Black Screen

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By cobracon2

Rookie (31)

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19-03-2018, 22:03

fahrenheit

By Manuel

Ascended (14552)

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19-03-2018, 22:25

You realize that most people on this board never use that obsolete unit? Tongue

By cobracon2

Rookie (31)

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19-03-2018, 22:39

I know. But in the US we use it everyday. But re-looking at the temps, I don't think they are right. So I would look at them at what gets hottest. Looking at the numbers this way, should the ram run as hot as the cpu and video chip?

By Grauw

Enlighted (7353)

Grauw's picture

19-03-2018, 23:59

cobracon2 wrote:

All LS chips 79F (26 ºC)
PD780c1 CPU: 91F (33 ºC)
Sound Chip: 92F (33 ºC)
TMS9118NL: 98.7F (37 ºC)
TMS4116: 92F (33 ºC)

Idk, I don’t know much about it but those don’t seem super hot…

By the way, TMS4116 is the VRAM, not the RAM (the RAM are the 2x µPD4168C-20 on the CPU board). I don’t think the VRAM is the issue, because the MSX would boot and beep and key click even if it was not functioning. Did you measure the RAM chips?

By cobracon2

Rookie (31)

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20-03-2018, 00:19

Yeah they were nice and cool

By Grauw

Enlighted (7353)

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20-03-2018, 00:42

Hm there goes one of my prime suspects, at least as far as this measurement is concerned. What about the ROM chip? That’s the HN613256PD19 next to the RAM I think. Also cool I guess. Another prime suspect.

Maybe the VDP is broken, I don’t know what a typical temperature is but it’s the hottest and it would cause a black screen. But it’s still all guessing for me, with a lot of other possible causes.

Since you seem to have quite a lot of equipment, do you happen to have a logic probe or oscilloscope or something?

By cobracon2

Rookie (31)

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20-03-2018, 00:57

Wish I did have them. Maybe I'll desolder the ram to make sure that's not the cause. I can always solder it back in. If that dont work I guess I will order a new video chip. Wish me luck. I'll report back on what I find.

By Grauw

Enlighted (7353)

Grauw's picture

20-03-2018, 01:01

Yeah that’s something you can try indeed, desoldering the RAM and inserting the mapper.

Grauw wrote:

Since I reckon you’re going to have to do some desoldering at some point anyway, for desoldering on a budget you need a desoldering pump, solder wick is also recommended, and a bit of patience and practice Smile.

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