Quadra 650 - Not Booting but PSU works

[pdyholman]

Hi @Phipli - I appreciate your help. C40 and C39 appear to be labelled "226 20K 329"

As it happens, @pizzigri saw their Q650's C40 cap blow last month: https://68kmla.org/bb/index.php?threads/problem-with-quadra-650.43389/#post-472912, and they identified it as a "22uF 20V Tantalum Kemet cap".

Using my multimeter, the + side of C40 is connected to pin 1 of the power molex (so in theory +12v, and I rechecked the voltage on the corresponding male pin coming from the ATX, its 12.3v).

 

[Phipli]

Hi @Phipli - I appreciate your help. C40 and C39 appear to be labelled "226 20K 329"

As it happens, @pizzigri saw their Q650's C40 cap blow last month: https://68kmla.org/bb/index.php?threads/problem-with-quadra-650.43389/#post-472912, and they identified it as a "22uF 20V Tantalum Kemet cap".

Using my multimeter, the + side of C40 is connected to pin 1 of the power molex (so in theory +12v, and I rechecked the voltage on the corresponding male pin coming from the ATX, its 12.3v).

Just realised it is stock on these. Saw tants, assumed it was recapped.

Tantalum capacitors do fail after a while (or instantly) sometimes. Replace it (and it's identical neighbour) with a 25v part of the same capacitance and it shouldn't need looking at again

 

[pizzigri]

Hey Pdyholman, thank for referencing me - I can confirm that once I replaced the Tantalum cap, using a 22uF 20V, the board fired up and all's well in the world.

 

[pdyholman]

Hi @philpli - thanks for this - good tip.
Hi @pizzigri - that's very encouraging (and congrats) - where did you source your 22uF caps from in the end (to help reduce the risk of me ordering ones which were slightly too big etc) ?

 

[pizzigri]

Mouser - kemet cap
It's a 2917 footprint, in other words it's 7.3mm long. measure your cap with a caliper and it should be the same.

 

[pdyholman]

A rainy Easter Monday gave me the opportunity to spend a little time with my '650, starting with a complete dismantling to ensure there wasn't any risk of shorting from any material under the logic board (this youtube video was useful)

I successful replaced the C40 capacitor (again youtube was helpful, with an additional tip about using a soldering hand in each hand to deftly remove the old one), and (thanks to @Phipli ) installed an ATX to 10pin Molex PSU adaptor.

Of course, I should have taken @Phipli 's advice - whilst power-on was successful, the neighbouring C39 promptly blew and needed replacing as well.

However, when both were replaced, really great to hear an apple chime and (after a nerve wracking few seconds) a grey screen with the classic flashing question mark icon.



Unfortunately (but not unsurprisingly), connecting the (original) Quantum Prodrive LPS) SCSI drive had the same error message....

Next steps (although advice always welcome) -

- investigate creating a version of "Disk Tools" on a floppy
- order a ZuluSCSI

 

[cheesestraws]

It lives! Hooray. Well done

 

[volvo242gt]

A rainy Easter Monday gave me the opportunity to spend a little time with my '650, starting with a complete dismantling to ensure there wasn't any risk of shorting from any material under the logic board (this youtube video was useful)

I successful replaced the C40 capacitor (again youtube was helpful, with an additional tip about using a soldering hand in each hand to deftly remove the old one), and (thanks to @Phipli ) installed an ATX to 10pin Molex PSU adaptor.

Of course, I should have taken @Phipli 's advice - whilst power-on was successful, the neighbouring C39 promptly blew and needed replacing as well.

However, when both were replaced, really great to hear an apple chime and (after a nerve wracking few seconds) a grey screen with the classic flashing question mark icon.

View attachment 55012

Unfortunately (but not unsurprisingly), connecting the (original) Quantum Prodrive LPS) SCSI drive had the same error message....

Next steps (although advice always welcome) -

- investigate creating a version of "Disk Tools" on a floppy
- order a ZuluSCSI

I have a 250MB Quantum drive that I will be replacing later today with a larger drive on my C650. Getting it to the UK might be more than it's worth, but there is that option. Drive would come as is, with System 7.6.1 installed and various programs from the 'garden installed as well. No personal data, obviously, since I keep that stuff on my more modern machines' drives, etc.

 

[pdyholman]

Hi @volvo242gt : thanks, that's a really great and generous offer much appreciated! I'm going to experiment some more (disk tools / replacement cable), and I'll see how far I get with the existing drive, but could be useful.

(as it happens, I'm visiting California and South Carolina in a couple of month for work and to see both my siblings)

 

[Phipli]

Hi @volvo242gt : thanks, that's a really great and generous offer much appreciated! I'm going to experiment some more (disk tools / replacement cable), and I'll see how far I get with the existing drive, but could be useful.

(as it happens, I'm visiting California and South Carolina in a couple of month for work and to see both my siblings)

Does the disk spin up? Does it then go "click clickclickclick.... Click" or similar?

Does it spout flames and scream an angry grinding noise?

Is there an LED on it?

 

[volvo242gt]

Hi @volvo242gt : thanks, that's a really great and generous offer much appreciated! I'm going to experiment some more (disk tools / replacement cable), and I'll see how far I get with the existing drive, but could be useful.

(as it happens, I'm visiting California and South Carolina in a couple of month for work and to see both my siblings)

If they're ok with a hard drive being mailed to them, we can make it work...

 

[jmacz]

@pdyholman was it always the two tantalum caps (C40/C39) that were the problem, or was it a bad power supply and the process of trying the ATX caused an accidental burn out of those two caps, or was it both the power supply and both caps were about to go bad? Just asking out of curiosity.

 

[pdyholman]

@pdyholman was it always the two tantalum caps (C40/C39) that were the problem, or was it a bad power supply and the process of trying the ATX caused an accidental burn out of those two caps, or was it both the power supply and both caps were about to go bad? Just asking out of curiosity.

Hi @jmacz

Whilst the original power supply wasn't completely dead, a couple of the voltages it generated under light load (shorting pins 9 and 10 so that the PSU powered up the fan) were more than 10% off their expected values.

So I suspect that it was on it's last legs (and thus not able to power up the logic board), and whilst replacing the PSU caps might have delayed the inevitable, better to switch to a modern PSU, is probably both safer and more reliable.

(Given the ATX PSU was rescued from a written-off PC from work, I also measured its voltages when running its fan before use - all were within 10%),

Given @pizzigri had exactly the same problem with C40 (powering up another '650 with (I assume) its original PSU), I suspect that the capacitor problem was unrelated, and simply the result of C40 experiencing

I wanted to document "my journey" just in case other '650 owners encountered the same problem !

 

[pdyholman]

Does the disk spin up? Does it then go "click clickclickclick.... Click" or similar?

Does it spout flames and scream an angry grinding noise?

Is there an LED on it?

@Phipli - I need to investigate when I get free time (am in office today). However, there is cause for hope - there was a flashing red le to suggest drive activity, but no grinding noises. (I've found a USB floppy drive from an old VAIO and will try and see if (a) I can create a bootable diskette with Disk Tools and (b) the floppy drive works).

> If they're ok with a hard drive being mailed to them, we can make it work...
@volvo242gt - thanks so much ! I'll see how well I do this weekend and get back to you.

Indeed - really appreciate everyone's help on this thread!

 

[pdyholman]

> there was a flashing red led to suggest drive activity, but no grinding noises. (I've found a USB floppy drive from an old VAIO and will try and see if (a) I can create a bootable diskette with Disk Tools and (b) the floppy drive works).

I was able to spend a few more minutes with the '650 this evening.

Errata : the HDD is pulsating green (every few seconds). However, it's to hear if there is activity inside the drive.

Update : The good news is that whilst the old VAIO USB Floppy Drive doesn't work reliably with modern macs, I was able to create bootable disk tools diskette using a PC (rawrite) which booted successful on the '650. The bad news is that it was a System 7.0 .img (and thus rejected by the '650), so now searching the Web for an .img between 7.1 and 8.1...

 

[volvo242gt]

System 7.5 images: https://macintoshgarden.org/sites/macintoshgarden.org/files/apps/MacOS75.ZIP

 

[Apfelklassik.de]

Congrats on the revival! This gives me hope for my 840 ...

 

[pdyholman]

Progress update:

1. I attempted to burn bootable CDs (finding I had a stack of 50 of them in a drawer) and floppies using Win11 and OSX Macs - but to no avail. Hopefully, I'll be able to renovate the CD drive and floppy drive, but decided it was probably best to do so when I have a working OS (who knows, the problem might lie with trying to use obsolete software and hardware on modern PCs rather than mechanical/electronic problems)
2. Meanwhile, I ordered a ZuluSCSI RP2040 from AmigaKit (arrived today, took 10 days)
3. Whilst waiting, I prepared a 16GB SD card according to the ZuluSCSI manual
   1. labelling the SD Card as "SDHC"
   2. adding a Mac System 7.6.1 .iso (renamed to be CD2.iso) from Macintosh Garden
   3. added an image of a 500MB hard disk (renamed to be HD1.hda), created using the "Disk Jockey" app (targeting BlueSCSI)
   4. Added the binary for the latest firmware update for the RP2040 from the ZuluSCSI website (ZuluSCSI_RP2040_2023-04-11.bin currently)
4. Adding the SD card to the RP2040, I connected it via micro UBS to a power supply to allow it to update its firmware
5. I then swapped out the internal CD drive for the RP2040
6. Powered up, and everything worked - 7.6 "CD" booted up, and I was able to set up the Zulu virtual HDD, so now I have a working Quadra to help debug the rest of the hardware. Very nostalgic !
7. OK - I admit everything isn't working . The keyboard (an M3501 Apple Extended II) doesn't seem to be working (although the mouse, connected via one of the ADB ports on the keyboard is working). Oddly, the soft-power button seemed to be working when I first started this journey .... anyway next step will be to strip it down and check for problems ..

 

[mdeverhart]

The keyboard (an M3501 Apple Extended II) doesn't seem to be working (although the mouse, connected via one of the ADB ports on the keyboard is working). Oddly, the soft-power button seemed to be working when I first started this journey ....

That’s not too surprising. ADB is a shared bus, so as long as the electrical connection between the mouse, through the keyboard, and to the computer is OK the mouse should work even if the keyboard doesn’t. Similarly, the soft-power button doesn’t go through the keyboard controller, it’s just a switch that pulls the “soft-power-on” signal low, so it’ll work even if the rest of the keyboard isn’t.

 

[pdyholman]

Hi @mdeverhart - good to know, thanks.

The good news is that taking the M3501 keyboard apart (this ifixit was useful), and dusting 30 years of dust, it works. However, it only currently works whilst dismantled (case removed), but not when I put it back in its case (so a tip for anyone finding this post is to try using the keyboard before reassembly). Can't see an obvious short, but will have a look again over the weekend.

In parallel, I'm trying the '650s original peripherals that I had boxed:

- The Apple Transceiver (Model M0437) powers up (green LED), and is seen by my switch (LED lights up), but isn't appearing on my router's client's list. The Mac has a TCP/IP control panel, but using "DHCP", isn't automatically obtaining an IP address etc. I'll add this to my backlog for research, too.
- Fired up an external SCSI Sony CD-Rom Drive, and popped an audio CD into the caddy. Powers up, and appears to have drive activity - but not appearing on the Mac's desktop. Not essential, so will come back to that.

So overall, some progress