[N8VEM: 16571] Debugging Zeta Build

[Jim Strickland]

Hi. I've done first powerup on my zeta.

Problem #1: When loaded with the 20mhz crystal, it spews a continuous
stream of gibberish out the serial port.

Problem #2: Dropping the clock speed down to 8mhz using the floppy system
clock (no fd installed yet anyway) the gibberish clears up and I get the
startup screen, but can't type back to it.

Problem #3: Sometimes the board starts up halted. Resetting returns me to
problem #2.

My hypotheses right now are that problem #1 is from the 74LS06s that Sergey
mentions in some places as being too slow and that #2 is the result of
deficiencies in my charge pump caps. While they are all .1uF, and the
chip's datasheet specifies these, the disk ceramics I'm using have a huge
tolerance, and if I got one bad one, it would mean one line never goes high
enough to work. I'll be putting new caps in the charge pump lines soon.
Problem #3 has me stumped. It could be a side effect of #1 or #2, I
suppose. Thoughts?

Problem #4 (New development) I just put the cr2032 battery in, and now when
the board is powered up, u25 and x1 get too hot to touch very quickly.
Likewise an area on the board down around r2, d1, and c30 gets very hot. No
changes in operation, however, except that I shut it down very quickly when
I noticed the heating problem

Back to the schematics for me, I guess.

Meantime, some questions:

1. Are full can crystals polarized? I put my 20mhz one in "upside down" at
one point and it very swiftly got too hot to touch. This is in the same
socket where it has run barely warm enough to feel with cold hands most of
the time, and the same socket the 8mhz crystal does the same.

2. Could we have a definite yay or nay whether 74LS06s work at 20mhz,
please? They're what is specified in the BOM.

3. Does anyone see anything obvious wrong with my serial IC selections:
UART: NS16450N
Driver: TRS232ECN (I've read that .1uF caps on these are often
insufficient, so I'll be going to 1.0s when I replace them.)

4. I noted in the discussion about the N8 that it was necessary to put a
450uF cap across power to slow the startup. With all ICs installed, my Zeta
comes up halted at least half the time. With only the bare essentials -
ROM, RAM, UART, Serial, plus all the TTL, the number of halts on startup
drops off dramatically. Was there a revision that I missed when installing
my caps?


-JRS

[Jim Strickland]

update: found an unsoldered pad on pin1 of the FDC9266. Soldering that and cleaning the flux off the board seem to have fixed the hot chip problems.

[Jim Strickland]

Update: Cleaning the board and soldering pin1 of the FDC controller seems to have resolved both the hot chip and coming up halted problems. Looks very much like I'm down to just the serial port problem at 8mhz. At 20, I still get gibberish.

[AG5AT]

I built my Zeta at 20 mhz using 74AHCT chips from Mouser.

Serial chip is a 16550D from Jameco
Parallel port is TMP82C55AP-10 that I got from Sergy. I recently got some
from Ebay in China. So they are available.
Z84C0020PEC from Ebay in China.

Aug

Post by Jim Strickland
Update: Cleaning the board and soldering pin1 of the FDC controller seems
to have resolved both the hot chip and coming up halted problems. Looks
very much like I'm down to just the serial port problem at 8mhz. At 20, I
still get gibberish.

[Jim Strickland]

My parallel chip is a NEC D8255AC-5. Clearly, I've built a low speed
machine.

-JRS

Post by AG5AT
I built my Zeta at 20 mhz using 74AHCT chips from Mouser.
Serial chip is a 16550D from Jameco
Parallel port is TMP82C55AP-10 that I got from Sergy. I recently got some
from Ebay in China. So they are available.
Z84C0020PEC from Ebay in China.
Aug

Post by Jim Strickland
Update: Cleaning the board and soldering pin1 of the FDC controller seems
to have resolved both the hot chip and coming up halted problems. Looks
very much like I'm down to just the serial port problem at 8mhz. At 20, I
still get gibberish.

[Max Scane]

Hi Jim,

Those "full can crystals" are crystal oscillators They are definitely
polarised. Normally there is a spot of paint or the can has a point to
indicate pin 1. If they are inserted incorrectly you may be shorting the
5V line.

Check your oscillators, changing the CPU oscillator should not impact the
console baudrate. The oscillator closest to the DE9 (U23) is the FDC, this
should be 8 MHz, the middle one (U22) is the UART oscillator and should be
1.8xxx MHz and the furthest away from the DE9 is the CPU oscillator and can
range from 4 -20 MHZ.

The 74LS06 is just a driver for the FDC signals and also the INT signal. I
can't see it being impacted by any speed related issues.

The Zeta's power on reset circuit work fine for me I think your problem is
else where.

Note that you need to have the battery in circuit for the RAM to work
correctly so that might be your problem.

I hope this helps,

Regards,

Max

Post by Jim Strickland
Hi. I've done first powerup on my zeta.
Problem #1: When loaded with the 20mhz crystal, it spews a continuous
stream of gibberish out the serial port.
Problem #2: Dropping the clock speed down to 8mhz using the floppy system
clock (no fd installed yet anyway) the gibberish clears up and I get the
startup screen, but can't type back to it.
Problem #3: Sometimes the board starts up halted. Resetting returns me to
problem #2.
My hypotheses right now are that problem #1 is from the 74LS06s that
Sergey mentions in some places as being too slow and that #2 is the result
of deficiencies in my charge pump caps. While they are all .1uF, and the
chip's datasheet specifies these, the disk ceramics I'm using have a huge
tolerance, and if I got one bad one, it would mean one line never goes high
enough to work. I'll be putting new caps in the charge pump lines soon.
Problem #3 has me stumped. It could be a side effect of #1 or #2, I
suppose. Thoughts?
Problem #4 (New development) I just put the cr2032 battery in, and now
when the board is powered up, u25 and x1 get too hot to touch very quickly.
Likewise an area on the board down around r2, d1, and c30 gets very hot. No
changes in operation, however, except that I shut it down very quickly when
I noticed the heating problem
Back to the schematics for me, I guess.
1. Are full can crystals polarized? I put my 20mhz one in "upside down" at
one point and it very swiftly got too hot to touch. This is in the same
socket where it has run barely warm enough to feel with cold hands most of
the time, and the same socket the 8mhz crystal does the same.
2. Could we have a definite yay or nay whether 74LS06s work at 20mhz,
please? They're what is specified in the BOM.
UART: NS16450N
Driver: TRS232ECN (I've read that .1uF caps on these are often
insufficient, so I'll be going to 1.0s when I replace them.)
4. I noted in the discussion about the N8 that it was necessary to put a
450uF cap across power to slow the startup. With all ICs installed, my Zeta
comes up halted at least half the time. With only the bare essentials -
ROM, RAM, UART, Serial, plus all the TTL, the number of halts on startup
drops off dramatically. Was there a revision that I missed when installing
my caps?
-JRS
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[oscarv]

Jim,

Problems #2 and #3 are indeed the symptoms of what happens if you do not
have a good battery installed.

Regards,

[Jim Strickland]

Last night, I tracked down my communication problems to my RD line. Sniffing the rd line on the uart showed it /never/ going high. Even with serial loopback, nothing happened. I figured my charge pump caps were bad, even though how that would effect an input puzzled me, and replaced them. It didn't make a particle of difference. Today I finally got out the volt/ohm meter and started testing for continuity on the various lines, from the socket to the rs232 driver. The problem turned out to be pretty simple, if a pain in the butt to solve, and it's pure builder error on my part. A /shopping/ error.

It's been a long time since I dealt with RS232 and I got my DE9ms and DE9fs mixed up. (If you think about it, the female plug's shell is inside the male plug, hence my confusion.) What I have on this board is a DE9f. This means that the serial port pinout is backwards. What should be my pin 2, RD, is really pin 4, which is DTR. That is why I'm not getting serial data into the board. I'd forgotten how much fun rs232 is. :P

-JRS

[Kip Koon]

Hi John!
When I was initially building the breadboard prototype of the 6-Chip 6809
computer, I ran into RS-232 problems myself. I called a very close friend
of mine about my situation and he said to me that he also has had fun
working with RS-232 in the past. I imagine RS-232 male and female plug pin
outs have plagued many people over many years. I know it's made my brain go
into overdrive on more than one occasion. :)
Kip

-----Original Message-----
From: n8vem-/***@public.gmane.org [mailto:n8vem-/***@public.gmane.org] On Behalf Of
Jim Strickland
Sent: Tuesday, November 26, 2013 6:48 PM
To: n8vem-/***@public.gmane.org
Subject: [N8VEM: 16577] Re: Debugging Zeta Build

Last night, I tracked down my communication problems to my RD line. Sniffing
the rd line on the uart showed it /never/ going high. Even with serial
loopback, nothing happened. I figured my charge pump caps were bad, even
though how that would effect an input puzzled me, and replaced them. It
didn't make a particle of difference. Today I finally got out the volt/ohm
meter and started testing for continuity on the various lines, from the
socket to the rs232 driver. The problem turned out to be pretty simple, if a
pain in the butt to solve, and it's pure builder error on my part. A
/shopping/ error.

It's been a long time since I dealt with RS232 and I got my DE9ms and DE9fs
mixed up. (If you think about it, the female plug's shell is inside the male
plug, hence my confusion.) What I have on this board is a DE9f. This means
that the serial port pinout is backwards. What should be my pin 2, RD, is
really pin 4, which is DTR. That is why I'm not getting serial data into the
board. I'd forgotten how much fun rs232 is. :P

-JRS

[Arlen]

Those with a taste for British humour might appreciate this wacky puppet
tribute to the notorious RS-232 interface:

Arlen Michaels

Post by Kip Koon
Hi John!
When I was initially building the breadboard prototype of the 6-Chip 6809
computer, I ran into RS-232 problems myself. I called a very close friend
of mine about my situation and he said to me that he also has had fun
working with RS-232 in the past. I imagine RS-232 male and female plug pin
outs have plagued many people over many years. I know it's made my brain go
into overdrive on more than one occasion. :)
Kip
-----Original Message-----
On Behalf Of
Jim Strickland
Sent: Tuesday, November 26, 2013 6:48 PM
Subject: [N8VEM: 16577] Re: Debugging Zeta Build
Last night, I tracked down my communication problems to my RD line. Sniffing
the rd line on the uart showed it /never/ going high. Even with serial
loopback, nothing happened. I figured my charge pump caps were bad, even
though how that would effect an input puzzled me, and replaced them. It
didn't make a particle of difference. Today I finally got out the volt/ohm
meter and started testing for continuity on the various lines, from the
socket to the rs232 driver. The problem turned out to be pretty simple, if a
pain in the butt to solve, and it's pure builder error on my part. A
/shopping/ error.
It's been a long time since I dealt with RS232 and I got my DE9ms and DE9fs
mixed up. (If you think about it, the female plug's shell is inside the male
plug, hence my confusion.) What I have on this board is a DE9f. This means
that the serial port pinout is backwards. What should be my pin 2, RD, is
really pin 4, which is DTR. That is why I'm not getting serial data into the
board. I'd forgotten how much fun rs232 is. :P
-JRS
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[Andrew Lynch]

Ugh. I hate it when that happens. Removing the DE9 is going to be a PITA.
Consider a butane mini torch and a flush cutters. Almost certainly the part
will be destroyed so don't worry about preserving it.

Good luck and keep us posted! Thanks and have a nice day!

Andrew Lynch

Post by Kip Koon
-----Original Message-----
Behalf Of Jim Strickland
Sent: Tuesday, November 26, 2013 6:48 PM
Subject: [N8VEM: 16577] Re: Debugging Zeta Build
Last night, I tracked down my communication problems to my RD line.
Sniffing the rd line on the uart showed it /never/ going high. Even with

serial

Post by Kip Koon
loopback, nothing happened. I figured my charge pump caps were bad, even
though how that would effect an input puzzled me, and replaced them. It
didn't make a particle of difference. Today I finally got out the volt/ohm
meter and started testing for continuity on the various lines, from the

socket

Post by Kip Koon
to the rs232 driver. The problem turned out to be pretty simple, if a pain

in

Post by Kip Koon
the butt to solve, and it's pure builder error on my part. A /shopping/

error.

Post by Kip Koon
It's been a long time since I dealt with RS232 and I got my DE9ms and

DE9fs

Post by Kip Koon
mixed up. (If you think about it, the female plug's shell is inside the

male

Post by Kip Koon
plug, hence my confusion.) What I have on this board is a DE9f. This means
that the serial port pinout is backwards. What should be my pin 2, RD, is

really

Post by Kip Koon
pin 4, which is DTR. That is why I'm not getting serial data into the

board. I'd

Post by Kip Koon
forgotten how much fun rs232 is. :P
-JRS
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[Borut]

Just make a short adapter cable rewiring the pins correctly.

Best regards,
Borut

Post by Andrew Lynch
Ugh. I hate it when that happens. Removing the DE9 is going to be a PITA.
Consider a butane mini torch and a flush cutters. Almost certainly the part
will be destroyed so don't worry about preserving it.
Good luck and keep us posted! Thanks and have a nice day!
Andrew Lynch

Post by Kip Koon
-----Original Message-----
Behalf Of Jim Strickland
Sent: Tuesday, November 26, 2013 6:48 PM
Subject: [N8VEM: 16577] Re: Debugging Zeta Build
Last night, I tracked down my communication problems to my RD line.
Sniffing the rd line on the uart showed it /never/ going high. Even with

serial

Post by Kip Koon
loopback, nothing happened. I figured my charge pump caps were bad, even
though how that would effect an input puzzled me, and replaced them. It
didn't make a particle of difference. Today I finally got out the

volt/ohm

Post by Kip Koon
meter and started testing for continuity on the various lines, from the

socket

Post by Kip Koon
to the rs232 driver. The problem turned out to be pretty simple, if a

pain
in

Post by Kip Koon
the butt to solve, and it's pure builder error on my part. A /shopping/

error.

Post by Kip Koon
It's been a long time since I dealt with RS232 and I got my DE9ms and

DE9fs

Post by Kip Koon
mixed up. (If you think about it, the female plug's shell is inside the

male

Post by Kip Koon
plug, hence my confusion.) What I have on this board is a DE9f. This

means

Post by Kip Koon
that the serial port pinout is backwards. What should be my pin 2, RD,

is
really

Post by Kip Koon
pin 4, which is DTR. That is why I'm not getting serial data into the

board. I'd

Post by Kip Koon
forgotten how much fun rs232 is. :P
-JRS
--
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Groups

Post by Kip Koon
"N8VEM" group.
To unsubscribe from this group and stop receiving emails from it, send

an

Post by Kip Koon
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[oscarv]

Hi,

I made a similar mistake once (put the riser connector between the 6x0x and
its Mezzanine board on the wrong side of the PCB).

After a failed job with wick and solder sucker, I bought one of these cheap
desoldering stations (I got the ZD-915ESD Desoldering Station, easily
googled). For $65, it turned the nightmare (lifting pads, etc etc) into
something trivial: the thing just sucks every pin dry and the part pops out
clean and the board stays undamaged.

For sure, y'all experienced EE types know these things but for me it was a
revelation. It made replacing parts a total non-problem.

Well worth the $65 in my view!

Regards,

Oscar.

[Anders Carlsson]

Post by oscarv
I made a similar mistake once (put the riser connector between the 6x0x
and its Mezzanine board on the wrong side of the PCB).

In case this is the place for admitting mistakes, I can add that I bought
the kit for the MCX-128, an expansion cartridge for the Tandy MC-10
computer. While there was print on the PCB, it was not entirely clear to me
on which side the cartridge connector should go. I assumed it went on the
same side as all the other chips and components, but apparently it was the
other way around. I managed to hack the connector to bits and desolder it
from the PCB. One trace went bad, but fortunately I could source the signal
from elsewhere on the PCB. Also the spacing on the connector is the same as
ISA, so I could saw off a bit from a loose connector and put it into place.
Miracle, miracle but the cartridge did work after all that malhandling.

Anyway, wouldn't it be enough for the OP to use a M-M gender changer for DE9
or will the pins still end up in the wrong positions?

Best regards

Anders Carlsson

[Jim Strickland]

Thanks for the commiseration, gang. :) I'm pleased to say that as my recent mini-vacation in Vegas put me near a Frys, I got the connectors I needed, installed them, and my Zeta boots as advertised at 8mhz. No floppy yet, as the 8mhz oscillator I'm using for the CPU really belongs in in the floppy system. But yeah, the first big step is finally achieved. The board boots. :)

-JRS

For anyone who finds themselves needing to replace a db9 (or presumably db25) connector on a board, the method I worked out goes like this:
1. Unscrew the screw connectors and take the face plate off the db9.
2. Slice across the "back" of the db9 with a dremel tool cutoff wheel. The right depth should take you neatly through the metal brackets that held up the screw connectors and all the way through the boxy back of the db9.
3. With a small screwdriver, wiggle the sliced halves of the db9 plastic body out. You may have to unbend some of the wire leads going to the pins or cut any you missed with the dremel tool.
4. Unsolder the lower part of the metal brackets and suck the hole out with your solder sucker.
5. Unsolder each pin lead and suck the hole out with your solder sucker.
6. Dust, install new plug as usual.

[Jim Strickland]

Provisionally up, running, and stable at 8mhz. ParaPortProp worked second try after resetting the power jumper on the Zeta. (Woohoo! Disk space! VGA!) Thanks for your help, everyone. Next stop: Floppy interface and/or 20mhz. :) -JRS

[Jim Strickland]

My Zeta is now up and stable at 20mhz. F series logic and the intersil 8mhz
82c55 did the trick. :)

[Jim Strickland]

Long term followup:
One problem that never did quite go away was coming up halted. Even with a
new, fresh battery (didja know Ikea sells them in blister packs for cheap?)
the ramdisk was never stable across reboots and a battery would last only a
few days. If that sounds like a burned DS1210, you've got a good ear,
because that's exactly what it was. Replaced the DS1210 and the battery
lasts like you'd expect, boots are normal every time, the RTC holds time,
and the ramdisk holds data.

I also cut out R18, R19 and R20 from the parportprop per David Carter's
post and got much improved brightness on my old LCD.

New builders: thrift stores are a great place to get old VGA-only LCD
panels. This one cost me about 7 bucks U.S. Likewise, they often have
piles of old PS/2 port keyboards. I'm a keyboard snob, so I got an Alps
switch Dell keyboard from the late 1990s on Ebay, which makes typing a joy.

Now if I could just map the arrow keys to do the right thing in Wordstar...

-JRS