Video Toaster 4000 (Amiga A2000) just quit on me - Page 3

AmigaHope · 14 March 2019, 23:43

Any A500/A2000 Fat Agnus should work, OCS or ECS, though your RAM might not all be detected correctly. Any 1M ECS Fat Agnus 8372A would be most compatible, or 8375 part numbers 318069-16 (PAL) or 318069-17 (NTSC)

Tavis · 15 March 2019, 00:50

So what was this machine having a megachip benefit? I’m pretty sure there’s only 1mb of ram on the logic board. It did have that excellerator board with extra ram on it though and a video toaster.

Tavis · 23 March 2019, 03:41

I replaced the crystal and then removed the MegaChip and put the agnus directly on the main board and now I have a clock on all of the chips but still no video. Any suggestions on what to check next?

AmigaHope · 23 March 2019, 07:54

Having MegaChip lets you have more graphical screens open, or larger scrolling ones. It also lets you load more audio effects into memory without having to stream from another source. The Megachip has 1MB onboard which it uses in addition to the 1MB of chip RAM on the motherboard, thus giving you 2MB chipram. (The Agnus socket on the A2000 only has enough address lines to support 1MB, so the Megachip is a hack that has a 2MB Agnus with half the memory on the board itself) Without the megachip, you just have the 1MB on the motherboard -- an ECS Agnus can then address all of it as chipram whereas an OCS Agnus will only see 512k of it.

I think you definitely need to recheck every trace on your motherboard. I'm fairly certain the extensive corrosion is at fault -- definitely recheck the ground lines to make sure they have continuity and aren't routing through other components.

Tavis · 23 March 2019, 08:17

Quote:

Originally Posted by AmigaHope

Having MegaChip lets you have more graphical screens open, or larger scrolling ones. It also lets you load more audio effects into memory without having to stream from another source. The Megachip has 1MB onboard which it uses in addition to the 1MB of chip RAM on the motherboard, thus giving you 2MB chipram. (The Agnus socket on the A2000 only has enough address lines to support 1MB, so the Megachip is a hack that has a 2MB Agnus with half the memory on the board itself) Without the megachip, you just have the 1MB on the motherboard -- an ECS Agnus can then address all of it as chipram whereas an OCS Agnus will only see 512k of it.

I think you definitely need to recheck every trace on your motherboard. I'm fairly certain the extensive corrosion is at fault -- definitely recheck the ground lines to make sure they have continuity and aren't routing through other components.

Wow there's one meg onboard the MegaChip? that one chip is the 1 meg?
Do you think theres a chance that my MegaChip is ok but my Agnus is bad and thats what is causing it to NOT have a clock when connected to the MegaChip but it does have a clock when it's not on the MegaChip and directly on the motherboard? maybe it's faulty but good enough to have a clock on the motherboard?

Tavis · 23 March 2019, 17:52

Should the display do something other than black blank screen if the cpu is out of the socket? Trying to figure out where to trace back. Looks like I’m getting clock and address line pulses from every chip on the board.

AmigaHope · 03 April 2019, 18:29

Quote:

Originally Posted by Tavis

Wow there's one meg onboard the MegaChip? that one chip is the 1 meg?
Do you think theres a chance that my MegaChip is ok but my Agnus is bad and thats what is causing it to NOT have a clock when connected to the MegaChip but it does have a clock when it's not on the MegaChip and directly on the motherboard? maybe it's faulty but good enough to have a clock on the motherboard?

The Agnus on the MegaChip will not work properly directly on the motherboard, as it's a 2M Agnus (part used in A3000, specifically). If you're going to test without the MegaChip you need to use a 1M or 512k Agnus, appropriate to your motherboard and region. (Some Agnus are region agnostic but some are PAL/NTSC exclusive). See the part numbers I listed earlier.

1M ECS Fat Agnus 8372A would be most compatible, or 8375 part numbers 318069-16 (PAL) or 318069-17 (NTSC)

Tavis · 03 April 2019, 18:36

Quote:

Originally Posted by AmigaHope

The Agnus on the MegaChip will not work properly directly on the motherboard, as it's a 2M Agnus (part used in A3000, specifically). If you're going to test without the MegaChip you need to use a 1M or 512k Agnus, appropriate to your motherboard and region. (Some Agnus are region agnostic but some are PAL/NTSC exclusive). See the part numbers I listed earlier.

1M ECS Fat Agnus 8372A would be most compatible, or 8375 part numbers 318069-16 (PAL) or 318069-17 (NTSC)

OK thanks for the info maybe thats whats going on, my MegaChip might be bad

and now i need the other Agnus chip to find out.
I need NTSC so what could I search on eBay for besides 318069-17 ?

AmigaHope · 07 April 2019, 20:09

Quote:

Originally Posted by Tavis

OK thanks for the info maybe thats whats going on, my MegaChip might be bad

and now i need the other Agnus chip to find out.
I need NTSC so what could I search on eBay for besides 318069-17 ?

Either an 8372A or *specific variant of* 8375 will work on your motherboard.

The model# 8372A is PAL/NTSC agnostic (it uses a pin-select to determine what region mobo it's running on), so just searching for Fat Agnus 8372A should yield a part you can use.

The model# 8375 on the other hand covers a lot of subtly different and incompatible parts (why Commodore chose to do this I have no idea), so if you get an 8375 you will have to verify the part #. 8375 part# 318069-17 is for the NTSC 1M Fat Agnus that is correct for your system.

Tavis · 09 April 2019, 05:36

Quote:

Originally Posted by AmigaHope

Either an 8372A or *specific variant of* 8375 will work on your motherboard.

The model# 8372A is PAL/NTSC agnostic (it uses a pin-select to determine what region mobo it's running on), so just searching for Fat Agnus 8372A should yield a part you can use.

The model# 8375 on the other hand covers a lot of subtly different and incompatible parts (why Commodore chose to do this I have no idea), so if you get an 8375 you will have to verify the part #. 8375 part# 318069-17 is for the NTSC 1M Fat Agnus that is correct for your system.

Ok I found this one https://rover.ebay.com/rover/0/0/0?m...2F163639551546

That one should work?
Do I need to set a jumper on the board to put it in ntsc?

AmigaHope · 09 April 2019, 23:35

Quote:

Originally Posted by Tavis

Ok I found this one https://rover.ebay.com/rover/0/0/0?m...2F163639551546

That one should work?
Do I need to set a jumper on the board to put it in ntsc?

Yes that should work. The 8372A was the standard upgrade part of the time for A500/A2000 systems.

The NTSC/PAL setting is determined by pin 41 on the Agnus Socket. How you can affect this pin depends on the revision of the A2000 motherboard that you have -- however I think your NTSC board should have the pin set correctly by default for your system anyway.

Tavis · 09 April 2019, 23:47

Darn it. I waited to long and it sold.

Irl · 12 May 2019, 23:58

Just reading over this post. Have you tested the Agnus socket? As mentioned, their pins get loose over time and it could be that it isn't making appropriate contact with the MegaChip. I actually had an issue with my A2000 and discovered it was just the MegaChip was starting to work its way out of the Agnus socket. I suggest you check continuity of the socket alone, with the agnus in it, and with the MegaChip in it. You may find your results don't match between test scenarios.

Tavis · 13 May 2019, 01:11

Quote:

Originally Posted by Irl

Just reading over this post. Have you tested the Agnus socket? As mentioned, their pins get loose over time and it could be that it isn't making appropriate contact with the MegaChip. I actually had an issue with my A2000 and discovered it was just the MegaChip was starting to work its way out of the Agnus socket. I suggest you check continuity of the socket alone, with the agnus in it, and with the MegaChip in it. You may find your results don't match between test scenarios.

I have, and when i pull out the megachip and put the agnus from the megachip in directly then i do get a clock. So next step is to get an agnus that will work and rule out the megachip board.

Irl · 24 May 2019, 02:04

Sounds good. If you need any parts of a MegaChip tested for values (resistors, capacitors, etc), let me know and I will take mine apart and probe it.

Tavis · 24 May 2019, 16:49

Quote:

Originally Posted by Irl

Sounds good. If you need any parts of a MegaChip tested for values (resistors, capacitors, etc), let me know and I will take mine apart and probe it.

Thanks. What I need probably is someone to test my
Megachip on a known working Amiga.

AmigaHope · 27 May 2019, 23:01

Quote:

Originally Posted by Tavis

Thanks. What I need probably is someone to test my
Megachip on a known working Amiga.

The Megachip is definitely more valuable than the A2000 motherboard.

You might want to invest in this: http://www.diagrom.com/

It will let you debug over the serial port (assuming the CPU and serial port both work). It should help you hone in on what is broken. If just Agnus is messed up it will spit out an error message about it before dying.

Tavis · 15 March 2022, 17:34

Hey all, I am finally back to troubleshooting this.
I put an Agnus 8370 on the main board, removed all the cards so it’s stock and set the 101 jumper to the 1&2 position to address 512k right?

Anyway I’m getting data off the o’scope and the power led is blinking and the display is cycling shades of gray.

Would this happen if the ribbon cable to the floppy and hard drive are not connected? I just noticed what looks like a broken connector pin where the ribbon cable attaches.

Please see this video link: [ Show youtube player ]

Tavis · 15 March 2022, 19:43

The power led is blinking 6 times, then a pause, and then one more blink and it repeats.

The screen is self testing starting at black, then dark gray, lighter gray, lighter gray, and finally white and the. Repeats.

According to the error codes guide I found online the screen is saying everything is checking out ok but all I have found about the led blinking 6 times is saying corrosion in battery area. I haven’t found any bad traces yet but not sure exactly where to look. I removed the battery years ago.

I also swapped both CIA chips and no change.

Tavis · 15 March 2022, 21:41

its alive!
I had to move J300 to the 2&3 position and now it boots!
Looks like me Megachip is bad though

What Agnus can i get that would work in the megachip on NTSC so I can rule that out?

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14 March 2019, 23:43	#41
AmigaHope Registered User Join Date: Sep 2006 Location: New Sandusky Posts: 942	Any A500/A2000 Fat Agnus should work, OCS or ECS, though your RAM might not all be detected correctly. Any 1M ECS Fat Agnus 8372A would be most compatible, or 8375 part numbers 318069-16 (PAL) or 318069-17 (NTSC)

15 March 2019, 00:50	#42
Tavis Registered User Join Date: Feb 2019 Location: San Diego / USA Posts: 162	So what was this machine having a megachip benefit? I’m pretty sure there’s only 1mb of ram on the logic board. It did have that excellerator board with extra ram on it though and a video toaster.

23 March 2019, 03:41	#43
Tavis Registered User Join Date: Feb 2019 Location: San Diego / USA Posts: 162	I replaced the crystal and then removed the MegaChip and put the agnus directly on the main board and now I have a clock on all of the chips but still no video. Any suggestions on what to check next?

23 March 2019, 07:54	#44
AmigaHope Registered User Join Date: Sep 2006 Location: New Sandusky Posts: 942	Having MegaChip lets you have more graphical screens open, or larger scrolling ones. It also lets you load more audio effects into memory without having to stream from another source. The Megachip has 1MB onboard which it uses in addition to the 1MB of chip RAM on the motherboard, thus giving you 2MB chipram. (The Agnus socket on the A2000 only has enough address lines to support 1MB, so the Megachip is a hack that has a 2MB Agnus with half the memory on the board itself) Without the megachip, you just have the 1MB on the motherboard -- an ECS Agnus can then address all of it as chipram whereas an OCS Agnus will only see 512k of it. I think you definitely need to recheck every trace on your motherboard. I'm fairly certain the extensive corrosion is at fault -- definitely recheck the ground lines to make sure they have continuity and aren't routing through other components.

23 March 2019, 17:52	#46
Tavis Registered User Join Date: Feb 2019 Location: San Diego / USA Posts: 162	Should the display do something other than black blank screen if the cpu is out of the socket? Trying to figure out where to trace back. Looks like I’m getting clock and address line pulses from every chip on the board.

09 April 2019, 23:47	#52
Tavis Registered User Join Date: Feb 2019 Location: San Diego / USA Posts: 162	Darn it. I waited to long and it sold.

12 May 2019, 23:58	#53
Irl Registered User Join Date: Feb 2017 Location: Denver Posts: 76	Just reading over this post. Have you tested the Agnus socket? As mentioned, their pins get loose over time and it could be that it isn't making appropriate contact with the MegaChip. I actually had an issue with my A2000 and discovered it was just the MegaChip was starting to work its way out of the Agnus socket. I suggest you check continuity of the socket alone, with the agnus in it, and with the MegaChip in it. You may find your results don't match between test scenarios.

24 May 2019, 02:04	#55
Irl Registered User Join Date: Feb 2017 Location: Denver Posts: 76	Sounds good. If you need any parts of a MegaChip tested for values (resistors, capacitors, etc), let me know and I will take mine apart and probe it.

15 March 2022, 17:34	#58
Tavis Registered User Join Date: Feb 2019 Location: San Diego / USA Posts: 162	Hey all, I am finally back to troubleshooting this. I put an Agnus 8370 on the main board, removed all the cards so it’s stock and set the 101 jumper to the 1&2 position to address 512k right? Anyway I’m getting data off the o’scope and the power led is blinking and the display is cycling shades of gray. Would this happen if the ribbon cable to the floppy and hard drive are not connected? I just noticed what looks like a broken connector pin where the ribbon cable attaches. Please see this video link: [ Show youtube player ]

15 March 2022, 19:43	#59
Tavis Registered User Join Date: Feb 2019 Location: San Diego / USA Posts: 162	The power led is blinking 6 times, then a pause, and then one more blink and it repeats. The screen is self testing starting at black, then dark gray, lighter gray, lighter gray, and finally white and the. Repeats. According to the error codes guide I found online the screen is saying everything is checking out ok but all I have found about the led blinking 6 times is saying corrosion in battery area. I haven’t found any bad traces yet but not sure exactly where to look. I removed the battery years ago. I also swapped both CIA chips and no change.

15 March 2022, 21:41	#60
Tavis Registered User Join Date: Feb 2019 Location: San Diego / USA Posts: 162	its alive! I had to move J300 to the 2&3 position and now it boots! Looks like me Megachip is bad though What Agnus can i get that would work in the megachip on NTSC so I can rule that out?

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