QL not working

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colo
ROM Dongle
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QL not working

Postby colo » Tue Oct 31, 2017 2:31 pm

Hi,
please can you help me with troubleshooting of my QL:
I have replaced:
- new cpu
- new roms
- new coprocessor
- new ULAs (both)
but the result is the same - no RGB output, just the yellow LED is lighted
What should I replace, or what shoud I measure (I have multimeters and digital osciloscope)

Thank you !


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Pr0f
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Re: QL not working

Postby Pr0f » Tue Oct 31, 2017 3:11 pm

You could put a scope on the RGB socket and see what you get on the synch pins - this will tell you if the ULA is at least producing video timing pulses.

Yellow led suggests power is getting to the board, but it won't tell you much more than that. I would take a look a the circuit diagrams / and block diagrams from the Service manual - http://www.dilwyn.me.uk/docs/manuals/QL ... Manual.pdf

Check 5v from regulator, check clock on the cpu, and check DSL lines - see if these are showing a good waveform...


colo
ROM Dongle
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Joined: Sat Oct 21, 2017 4:38 pm

Re: QL not working

Postby colo » Tue Oct 31, 2017 3:23 pm

Thank you for info and manual
I will check what you have mentioned.

Some quick questions - if QL is running fine (I have never owned QL so it is difficult to me):
1. what is "default screen" - the menu in which user select video output with F1,F2 keys ?
2. should the microdrives start spinning when QL is powered on ?
3. is the RGB pinout the same as is on Sinclair +2 and +3 ?

Thank you


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Pr0f
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Re: QL not working

Postby Pr0f » Tue Oct 31, 2017 3:27 pm

The RGB pinout is shown in the service guide.

It's been a while since I owned one of these, but the splash screen starts first, with the F1 / F2 prompt, and if you don't hit any keys for about 30 seconds, the screen will default to TV mode - a blue screen and pink cursor. The left hand Microdrive will usually spin briefly if there is no cartridge in it, as it's looking for a boot file.

There is a good set of tips for troubleshooting in the service manual, so it should help you along quite a way :-) All the best with it :-)


colo
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Re: QL not working

Postby colo » Tue Oct 31, 2017 3:38 pm

Thank you again,
I will read the manual, but it will take some time

I have noticed somewhere on internet that when the QL doesn't starts it have usually 2 reasons:
1. some maybe regualtor or transistor (I don't recall exactly )
2. ULAs - but as I have mentioned I have replaced both with new one


Martin_Head
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Re: QL not working

Postby Martin_Head » Tue Oct 31, 2017 4:33 pm

Pr0f wrote:The RGB pinout is shown in the service guide.

It's been a while since I owned one of these, but the splash screen starts first, with the F1 / F2 prompt, and if you don't hit any keys for about 30 seconds, the screen will default to TV mode - a blue screen and pink cursor. The left hand Microdrive will usually spin briefly if there is no cartridge in it, as it's looking for a boot file.

There is a good set of tips for troubleshooting in the service manual, so it should help you along quite a way :-) All the best with it :-)
You should get a screen full of coloured pixels first, then the F1/F2 splash screen. Only Minerva ROMs will auto start after about 30 seconds.

If you switch on, wait 4 or 5 seconds, then press F1 or F2. If mdv1_ spins then you have some display problem, rather than a logic problem.


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Cristian
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Re: QL not working

Postby Cristian » Thu Nov 02, 2017 10:43 pm

colo wrote:2. should the microdrives start spinning when QL is powered on ?
No. First the startup screen should appear, then you can press F1 or F2, then Microdrive 1 will start spinning.

colo wrote:3. is the RGB pinout the same as is on Sinclair +2 and +3 ?
NO! Be careful!



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