hit bit hb-501f problem

By subzero79

Rookie (19)

subzero79's picture

22-11-2017, 17:54

hi to all
im ownef of hb-501f and i have thiw screen when bootup

checked all glue logic ls and used sockets on all ics ecept video encoder

second question i have i tried to read tmm23256p but without luck,how i can to obtain a dump??
cpu checked and its ok(on my old amstrad cpc 464)
please helpppppppppppppppppppp
(im awaiting 4464 ram chips and 4416)

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By Alexey

Paragon (1260)

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22-11-2017, 21:11

Was there anything sweet poured onto the board? Those stains look suspicious. Maybe they are partially conductive. So washing the board with white spirit could be an option. Also would be nice to have a close-up picture of the screen and the entire board.

By subzero79

Rookie (19)

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22-11-2017, 21:48

Alexey wrote:

Was there anything sweet poured onto the board? Those stains look suspicious. Maybe they are partially conductive. So washing the board with white spirit could be an option. Also would be nice to have a close-up picture of the screen and the entire board.

i dint know if swwet was poured on mainboard
arrived to me 3 days ago
i will try to clead

By gdx

Paragon (1689)

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23-11-2017, 00:37

I think your VRAM is defective. TMM23256P probably has a specific pinout. Try to copy the content by software.

By Eugeny_Brychkov

Paladin (880)

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23-11-2017, 19:20

subzero79 wrote:

im ownef of hb-501f and i have thiw screen when bootup

It would help to see the video how it boots up because it is not clear is this picture you have is a BASIC prompt, or this picture appears after power up and does not change.

By subzero79

Rookie (19)

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23-11-2017, 21:27

Eugeny_Brychkov wrote:
subzero79 wrote:

im ownef of hb-501f and i have thiw screen when bootup

It would help to see the video how it boots up because it is not clear is this picture you have is a BASIC prompt, or this picture appears after power up and does not change.

sometimes i have black screen
some times i have blue screen with vertical white lines
and soud does beep beep reboot

By subzero79

Rookie (19)

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26-11-2017, 19:51

cleaned the mobo and recap
replaced 4464 dram and boots on msx basic
but no all the times 3 times on 10 i have black screen 7 times boot normally on msx basic
LS Related problemm?

By Alexey

Paragon (1260)

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26-11-2017, 20:37

Did you replace VRAM too?

By subzero79

Rookie (19)

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26-11-2017, 20:43

no im awaiting for new parts but no corrupted screen at all

By Alexey

Paragon (1260)

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27-11-2017, 09:28

As most of the logic chips are in sockets, try to test them in a MiniPro (TL866) EEPROM programmer. That way I found 2 semi-dead chips on my Sony board.

By subzero79

Rookie (19)

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28-11-2017, 09:06

i think is the reset line
74ls014 related

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