Help with RGB Sony Hitbit HBF1XD - No Blue

By mbliss11

Supporter (7)

Аватар пользователя mbliss11

15-10-2022, 22:01

Hey MSXers! Looking for some guidance. Started making my own RGB cables recently to hook up to my PVM. Looked forum post on here for pinout using this:

Mitsubishi (Japan), National/Panasonic (except the FS-A1WSX), Sakhr, Sony and Yamaha computers + Sanyo MSX2/2+ computers

These computers use DIN 45326 type A. This is the official RGB pinout for the MSX, described in the MSX-Datapack and shown in the following table. It was used on Mitsubishi (Japan), National/Panasonic (except the FS-A1WSX), Sakhr, Sony and Yamaha computers and Sanyo MSX2/2+ computers

Pin Name Description SCART Connection
1 GND Ground To all SCART ground pins
2 AUDIO Audio To SCART pin 6
3 AV AV Control (+4.5V to +5V) To SCART pin 8
4 SYNC CSync 0.3Vpp / (CVBS on some machines) To SCART pin 20
5 YS Fast switch (+3V or +5V) To SCART pin 16
6 R Red signal To SCART pin 15
7 G Green signal To SCART pin 11
8 B Blue signal To SCART pin 7

Note: The Ys pin is used to superimpose the MSX image on the receiver. But on most MSX models this pin has just a fixed voltage. It's a data pin, so do not use it as Vcc.

Have it all hooked up and was not getting any blue signal. Red and Green are coming out but no blue. I scoped pin 8 and sure enough I am not getting anything. Red and Greed have activity and a 15khz signal. I took the computer down but have not removed the motherboard from the bottom shell yet. Any suggestions or do you know where I should look? I serviced the HIC board when I first got the machine it was in immaculate condition. Composite signal works just fine. Doesn't the HIC board handle video for the system? Should I look there first and see if I screwed it up doing the recap?

Thanks for any suggestions and help you can offer!

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By Pencioner

Scribe (1532)

Аватар пользователя Pencioner

15-10-2022, 23:56

check for cold soldering on connector, it is one of quite common issues (especially as you got blue on composite, that is very likely the problem is not a component failure but the signal delivery)

i got a habit to resolder connectors (heating with applying a bit of extra solder) on a retro stuff when i buy something because i had quite a few such issues: missing sync on an old Commodore 1084 monitor, cold joint issue on a joystick port on one of MSX computers and even a cold joint on a 50 pin slot connector which led to occasional freezes with cartridge inserted which got fixed after i reheated the soldering points

By mbliss11

Supporter (7)

Аватар пользователя mbliss11

16-10-2022, 16:49

Hey thanks so much for the reply Pencioner!

Got the board out and reflowed the joints but still had the same problem. Did more probing and saw a capacitor C64 was in line between the HIC and the port. I took it out and checked it and it was definitely bad. Thankfully had a spare 16v 470uf cap laying around from another project. Popped that in and sure enough I got Blue now! Smile Now I need to remake my original rgb cable since I suspected that was the fault initially haha.

Thanks again!