[Console Repair - steady beep on power-on]

2 hours ago, JJB said:

Did you check voltages for proper +5V, -5V and +12V? Given the heat it produces inside the console there is a chance of fried parts such as caps and voltage regulators.

I have checked the voltages at the Power Supply, VDP Ram, 9900, 9901, VDP, Grom, and Scratch RAM and all voltage levels look solid.

[Console Repair - steady beep on power-on]

19 minutes ago, matthew180 said:

 

Specifically the 99/4A Servicing Manual, it has troubleshooting flowcharts.  This is the manual created by and for the TI technicians repairing 99/4A consoles.

I’ll download it.  Maybe I can get a job with TI after I’ve mastered the process. ??

[Console Repair - steady beep on power-on]

Referring to Matthew180's comments on this thread:

I suppose the next steps would be to test out the DRAM.  Can I use a scope to checkout the DRAM before going through the hassle of desoldering each of these chips?  The solder looks pretty oxidized and those can be such a pain to desolder.  But if I must I must.  I will have to do this on my test board.  My test board has sockets for all the chips listed above, but I've never had the need to socket the DRAM until now perhaps.

 

Thoughts before I embark on this next step?

[TI Solid State Printer - Power Supply Issues?]

Thanks for the tips, I've identified and fixed the issue.  The issue appeared to be a bad solder joint for one of the regulators.  When I was testing voltage I noticed that most of the readings were accurate, but occasionally I got a bad reading which I assumed was me being clumsy.  

 

I spent some time inspecting the circuit board under magnification and found what looked like a cracked solder joint.  So I desoldered and resoldered the joint and it's back in business.

 

Thanks again for the tips and input from all!

Cory

[Console Repair - steady beep on power-on]

I know this topic has been covered multiple times, but was hoping to get some additional insight from the HW gurus around here.  

 

Symptom:  Console that produces the steady beep and no video on power up.  

 

So far, I have desoldered, removed, and tested the following chips on my known good test motherboard:

 

1) VDP - Good

2) 9901 - Good

3) 9900 - Good

4) Groms - Good

5) Sound Chip - Good

6) 2532 ROMS 1, 2 - Good

7) 8K 1, 2 - Good

8) Signal Generator - Good

9) Crystal - Good

 

So I've pulled out and validated all the main chips that normally are the culprits that cause the issue.  Now, I'm looking for what's next.  Is there a critical buffer or other logic chip that I should test?  I'm planning on re-watching a few YouTube videos out there that can help me use my scope to figure out where the issue is, but the two or three videos I know of found a bad ROM or RAM chips and those are known good on my board.

 

Any thoughts on next steps?

 

[What's this mod do?]

Curious whether the diode placement on the motherboard saves you from cutting the trace on the keyboard between the alpha lock and pin 6 on the keyboard connector.  It seems to me that it would and would be a simpler modification.

 

Is that true?

 

I guess "simpler" is a bit of a subjective term since you have to desolder a component to squeeze the diode in.

[What's this mod do?]

Given the tip from @jedimatt42, I found a previous post on the topic:

 

And read the article on http://www.mainbyte.com/ti99/console/alpha_lock.html

 

Does placing the diode on the motherboard save you from modifying the keyboard like this instructions from the mainbyte site: 

... you must remove a part of the lead that originaly ran to from the alpha-switch and the connector 6 on the keyboard connector

[What's this mod do?]

9 minutes ago, jedimatt42 said:

Looks like the motherboard equivalent of the diode fix for the capslock/joystick up fix..

Thank you!  

[What's this mod do?]

14 minutes ago, OLD CS1 said:

This would not be a development topic.

Thank you.  I'll post future topics like this over there.  

[What's this mod do?]

Does anyone know the purpose of this mod?  It appears to be tied to the keyboard, but not clear what the diode is protecting.  

 

Also, should I be posting these types of topics in this thread or the development thread?  

[838-IO Plus PREORDER is UP!]

@Shift838 - My order arrived today!  Thanks a ton for the fast turn.  I'm looking forward to getting this up and running this week!

 

Thanks for all the effort creating this and the additional effort building and fulfilling the orders; that's a ton of work! 

[Desolder equipment recommendations.]

10 hours ago, InsaneMultitasker said:

I ordered the FR301 Thursday based in part on above recommendations.   I damaged my Pacenter 20A desoldering iron that I've been using for nearly 25 years while trying to remove the tip.   I'm looking forward to trying the FR301 this weekend.

 

I think you’ll really like it! 

[Desolder equipment recommendations.]

12 hours ago, dhe said:

Yet the one in my gun has a bowl on top:

 

Anyone ran in to this?

 

I have the FR-301 and that is the proper part for the 301.  I can’t speak to the FR-300.

 

On 1/13/2020 at 2:40 PM, dhe said:

Ok, I bit the big one and got a FR-300. Now, for you folks with actual experience, what tip do you use on most TI Equipment?

 

I use the stock 1mm tip for all my TI work.  Just this week I desoldered the 9901, 9900, Roms, static ram and vram on two boards and socketed the boards for my diagnostic boards.  It went flawless.  I did think about getting a .6mm tip, but honestly I had no problems at all.  

I also considered the longer tip so you can suck up the solder from the top side of the board if you need to, but I found that reflowing some solder and then desoldering again did the trick nicely. 

 

Tip: make sure you make contact with the pin and it goes super fast and sucks up the solder nicely.  I use the medium heat setting.  It takes less than 2 seconds to melt the solder.  

 

[TI Related -- Ebay / Heads Up Notice]

7 hours ago, Ksarul said:

Looking at the number of packages in those two boxes tells me one thing: none of these packages is rare--and their sheer number probably exceeds the number of current collectors looking for them by a wide margin.

Exactly! 

[TI Related -- Ebay / Heads Up Notice]

10 hours ago, Andrewmacattack said:

According to eBay, who needs crypto!! 

[Jumpman JR actually does exist ;-) and other things....]

On 3/12/2014 at 6:37 PM, marc.hull said:

Back story is required here.

 

A while back I inherited Bill Gaskill's huge floppy library. About once every two weeks I get a box in the mail with about 300 disks in it. I'm up to about 6000 total at the present and for that I am grateful and at the same time overwhelmed with the amount of material.

I had an email exchange with Marc today and was asking about the disposition of all the disks he inherited from Bill Gaskill.   He said, "Most of them went out to people that were interested in looking through them.  I really never heard back from anyone until now. "   

 

Does anyone know who may have picked up that collection from Marc? 

[TI Solid State Printer - Power Supply Issues?]

23 hours ago, GDMike said:

Ahh. I think I'm looking at the print head motor instead of the form motor. Sorry. I'm not seeing that. I guess look at the advanced circuit.. my bad

Will report back what I find.  Thanks for the pointers. 

[Weather thread]

20 hours ago, mizapf said:

What about this as a contrast? Photo taken this evening outside of our house near Frankfurt. (By the way, not post-processed, just as delivered by the camera.)

Spectacular! 

[TI Solid State Printer - Power Supply Issues?]

If I read the schematics right, it looks like P3 should be +15V.  It’s reading 13.75.  Is that enough variance to effect the motor?  Would that be a failing regulator? 

[TI Solid State Printer - Power Supply Issues?]

51 minutes ago, GDMike said:

Verify voltage test at regulator output pins to start.

I'll need to do a little disassembly to get to the voltage regulators, but I did get the reading from the following connectors.  In the picture, the yellow box on the left:

 

Black and White = + 15V

White and Red + 5V

 

For the connector on the right from left to right:

 

Left Black and Left Red = +13.75V

Right Black and Right Red = -13.75V

 

 

The connector on the right goes to the motor that feeds the paper.  However, the paper doesn't feed if you press the paper advance button.  This is why I thought I had a power supply problem, which now it looks like it may be something else.

 

[TI Solid State Printer - Power Supply Issues?]

I've been poking around looking for some articles, blogs or videos on how to diagnose / repair a TI Solid State Printer.  Symptom - no power.  Are there schematics available?  Has someone gone through the diagnostic steps previously?  I'm pretty handy diagnosing digital circuits, but have been less successful when diagnosing power supply issues.

 

Any thoughts or helpful tips?

[TI Related -- Ebay / Heads Up Notice]

3 hours ago, GDMike said:

Hurry while supplies last $3000 only for this

https://www.ebay.com/itm/313999570374?hash=item491bd535c6%3Ag%3ACnoAAOSwpvhigtYR&LH_BIN=1

I honestly don't understand why people do this.  Reminds me of the person that listed the Amiga 1000 for $5,000 and then raised it 100 at the end of each auction period.

[Consoles, Consoles and more Consoles]

2 hours ago, apersson850 said:

I'm kind of more interested in how they ended up on the attic in the first place?

I received all of these and a ton of other vintage computers from a local collector years ago.  The deal was take them all or take nothing.  So I took them all 

 

I put a bunch of the boxes up in the attic and figured I'd get to them as I worked my way through everything.  Well that was years ago and now I really need to declutter and have no idea how I’d use all of these.

[Consoles, Consoles and more Consoles]

That sounds like a challenge.  I need to bust past the Snowman and Santa and get a full count!  I’m sure I can scrounge up 10 more up there. ?

[Consoles, Consoles and more Consoles]

I forgot to mention just how many consoles I found.  Here's a picture.  35 in total, though, I'm betting I'll find a few more as I make may way through the rest of the attic.  Got to get past the Snowman and Santa guarding the deep recesses of the attic first.