General troubleshooting w/Dexter

Post Reply
dgelias
Registered User
Registered  User
Posts: 2
Joined: Mon May 07, 2018 3:26 pm

General troubleshooting w/Dexter

Post by dgelias »

Hey folks,

Where to begin on this one. Longtime DLP member and I'm hoping some of the more experienced folks will have some suggestions so I can get this DL back up, running and over the hump. I've essentially been working on this cab on and very very off for the past 10 years.

Where I'm currently hung up;

Everything is up and connected via Dexter. Hurdle #1; I have no idea if my DL main board is supposed to be using the 7820, the LDV1000, or has the switch to go between the two. I know the Dexter is supposed to autodetect which it should be using, but it seemed to be autodetecting the 7820 when I first dropped it in, and then it seemed to be autodetecting the LDV1000, so
I'm not really sure what it looks at to autodetect, but maybe that was just my unfamiliarity with getting in and out of autodetect mode. (I'm pretty sure its autodetecting the 7820 at this point)

I'm fairly certain the ribbon cable is plugged in in the correct orientation, and the connector is a centronics style. FWIW, I am using the ribbon cable that came with the Hi-Tech board, which I've looped in on some attempts and others not just to see if it makes a difference. I've
removed that for now, to simplify troubleshooting.

*** when I switch this to LV931 mode I DO see a bootup ***

Audio is fine in this mode, and the attract mode starts, and then it begins looping through every scene. I'm pretty sure it does this in LD1430 mode as well. I have some questions on this -- in LV931 mode is the Dexter board communicating with the DL main board at all or is everything coming from the Dexter? I can't be certain that this main board or the ROMS are
100% functional, as its been kicking around for 10+ years. I do know that when I fire it up, the scoreboard does initially light up with an alternating 9/0 pattern. I have no idea if that's normal or not. (screenshot attached)

so I assume the board is getting power OK. I'm just not sure how to determine that the main board is 100% functional... at least then I'd know it's just a matter of getting the config right. Again, not sure what rev of the board this is (screenshot attached) and so I can't be sure the
jumpers are correct. Considering the price people are selling untested main boards for on eBay these days, I'd rather not drop $550 if I can help it.

I'm not sure if there's anything I can do in the way of more testing to determine if the board is bad or misconfigured. If anyone notices anything obvious, or thinks or something else I can test, I'd be eternally grateful. I put more quarters into this thing in my lifetime than I care to count... I just want to finally get this thing up and running once and for all.

Thanks!!
Dan

Image
Image
Image
Matt Ownby
DAPHNE Creator
DAPHNE Creator
Posts: 839
Joined: Sat Jan 20, 2001 1:00 am
Location: Salt Lake City,Utah, USA
Contact:

Re: General troubleshooting w/Dexter

Post by Matt Ownby »

Hi Dan! Thanks for posting here so we can help.
dgelias wrote: Everything is up and connected via Dexter. Hurdle #1; I have no idea if my DL main board is supposed to be using the 7820, the LDV1000, or has the switch to go between the two. I know the Dexter is supposed to autodetect which it should be using, but it seemed to be autodetecting the 7820 when I first dropped it in, and then it seemed to be autodetecting the LDV1000, so
I'm not really sure what it looks at to autodetect, but maybe that was just my unfamiliarity with getting in and out of autodetect mode. (I'm pretty sure its autodetecting the 7820 at this point)
I assume you've already watched my youtube video about how to use the auto-detect mode? If not, please watch http://www.youtube.com/watch?v=KxFz4-yxW3g. Sorry about the camera focus problems.

For Dragon's Lair, if the ribbon cable is plugged in backward, a DL main board that is supposed to work with a LD-V1000 often auto-detects as PR-7820. That is one thing to keep in mind. You can double check your ribbon cable orientation by looking at the picture viewtopic.php?f=28&t=3033".

I can't quite tell from your pictures, but it seems that it is plugged in correctly. It is still worth double checking.

Auto-detection is fairly reliable if the cable is plugged in properly. Turn on the game first, then power on Dexter. If Dexter is powered on before the game, it won't auto-detect properly. (powering on Dexter and the game at the same time also usually works, but it is most reliable to have the game powered on first while you are trying to get configured for the first time).

If you aren't getting consistent results doing this method, then that may raise a concern about the state of your DL main board.

I also notice that the windows on your EPROMs are uncovered. This means that they are at risk of slowly being erased over time as they are exposed to UV light. So you may also want to verify your ROMs to see whether they are correct, and then put a piece of tape over each window once said verification is complete.
I'm fairly certain the ribbon cable is plugged in in the correct orientation, and the connector is a centronics style. FWIW, I am using the ribbon cable that came with the Hi-Tech board, which I've looped in on some attempts and others not just to see if it makes a difference. I've
removed that for now, to simplify troubleshooting.

*** when I switch this to LV931 mode I DO see a bootup ***

Audio is fine in this mode, and the attract mode starts, and then it begins looping through every scene. I'm pretty sure it does this in LD1430 mode as well. I have some questions on this -- in LV931 mode is the Dexter board communicating with the DL main board at all or is everything coming from the Dexter? I can't be certain that this main board or the ROMS are
100% functional, as its been kicking around for 10+ years. I do know that when I fire it up, the scoreboard does initially light up with an alternating 9/0 pattern. I have no idea if that's normal or not. (screenshot attached)
VP-931 and LDP-1450 mode auto-play the disc, so that is likely what you are seeing. Dragon's Lair only works with either LD-V1000 or PR-7820 mode, so putting Dexter into VP-931 or LDP-1450 modes only has the benefit of letting you test your video and audio.

If you don't want to deal with troubleshooting your DL hardware, I believe that Shaun Wood has been known to fix DL main boards. You could ask him what his terms are to look at yours.
Check out my cool projects!
dgelias
Registered User
Registered  User
Posts: 2
Joined: Mon May 07, 2018 3:26 pm

Re: General troubleshooting w/Dexter

Post by dgelias »

Hey Matt,

Thanks for the response. I shot Shaun an email, will see what he thinks.

Any way of telling which rev. that board is from the pics? I certainly couldn't tell. I'll get those ROMS covered asap, though I'm likely going to pick up a Merlin DX in order to swap between DL/SA.
Matt Ownby
DAPHNE Creator
DAPHNE Creator
Posts: 839
Joined: Sat Jan 20, 2001 1:00 am
Location: Salt Lake City,Utah, USA
Contact:

Re: General troubleshooting w/Dexter

Post by Matt Ownby »

dgelias wrote:Hey Matt,

Thanks for the response. I shot Shaun an email, will see what he thinks.

Any way of telling which rev. that board is from the pics? I certainly couldn't tell. I'll get those ROMS covered asap, though I'm likely going to pick up a Merlin DX in order to swap between DL/SA.
Try http://www.dragons-lair-project.com/tec ... ges/dl.asp
Check out my cool projects!
User avatar
Shaun Wood
Registered User
Registered  User
Posts: 2
Joined: Fri Mar 21, 2008 3:00 am
Location: Midlothian, TX
Contact:

Re: General troubleshooting w/Dexter

Post by Shaun Wood »

That is a revision-A boardset.
Rev-A is designed to operate a PR-7820, but many boards have been modified over the years, so that's no guarantee.

The true indicator here is the alternating 0909 on the scoreboard. That's almost always a sign of a non-booting board.
It's usually due to bad ROMs, or a dead Z80A CPU chip.

Since your ROMs are uncovered, and not original (a Rev-A board always came with 5 ROM chips), I'm going to guess EPROMs.
Covering them now, won't help, the bits are out of the barn.

Sure dgelias, I'd be happy to look at it for you.
-Shaun
ginazz
Registered User
Registered  User
Posts: 4
Joined: Tue Jan 05, 2016 10:42 pm

Re: General troubleshooting w/Dexter

Post by ginazz »

dgelias wrote:Hey Matt,

though I'm likely going to pick up a Merlin DX in order to swap between DL/SA.
I highly recomend getting a Merlin D X Also If I was You I would get it with D L 2 E . You will not be disapointed
Post Reply