V9958 Problems, screen flickers.

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By l1nux1n

Champion (401)

Аватар пользователя l1nux1n

31-03-2009, 10:01

Hi,

I installed v9958 on a NMS-8245, everything ok, but when you take 2 minutes turned on the screen flashes black every time faster.
I have a refrigeration unit in the IC.

You know what can happen? The v9958 is defective?

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By Erikie

Champion (324)

Аватар пользователя Erikie

31-03-2009, 11:20

maybe your vcc is not stable enough? How did you exactly put it in?
I did not have any trouble putting v9958 in 8250's ...

By l1nux1n

Champion (401)

Аватар пользователя l1nux1n

31-03-2009, 12:39

this is my connection:

Pin 1 --> 4 (not conected to mainboard), 27 (not conected to mainboard)
Pin 58 (+5v) --> 21 (not conected to mainboard)
Ping 26 (not conected to mainboard) --> Z80 pin 24 with Diode 1N4148

I can try another v9958 I have no more, with the v9938 all ok.

Thanks.

By Erikie

Champion (324)

Аватар пользователя Erikie

31-03-2009, 12:57

Checked some documents and some are suggesting to put resistor between pin 4 and gnd / vcc.
V9958 could overheat without it. You can allways try that and see if it helps. Do you have any around > 2K ?

By l1nux1n

Champion (401)

Аватар пользователя l1nux1n

31-03-2009, 13:17

I have 2k resistor. Then connect well?

Pin 1 - (2k Resistance) -> Pin 4

And the pin 27 which also connects to gnd?

By Erikie

Champion (324)

Аватар пользователя Erikie

31-03-2009, 13:32

for pin 4 should be enough. Hope it helps. Is your v9958 really warm when it starts to flicker?

By l1nux1n

Champion (401)

Аватар пользователя l1nux1n

31-03-2009, 16:11

if heated too little, the flashing starts after about 60 seconds to boot.
Thanks for the advice.

By Erikie

Champion (324)

Аватар пользователя Erikie

31-03-2009, 19:23

so it did not work?

By l1nux1n

Champion (401)

Аватар пользователя l1nux1n

01-04-2009, 00:12

Place the resistance does not work. When heated slightly, the image flickers. I think that the IC is defective. Crying

By Erikie

Champion (324)

Аватар пользователя Erikie

01-04-2009, 08:09

what are you using for output? Scart or composite?
I have an 8250 which acts very strangely with composite (lots of stripes) but fine with scart.

By l1nux1n

Champion (401)

Аватар пользователя l1nux1n

02-04-2009, 00:01

Use Scart/RGB, and I can not think of anything. With perfect v9938, v9958 but with as hot flashes ever faster.

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