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- Thu Apr 11, 2024 9:25 am
- Forum: 8 BIT CORNER
- Topic: OSI 600D Superboard Build
- Replies: 370
- Views: 57547
Re: OSI 600D Superboard Build
A quick aside, one of the guys over on Osiweb.org has created a new monitor ROM that allows for 48 columns as well as 24, selectable at boot time. As well as the new ROM, there is a small bodge, represented by a jumper wire here: IMG20240411085229.jpg And the results are great: IMG20240411085334.jpg...
- Wed Apr 10, 2024 11:26 pm
- Forum: MEMBER BLOGS
- Topic: Raven. A homemade Atari-like computer
- Replies: 50
- Views: 4102
- Wed Apr 10, 2024 2:51 pm
- Forum: 8 BIT CORNER
- Topic: OSI 600D Superboard Build
- Replies: 370
- Views: 57547
Re: OSI 600D Superboard Build
I did check all the inputs and I'm sure clear was OK, but certainly worth another look.stephen_usher wrote: ↑Wed Apr 10, 2024 2:48 pm Sounds like something isn't clocking in the data on the 74LS76, or the clear is being kept low. That would be my next point of investigation.
- Wed Apr 10, 2024 2:18 pm
- Forum: 8 BIT CORNER
- Topic: OSI 600D Superboard Build
- Replies: 370
- Views: 57547
Re: OSI 600D Superboard Build
How are you getting on with the tape interface? Well, not got any further, I replaced the IC but no different. I lifted a leg of the cap and no difference, and the cap was the right value. I also lifted the leg on the resistor before the cap and the value is correct and with the leg lifted the sign...
- Tue Apr 09, 2024 10:44 pm
- Forum: MEMBER BLOGS
- Topic: General Stuff(tm)
- Replies: 1762
- Views: 331980
Re: General Stuff(tm)
Yeah, three 5W Zeners is 15 watts, that's over 2 amps at 7.5V. The current limiter would kick in well before that and bring the voltage down. Therefore three Zeners is overkill a bit but it's best to engineer for the worst case. Belt and braces is always a good plan. Under test with the bench power...
- Tue Apr 09, 2024 9:32 pm
- Forum: MEMBER BLOGS
- Topic: General Stuff(tm)
- Replies: 1762
- Views: 331980
Re: General Stuff(tm)
So what does the 1.37 represent? Amps? Yes, that's what the bulb is drawing. I don't like the regulation, it's a bit pants. As the load decreases the voltage goes up, levelling out at just under 9V. I think I'm going to have to put a large Zener diode clamp into the circuit to keep it stable, or ra...
- Tue Apr 09, 2024 8:46 pm
- Forum: MEMBER BLOGS
- Topic: General Stuff(tm)
- Replies: 1762
- Views: 331980
Re: General Stuff(tm)
The Direct from China eBay variable step-down regulator with current limiter arrived today. Of course, no instructions so getting the voltage to change etc. was very much trial and error. Anyway, it does work: IMG_3672.jpeg I have it on test at the moment. The regulation isn't massively great as th...
- Tue Apr 09, 2024 4:46 pm
- Forum: HARDWARE ISSUES
- Topic: 1040 STFM resurrection project. Need help
- Replies: 8
- Views: 209
Re: 1040 STFM resurrection project. Need help
Hi @rubber_jonnie Sorry no bench PSU available. I heard very good things about the meanwell PSU and can buy here in Germany for about 15 Euro, so may give it a shot. What about the blown capacitor on the mainboard in modulator section please? Wise to recap the whole board as there are almost 20 cap...
- Tue Apr 09, 2024 4:17 pm
- Forum: HARDWARE ISSUES
- Topic: 1040 STFM resurrection project. Need help
- Replies: 8
- Views: 209
Re: 1040 STFM resurrection project. Need help
@rubber_jonnie Hi There, Thanks for your comment. Appreciated. Now, as the PSU appears not to be working at all, does anybody of you have any idea looking at the photos what may be the root cause, as I don't think merely replace the caps will bring it to live again. Thanks in advance. Do you have a...
- Tue Apr 09, 2024 3:25 pm
- Forum: CHAT FORUM PUBLIC
- Topic: Eclipse 2024
- Replies: 7
- Views: 273
Re: Eclipse 2024
Nice