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Messages - Wolfgang

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Other topics / How can one switch between WP versions?
« on: Yesterday at 19:46 »
Beginner question:
EXDOS 2.4 ROM contains two WP versions (2.1 and 2.6). How can I load each version?
:WP seems to load WP2.6


Hardware / Re: RF signal only black&white
« on: 2020.September.24. 16:33:23 »
This was a hard one. I replaced the LM1889, the LM1886, all electrolytic capacitors, the 78L12, most of the transistors and a couple of ceramic capacitors in the LM1889's oscillator circuitry. In the end, changing the 4.433619MHz oscillator solved the color issue. :) 

Hardware / Re: Capacitors - wrong orientation?
« on: 2020.September.18. 11:06:51 »
I'm quivering with anticipation, waiting for his reply! ;)

I did a search on forum, looking for all references to "C9", but it didn't turn up any satisfactory explanation.
Same here. :)
All available (different) schematics show the same direction.

Hardware / Re: Capacitors - wrong orientation?
« on: 2020.September.16. 22:26:21 »
I don't think that the schematics are wrong.
In fact the capacitor in this  image

is strange. The - arrows point in the direction of the narrowing, opposite to the usual way. Since the visible right side of C9 seems to be metal, I would assume that this is the GND side.

To sum it up, I think
- the right side should be minus
- the arrow on the capacitor in the image above is wrong
- the capacitor in the image above is mounted correctly (+ left / - right)
- the silk screen on the pcb seems to be wrong

I am not an electronics expert, so please convince me that I am wrong.:)

Hardware / Re: RF signal only black&white
« on: 2020.September.16. 22:09:04 »
Just curious but did you replace anything to get RGB/scart or was that going for the start? :)
Scart worked right away.

Hardware / Re: Capacitors - wrong orientation?
« on: 2020.September.16. 18:25:11 »
Hmmm. Interesting. When I did my recap Ioriented my new C9 as it was on the board. + to the right. So I have the same layout as Wolfgang.

Here are the old. And here the new.

Not to hijack the thread but maybe this error is causing my noise. If it is an error, that is!
I actually turned the new C9 around, since it seems the correct orientation to me.
No real difference to see (yet), at least no smoke and interesting smells.:razz:

Btw., no reason to apologize, I am in the same boat. I also got an Egyptian EP and I am trying to get it up to speed. So far, I upgraded the ROM to EXOS2.4 and built my memory expansion. Now, I am fighting the missing color of the RF signal.:smt017

Hardware / Capacitors - wrong orientation?
« on: 2020.September.16. 11:49:54 »
In both my EP64s C9 is oriented like this(minus to the left): https://www.nightfallcrew.com/gallery/enterprise-128-one-two-eight-boxed/IMG_5573.jpg

According to the schematics, the orientation of C9 should be like this (minus to the right):

Why are they different?

Interface / Re: Internal memory expansion
« on: 2020.September.16. 08:10:41 »
The TracoPower can be installed(TSR 1-2450, or even better the 2 Amp TSR 2-2450), I did it on one of my EPs, but some bending has to be done on its little pins.
This worked for me with the front regulator, but not for the rear one. The space between the power connector and the cooler was too small to get the Traco in. May this is only be an ISSUE 4 problem?

Interface / Re: Internal memory expansion
« on: 2020.September.15. 21:38:12 »
That's a neat little replacement for the 7805! :)

Why did you make the change? Were you having problems with your EP64?

It is more of a habit. I usually replace every 7805 in old computers either with the OKI-78SR or the TSR 1-2450 in order to reduce the heat. I generally prefer the TSR 1-2450, but they don't fit in the EP without removing the cooler and that would leave an ugly hole.

Hardware / RF signal only black&white
« on: 2020.September.15. 16:43:43 »
While I get a good quality color picture on scart, I am unable to see color with my rf modulator. I already replaced LM1886, LM1889, TR6, C38,C39,C36 without any success. What else could be wrong?

Interface / Re: Internal memory expansion
« on: 2020.September.14. 18:25:43 »
I removed the header. Now I can close it properly. :)
I also replaced the 7805s with OKI-78SR; quite the difference now......

Interface / Re: Creating EXDOS card clone
« on: 2020.September.14. 08:29:48 »
Is it a proven supplier ? Someone has already shopped there ?
Payment by card only directly from the site. Too risky without checking.

Exxos (Chris) is a well known person in the ATARI scene. Many years ago, I financed the last run of the PeST mouse controller by him and never had a problem. He had bad experiences with Paypal and therfore refuses to use it.

Interface / Re: Internal memory expansion
« on: 2020.September.13. 19:55:53 »
Congratulations! It is excellent to see another successful breadboard circuit, just like Dangerman's pictures a few pages ago. :)

I see that you have added a header to EXP2 instead of wiring the cable directly into the motherboard ... how is that working out for you?

I was under the impression that there isn't enough physical height inside the case at that point for a header and DuPont connectors, which is why SainT and the others wired the cable directly into the motherboard.

Have I misunderstood the earlier posts?

It would certainly be easier to use 2 5-pin DuPont cables instead of soldering the wires directly into the motherboard.

Thanks. Unfortunately, I was too optimistic about EXP2. I can close the top, but it bends the plastic out about 1mm. I will remove the header or at least the front row and solder the cables directly. Btw., I was not able to use a standard double-row header on EXP1. It seems the distance between the two rows is off. I used two single rows instead.

Interface / Re: Internal memory expansion
« on: 2020.September.13. 15:04:01 »
As I am new to EP (yes I got my EP64 from Egypt), I followed this great thread and built my own memory extension (prototype). I am using a GAL16V8 for address decoding and a AS6C4008 SRAM chip.
I just finished my prototype and at least the boot screen seems to work. It is a bit scary to unplug and reconnect the  keyboard membrane since it seems to be very thin, so no real tests yet.

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