VG 8235/00 Cartridge Port 1 > no function :(

By turbofoen

Supporter (3)

turbofoen's picture

12-06-2021, 14:38

Hi there Smile
I have a problem with one of my 8235s:
The first cartridge port is dead and no cartridge will be detected in there, the 2nd port works fine.

I have re-soldered all the joints at the bottom side and rebend all the contacts at the edge connector. But still no function.
Measurement with a Multimeter says, all contacts are fine. At least mechanically, all soldering points are ok and there are no cold joints.
The Contacts at the Edge-Connector are clean (cleanded up with glass fibre pen).

So i think it must a electrically problem. But what can i do next, to find out what's the problem?
The only mesurement tool i own is a Multimeter -.-

thx

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By Jipe

Paragon (1488)

Jipe's picture

12-06-2021, 15:59

all the signals of the slots are in parallel and the only different signals are /SLTSL1 and /SLTSL2 ( pin 4 of slots )
these signals arrive directly on the S3527 system chip at pins 87 and 88
check the continuity
on this link you can see picture of the S3527
http://alucard.nl/~tristan/repairs/LordZett/VG8235/2018-05-0...
/SLTSL1 and /SLTSL2 are on the holes between mark 80 and 09 at the left of S3527

By turbofoen

Supporter (3)

turbofoen's picture

12-06-2021, 16:16

Thanks for your advice!
But it seems to be ok....

Port1 >> Pin87
Port2 >> Pin88

By gdx

Enlighted (4481)

gdx's picture

12-06-2021, 16:18

/BUSDIR is not in parallel. If you link those of two slots it can cause issue when two cartridges that manage this signal are inserted.

By Jipe

Paragon (1488)

Jipe's picture

12-06-2021, 16:31

this MSX VG8235/00 have no /BUSDIR connected on pin 10
some cartridges with tinned connectors may leave deposits on the lyres of the slot

By turbofoen

Supporter (3)

turbofoen's picture

13-06-2021, 00:24

I cleaned up all the contacts again....nothing Sad
I measured the voltages...all fine.

By Pentarou

Champion (375)

Pentarou's picture

13-06-2021, 01:10

Flip the two /SLTSL signals and see if the working/non working slot situation is reversed.
If that's the case then /SLTLS1 is damaged and you can try to use /SLOT0131 (only on a non-expanded cart) as a replacement.

By gdx

Enlighted (4481)

gdx's picture

13-06-2021, 11:07

Jipe wrote:

this MSX VG8235/00 have no /BUSDIR connected on pin 10

The problem arises when you connect the BUSDIR signals of two cartridges which manage this signal. Therefore /BUSDIR signals of cartridge slots must remain never connect directly between them.