Wavy 23 video issue

Por pmack

Master (130)

imagem de pmack

21-02-2017, 04:31

All,
Just got a new Sanyo Wavy 23 and when I turn it on I get a black screen. Any tips? Does anyone have the pcb details for this computer?

Thanks

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Por RetroTechie

Paragon (1563)

imagem de RetroTechie

21-02-2017, 12:06

Sorry to hear that, pmack! Sad You could start with the checks I suggested in this thread. And if possible, provide answers to all those questions.

Supply voltages can even be checked through the cartridge slot(s) if necessary - as long as there isn't a voltage-cutting switch in the cartridge slot like on some MSX models.

Btw "new": was it working before? Or unknown state when you got it? Don't think I've ever seen a schematic for this machine...

Por pmack

Master (130)

imagem de pmack

24-02-2017, 02:56

Hi RetroTechie,
Here are the answers, any help is appreciated!

Which MSX model are we talking about?
- Sanyo Wavy 23
Do you have a voltmeter to check supply voltages on the main board?
- I can get a voltmeter but I need some assistance on how to check the voltages
What connector are you using for video output? (RGB / composite video / RF). Have you tried another video connector on this MSX?
- I've tried both composite and RF
Is cable known good / have you tested cable (or monitor) with another machine?
- Yes, cables and TV are good
Do you have an external RAM cartridge?
- No
If machine is switched on, power LED goes on?
- No, but I can see that a signal is being sent to the TV (all black screen though). So not sure if the LED is not working or if there is a power supply issue
If you hold [CAPS LOCK] pressed, does CAPS LOCK led flicker?
- There's no caps light for this model
If you press [CRTL-G] on the keyboard, do you hear a beep?
- I have the computer disassembled, not sure
If you switch on with a sound-producing (game) cartridge inserted, can you hear sound?
- No

Por Manuel

Ascended (17083)

imagem de Manuel

24-02-2017, 07:42

Um, this model does have a led for caps! It's above the F5-key, marked CAPS.

Por RetroTechie

Paragon (1563)

imagem de RetroTechie

24-02-2017, 15:33

pmack wrote:

- I can get a voltmeter but I need some assistance on how to check the voltages

If just checking voltages is something you need help with, then maybe it would be better to enlist some help for this...

Anyway, you could use the cartridge slot(s). Easy to access with machine disassembled!

I'll be referring to this image of PHC-23J internals. Should yours look noticeable different inside, please let us know!

You take voltmeter & put in a low DC range (usually there's a 20V DC range - use that). You put black test pin on a 0V (GND) reference point. An easy point for that is the metal case of the RF modulator.
Then refer to this image of an MSX cartridge slot. When sitting in front of the computer, picture that image rotated 90 degr. clockwise. Pins of interest (GND, +5V, +12, -12V) are on the left side in the connector(s) then.
With power switched on & black pin on RF modulator case, carefully probe the supply voltage pins with red test pin & note the reading. Please post here? Don't power on machine longer than needed. And be careful not to cause short circuits between cartridge slot pins! Better do a "dry run" before taking readings with machine powered up.

On the photo above I saw what looks like an EPROM (left one of the 2 ROMs). Is that present in your machine? And if so, is it in a socket? Also could you tell what markings are on the (3-pin?) part screwed to that black heatsink? Is there any other part screwed to that heatsink? If so, please read markings on that part too? (if possible)

If there's any way you can get your hands on a logic tester, or better: an oscilloscope, please do! But note you don't need a scope - I don't even own one myself...

引用:

- No, but I can see that a signal is being sent to the TV (all black screen though). So not sure if the LED is not working or if there is a power supply issue

That would suggest at least some kind of (video) signal is being put out. Perhaps VDP goes into some default sync-generating mode, but doesn't get initialized further when machine doesn't boot? Anyway, kind of strange when power LED doesn't light. Power LEDs don't die really.

引用:

If you switch on with a sound-producing (game) cartridge inserted, can you hear sound?
- No

Please find a way to hook up speaker / amplifier / headphone / whatever. Checking for sounds is really helpful if video output is gone but machine still works.

Por pmack

Master (130)

imagem de pmack

25-02-2017, 03:33

Thanks everyone for the responses. Clarifications below:
- It looks like one of the cables connecting the board to the top was lose. Once I reconnected it, the green power light does come on when the computer is turned on.
- That's right, there is a CAPS light for it. I had the top of and was looking for a light by the button. However, that light is not coming on when I press that button.
- No matter what I press on the keyboard, no sound can be heard.
- I compared my board to the pic and they look identical. There are no sockets here, all chips are soldered to the board. I tried to press them but no changes on anything.

I will pick up a voltmeter with a friend and try the check you described. I will post results later. Thanks!