Issue 6 board updates

[Peter]

What are you doing about the ROM port connector? Did you find a replacement or will you unsolder it from your original board?

[Pr0f]

Edit: Also I see about xtals... and I wonder... what is the difference between low and "high" profile? (size). Mainly I can find low profile (not sure if that is right in English). But I hesitate about differences.
X4... Somebody knows where to buy this xtal of 11Mhz 10ppm?

Edit2:
Also I have notice other mistakes in the service manual (Scanned version)... C38,C40,C21,C22 are typed as Axial but they are actually Radial.

The lower profile xtal (crystal) package variety work fine - I used them when I built out the T1 board I had. I seem to remember having some fun sourcing the 11MHz crystal as well. Ironically - the original 8049 IPC had been designed to provide it's own baud clock timing for serial ports - then the value isn't the best choice. But the serial port clock x 4 comes from the ZX8302 (baudx4), so the 11MHz needs to be close but 10ppm is probably not necessary. Now having said all of that Hermes (not superHermes) - doesn't use the baudx4 clock and uses tuned timing loops withing the code to achieve the successful 19200 baud receive - so crystal accuracy comes back into play again.

[Derek_Stewart]

Looks to be a modification to Issue 6 boards, but not detailed in the scanned manual.

I will check this with my paper Service Manual.

Very interesting
I thought, the scanned manual should show the same than paper. But now you mention it and considering the bunch of mistakes in docs... it makes sense that even different manuals shows different information.

Thank you Derek

Edit: Also I see about xtals... and I wonder... what is the difference between low and "high" profile? (size). Mainly I can find low profile (not sure if that is right in English). But I hesitate about differences.
X4... Somebody knows where to buy this xtal of 11Mhz 10ppm?

Edit2:
Also I have notice other mistakes in the service manual (Scanned version)... C38,C40,C21,C22 are typed as Axial but they are actually Radial.

The manual on the QL HOmepage is a photocoped scanned image.

The original manual had Black front and back covers

I remember Tony Firshman saying there were many errors in the QL Service manual and schematic.

I would look at the schematics done by Silvester, at the start of this thread.

[Derek_Stewart]

What are you doing about the ROM port connector? Did you find a replacement or will you unsolder it from your original board?

Most the Romport connectors on the QLs I have have 90 degree edge connector that looks to be cut down from a larger edge connector.

I did look for 2x15 90 deg. edge connectors, but was unsuccessful.

[Peter]

Most the Romport connectors on the QLs I have have 90 degree edge connector that looks to be cut down from a larger edge connector.

Even if cut from larger ones, I found no mechanically identical parts. That's why I asked.

[klausfrank]

Hi,
I have the corrections Tony Firshman wrote about, I could place them here, if interested . Otherwise you can find them in the Service Manual I put together, it is the largest version of the S M in Dilwyn’s documents.
Klaus

[Derek_Stewart]

Most the Romport connectors on the QLs I have have 90 degree edge connector that looks to be cut down from a larger edge connector.

Even if cut from larger ones, I found no mechanically identical parts. That's why I asked.

Hi Peter,

Looks like I did search close enough, here is a picture of some 2x15 Right Angled Edge Connectors:
https://adamconn.com/product/card-edge- ... ight-angle

Needs a guide for pin 6AB

Looks like a supplier in China...

[Peter]

Hi Derek, the point was to get a mechanically identical connector, not just some card edge connector with unknown geometry. I don't see a drawing for the part in your link.

[Popopo]

What are you doing about the ROM port connector? Did you find a replacement or will you unsolder it from your original board?

Hi,
By now... nothing... firstly I want to get all components that I can order without too much effort... but time. Then I will focus in that kind of Issues... maybe I will try to use the 3D printer...

[Popopo]

The lower profile xtal (crystal) package variety work fine - I used them when I built out the T1 board I had. I seem to remember having some fun sourcing the 11MHz crystal as well. Ironically - the original 8049 IPC had been designed to provide it's own baud clock timing for serial ports - then the value isn't the best choice. But the serial port clock x 4 comes from the ZX8302 (baudx4), so the 11MHz needs to be close but 10ppm is probably not necessary. Now having said all of that Hermes (not superHermes) - doesn't use the baudx4 clock and uses tuned timing loops withing the code to achieve the successful 19200 baud receive - so crystal accuracy comes back into play again.

Wauuu... really hard to decide...
By now I will skip it... and probably I will use SuperHermes, by now I got Hermes from my Iss5 board cause I'd replace it for SuperHermes.
Thank you