CDTV boots to black screen

[solarmon]

I acquired a faulty CDTV which I'm trying to resurrect.

Initially, it was booting up with a white screen. I took it apart to inspect the CD drive as I heard that could cause such a white screen.

I re-seated and cleaned up all the socketed chips, and all the connectors.
However, when I put everything back, it now boots to a black screen. A step backwards from my experience, with other Amigas.

I'm connecting via the RGB video out to a SCART TV.

I did take out the J15 jumper so that it would just behave like a normal A500, but still no change.

I tried DiagROM 1.2.1 but I still not getting anything, not even serial output.

I tried removing the U75, which I understand is the keyboard controller, as I read somewhere that this could also stop it from booting, but still same issue.

Reset and Halt signals on CPU seems to be behaving as expected - briefly low and then staying high.

CPU, Agnus, Kickstart, Gary, Paula, Denise and CIA chips have been tested to be working in an A500. I don't have another CDTV to test any of the other socketed chips.

Any suggestions what I else I can check/do?

EDIT: Checked voltages on CN21 - all seems to OK: -12.22V, 12.25V, 5.01V

[alexh]

You have to start with the PSU. Check the output voltages.

Are you sure you put all the chips back in the correct sockets with the correct orientation? No bent pins?

Apparently you get a black screen if the CDTV keyboard controller (252609-02) is broken.

http://eab.abime.net/showthread.php?t=58301

[utri007]

Tv-output card is needed to get picture from 23 pin connector. You took it abart so maybe you are trying without it?

[solarmon]

Originally Posted by alexh

You have to start with the PSU. Check the output voltages.

Are you sure you put all the chips back in the correct sockets with the correct orientation? No bent pins?

Apparently you get a black screen if the CDTV keyboard controller (252609-02) is broken.

http://eab.abime.net/showthread.php?t=58301

Sorry, I forgot to say:

Checked voltages on CN21 - all seems to OK: -12.22V, 12.25V, 5.01V

Yes, I tried taking out the keyboard controller, but made no differences.

[solarmon]

Originally Posted by utri007

Tv-output card is needed to get picture from 23 pin connector. You took it abart so maybe you are trying without it?

I did put back the card in the video slot. Didn't make any difference. I did even try RGBtoHDMI on the Denise - the HDMI output also showed a black screen.

With JP15 jumper not bridged, and with an external floppy drive, I would expect some activity if it was just a display issue.

I don't think the issue is just a display issue. The machine is just not booting up, regardless whether display output is working or not.

[solarmon]

Originally Posted by alexh

Are you sure you put all the chips back in the correct sockets with the correct orientation? No bent pins?
http://eab.abime.net/showthread.php?t=58301

I have triple-checked it all and I cannot find any issues with chip orientation or bent pins.

[alexh]

Did you try a known good ,68000?

[solarmon]

Originally Posted by alexh

Did you try a known good ,68000?

Sorry, yes, I did test the CPU on the A500 too.

I've updated the original post to state that.

[alexh]

Remove the Extended kickstart ROM EPROMs? With J15 in the right setting they are not used anyway. Exclude a broken one affecting the bus

[solarmon]

Originally Posted by alexh

Remove the Extended kickstart ROM EPROMs? With J15 in the right setting they are not used anyway. Exclude a broken one affecting the bus

Great suggestion!

I did that, but it didn't seem to change anything.

[solarmon]

Progress!

I suspected Agnus since that was the most crusty looking. I took it out for the fourth time and cleaned the pins and socket again, and made extra effort to get it aligned before pushing it down.

And with JP15 not jumpered, it booted to the Kickstart 1.3 screen. I was able to use an external drive to load Amiga Test Kit and memory and CIA tests all seems good.

However, it still boots to white screen with JP15 jumpered, so there must be something wrong with the CDROM drive.

[8 Bit Dreams]

If Jumper JP15 is closed and You are getting white screen- there can be several things:
1. Check extended ROMs
2. Check connection of the CD-ROM Drive connection (power and ide) - must be connected...

[solarmon]

I'm waiting for some new extended ROMs from sordan.ie to rule that out.

[8 Bit Dreams]

If You have TL866 programmer - you can build a simple adapter and do compare test - there are only two addresses that need to be swapped..

Hopefully You have an UV eraser, there will be brand new extended 2.35 ROMs available soon

[solarmon]

Yes, I do have a TL866 programmer. Do you have the details on the pin swap and what to select when programming it in the TL866 programmer?

[8 Bit Dreams]

You need to choose 27C1001, since 27C1000 isn't available,
About pins - need to compare datasheets, don't remember exactly wich two pins are swapped...

EDIT
27C1000 EPROMS. (IIRC, pin compatible to 27C301)

The only difference between 27C1001 and 27C1000
On the 27C1001, pin 2=A16, pin 22= /OE
On the 27C1000, pin 2= /OE, pin 22= A16.

EDIT
NOT THE MX27C1001 ONES! MX Pinout seems to be equal to 27C1000!!!!

[supaduper]

Goose on Exxos forum made a adapter to swap pins 2 and 24, I have one and it works great.
Below is his post on the Exoss forum:

Unfortunately that standard 400/800 EPROM adapter won't handle the pin swap for the M27C1000 / M27C1001s as far as I'm aware. I looked into adding the M27C1000 / M27C1001 functionality into the open source design for a similar adapter but it would have required extensive changes to make it work from the existing design.

The adapter shown above is very simple and only requires a 32pin ZIF socket and two rows of 16X2.54mm pitch pins in addition to the PCB. It should be able to be built for ~ €4 total.

If you only need to program the M27C1000s once you can pre heat then gently bend pins 2 and 24 out of the way and swap them over using taped wires directly in the TL866 but this is not a viable solution if you need to program multiple chips, or the same chips multiple times.

[RoC]

Same here.

Thanks to the fellow who made it for me (I don’t say the name, but he is welcome to come forward), I have been using a ZIF adapter that sits on the TL866IIplus. There are two pin inverted, like 8 Bit Dreams said.

With that adapter, I am able to burn the 27C1000 by setting 27C1001 on the software.

You should byte-split (not word-split) the rom before burning. EpromHexxer has just added this feature in the latest release.

[solarmon]

I got the new v2.30 extended ROMs from sordan.ie. But instead of a white screen, I now get a black screen (it flashes purple first, then stays on black) with JP15 jumpered.?? I even swapped them between U34 and U35 just in case they were burned or labelled incorrectly. Should the CDTV be able to boot up without the CDROM drive connected? I've tried it both connected and unconnected and that does not seem to make a difference.

With JP15 unjumpered, it boots OK to the new Kickstart 3.1 ROM I also got with the new extended ROMs.

[cpiac64]

connect the cd-rom