Re: Gravis ultrasound classic ver 2.4 repair

Posted on 2019-07-20, 20:25

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by GoXoD

in Marvin \ Sound

in Marvin \ Sound

So I did some deductive logic and took a shot, the card is detected in dos through the setup program!! But when I try and fill all banks with memory it locks up the memory check. if I only fill 3/4 it detects all 768kb ram. I can get the irq tests to pass, but the dma test always fails. i have tried …

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Re: Gravis ultrasound classic ver 2.4 repair

Posted on 2019-07-19, 05:07

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by GoXoD

in Marvin \ Sound

in Marvin \ Sound

Thank you for the reply, ya great differences indeed, they took all the logic chips and made that gf101 chip I bet. All of the parts i had questions about are in the locations that you don't have on your model. I think I know where all the parts go, but I would still love to double check before i …

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Re: Gravis ultrasound classic ver 2.4 repair

Posted on 2019-07-17, 03:23

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by GoXoD

in Marvin \ Sound

in Marvin \ Sound

Well I got lucky on the electrolytic caps I found a txt doc I made before ordering it had all values. I would be willing to share for all if people need it. But I still dont have any values for the Ceramic capacitors. Thanks guys.

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Gravis ultrasound classic ver 2.4 repair

Posted on 2019-07-16, 12:32

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by GoXoD

in Marvin \ Sound

in Marvin \ Sound

Hi all I am working on a gus 2.4 I had to replace a lot of parts and I made the mistake of not marking some capacitors. Does any one have a schematic or listing of the values of there capacitors? I have included a picture everything from voltage regulator to the end of the card I did not mark down, …

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Re: Apple Power Macintosh 7300 video

Posted on 2018-08-20, 19:52

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by GoXoD

in Marvin \ Video

in Marvin \ Video

Thank you for the info, It figures that would be the case. I just ordered 2mb vram, thanks!

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Apple Power Macintosh 7300 video

Posted on 2018-08-20, 16:05

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by GoXoD

in Marvin \ Video

in Marvin \ Video

Not really sure where to put this question or if I should post on another forum as 90% of the posts here are pc related. I recently picked up a power Macintosh 7300 missing its cpu, bought a 200mhz one, replaced the battery and found a ati radeon 7000 mac 32m pci put it all together this morning and …

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Re: What retro activity did you get up to today?

Posted on 2017-12-11, 17:54

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by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I have been working on a mac se, it did not have its neck board after buying that i found the psu was toast. I suspect a few caps, but since another psu on ebay costs $30 i am not 100% on what way to go. Fixing psu's is one of my weak points.. dc I have no issues with, ac is not my friend. :blah: I …

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Re: G486-evb with AM486 dx4-100

Posted on 2017-01-26, 23:29

by

by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Just an update, I ordered the 3.3v reg and the 22uf cap it was outputting 4v for some odd reason. I looked over the area and found two unpopulated resistor spots and it made me think I should have got an adjustable regulator not a fixed, so i tried a 5k ohm trimmer in that spot adjusted it and It is …

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Re: G486-evb with AM486 dx4-100

Posted on 2017-01-23, 19:54

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by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Ya I have been staring at the board and I think All i need is a 3.3 fixed voltage reg and a 22uf tantalum cap for voltage smoothing. I think I am going to pull the trigger and order the parts through digikey after looking at data sheets and tracing out the voltage circuit I'm pretty confident. The …

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Re: G486-evb with AM486 dx4-100

Posted on 2017-01-23, 17:08

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by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

schematics for a 24 year old motherboard.. That would be something to see! I did some searching for them and found nothing. I think I would have better luck finding another user with them populated, and having them sending me pictures. maybe i will poke around the net for high res photos and get …

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Re: G486-evb with AM486 dx4-100

Posted on 2017-01-23, 15:47

by

by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks for the reply I thought that was the case. I am pretty decent at electronics and had a crazy thought of populating the voltage regulator and the missing components around it. Eh its probably not a good idea as I would not want to take the chance and mess up a working board. Oh well thanks …

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G486-evb with AM486 dx4-100

Posted on 2017-01-20, 18:03

by

by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi all, I am working on G486-evb with a am486 dx4-100 as you can tell by the title. The cpu says its a 3 volt processeser but the only way i can get it to post is setting the board to 5v. after further inspection, the jumper settings for voltage list 5v and 3.3v but everything connected to the …

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Re: Roland SC-88 repair

Posted on 2016-05-16, 16:31

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by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Ya I was figuring I was at a dead end without another unit with a working chip. I am still stuck on a website i found that says the reset line is low for about 5 seconds then goes high.. my unit is always high "5v", granted this website is google translated but idk still has me wondering. anyways I …

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Re: Roland SC-88 repair

Posted on 2016-05-13, 16:43

by

by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Hi all, Well after an extensive search on alibaba, aliexpress, tabao, and talking to digikey, mouser, newark, nec, and renesas "took over nec ic manufacturing" reps I am at a loss for finding a replacement part for ic27 "uPD65622GF-138-3B9" on the sc-88. This ic was a custom chip made by nec and is …

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Re: Roland SC-88 repair

Posted on 2016-04-15, 15:26

by

by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Don't worry about hijacking, I wanted this to be a reference point for people to look at when repairing there own units. That being said, heed bloodycactus's warning, do not rip off caps if the unit is working, you can just clean the whole board. caps that have leaked make the solder harder to work …

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Re: Roland SC-88 repair

Posted on 2016-03-30, 15:56

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by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I checked the input signals from the cpu, and they look like they are working. "lots of activity" so with this we would assume that either this chip gets halted on boot? or is dead. :( If its toast I think that might be the end of this unit. I did some searching and its a custom chip, the closest …

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Re: Roland SC-88 repair

Posted on 2016-03-28, 14:33

by

by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

good morning all, Using the Logic probe pins 1-7 are high pins 77, 78, 80 are high and 79 is low.. no pulsing..

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Re: Roland SC-88 repair

Posted on 2016-03-27, 03:38

by

by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

No sorry, I won't be able to check that until Monday I left the rest of the unit at work, and I have been super busy this weekend.

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Re: Roland SC-88 repair

Posted on 2016-03-26, 18:44

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by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Morning, The ic I selected was HN27c4096H I even tryed the HN27c4096G and HN27c4096 and they all dumped the same code. Nether one of those are options when i search devices in this program. I downloaded HxD to look at the code outside the programmer but it does not line up correctly im not sure what …

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Re: Roland SC-88 repair

Posted on 2016-03-25, 23:53

by

by GoXoD

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I just checked that file against a new dump and it verified good. I am using a minipro tl866cs with the software provided.

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