A600 suspect dead Denise - strange DiagROM behaviour

psoma · 02 April 2022, 11:48

Hi all,

A mate gave me his recapped 600 to take a look at. He bought an RGBtoHDMI adapter and fit the hat on the Denise upside-down. Now... aside from thinking that's a fair effort considering the cutaway, the RGBtoHDMI doesn't work after he corrected it, and in-fact, nothing displays at all through RGB after the RGBtoHDMI was been removed.

I threw the Diagrom in there first up - interestingly, the power up colours DO flash out through the RGB port... I can see green, red, grey, then flashing through the different gradients of RGB. And then: nothing. The structured text portion of Diagrom doesn't work. I can connect through the serial and everything else tests out OK (with the exception of sound which is scratchy and distorted interestingly - related?!?).

So, despite not working out how based on the pin alignments and the fact that the Pi itself isn't providing power anything could have fried here... I'm thinking the Denise is dead. But how is the Diagrom able to send signal out as a full-screen image, and then nothing afterwards?!

Cheers,

Tom

LIV2 · 02 April 2022, 18:29

>But how is the Diagrom able to send signal out as a full-screen image, and then nothing afterwards?!

When doing the colour cycling diagrom is only changing the palette value of the background colour so it doesn't need to feed pixel information at all at this point.

cpiac64 · 02 April 2022, 19:02

for audio scratchy and distorted sometime verify +12 and -12 volt

psoma · 03 April 2022, 02:08

Thanks folks - that explains the partial functionality of the Denise then. The good news is, that discounts anything downstream of Denise as it is outputting the full spectrum fine. Have now removed it to test with a replacement.

Checked for +12V and -12V at the Op Amp, both good. Confirmed all 4 channels are screwed. I’ll do some further diag if I get the Denise going again… one issue at a time!

Thanks again,

Tom

psoma · 03 April 2022, 07:01

Nope! Wasn't the Denise. Performing exactly the same with a replacement Denise. What else could cause the Raster, background and colour data to be fine, but not be able to display pixel info?!?

02 April 2022, 11:48	#1
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	A600 unable to display pixel data, background/raster fine, NOT Denise. Hi all, A mate gave me his recapped 600 to take a look at. He bought an RGBtoHDMI adapter and fit the hat on the Denise upside-down. Now... aside from thinking that's a fair effort considering the cutaway, the RGBtoHDMI doesn't work after he corrected it, and in-fact, nothing displays at all through RGB after the RGBtoHDMI was been removed. I threw the Diagrom in there first up - interestingly, the power up colours DO flash out through the RGB port... I can see green, red, grey, then flashing through the different gradients of RGB. And then: nothing. The structured text portion of Diagrom doesn't work. I can connect through the serial and everything else tests out OK (with the exception of sound which is scratchy and distorted interestingly - related?!?). So, despite not working out how based on the pin alignments and the fact that the Pi itself isn't providing power anything could have fried here... I'm thinking the Denise is dead. But how is the Diagrom able to send signal out as a full-screen image, and then nothing afterwards?! Cheers, Tom Last edited by psoma; 03 April 2022 at 07:01.

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02 April 2022, 18:29	#2
LIV2 Tinkerer Join Date: Jan 2020 Location: NZ Posts: 105	>But how is the Diagrom able to send signal out as a full-screen image, and then nothing afterwards?! When doing the colour cycling diagrom is only changing the palette value of the background colour so it doesn't need to feed pixel information at all at this point.

02 April 2022, 19:02	#3
cpiac64 Registered User Join Date: Apr 2010 Location: Italy Posts: 1,136	for audio scratchy and distorted sometime verify +12 and -12 volt

03 April 2022, 02:08	#4
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	Thanks folks - that explains the partial functionality of the Denise then. The good news is, that discounts anything downstream of Denise as it is outputting the full spectrum fine. Have now removed it to test with a replacement. Checked for +12V and -12V at the Op Amp, both good. Confirmed all 4 channels are screwed. I’ll do some further diag if I get the Denise going again… one issue at a time! Thanks again, Tom

03 April 2022, 07:01	#5
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	Nope! Wasn't the Denise. Performing exactly the same with a replacement Denise. What else could cause the Raster, background and colour data to be fine, but not be able to display pixel info?!?

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