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Kaypro keyboard fault

Tez,
I'm afraid it's still a toss up between the crystal and the baud rate generator, but as you tried another type crystal and nothing changed at all, the scale may tip toward the 8116 a little as being the curprit.
 
dave_m said:
Tez,
I'm afraid it's still a toss up between the crystal and the baud rate generator, but as you tried another type crystal and nothing changed at all, the scale may tip toward the 8116 a little as being the curprit.
Click to expand...

Yup. I guess I'll just have to bite the bullet on this and get another one from somewhere.

I've been looking for 8116 ICs and the most common around seem to be AY-5-8116 ICs followed by COM8116 ICs.

The one in the Kaypro is (a lot less common) WD8116M-00. I can't find the datasheet for this one. Do you think it would be compatible with those commoner ones?

Tez
 
tezza said:
I've been looking for 8116 ICs and the most common around seem to be AY-5-8116 ICs followed by COM8116 ICs.

The one in the Kaypro is (a lot less common) WD8116M-00. I can't find the datasheet for this one. Do you think it would be compatible with those commoner ones?
Click to expand...

I couldn't find anything specific on the WD8116 either but I'm pretty sure they're all close enough to equivalent - all 5V TTL parts with the same pinout. The GI (AY-5-8116) datasheet even specifically states it's pin-compatible with the COM8116.

You may even be able to use a 8136 (there are data sheets on the WD version out there) as it would appear the only difference is an extra output on pin 10, which doesn't seem to go anywhere on the Kaypro anyway.
 
cosam said:
You may even be able to use a 8136 (there are data sheets on the WD version out there) as it would appear the only difference is an extra output on pin 10, which doesn't seem to go anywhere on the Kaypro anyway.
Click to expand...

Thanks Steve, I'll bear that in mind.

Tez
 
Hi Tez,

I have them.

http://www.arcadecomponents.com/catalog/item/2251652/1708942.htm

But... you already found them based on the PM you sent me. ;)

Sorry, but I haven't been following the thread or I would've chimed in awhile ago. You can take any crystal and hook it up to the 8116 to see if it's a dead crystal. If you put a 4MHz crystal in and it doesn't work then it's the chip. A 4MHz crystall will work in the circuit, but all the baud rates will be screwed up so it won't sync up and communciate over the ports. At least it will help you troubleshoot.

Raymond
 
channelmaniac said:
Hi Tez,

I have them.

http://www.arcadecomponents.com/catalog/item/2251652/1708942.htm

But... you already found them based on the PM you sent me. ;)

Sorry, but I haven't been following the thread or I would've chimed in awhile ago. You can take any crystal and hook it up to the 8116 to see if it's a dead crystal. If you put a 4MHz crystal in and it doesn't work then it's the chip. A 4MHz crystall will work in the circuit, but all the baud rates will be screwed up so it won't sync up and communciate over the ports. At least it will help you troubleshoot.

Raymond
Click to expand...

Yes, thanks Ray,

As you are aware (through the PM I sent) I was looking for a 8116 on the web...saw there was 8136 on arcadecomponents.com and suddenly remembered you ran that site. I then noticed you had a 8116 also.

I'm pretty sure it's the 8116 at fault. A replacement Xtal was as dead as a doornail.

Just have to rush off to another part of the country right now, but I'll order one when I get home...and another few bits and pieces for other machines I have. Might as well make the most of the postage :|

Thank goodness someone keeps these old components!

Tez
 
Thanks Tez,

Yeah, the USPS folks keep raising rates so I had to up the postage costs recently to keep up with them. Luckily it's flat rate international shipping so it's all I can stuff into the envelope up to 4 pounds of weight. All chips are shipped in chip tubes to keep them from getting damaged in shipping.

Dave - I have 400 in stock, but have yet to update the website. I'm going insane iwth the day job with the most visible project of my career. I've been fairly quiet on a lot of forums lately because of it.

I still have to update my site with the new company logo (see: avatar), but that's been something needed for months now. Repairs and parts sales have come first while website updates and inventory updates are on the back burner. I have a HUGE amount of chips I picked up the past few trips to the left coast that have yet to be added to the site - some pretty rare.

RJ
 
Tezza -

Sent you a private message, but it will not let me add the attachment of the Kaypro Hardware Bulletin on the grounding fix for keyboards you requested.

I gave you my main email address in my PM to you for us to correspond further.

Frank
 
Hiya Guys,

Just an update on this. The 8116 from Channelmanic hasn't arrived yet (things always take a while to get to NZ) but I can tell you that IC is certainly the fault. Philip Avery (pavery) recently scored himself a Kaypro II and he bought this machine over today. We swapped his 8116 over to mine and everything suddenly worked just fine.

Diagnosis confirmed!

Tez
 
Tez, that is wonderful. You did some good troubleshooting. You also discovered the usefulness of a logic probe. It was a nice project that gave all of us a chance to review stuff like the 8049, baud rate generators, SIO chips, crystals, etc. I think the big breakthrough was when you discovered normal bus activity on the system and no extra bus activity or interrupts when keys were depressed which indicated an isolated failure in the UART subsystem.

My favorite part was when we thought you reported a dead bus and we all got quite excited and came up with some facinating hypotheses on what could cause that to happen.

Please report back when you install the replacement chip and get to the bottom of the BEEP signal.
-Dave
 
Excellent!

I know I had fun and learned one or two things; thanks.

So Philip is broadening his collecting horizons beyond Radio Shack computers (and bulldozers)?

mike
 
The 8116 arrived in the post yesterday. Since I'd already confirmed the diagnosis using Philip Avery's 8116 I knew it would work.

And it did. So...My Kaypro is back to fully operational status.

As usual, I've written the episode up as a blog article. Thanks to everyone!

Tez signing off (until the next time something blows up!)
 
MikeS said:
We're all looking forward to that ;-)
Click to expand...

The signing off, or the blowing up? ;)

Hehehe...there could be more of the latter. Talking with Philip Avery, I've decided my machines need a "burn-in" test where I leave them going for 8 hours or so, just to make sure there are no weaknesses there.

Of course there are practical difficulties with this. You have to be around to switch off the power when a capacitor goes up in flames otherwise you might lose more than the cap. Who wants to babysit 36+ computers for 8 hours at a stretch though? Even I'M not that fanatical.

Bringing each one into work one at a time is an option. I'm sure they will be conversation pieces!

Anyway...we'll see. Leaving the machines on for 8 hours is a scary prospect. I think I'll have to steel myself to do it first....and budget for many hours at the repair desk (and on the forums) afterwards! :)

Tez
 
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