Yamaha YIS-503/CX5F no video/audio, caps/kana lock works

By popolon_

Master (162)

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03-08-2021, 19:11

What could be wrong with yamaha YIS-503, as there is no video and no audio. Caps lock and kana lock however works. I have replaced all electrolytic capacitors in mainboard. Voltages are fine. Also there seems clock signal in vdp and some kind of videosignals from VDP output pins. From rom pins I saw activity in data and address lines. No IC is heating up noticable. So are the typical that for example video conversion circuitry could be dead with the audio amp also?

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By Alexey

Guardian (3164)

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03-08-2021, 19:58

LVA510 with very high probability.

By popolon_

Master (162)

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03-08-2021, 20:59

but this is japan computer, so no LVA510 chip. only Sharp IR9311, SN75451BP, and 4558DV

By Alexey

Guardian (3164)

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03-08-2021, 22:42

Would be nice to make a picture of the motherboard. There should be some sort of video converter board attached to it.

By sdsnatcher73

Prophet (2152)

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04-08-2021, 06:43

From the Wiki (not very clear):

No audio is not very common, do you have any game cartridge with an intro demo/sound (e.g. F1-Spirit, Nemesis series) to confirm there is no audio?

By popolon_

Master (162)

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04-08-2021, 08:44

I have tried with nemesis and F1 spirit, no sound. I will next try to connect Y signal from 60pin connector to composite input.

By popolon_

Master (162)

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04-08-2021, 09:07

And i have both yis and cx5f, and the mainboards have different video converter boards. In Yis it has only SMD components, when in cx5f there is through mount electrolytic capacitors. In the yis, the is no green wire from Vdp towards video converter. There is black wire towards 60pin slot. Mainboard revision is 4 (YMX-CPU LC56040 4) in YIS, when it is 5 in cx5f.
[edit] here are pictures from those two converters, and the green/black wires
CF5X converter back side:
cf5x converter back
CF5X converter front side:
cf5x converter front
YIS503 converter back side:
yis503 converter back
YIS503 converter front side:
yis503 converter front

By popolon_

Master (162)

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04-08-2021, 09:27

In YIS converter board there is AN6041 chip, when in cx5f it is AN6040. Would this chip be dead?

By popolon_

Master (162)

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04-08-2021, 09:50

yes, with Y-signal connected to TV composite input (via 33uF capa), there is black and white picture. However no sound. Nemesis starts to play intro and demo play.

By popolon_

Master (162)

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09-08-2021, 19:15

the real problem was that the connector described in wiki page is wrong!
In this wiki page "https://www.msx.org/wiki/Composite_monitor_(5-pin_DIN_41524)" , it shows pinout for female connector (MSX computer side), but the pinout would be suitable for male connector.
Anyway the yis works when using proper pinout.

By sdsnatcher73

Prophet (2152)

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09-08-2021, 20:57

Ah good find. I use an original Yamaha cable as well as Philips VG luminance cables, used to connect the monitor output of VG8000/VG8010/VG8020 as well as VG8230/VG8235 and NMS8245 to a monochrome monitor. The photo on the wiki of the female output should have the 4 and 5 pin mirrored.