CT60 oscillator issues :evil:

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exxos
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CT60 oscillator issues :evil:

Postby exxos » Sun May 22, 2016 8:44 pm

I have one of the first batches created of the CT60. After much trouble with it, I now find that since killing my CTCM module, only 1 66mhz oscillator works. I know the CPU can take 90mhz, but I have tried no end of 80mhz, 75mhz, versions and nothing works.

The CTCM would work between 66mhz and 90mhz until I jumped to 95mhz and had no way to set it back (believe me I've tried everyone's suggestions and just got nowhere). Last time I over-killed the CTCM I changed the IC, and it would default back to about 60mhz so I could boot again. Though changing the IC this time , it still ended up at 95mhz somehow. In anycase, I've given up with the thing.

Few days ago I got a LT resistor set oscillator so I could change the frequency from 50-170mhz or there abouts. Nothing works with that either. I've tried 5V, 3.3V. Tried adding resistors in series with the clock, tried adding a pull down resistors, capacitors, and the CT60 just refuses to work with anything but the 66mhz oscillator. (and no its not the CPU!)

Has anyone had these issues or know why this happens ?? Its pretty stupid that a simple clock input is causing so much trouble :(
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Re: CT60 oscillator issues :evil:

Postby exxos » Mon May 23, 2016 11:50 am

Some progress. Its seems the CT60 only likes oscillators with a very particular voltage on them. If its around 0.1V to much/little voltage, then it fails to boot. IF the low level voltage is to low/high, it fails to boot.

My RSO works up until around 85mhz then the voltage starts dropping off to much and it fails to boot again. I've got a variable 500R resistor in the line, so now speeds of 66mhz works, if I keep adjusting the voltage until it boots.

This is a royal pain in the rear end to fix properly. The RSO is good as it can be adjusted manually, though with the output voltage varying, it needs some buffer and some regulator to keep the CT60 voltage side constant. I think if I could develop a small adapter to take a fixed oscillator and "clean up" the output for something the CT60 likes, then it would solve a lot of problems for me. I could also put the RSO onboard though they likely are not going to be as stable as a fixed frequency oscillator. So not sure what direction to take yet.

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Re: CT60 oscillator issues :evil:

Postby exxos » Mon May 23, 2016 4:44 pm

I've noticed something else aswell. While ive been pushing now 100mhz speeds. I've been pressing the reset button checking speeds etc though on powerdown it stopped working totally. Even going back to 66mhz speeds not working agian. Though at one point while it was set at 80mhz, on boot it said 45mhz.

Looking at the chip next to the osc, its a CY2309 PLL driver :evil: So the PLL is latching onto a frequency half of what its supposed to be. I suspect that is the problem I've had all day. There doesn't seem any way to disable the PLL either. So only way to "bypass it" is to bodge in some other buffer IC :roll: Its odd that a PLL would reset with the rest button though, not just a power down. The CT60 reports the frequency change on boot, so not sure how that can happen as a PLL normally latches on power up, or signal detected :shrug:
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Re: CT60 oscillator issues :evil:

Postby Rustynutt » Wed May 25, 2016 3:10 am

I've swapped can oscillators in and out of a first run CT60, think it went up to about 95mhz before it would hick up. I smoked my CT63 with the CTCM, can't elaborate much about those.
Picked up another CT63 Falcon, really nice setup, but won't even bugger with it until far down the road. It came with a USB programmer, the CT60 I have needs to be updated for SV, and it will make life much easier having a working machine to go from.

Could you go on about just removing the CTCM and set up for a can oscillator?

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Re: CT60 oscillator issues :evil:

Postby exxos » Wed May 25, 2016 7:42 am

Rustynutt wrote:I've swapped can oscillators in and out of a first run CT60, think it went up to about 95mhz before it would hick up. I smoked my CT63 with the CTCM, can't elaborate much about those.
Picked up another CT63 Falcon, really nice setup, but won't even bugger with it until far down the road. It came with a USB programmer, the CT60 I have needs to be updated for SV, and it will make life much easier having a working machine to go from.

Could you go on about just removing the CTCM and set up for a can oscillator?


The only can oscillator which works for me is a 66mhz one. I've not been able to get any other working. Not even a 75mhz one. From posts in the FB group, seems people had issues even with the CTCM. In fact it used to work for me, but not anymore. I feed the 66mhz clock into the CT60 and had the CTCM plugged in, to fool the CT60 into the CTCM was providing the clock. Then I could set it back to 66mhz. And it still doesn't work. Though sometimes in control panel it seems to jump to 101mhz by itself :shrug:

I think its a inherent problem with the CT60 itself. Somewhere along the line im seeing 1volt between CT60 gnd and the motherboard gnd. I might try hard wiring some gnd wires somewhere to the CT60 to see if that helps.

I've added 2 330pF capacitors to the PLL driver and that seems to have helped. The PLL output seems to be running ok prettymuch, I can't actually find any difference as to why different voltages on the oscillator is effecting the PLL or the CT60 from booting.

Iv'e put my falcon back in the cupboard anyway. To be honest I don't think its designed very well and I'm getting a bit sick of debugging other peoples hardware designs. Hopefully willy will do a better job with its design and be a lot less fickle.
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Re: CT60 oscillator issues :evil:

Postby DarkLord » Wed May 25, 2016 6:34 pm

I've got a CTCM and so far <keeping fingers crossed>, I've never had a problem with it.
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Re: CT60 oscillator issues :evil:

Postby exxos » Wed May 25, 2016 8:35 pm

DarkLord wrote:I've got a CTCM and so far <keeping fingers crossed>, I've never had a problem with it.


Mine worked fine for ages, granted ive had to change the IC a couple of times, but its the same series chip. so :shrug: I'd like to do a new clock module one I can set with a resistor, thats easy enough, but its debugging the CT60 design as to why the clock input is such a huge issue thats the problem. So likely will have to wait until I get more time to look into it.
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Re: CT60 oscillator issues :evil:

Postby Rustynutt » Wed May 25, 2016 11:33 pm

I've played with 68060 socket adapters for the 040 setup, the clock spec on the 060 is a pain. Sent my Milan up State where Rodolphe P is going to (at some point) continue working on an 060 adapter for it, and hopefully shed some light on possible daughter card for the Afterburner. I still can't let mine go, I do like the NOVA ATI MACH 64 and Expose cards too much to give it up.
Supposedly the MC88LV926 makes this a piece of cake, and indeed it works well splitting up the clock on my Afterburner Falcon. The 060 wants to have a few lines tied during reset, and most of the designs I've seen so far depend on running the signal through an inverter, even the Milan adapter. I've been told those were buggy at times too. Haven't looked at the CT stuff to see what it does, Cubza was pretty finicky with his timing, wouldn't think he'd of gotten that incorrect, but noise on the board, yea, that can and was missed I guess.

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Re: CT60 oscillator issues :evil:

Postby paul92706 » Thu Jul 21, 2016 10:29 pm

Looks like i am having same issues as you chris! Ayie!!
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Re: CT60 oscillator issues :evil:

Postby Rustynutt » Sat Aug 19, 2017 6:32 pm

Chris, have you ever sketched a power route for the CT?
At a point where I want to start tracing CT 60 power. When I mis-aligned the ST RAM card, the Falcon board "resistance" point was just to the left of the original power plug on the Falcon. Determined by heat :(
I've had the VIDEL, COMBEL and CPU replaced on that Falcon, still need to work through power on that board. Have most other ICs as well to replace along the way. Fairly easy to trace with the Falcon schematics.

Haven't yet looked the spare CT, something was smoked there as well. Hoping it was just a diode or fuze. Don't know if the overload on the CT was at the ATX connector, or power from the expansion pins.


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