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Myarc cards for sale/repair tips


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1 hour ago, GDMike said:

I hate handling these myself, just put them in and leave em, take photos prior to install.

This is a very, very good habit.  I recently started doing the same during repair work as @Shift838 can attest to. It is soooo convenient and such a potential 'life' saver!

 

Speaking of glue....

To secure the wires, what do people recommend, keeping in mind that many Geneves are fragile and may not take kindly to the adhesive's removal..?

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55 minutes ago, InsaneMultitasker said:

To secure the wires, what do people recommend, keeping in mind that many Geneves are fragile and may not take kindly to the adhesive's removal..?

Small dabs of hot glue; if the glue needs to be removed, isopropyl alcohol will detach the drop of glue from the board without damaging the board or leaving any residue at all.

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6 hours ago, RickyDean said:

As I said, when I pulled it from storage the wire was broke off and floating, at the same time as that resistor was pulled out of the jumper hole. I do not know if it was originally connected to that resistor or not, thought when I "fixed" it the Geneve seemed to work and boot. But somewhere in that process,  the other end came loose and as I did not take pictures, I didn't know where it went. I looked over the points and tried to picture which solder point it had been attached to, so as it looked like it could have been attached to that point at the regulator, I attached it there. That's how I believe I remember it.

The red wire doesn't look long enough to have been attached between the two likely connection points, so we need to confirm whether or not there is continuity between the two 'pin 2' of the Atmel and RAM, which also should have continuity with the blue wire with the red X.  

 

 If there is no continuity, then my best guess is the wire running through the circled through-hole was yanked from pin 2 of the 128k chip, through the hole.  A new wire would need to be routed through the hole - one end affixed to the underside of the 128Kx3 chip stack pin 2, the other end to the red X with the blue wire.   Mind you, this is only a guess based on the pictures and process of elimination.

 

image.png.fd2997f91c647cf121f134054c16eab6.png

 

 

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3 minutes ago, InsaneMultitasker said:

The red wire doesn't look long enough to have been attached between the two likely connection points, so we need to confirm whether or not there is continuity between the two 'pin 2' of the Atmel and RAM, which also should have continuity with the blue wire with the red X.  

 

 If there is no continuity, then my best guess is the wire running through the circled through-hole was yanked from pin 2 of the 128k chip, through the hole.  A new wire would need to be routed through the hole - one end affixed to the underside of the 128Kx3 chip stack pin 2, the other end to the red X with the blue wire.   Mind you, this is only a guess based on the pictures and process of elimination.

 

image.png.fd2997f91c647cf121f134054c16eab6.png

 

 

Okay, my fluke died today, will need to get another battery tomorrow and try again. I figure that could be a likely scenario, and I just thought it could have been attached to the resistor.

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Later this year if time permits I will try to document the PFM+/384K combo installation.  I've said this before: some of my sketches were drawn without all necessary info and/or in a confusing manner due to (the actions of) a few unscrupulous people.  That was all well and good when the modification process was fresh in my mind 25+ years ago.  Once we started using the 512K chips to simplify the design and work, there was no looking back.  

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18 hours ago, InsaneMultitasker said:

The red wire doesn't look long enough to have been attached between the two likely connection points, so we need to confirm whether or not there is continuity between the two 'pin 2' of the Atmel and RAM, which also should have continuity with the blue wire with the red X.  

 

 If there is no continuity, then my best guess is the wire running through the circled through-hole was yanked from pin 2 of the 128k chip, through the hole.  A new wire would need to be routed through the hole - one end affixed to the underside of the 128Kx3 chip stack pin 2, the other end to the red X with the blue wire.   Mind you, this is only a guess based on the pictures and process of elimination.

 

image.png.fd2997f91c647cf121f134054c16eab6.png

 

 

Well got a new battery,  the Fluke is purring like a kitten. I am getting continuity between pin two of the 128k ram and the 29c010.

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20 hours ago, InsaneMultitasker said:

It's directly proportional to how many times the card has been shipped. ;)

 

For these mods, the cards were always intended to be kept inside their respective cases, and nearly all 384k/pfm modified Geneves started with their own case. Back in the day, a case was added if the customer did not have one. Many customers removed the cases because of past overheating problems, even after replacing the regulator and heat sink made doing so unnecessary.

 

Wires do not just fall off for no reason.

 

Yeh, Mine was in installed in a whopping big tower case and I was constantly updating and adding functionality. I had removed the case to built a cage to hold the top of each card to prevent "droop", and to facilitate my additional backplane, that I made a connection cable for as depicted here on AtariAge a few years ago. The case was placed in small storage which became deep storage for 17 years in a semi trailer. The tower was stripped down and the Geneve(s) and other cards stored in heavier storage cases, bare nekked, till I started pulling them out 6 years ago. Hence the original wire issue.

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5 minutes ago, RickyDean said:

Well got a new battery,  the Fluke is purring like a kitten. I am getting continuity between pin two of the 128k ram and the 29c010.

Ok.Let's think about this differently. Some Geneve's had one or two red wires to correct problems with the board revision. Let me pull open my Geneve cards to look for a possible match in that location, as I'm pretty sure there is one correction near the top that I've seen in the past...

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1 hour ago, RickyDean said:

I am getting continuity between pin two of the 128k ram and the 29c010.

I have one card with a modification in that same area, however, upon closer inspection of your picture, I can see that the trace is routed to the correct through-hole.   Are you comfortable with removing the 384K chip stack from the socket so we can see what's going on with that stack?  Nothing else is coming to mind at the moment.

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38 minutes ago, InsaneMultitasker said:

I have one card with a modification in that same area, however, upon closer inspection of your picture, I can see that the trace is routed to the correct through-hole.   Are you comfortable with removing the 384K chip stack from the socket so we can see what's going on with that stack?  Nothing else is coming to mind at the moment.

Yes, just remove the chips from the socket or disconnect the wires too?

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On 1/26/2021 at 6:35 PM, RickyDean said:

Yes, just remove the chips from the socket or disconnect the wires too?

Just carefully pry the 128x3 stack, from the DRAM side of the board.  I traced the wires that are soldered to my Geneve's memory stack:

 

Pin 30 and 32 are connected to each other via a short jumper on the chip stack

Pin 31 runs via a red wire to JM3 pins 1,2 (which are jumpered), located just to the left of the battery, and is partially obscured when the memory is in the socket

Pin 22, top 128k chip, runs to the LS138 (under the 139) pin 11

Pin 22, middle 128k chip, runs to the LS138 (under the 139) pin 10

Pin 2 runs a blue wire to a jumper to the left of the 9995 (where my earlier photo of the underside shows two wires connected to the same point)

For reference, LS138 pin 9 wire runs to the throughhole directly below the battery, where the print should say 'C128'

 

Not the best markup but it might help to ensure we care referencing the same pins. 

image.thumb.png.a0d3b031834cae5da7c8912424727c34.png

 

 

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12 minutes ago, InsaneMultitasker said:

Just carefully pry the 128x3 stack, from the DRAM side of the board.  I traced the wires that are soldered to my Geneve's memory stack:

 

Pin 30 and 32 are connected to each other via a short jumper on the chip stack

Pin 31 runs via a red wire to JM3 pins 1,2 (which are jumpered), located just to the left of the battery, and is partially obscured when the memory is in the socket

Pin 22, top 128k chip, runs to the LS138 (under the 139) pin 11

Pin 22, middle 128k chip, runs to the LS138 (under the 139) pin 10

Pin 2 runs a blue wire to a jumper to the left of the 9995 (where my earlier photo of the underside shows two wires connected to the same point)

For reference, LS138 pin 9 wire runs to the throughhole directly below the battery, where the print should say 'C128'

 

Not the best markup but it might help to ensure we care referencing the same pins. 

image.thumb.png.a0d3b031834cae5da7c8912424727c34.png

 

 

Okay, I'll trace those down tomorrow sometime, I am uploading 3 photos I took. In the next post. Running out of data minutes and all is slowing down.

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23 hours ago, InsaneMultitasker said:

Just carefully pry the 128x3 stack, from the DRAM side of the board.  I traced the wires that are soldered to my Geneve's memory stack:

 

Pin 30 and 32 are connected to each other via a short jumper on the chip stack

Pin 31 runs via a red wire to JM3 pins 1,2 (which are jumpered), located just to the left of the battery, and is partially obscured when the memory is in the socket

Pin 22, top 128k chip, runs to the LS138 (under the 139) pin 11

Pin 22, middle 128k chip, runs to the LS138 (under the 139) pin 10

Pin 2 runs a blue wire to a jumper to the left of the 9995 (where my earlier photo of the underside shows two wires connected to the same point)

For reference, LS138 pin 9 wire runs to the throughhole directly below the battery, where the print should say 'C128'

 

Not the best markup but it might help to ensure we care referencing the same pins. 

image.thumb.png.a0d3b031834cae5da7c8912424727c34.png

 

 

Okay,  you state that 1 and 2 should be jumpered, meaning there should be continuity between them. There is not. So could this red wire be the missing blue wire you just mentioned?

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1 hour ago, RickyDean said:

Okay,  you state that 1 and 2 should be jumpered, meaning there should be continuity between them. There is not. So could this red wire be the missing blue wire you just mentioned

Unlikely, as the jumper is usually just a piece of wire soldered into the two through holes.  Holes 1 and 2 are only about 1/8 inch apart.

 

Just to clarify, the 1 and 2 refers to the jumper holes, not pins on the memory chip.  I'll double-check my card this weekend just in case I gave the wrong numbers. 

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50 minutes ago, InsaneMultitasker said:

Unlikely, as the jumper is usually just a piece of wire soldered into the two through holes.  Holes 1 and 2 are only about 1/8 inch apart.

 

Just to clarify, the 1 and 2 refers to the jumper holes, not pins on the memory chip.  I'll double-check my card this weekend just in case I gave the wrong numbers. 

2 is the hole that the resistor is soldered into. Mine was the one that had been pulled out, there is no continuity between one and two, and if a wire was soldered there, there should be. Any how I believe the core was pulled from two when I found the resistor pulled out after removing from storage. I did some repair there and placed in the resistor back then. So should I connect 1&2 then place a wire were your blue one runs and see if she boots up?

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I'll compare the pictures to my Geneve.  At first glance, it looks to be correctly wired, peculiar jumper wires aside.

 

Note that schematic is wrong for JM3 and JM2.  My penciled-in notes are as-built and based on what I see in the picture, your JM3 is labeled properly.

 

The +5 for jumper pin 2 (JM2 and JM3) should connect to 5v from the bottom, front 5v regulator, based on the schematic. I will confirm.

 

image.thumb.png.88838516a2f0a3e0a64a545b5f4a3103.png

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1. The schematic corrections penciled in are correct.  I confirmed with both an unmodified, working Geneve and the 384K stacked Geneve.  

2. JM2 and JM3 jumper hole 2 is confirmed as connecting to the bottom, front 5v regulator output.  

3. The 384k Jumper changes to JM2 and JM3 are correct; both jumpers are to be moved from pins 1-2 to 1-3, enabling AB1 and AB0.  

 

4. Remove one end of the mystery red wire and then confirm continuity:  

a. JM3 hole 2 (test top AND bottom) must connect to the +5 output of the bottom, front 5v regulator. Both sides of the through hole/ must be tested due to the core hole problem you referenced. 

b. Between the regulator output and the resistor lead soldered to hole 2. 

c. Confirm the through hole is NOT connected to the ground plane.

 

5. This red wire is correct, we see jumper between 1-3 on JM3 and the red wire appears to connect to memory pin 31. 

a. My earlier comment in post 389 re: JM3 was incorrect.

b. The white wire should tie into JM1 pin 3 (next to the 9995), it appears to be heading that direction from your pin.

 

image.png.0b108d77f6f700dd47e4357ba176a2d6.png

 

 

6. Based on picture below

a. Did you confirm the other red wire here provides continuity between memory pins 30-32?  This is necessary to power the SRAM. 

b. Also confirm the jumper wire is not shorting to pin 31.

image.png.1b9028f662ef8a48e520e8a0334d7b8c.png

 

 

 

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5 minutes ago, InsaneMultitasker said:

1. The schematic corrections penciled in are correct.  I confirmed with both an unmodified, working Geneve and the 384K stacked Geneve.  

2. JM2 and JM3 jumper hole 2 is confirmed as connecting to the bottom, front 5v regulator output.  

3. The 384k Jumper changes to JM2 and JM3 are correct; both jumpers are to be moved from pins 1-2 to 1-3, enabling AB1 and AB0.  

 

4. Remove one end of the mystery red wire and then confirm continuity:  

a. JM3 hole 2 (test top AND bottom) must connect to the +5 output of the bottom, front 5v regulator. Both sides of the through hole/ must be tested due to the core hole problem you referenced. 

b. Between the regulator output and the resistor lead soldered to hole 2. 

c. Confirm the through hole is NOT connected to the ground plane.

 

5. This red wire is correct, we see jumper between 1-3 on JM3 and the red wire appears to connect to memory pin 31. 

a. My earlier comment in post 389 re: JM3 was incorrect.

b. The white wire should tie into JM1 pin 3 (next to the 9995), it appears to be heading that direction from your pin.

 

image.png.0b108d77f6f700dd47e4357ba176a2d6.png

 

 

6. Based on picture below

a. Did you confirm the other red wire here provides continuity between memory pins 30-32?  This is necessary to power the SRAM. 

b. Also confirm the jumper wire is not shorting to pin 31.

image.png.1b9028f662ef8a48e520e8a0334d7b8c.png

 

 

 

Okay, was setting down to work on my Corcomp Ramdisk, will do this instead.

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1 hour ago, arcadeshopper said:

I have a genmod Geneve I picked up from bill in az and it has this loose cap right below the orange bodge wire.. I assume I need to put it back in there

Yes, though the preferred course of action is to replace it considering the potential force applied to remove it. Is the through-hole core intact?

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