Cory

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

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

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?

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

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?

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.

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

Thank you!

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

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?

@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!

I think you’ll really like it!

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

Exactly!

According to eBay, who needs crypto!!