A3640 diagnostic help, GALs not working?

jbenam · 14 June 2021, 09:42

Hi everyone,

While trying to do SpeedGeek's state mod for A3640, I have used truly sucky tools for hot air (as I am extremely impatient) to remove the GALs and put some sockets in.

Anyway, the sockets kinda worked (sometimes I had to press on one of the GALs) and I discovered that some of the new GALs I had burnt (ATF22V10C and ATF16V8C at 5ns and 7ns respectively) were not working correctly. I didn't have the foresight to flash the original JEDs just to check if it was some incompatibility with SpeedGeek's mod or not, but anyway I decided to remove the sockets and finally use a decent hot air station to put them back in.

After soldering everything back... The A4000D doesn't boot anymore. Since I know Chucky and the others always advice to not use sockets, I have resoldered everything back by hand aaaand.... it still doesn't work.

Before doing this, I tried verifying the GALs with my TL866II (XGecu Pro) and only one of them was correctly verified. I just thought it was something to do with GAL encryption and left that alone.

Before desoldering and resoldering everything for the Nth time:

1) Can I actually verify the original GAL 22V10B and 16V8Bs in my TL866s? I have read on another thread that they should actually be unprotected so in theory it should work - if that's the case some of my original GALs became damaged or corrupted (how?).

2) Are GAL timings binding? I mean, are my 7ns and 5ns GALs going to be working or not? I am currently using the 5ns GALs for the PIO2 mod and it's working fine.

Anything else I can try? I have a logic probe but no oscilloscope (I should definitely buy one...). Thanks.

SpeedGeek · 14 June 2021, 13:45

Sorry, to hear about your bad luck. You might want to consider sending your A3640 to vibros but you will need to contact him on Amibay.

https://www.amibay.com/showthread.ph...state-on-A3640

jbenam · 14 June 2021, 14:41

Quote:

Originally Posted by SpeedGeek

Sorry, to hear about your bad luck. You might want to consider sending your A3640 to vibros but you will need to contact him on Amibay.

https://www.amibay.com/showthread.ph...state-on-A3640

Hi, thanks for the link - while vibros' price is quite acceptable indeed, I can do everything myself as I have the right equipment (I do actually have a brand-new top-tier hot air station which I am itching to use, along with my top-tier Metcal soldering station) and the expertise to do so, I just need to know if there is a way to confirm somehow that the GALs are working or not without having another A3640 around (which I do not own).

The mod went wrong since I got impatient and tried doing this without a proper hot-air station the first time around. Uh, and also because it isn't really specified anywhere anything about using faster GAL timings and/or ATFs in place of GALs.

If I need an oscilloscope to understand what is going on, then it is high time that I do get one - I just need to be sure that I do need one

reinauer · 16 June 2021, 07:18

I ran into some problems too with GALs:

* You have to use UES mode when programming ATF22V10C. Otherwise the input files are not compatible (they will program but not work) Not sure if all programmer software supports UES mode. On the 16V8 there is no such mode, they are fine with "normal mode"
* There are a few different dumps of A3640 GALs out there, and depending on the programmer the file format, while technically equivalent, becomes incompatible with some other programmers. In my case I am using a Galep5 programmer and it read the speedgeek files just fine but NOT the other GALs that John Hertell has for download (I believe those are the Dave Haynie ones?)
* I have found timing of the chips to be largely inconsequential in practice, at least as long as you go faster. But I have gone slower on a lot of them in the past and it has never even once caused the system to not boot
* Chances are however, especially if you buy Lattice GALs off eBay that they are not what is printed on them. Generally I have seen slower chips relabeled as faster ones, or what seemed like just dead, black blobs. Buy only ATFs and be happy.
* The A3640 files should verify just fine. If they don't either your software or your programmer or your GALs are bad.
* That theatre around sockets is a bit of a cargo cult. Put sockets down. They cost very little but will save you lots of head aches. Yes, you will miss pins. Practice. Check every pin with a needle or dentist's tool. Fix it. Try again. Only leave the sockets off if you have a second card with sockets in which you can test the GALs before soldering them down.
* (off-topic) PLCC in general is a mess to solder. If you use 22V10 in your own design, use TSSOP.

Logic probe might be more useful that an oscilloscope. Maybe start following the signals around, starting with clocks. But there's a lot you can do before.

- do you get anything from DiagROM (eg on the serial console)
- Does the power LED change brightness?
- Is your screen black? dark gray? light gray?

jbenam · 17 June 2021, 00:45

Hi, thanks for your very informative post!

1) This explains why the ATF16V8C worked fine for the PIO2 mod while the A3640 mod went nowhere. My TL866II seems to support UES mode.
2) I'll try both the Speedgeek ones and the ones Chucky put on his site. I need to do a byte comparison of the ones on the Amigawiki, those on there are definitely from Dave Haynie himself.
3) Excellent news. I should be okay with my 7ns/5ns ones then.
4) And that's exactly why I went for the ATFs from Digikey, I don't trust the eBay resellers enough.
5) One of the 22V10 verified fine, the others didn't. This could explain why my properly socketed trial run went nowhere, even if everything looked to be properly soldered.
6) Damn, so true - it took me ages to solder them by hand while I can socket everything in short order with hot air + solder paste. And that's using a super el-cheapo Chinese brand (Mechanic). Can't wait to purchase some Kester.
7) Haven't designed anything yet but yes, TSSOP is so much better. You can also drag solder it easily.

Now about the troubleshooting questions:

1) Nothing at all on screen, I was looking for my null-modem cable which I have finally found, so I will have a look at the serial output soon.
2) It doesn't.
3) Black. It's the same if I remove the CPU card entirely.

I will have a look with my logic probe and see if I can get clocks.

Thanks again for the very helpful post, will report back.

jbenam · 19 June 2021, 15:08

Thar she blows (again)!

One of my old GALs was corrupted. It was just that.

Pro-tip if anyone has the same issue in the future: GALs can be easily read out so you can verify the contents. The same can't be done for ATFs, these needs to be encrypted for them to work. At least with my TL866II.

Also the UES tip was awesome - my 22V10s most certainly weren't being programmed right without it.

Soldering the sockets with my new hot air station was a breeze and it went well on first try. Onwards to more A3640 mods along with the Ramsey mod

Thank you reinauer for taking the time to read my long-winded posts and point me towards the solution!

hooverphonique · 19 June 2021, 16:51

Quote:

Originally Posted by jbenam

Onwards to more A3640 mods along with the Ramsey mod

Are you talking about the read-waitstate or 64/112MB mod?
Because the former doesn't work with the Ramsey present in the A4000D, I already tried this while discussing it with SpeedGeek (in a thread on Amibay).

jbenam · 19 June 2021, 17:33

Quote:

Originally Posted by hooverphonique

Are you talking about the read-waitstate or 64/112MB mod?
Because the former doesn't work with the Ramsey present in the A4000D, I already tried this while discussing it with SpeedGeek (in a thread on Amibay).

Welp, you're right. One less mod to do I guess.

I will just do the 64MB mod (I still want to be able to use SpeedRamsey) and the A3640's delay line mod...

That should be all, from what I can remember?

hooverphonique · 20 June 2021, 12:53

Quote:

Originally Posted by jbenam

I will just do the 64MB mod (I still want to be able to use SpeedRamsey) and the A3640's delay line mod...

I have the 64MB mod in mine, and with the system overclocked to 33MHz, speedramsey isn't reliable (I've got 60ns 16MB SIMMs).

jbenam · 20 June 2021, 17:24

Quote:

Originally Posted by hooverphonique

I have the 64MB mod in mine, and with the system overclocked to 33MHz, speedramsey isn't reliable (I've got 60ns 16MB SIMMs).

Hmm, I guess I will give it a try anyway, maybe I will be lucky with the overclocking lottery

Thanks for the heads-up!

14 June 2021, 09:42	#1
jbenam Italian Amiga Zealot Join Date: Jan 2009 Location: Italy Age: 36 Posts: 1,912	A3640 diagnostic help, GALs not working? Hi everyone, While trying to do SpeedGeek's state mod for A3640, I have used truly sucky tools for hot air (as I am extremely impatient) to remove the GALs and put some sockets in. Anyway, the sockets kinda worked (sometimes I had to press on one of the GALs) and I discovered that some of the new GALs I had burnt (ATF22V10C and ATF16V8C at 5ns and 7ns respectively) were not working correctly. I didn't have the foresight to flash the original JEDs just to check if it was some incompatibility with SpeedGeek's mod or not, but anyway I decided to remove the sockets and finally use a decent hot air station to put them back in. After soldering everything back... The A4000D doesn't boot anymore. Since I know Chucky and the others always advice to not use sockets, I have resoldered everything back by hand aaaand.... it still doesn't work. Before doing this, I tried verifying the GALs with my TL866II (XGecu Pro) and only one of them was correctly verified. I just thought it was something to do with GAL encryption and left that alone. Before desoldering and resoldering everything for the Nth time: 1) Can I actually verify the original GAL 22V10B and 16V8Bs in my TL866s? I have read on another thread that they should actually be unprotected so in theory it should work - if that's the case some of my original GALs became damaged or corrupted (how?). 2) Are GAL timings binding? I mean, are my 7ns and 5ns GALs going to be working or not? I am currently using the 5ns GALs for the PIO2 mod and it's working fine. Anything else I can try? I have a logic probe but no oscilloscope (I should definitely buy one...). Thanks.

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14 June 2021, 13:45	#2
SpeedGeek Moderator Join Date: Dec 2010 Location: Wisconsin USA Age: 60 Posts: 841	Sorry, to hear about your bad luck. You might want to consider sending your A3640 to vibros but you will need to contact him on Amibay. https://www.amibay.com/showthread.ph...state-on-A3640

16 June 2021, 07:18	#4
reinauer Registered User Join Date: Jan 2020 Location: Mountain View, California Posts: 56	I ran into some problems too with GALs: * You have to use UES mode when programming ATF22V10C. Otherwise the input files are not compatible (they will program but not work) Not sure if all programmer software supports UES mode. On the 16V8 there is no such mode, they are fine with "normal mode" * There are a few different dumps of A3640 GALs out there, and depending on the programmer the file format, while technically equivalent, becomes incompatible with some other programmers. In my case I am using a Galep5 programmer and it read the speedgeek files just fine but NOT the other GALs that John Hertell has for download (I believe those are the Dave Haynie ones?) * I have found timing of the chips to be largely inconsequential in practice, at least as long as you go faster. But I have gone slower on a lot of them in the past and it has never even once caused the system to not boot * Chances are however, especially if you buy Lattice GALs off eBay that they are not what is printed on them. Generally I have seen slower chips relabeled as faster ones, or what seemed like just dead, black blobs. Buy only ATFs and be happy. * The A3640 files should verify just fine. If they don't either your software or your programmer or your GALs are bad. * That theatre around sockets is a bit of a cargo cult. Put sockets down. They cost very little but will save you lots of head aches. Yes, you will miss pins. Practice. Check every pin with a needle or dentist's tool. Fix it. Try again. Only leave the sockets off if you have a second card with sockets in which you can test the GALs before soldering them down. * (off-topic) PLCC in general is a mess to solder. If you use 22V10 in your own design, use TSSOP. Logic probe might be more useful that an oscilloscope. Maybe start following the signals around, starting with clocks. But there's a lot you can do before. - do you get anything from DiagROM (eg on the serial console) - Does the power LED change brightness? - Is your screen black? dark gray? light gray?

17 June 2021, 00:45	#5
jbenam Italian Amiga Zealot Join Date: Jan 2009 Location: Italy Age: 36 Posts: 1,912	Hi, thanks for your very informative post! 1) This explains why the ATF16V8C worked fine for the PIO2 mod while the A3640 mod went nowhere. My TL866II seems to support UES mode. 2) I'll try both the Speedgeek ones and the ones Chucky put on his site. I need to do a byte comparison of the ones on the Amigawiki, those on there are definitely from Dave Haynie himself. 3) Excellent news. I should be okay with my 7ns/5ns ones then. 4) And that's exactly why I went for the ATFs from Digikey, I don't trust the eBay resellers enough. 5) One of the 22V10 verified fine, the others didn't. This could explain why my properly socketed trial run went nowhere, even if everything looked to be properly soldered. 6) Damn, so true - it took me ages to solder them by hand while I can socket everything in short order with hot air + solder paste. And that's using a super el-cheapo Chinese brand (Mechanic). Can't wait to purchase some Kester. 7) Haven't designed anything yet but yes, TSSOP is so much better. You can also drag solder it easily. Now about the troubleshooting questions: 1) Nothing at all on screen, I was looking for my null-modem cable which I have finally found, so I will have a look at the serial output soon. 2) It doesn't. 3) Black. It's the same if I remove the CPU card entirely. I will have a look with my logic probe and see if I can get clocks. Thanks again for the very helpful post, will report back.

19 June 2021, 15:08	#6
jbenam Italian Amiga Zealot Join Date: Jan 2009 Location: Italy Age: 36 Posts: 1,912	Thar she blows (again)! One of my old GALs was corrupted. It was just that. Pro-tip if anyone has the same issue in the future: GALs can be easily read out so you can verify the contents. The same can't be done for ATFs, these needs to be encrypted for them to work. At least with my TL866II. Also the UES tip was awesome - my 22V10s most certainly weren't being programmed right without it. Soldering the sockets with my new hot air station was a breeze and it went well on first try. Onwards to more A3640 mods along with the Ramsey mod Thank you reinauer for taking the time to read my long-winded posts and point me towards the solution!

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