is not necessary, WDC reused pin 1 for a new output signal ("VPB" to indicate interrupt execution). You can plug a newer W65C02S into an older machine exepecting an old 65C02 - but you should isolate (or clip) pin 1 in this case. Otherwise the CPU's VPB output is grounded - basically resulting in a short circuit. Not healthy for the CPU...

So isolating or clipping pin 1 may have been correct, if this was a newer W65C02S. Otherwise, for an older 6502 (or old 65C02) pin 1 must be connected to ground, of course...

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MacFly wrote:mabalmer wrote
MacFly wrote:
mabalmer wrote:
until I discovered that pin 1 of the 65C02 processor had been clipped off completely

Well, what kind of 65C02 was the CPU? Maybe a W65C02S? This is the latest 6502 made by WDC.

The original 6502 had two ground pins: pins 1 and pin 21 were both ground. Since a duplicated

 

A PAL //e will have its expansion slot in-line with slot 3, rather than on the side of the board. PAL Vs. NTSC determination is something to resolve first. I could swear that the actual output voltage of the //e PSU is > 12V when not connected and that it is regulated down to 12VDC once connected, but I'll need to check. 

 

Some photos of the system would be useful. It is extremely odd that it only does this when connected to your display. 

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I have chosen to throw in the

I have chosen to throw in the towel on this one for now. It became obvious after looking further around the board that this machine had essentially been scavenged for parts. 

I did not realize until later that this machine was supposed to ship with an 80-column card installed in the AUX slot -- this slot was empty. The speaker had been taken off of its header and the housing removed. The mounting of the keyboard to the upper frame had been corrected with some kind of disgusting foamy epoxy that caused it to sit low inside the frame. Even more ridiculous, there were case screws missing -- two of the self-tapping screws that hold the bottom mounting plate on to the top of the case weren't present when I went to take the motherboard out of the case.

The motherboard itself looked clean, but with the damage done to the CPU, I decided to look at the other socketed chips -- most looked OK, but the Video ROM chip had somewhat distressed pins, looking like it had been pulled and reinserted multiple times with a bit more force than was probably necessary. 

The PSU I used to initially start the board up was swapped out with a known good IIe power supply from another working machine (also a Platinum); it made no difference in how the system started up. 

Eventually, I stopped getting even the initial beep and started simply seeing full-brightness garbage sprayed on the screen when I flipped it on regardless of what I did to it.

Something else is seriously wrong, and given that I didn't have a lot of time to test things, I decided to shelve it for now. I may revisit it later, but my next guess is that there's a bad logic chip somewhere in there, or there's actually something wrong with the board itself given the odd issue of getting no response when hooked up to a standard Apple monitor, but with one that doesn't load the connection, it comes up.

 

To answer some other questions from upthread: 

With no monitor: CTRL-RESET followed by CTRL-G does nothing. 

The monitor itself: It's a known good composite monochrome monitor. It worked fine attached to the known working IIe we had.

The replacement 65C02 was an old NCR part; it was not one of the newer ones made by WDC. The damaged part in the computer originally was the Rockwell-renumbered version that would've been standard in the machine.

With the knowledge about PAL vs. NTSC, it is not a PAL machine. The AUX slot was on the left side, not in line with any of the expansion slots. 

 

It's possible that I may revisit this machine later, but for now, it's going in the "dead for now" pile.

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