Sequential Six-Trak Lock Ups

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dstrength
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Sequential Six-Trak Lock Ups

Post by dstrength » Thu Apr 10, 2014 7:10 pm

Anyone here familiar with the Six-Trak / Multi-Trak? I've got one that won't 'boot' per se. That is, it starts up, then locks up within a couple seconds...with no response from the front panel or keys. It never produces sound.

The power supply looks ok, even though I've got 200 mv ripple on the 5 volt Vd. I'm planning on replacing the two filter caps and the regulator...but I can't imagine that's what's causing the lockup.

Watching the Z80 with a scope, I've got a good solid clock signal, and see a good reads and writes on the data lines. The MREQ line is pulsing nicely...but IOREQ only pulses for a second or two and then stops. At that point, WR's to the 8253 counter/timer stop as well. But, I'm not sure what's causing it. I'm guessing it could be the RAM, the 8253, the Z80...or even something else on the IOREQ line like the UART. All of the pins these IC's look ok and beep out fine with a DVM, and the board looks to be in great shape. It has a new v11 ROM installed.

Anyone have any ideas before blindly replacing components? I'm far from a Z80 expert.

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Re: Sequential Six-Trak Lock Ups

Post by rhino » Thu Apr 10, 2014 8:13 pm

Welcome to the board!

Had one come in 'frozen'. New Z-80 cured it.
When the wise man points to the stars, the fool looks at the finger.
- Confucius

dstrength
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Re: Sequential Six-Trak Lock Ups

Post by dstrength » Thu Apr 10, 2014 8:28 pm

Thanks for the heads up. That's the second reference I've heard to a failed z80. Guess once I line out the PSU, I'll try replacing the z80.

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Re: Sequential Six-Trak Lock Ups

Post by dstrength » Tue Apr 15, 2014 2:54 pm

rhino,

Did you happen replace the cpu with the original Z8400APS? Or did you use a more readily available modern version. I'm not sure, but it looks like I could use Z84C006. Not real familiar with this stuff. Any ideas?

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modulator_esp
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Re: Sequential Six-Trak Lock Ups

Post by modulator_esp » Wed May 21, 2014 1:49 pm

dstrength wrote:rhino,

Did you happen replace the cpu with the original Z8400APS? Or did you use a more readily available modern version. I'm not sure, but it looks like I could use Z84C006. Not real familiar with this stuff. Any ideas?
I'd quite like to know this too, as I have a locked up Six-trak too
mostly enjoying adventures in sound :)

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