QL-SD problem - help needed

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Andrew
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QL-SD problem - help needed

Postby Andrew » Mon Sep 03, 2018 1:56 pm

Today I tried to install the QL-SD in my QL - and failed.
After I removed the ROMS I tried to install the QL_SD with Minerva RON. This was not possible, as the pins of the QL-SD were too short and it would not stay firm in the socket. So I added some pin strips, then installed the Minerva ROM
When i started the QL all I could see on the screen is this:
Image
and a lot of noise coming from the speaker...

I reinstalled the original ROMS - the QL works as it should, so nothing was fried. I removed the ROMS again and installed the QL-SD with Minerva ROM in the other socket - same image :(

I know that the QL has 1 or 2 chips with ROM installed in 2 sockets. My QL has 3 chips D27128-3 one of them riding piggyback on the one in the left socket (i can see the markings on 2 chips, I presume the third is of the same type).
From the upper chip there is a red wire that goes to a pin near the ULA (i believe it is some sort of chip select, but honestly I have no idea what it is)
Image

Image

Image

I do not know what type of ROM is the one installed in the QL - I presume is a JM based on the serial number D06-003564
The motherboard has only the following markings - SINCLAIR QL 1984 and 8418 PCP in the upper left corner
Image

Does anyone have any idea what is wrong here ? And how can I get the QL-SD to work ?


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tofro
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Re: QL-SD problem - help needed

Postby tofro » Mon Sep 03, 2018 2:24 pm

Interesting. You seem to have an issue 6 QL that was retrofitted with EPROMs. (Issue 6 normally came with ROMs and lacked the circuitry issue 5 had that allowed to easily change between various ROM and EPROM configurations).

An issue 6 QL should have a 23256 as IC33 and a 23128 as IC34. Yours seems to be equipped with three 27128, two of them stacked - Those have a slightly different pinout, so we can assume you have some motherboard mods you need to revert before you can fit QLSD. The effect you see (the stripes) is that the CPU doesn't start properly because it can't see a ROM.

From the stickers on the EPROMs I would even assume someone has fitted AH. Why anyone would do that, though, is beyond me. I don't know any program that would only run on AH ROMs.

Can you maybe make some more detailed pictures of the PCB area around the ROM sockets (also from the underside of the PCB) and identify the ULA pin the red wire goes to - We need to be able to identify the mods to help you revert the changes.

Tobias


ʎɐqǝ ɯoɹɟ ǝq oʇ ƃuᴉoƃ ʇou sᴉ pɹɐoqʎǝʞ ʇxǝu ʎɯ 'ɹɐǝp ɥO
Andrew
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Re: QL-SD problem - help needed

Postby Andrew » Mon Sep 03, 2018 5:19 pm

Pictures are hosted on Photobucket - and the site resizes the images. I can send the large pictures on email. if you send me your email

Image

Image


in order to take pictures of the other side I have to remove the reset button. How do I do that ???


Andrew
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Re: QL-SD problem - help needed

Postby Andrew » Mon Sep 03, 2018 6:07 pm

ok - I figured how to disassemble the reset button :)
The motherboard is an ISSUE 5 - and is as described in http://www.sinclairql.net/srv/qlsm5.html - Build Standard D6, IC33 2 x 16k EPROM, IC34 16k EPROM, AH
Looking on the pcb i do not see anything that might look like mods. Everything looks factory made

Image

The ROM area
Image

And rest of pictures (all motherboard)
Image
Image
Image


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tofro
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Re: QL-SD problem - help needed

Postby tofro » Mon Sep 03, 2018 7:23 pm

That means your QL has very probably seen a motherboard change - The serial number seems to be for an issue6.

Issue 5 QLs can be reconfigured by changing JU1 and to JU6. The circuit diagram here has a dotted box to the bottom right that gives the proper jumper setting. You need configuration (7), which was the "standard" one, so set JU2 and JU3 only and remove IC17 (not sure if the latter is really needed, I have never owned an issue 5 myself, so take this with a grain of salt). The jumpers are located just to the right of the ROMs and look like normal resistors (but designated "0 Ohms"). Use the component layout here.

Tobias


ʎɐqǝ ɯoɹɟ ǝq oʇ ƃuᴉoƃ ʇou sᴉ pɹɐoqʎǝʞ ʇxǝu ʎɯ 'ɹɐǝp ɥO
Andrew
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Re: QL-SD problem - help needed

Postby Andrew » Mon Sep 03, 2018 7:53 pm

Thank you ! I have not soldered/ desoldered anything in the last 20 years ... so it's time to start again :)
And what should I do with that red wire ? just cut it ? Do you know what it was it used for ? I do not find it on the circuit diagram.


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tofro
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Re: QL-SD problem - help needed

Postby tofro » Mon Sep 03, 2018 8:27 pm

Andrew wrote:Thank you ! I have not soldered/ desoldered anything in the last 20 years ... so it's time to start again :)
And what should I do with that red wire ? just cut it ? Do you know what it was it used for ? I do not find it on the circuit diagram.


Some stuff I forgot:
  1. You probably have an AH ROM now (as designated in the service manual), so it seems to be not a mod, but rather as built from the factory as the first build standard that didn't have the dongle. You can verify by entering "PRINT VER$"
  2. After looking at the circuit diagram for some time, I am pretty sure IC17 needs to be removed (maybe someone who has an issue 5 board can confirm that). I am also quite sure JU4 needs to be set as well.
  3. The red wire was in there to activate the "upper" EPROM of the "pickaback" for the middle 16k of ROM. Once you have the jumpers set to the 32k+16k ROM configuration, it shouldn't be needed anymore.
  4. The service manual describes exactly the steps you need to take under "4. Firmware upgrade". You need to take your board to build level D11 to make it work with QL-SD. Apparently, you have to remove IC17 and set JU2, JU3 and JU4 (so JU4 must be set as well, contrary to what I wrote in the last post). It also says you should remove the wire. (I am pretty sure you can skip the "Return EPROMs to Sinclair Research Ltd." step, however.)

Happy soldering,
Tobias


ʎɐqǝ ɯoɹɟ ǝq oʇ ƃuᴉoƃ ʇou sᴉ pɹɐoqʎǝʞ ʇxǝu ʎɯ 'ɹɐǝp ɥO
martyn_hill
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Re: QL-SD problem - help needed

Postby martyn_hill » Mon Sep 03, 2018 10:44 pm

Hi Andrew

Further to the guidance given earlier, you might want to read the installation section of the Minerva Mk1 (or Mk2) ROM replacement as it specifies exactly how to convert an Issue-5 configured for EPROMs to work with the Minerva daughter board - the QL-SD simply takes the original Minerva approach further, but relies on the very same conversion procedure - effectively to configure for ROM (and then allow the Minerva or QL-SD daughter-board re-configure internally back to EPROM!)

The Minerva install guide can be found on Dilwyn's site here:

http://www.dilwyn.me.uk/docs/manuals/mi ... ual_11.pdf

The section 'Fitting (MKI)' on page 62, under the heading 'AH Conversion' is functionally the same as the steps listed below by Tobi, but I find the Minerva instructions slightly easier to follow than Sinclair's original Service Manual...

Good luck!


Andrew
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Re: QL-SD problem - help needed

Postby Andrew » Fri Sep 07, 2018 5:01 pm

Thank you all for your advice. All upgrades are now made and everything works.
Now is time to add programs to WIN1_ :)



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