Dokert
Well-known member
I think VR362 is an error in the scat, and it should be VR451.
Donkey Kong Sanyo (20EZ?) B+ problem
- Thread starter hindered
- Start date
Dokert
Well-known member
Found a better scat, try this
OP
OP
Sounds good to me.
Ok, I FINALLY tested the pot like you said about 30 posts ago.
It maxes out at 2.7k resistance instead of 3. I sprayed it with electronics cleaner and turned the pot back and forth -- no improvement. This could be why the 100k resistor was wired in parallel to R462, which would make the actual resistance about 15k (if this site is right http://www.1728.com/resistrs.htm). Maybe this was done to compensate for the pot only resisting up to 2.7k instead of 3k?I'm just spitballing here -- any other theories are welcome. Even if the theory is right and putting the resistor back helps, even with the resistor there, I was unable to get the picture to sync properly...
OP
OP
Wow, that means very little to me. :\ I never got the knack for reading these.
Dokert
Well-known member
Put the resistor back where it was and try it again with some fresh solder. May have just been a cold solder joint between the resistor and the pot.
OP
OP
I'll give this a shot in the AM... been messing with this on and off all day and am pretty burned out.
Pretty tired of lugging that monitor out too -- I live in an apartment, the cab is currently in my bedroom and my only workspace is out in the dining room. Good times. Do you think the pot on the game pcb that adjusts sound (I have the 2 board version) could be the cause of the weird noise I'm hearing? I did tweak that before when trying to fix the sync issue (before I remembered I have a manual and looked up what it actually does).
P.S. Thanks so much for all your help on this -- I really appreciate you taking the time to assist.
RPO_Z06
New member
OP
OP
There are two pots on one pcb that do this, yes. There is a pot on the other pcb that has to do with sound.
Dokert
Well-known member
Just thought about something you said early on, went back and checked to make sure. C471 could be your problem, it is in the affected circuit.
OP
OP
Hmm, maybe. The monitor was syncing properly before the cap kit though... I was just experiencing the wavy screen, similar to this video (look at the bottom of the water/islands) http://www.youtube.com/watch?v=fBqHJpeSTFU
Ha, that URL ends in "STFU".
RPO_Z06
New member
I'm aware of pot on the CPU board for background sounds, I just wanted to be sure you were aware of the two pots on the Video board.
I've recently been where you are, the video you posted was mine.
OP
OP
WOW... I just doublechecked and these caps are present, accounted for, and installed. I simply forgot to mark them off my list as I was going. Again -- WOW. My apologies to Bob.
Dokert, seems C471 isn't the issue.
OP
OP
What!
Ok, tackled this thing fresh this morning (I had put about 4-5 hours into it yesterday on top of family obligations) and soldered the 100k resistor back in at R462 solder side. I tested the brightness pot on the chassis and it was only resisting at 8.5k instead of 10k, so I went to Radio Shack and got a replacement. After soldering it in, I touched up a few more possible cold solder joints, centered the flyback brightness, chassis brightness, and turned B+ way down as outlined in Dokert's flowchart.
I stuck it back into the machine, got the brightness situation worked out, and adjusted B+ to ~108vdc. I fiddled with the horizontal sync pot until only vertical hold was unstable, and then tweaked vertical hold to get the picture to snap in place. I thought I had jail bars, but the brightness was still up kinda high so I turned it down on the flyback a hair. From there it was just a matter of fiddling with the color pots on the neckboard until the picture looked good. Could maybe still use an adjustment or two but I'm really happy with how it looks.
HOWEVER (there's always a however in my threads), in my tiredness and impatience last night, I must have yanked the monitor out without removing the sound connector on the game PCB, because the connector looked half pulled off the PCB when I went to reattach everything this morning. The game sound still works fine, but I still have that "pac man" kind of sound, and a LOUD hum, much worse than the "normal" hum that was there prior to the cap kit and prior to me yanking the header off. BTW tweaking the sound pot on the PCB did nothing to clear up the hum or the "pac man" type sounds.
I'm going to pull the game PCB and try to resolder the connector to see if that helps clear anything out. I'll follow up with a post in the General Repair section, since this is now more of an audio/game PCB issue, and will probably link the two threads to each other for anyone in the future who needs to learn from my misadventures.
Thanks to everyone for helping me sort this, especially Dokert for the posting megasession yesterday.
Ok, tackled this thing fresh this morning (I had put about 4-5 hours into it yesterday on top of family obligations) and soldered the 100k resistor back in at R462 solder side. I tested the brightness pot on the chassis and it was only resisting at 8.5k instead of 10k, so I went to Radio Shack and got a replacement. After soldering it in, I touched up a few more possible cold solder joints, centered the flyback brightness, chassis brightness, and turned B+ way down as outlined in Dokert's flowchart.
I stuck it back into the machine, got the brightness situation worked out, and adjusted B+ to ~108vdc. I fiddled with the horizontal sync pot until only vertical hold was unstable, and then tweaked vertical hold to get the picture to snap in place. I thought I had jail bars, but the brightness was still up kinda high so I turned it down on the flyback a hair. From there it was just a matter of fiddling with the color pots on the neckboard until the picture looked good. Could maybe still use an adjustment or two but I'm really happy with how it looks.
HOWEVER (there's always a however in my threads), in my tiredness and impatience last night, I must have yanked the monitor out without removing the sound connector on the game PCB, because the connector looked half pulled off the PCB when I went to reattach everything this morning. The game sound still works fine, but I still have that "pac man" kind of sound, and a LOUD hum, much worse than the "normal" hum that was there prior to the cap kit and prior to me yanking the header off. BTW tweaking the sound pot on the PCB did nothing to clear up the hum or the "pac man" type sounds.
I'm going to pull the game PCB and try to resolder the connector to see if that helps clear anything out. I'll follow up with a post in the General Repair section, since this is now more of an audio/game PCB issue, and will probably link the two threads to each other for anyone in the future who needs to learn from my misadventures.
Thanks to everyone for helping me sort this, especially Dokert for the posting megasession yesterday.
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RPO_Z06
New member
The hum is normal on all DK series boards, you can install a 2200uf 16v cap in the speaker output accross the pos/neg and it will remove the buzz/hum.
Congrats on the monitor.
Congrats on the monitor.
OP
OP
The hum is normal on all DK series boards, you can install a 2200uf 16v cap in the speaker output accross the pos/neg and it will remove the buzz/hum.
Congrats on the monitor.
Thanks.. I know the hum is normal, this hum was NOT normal. Fortunately only the plastic covering was loose and I pushed it back into place and now the hum is back to "normal". Thanks for the tip on the cap, I might try it out if the hum starts to drive me crazy.
I found a thread about the weird "woop woop" sound in the background.. On game startup, the jump sound plays, and then it seems to play infinitely in the background. Read more here: http://forums.klov.com/showthread.php?t=104353
