LC575 computer killed LC520 motherboard! š
- Thread starter JDW
- Start date
-
- Tags
- color classic lc520 lc575 repair
-
Please can you read through and vote on the following proposition for changes to the board structure by clicking here.
I am testing my LC 520 board in my Color Classic using the reproduction TechStep.
ADB mode works for me.
1. Mac power switch off.
2. Plug in all cables to TechStep
3. Mac power switch on.
4. Power up TechStep
5. Choose LC520
6. Choose 3. TstMde
It turns on the Mac as though the keyboard power button was pressed (fan, drive) and then it successfully enters test mode using ADB.
For my LC520 board, my screen is blank during TechStep testing except step 7 gray pattern. When booted normally, my screen works. For Color Classic, gray screen the entire time. But, my Color Classic body and LC 520 board are both stock. That may explain the difference.
Color white = same results as you
Color green = my results are similar
Color orange = my results are different
1. Power Supply: 4.92V (normal)
2. Power Up Voltage 4.94V (normal)
3. TstMd: Enabled via ADB
4. CPU ID: LC 520 (have you modified your 520 board to run as a CC II with the resistor removal?), but it also shows: ROM Version: $67C, Subversion: $25F1
5. Logic
7. Built-in Video
9. More RAM Tests: did not perform
10. ADB Status: PASSED
11. SCSI Functions:
ADB mode works for me.
1. Mac power switch off.
2. Plug in all cables to TechStep
3. Mac power switch on.
4. Power up TechStep
5. Choose LC520
6. Choose 3. TstMde
It turns on the Mac as though the keyboard power button was pressed (fan, drive) and then it successfully enters test mode using ADB.
For my LC520 board, my screen is blank during TechStep testing except step 7 gray pattern. When booted normally, my screen works. For Color Classic, gray screen the entire time. But, my Color Classic body and LC 520 board are both stock. That may explain the difference.
Color white = same results as you
Color green = my results are similar
Color orange = my results are different
1. Power Supply: 4.92V (normal)
2. Power Up Voltage 4.94V (normal)
3. TstMd: Enabled via ADB
4. CPU ID: LC 520 (have you modified your 520 board to run as a CC II with the resistor removal?), but it also shows: ROM Version: $67C, Subversion: $25F1
5. Logic
- ROMck: ROM Checksum PASSED
- RAMsz: Soldered 4MB (correct because I have no RAM SIMM installed)
- Addr.: Address Bus Test PASSED
- Data: Data Bus Test PASSED
- RAM: Standard Test PASSED
- VIA: PASSED
- RBV: RBV Registered FAIL : Mon Mismatch (I haven't modified my CC monitor resolution) Expected 14" found 10"
- VRMsz: Video RAM Size 1 MB (I have a VRAM SIMM installed. Forgot to remove it)
- VRAM: Video RAM Test PASSED
- CLUT: Color Lookup Table PASSED
- Clock: Clock Test PASSED
- P/RAM: Non-Destructive Test PASSED, Destructive Test PASSED
- ADB: ADB Test PASSED
- SCC: Serial Comm. Test PASSED
- SCSI: SCSI Logic Test FAIL (Data Xfer) Same as you!
- SWIM: PASSED (I heard the floppy drive make a brief sound during this test)
- Sound: PASSED
7. Built-in Video
- Turn PwSvr ON: "Screen should be solid black" (my comment: well, it is because it never turns on!)
- Turn PwSvr OFF: "In 10-30s, screen should turn gray" mine turned on and showed gray
- Video Patterns (test): failed because it did not recognize monitor
9. More RAM Tests: did not perform
10. ADB Status: PASSED
11. SCSI Functions:
- Termination Power: 4.68V (Normal is >4.15V)
- SCSI Term Check: PASSED
- SCSI Bus SCAN Found my internal drive at 0
- Power OFF CPU: Command Worked. Case Fan and HDD powered OFF.
- Power ON CPU: Command Worked (without any bong because I have the headphone jack plugged in as part of the TechStep). Case Fan and HDD powered up.
@Garrett
Thank you for your advice. I actually had removed both ROM chips and re-socketed them at the time I recapped and overclocked (via resistor removal) the board even though the board was working fine. I did that restocking just to make sure everything would be OK. Even so I could go further and āscrape the legsā as you suggest.
Iāve noted how more than one of you have said that āthese boardsā are finicky. Your use of the plural term ātheseā seems to indicate youāre referring to all of them: the stock Color Classic board, the LC 520 board, the LC 550 and 575 boards. But hereās the thing. Iāve used my 575 board for a very long time and never had a single problem with it. That significant because Iāve handled it a lot. Iāve swapped in RAM, VRAM, CPU, etc. many times and I even soldered in a ROM socket and Iāve been using a custom ROM too. Iāve added and removed CPU heatsinks and fans, Spicy OāClock, and the Apple IIe card. In fact, Iāve done more to this 575 board than any of my SE/30 boards or any other motherboard Iāve ever owned. And through it all, thereās not been one problem with that board. Itās the single most real best board I have. And so, Iām trying to put your word āfinickyā into perspective in light of my good experience with that particular board.
But the good experience Iāve had doesnāt just stop there with a 575 board either. Iām not had a single issue with the stock Color Classic board either.
Maybe my experience is just abnormal and maybe most people find that all of these motherboards boards can be finicky. All I can say is that my LC520 board worked flawlessly until I tried it in the LC 575 body. And because of that, thereās no way Iām going to try either of my other two boards in that body just to see what happens, even though that would be the definitive test.
But if you read what I wrote previously, there is a curious thing. I donāt know if any of you picked up on it or not, so Iāll emphasize that point now. When I use the LC 520 board in my CC body and press the power key on the keyboard, the case fan turns on and the hard drive (spinning platter) spins up. But when I do the same test in the LC 575 body, the fan and hard drive donāt power up and thereās no sign of life.
Thank you for your advice. I actually had removed both ROM chips and re-socketed them at the time I recapped and overclocked (via resistor removal) the board even though the board was working fine. I did that restocking just to make sure everything would be OK. Even so I could go further and āscrape the legsā as you suggest.
Iāve noted how more than one of you have said that āthese boardsā are finicky. Your use of the plural term ātheseā seems to indicate youāre referring to all of them: the stock Color Classic board, the LC 520 board, the LC 550 and 575 boards. But hereās the thing. Iāve used my 575 board for a very long time and never had a single problem with it. That significant because Iāve handled it a lot. Iāve swapped in RAM, VRAM, CPU, etc. many times and I even soldered in a ROM socket and Iāve been using a custom ROM too. Iāve added and removed CPU heatsinks and fans, Spicy OāClock, and the Apple IIe card. In fact, Iāve done more to this 575 board than any of my SE/30 boards or any other motherboard Iāve ever owned. And through it all, thereās not been one problem with that board. Itās the single most real best board I have. And so, Iām trying to put your word āfinickyā into perspective in light of my good experience with that particular board.
But the good experience Iāve had doesnāt just stop there with a 575 board either. Iām not had a single issue with the stock Color Classic board either.
Maybe my experience is just abnormal and maybe most people find that all of these motherboards boards can be finicky. All I can say is that my LC520 board worked flawlessly until I tried it in the LC 575 body. And because of that, thereās no way Iām going to try either of my other two boards in that body just to see what happens, even though that would be the definitive test.
But if you read what I wrote previously, there is a curious thing. I donāt know if any of you picked up on it or not, so Iāll emphasize that point now. When I use the LC 520 board in my CC body and press the power key on the keyboard, the case fan turns on and the hard drive (spinning platter) spins up. But when I do the same test in the LC 575 body, the fan and hard drive donāt power up and thereās no sign of life.
@David Cook
I really appreciate the time you took to do that TechStep testing and provide a detailed report. Thank you!
Iām getting ready for work now, so it all will have to be done after work tonight. Specifically:
1. Remove and scrape all legs of both ROM chips. Test and see what happens.
2. Use headphones to test headphone jack and listen for the bong at time of Power Key press.
============
Yes, I have removed the 3 resistors to Overclock to 33MHz and that was done in this video.
David, if you have the stock CC motherboard too, can you test that with your TechStep? I ask because I wasnāt able to enter test mode when I tested my stock CC board. (This is unrelated to the LC520 problem.)
I really appreciate the time you took to do that TechStep testing and provide a detailed report. Thank you!
Iām getting ready for work now, so it all will have to be done after work tonight. Specifically:
1. Remove and scrape all legs of both ROM chips. Test and see what happens.
2. Use headphones to test headphone jack and listen for the bong at time of Power Key press.
============
Yes, I have removed the 3 resistors to Overclock to 33MHz and that was done in this video.
David, if you have the stock CC motherboard too, can you test that with your TechStep? I ask because I wasnāt able to enter test mode when I tested my stock CC board. (This is unrelated to the LC520 problem.)
What have we learned?
Your CPU is working. Your ROMs are good (checksum passed). Your bus is working (memory and ROM tests).
Your CUDA is working (crystal, PRAM, clock, power on, and ADB tests).
That's why the TechStep is saying it doesn't recognize the CPU. The id has been changed from LC 520 (#56) to Color Classic II (83). That means those test 'failures' are red herrings.
Yes. I am able to enter test mode using ADB using my reproduction TechStep with the Color Classic unmodified body and motherboard. Please note my steps differ slightly from your video, in that my Color Classic starts in the off state (power switch off, plug in tech step, power switch on, power up tech step, choose color classic, choose 3 TstMde).
In your video, yours is already on, then you attempt test mode, then you turn power switch off/on. See below... I don't start test mode in that state. Oh, maybe you already tried and failed to enter ADB mode when you shot this portion of the video.
11. SCSI Functions: SCSI Bus SCAN (Let's you type any SCSI ID, but the TechStep is ID6. I tried all others but the internal HDD was not found. Interesting.)
Does yours show the 0?
Your CPU is working. Your ROMs are good (checksum passed). Your bus is working (memory and ROM tests).
Your CUDA is working (crystal, PRAM, clock, power on, and ADB tests).
That's why the TechStep is saying it doesn't recognize the CPU. The id has been changed from LC 520 (#56) to Color Classic II (83). That means those test 'failures' are red herrings.
Yes. I am able to enter test mode using ADB using my reproduction TechStep with the Color Classic unmodified body and motherboard. Please note my steps differ slightly from your video, in that my Color Classic starts in the off state (power switch off, plug in tech step, power switch on, power up tech step, choose color classic, choose 3 TstMde).
In your video, yours is already on, then you attempt test mode, then you turn power switch off/on. See below... I don't start test mode in that state. Oh, maybe you already tried and failed to enter ADB mode when you shot this portion of the video.
11. SCSI Functions: SCSI Bus SCAN (Let's you type any SCSI ID, but the TechStep is ID6. I tried all others but the internal HDD was not found. Interesting.)
Does yours show the 0?
I got my reproduction TechStep from @max1zzz during the following thread:
68kmla.org
You could reach out to him to see if he has a newer version of Vol. 4 tests or whether his is better at entering test mode for some reason.
Recreateing the Apple TechStep
Me and @jajan547 are currently working on creating a replica of the Apple Techstep This will be a functional and (mostly) electrical clone of the original but will not be a exact 1:1 copy as the design will be optimised where changes can be made to make the board easier or cheaper to assemble...
68kmla.org
You could reach out to him to see if he has a newer version of Vol. 4 tests or whether his is better at entering test mode for some reason.
One more thing when you get home from work. Confirm that you hear a sound from the floppy drive during test step 5 SWIM test.