Any trick to discharging ADM-3A
So I was about to swap out my ADM5 for my ADM3a with my ALTAIR and realized while I did replace the electrolytic and tantalum caps on the main board, I didn’t change the electrolytic caps on the analog board behind the tube. No big deal except that the rubber cup is on the top where I can’t get to it without removing the tube and you aren’t really supposed to remove the tube till you discharge it under the rubber cup. So chicken or the egg? Or am I just supposed to let the ADM sit unplugged for a few weeks and just assume it self discharged? Just when I thought I was finished with this project and was going to move onto my TI silent rebuild. Thanks, Cheers, Corey corey cohen uǝɥoɔ ʎǝɹoɔ
On 02/07/2018 06:29 PM, corey cohen via vcf-midatlantic wrote:
So I was about to swap out my ADM5 for my ADM3a with my ALTAIR and realized while I did replace the electrolytic and tantalum caps on the main board, I didn’t change the electrolytic caps on the analog board behind the tube.
No big deal except that the rubber cup is on the top where I can’t get to it without removing the tube and you aren’t really supposed to remove the tube till you discharge it under the rubber cup. So chicken or the egg?
I didn't work on any ADM so I can't say. Just recall being taught to take this heavy gauge stranded wire, attached to a 3 foot long screw driver and ram it carefully under the rubber boot until it touched the prongs in the tube. CRACK! when the power. Not one of my favorite jobs. -- Linux Home Automation Neil Cherry ncherry@linuxha.com http://www.linuxha.com/ Main site http://linuxha.blogspot.com/ My HA Blog Author of: Linux Smart Homes For Dummies
I don't remember any particular trick or real difficulty in doing it. Maybe you needed to get the tube loose to get the screwdriver in there? But I thought it would fit in there without too much problem. I know I've done it a whole bunch of times and nothing sticks out at me as being out of the ordinary about working on the 3A. Remember you don't need to disconnect the anode connection right away, just discharge it. If you're doing a lot of work on one of those monitors, sometimes you do need to get a bit creative though: https://i.imgur.com/k2wPmw3.jpg https://i.imgur.com/UwU3gek.jpg -Ian On Wed, Feb 7, 2018 at 6:29 PM, corey cohen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
So I was about to swap out my ADM5 for my ADM3a with my ALTAIR and realized while I did replace the electrolytic and tantalum caps on the main board, I didn’t change the electrolytic caps on the analog board behind the tube.
No big deal except that the rubber cup is on the top where I can’t get to it without removing the tube and you aren’t really supposed to remove the tube till you discharge it under the rubber cup. So chicken or the egg?
Or am I just supposed to let the ADM sit unplugged for a few weeks and just assume it self discharged?
Just when I thought I was finished with this project and was going to move onto my TI silent rebuild.
Thanks, Cheers, Corey
corey cohen uǝɥoɔ ʎǝɹoɔ
I’ve done the screwdriver trick myself. Because often, even after waiting a few weeks, there can still be enough voltage to make your hair stand on end. LOL On Wed, Feb 7, 2018 at 7:05 PM Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I don't remember any particular trick or real difficulty in doing it. Maybe you needed to get the tube loose to get the screwdriver in there? But I thought it would fit in there without too much problem. I know I've done it a whole bunch of times and nothing sticks out at me as being out of the ordinary about working on the 3A. Remember you don't need to disconnect the anode connection right away, just discharge it.
If you're doing a lot of work on one of those monitors, sometimes you do need to get a bit creative though:
https://i.imgur.com/k2wPmw3.jpg https://i.imgur.com/UwU3gek.jpg
-Ian
On Wed, Feb 7, 2018 at 6:29 PM, corey cohen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
So I was about to swap out my ADM5 for my ADM3a with my ALTAIR and realized while I did replace the electrolytic and tantalum caps on the main board, I didn’t change the electrolytic caps on the analog board behind the tube.
No big deal except that the rubber cup is on the top where I can’t get to it without removing the tube and you aren’t really supposed to remove the tube till you discharge it under the rubber cup. So chicken or the egg?
Or am I just supposed to let the ADM sit unplugged for a few weeks and just assume it self discharged?
Just when I thought I was finished with this project and was going to move onto my TI silent rebuild.
Thanks, Cheers, Corey
corey cohen uǝɥoɔ ʎǝɹoɔ
-- Normal Person: Hey, it seems that you know a lot. Geek: To be honest, it's due to all the surfing I do. Normal Person: So you go surfing? Normal Person: But I don't think that has anything to do with knowing a lot... Geek: I think that's wrong on a fundamental level. Normal Person: Huh? Huh? What?
Ok. Well then let me ask you and Ian this.. Can I safely disconnect the plug at the end of the CRT neck without discharging? That would make it easier to take the tube out while the anode wire is still connected and then in can discharge the tube with a screwdriver. Also is the best place to clip onto the implosion bracket since the ADM doesn’t really have a metal chassis? Thanks, Corey corey cohen uǝɥoɔ ʎǝɹoɔ
On Feb 8, 2018, at 12:01 AM, Joseph Oprysko via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I’ve done the screwdriver trick myself. Because often, even after waiting a few weeks, there can still be enough voltage to make your hair stand on end. LOL
On Wed, Feb 7, 2018 at 7:05 PM Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I don't remember any particular trick or real difficulty in doing it. Maybe you needed to get the tube loose to get the screwdriver in there? But I thought it would fit in there without too much problem. I know I've done it a whole bunch of times and nothing sticks out at me as being out of the ordinary about working on the 3A. Remember you don't need to disconnect the anode connection right away, just discharge it.
If you're doing a lot of work on one of those monitors, sometimes you do need to get a bit creative though:
https://i.imgur.com/k2wPmw3.jpg https://i.imgur.com/UwU3gek.jpg
-Ian
On Wed, Feb 7, 2018 at 6:29 PM, corey cohen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
So I was about to swap out my ADM5 for my ADM3a with my ALTAIR and realized while I did replace the electrolytic and tantalum caps on the main board, I didn’t change the electrolytic caps on the analog board behind the tube.
No big deal except that the rubber cup is on the top where I can’t get to it without removing the tube and you aren’t really supposed to remove the tube till you discharge it under the rubber cup. So chicken or the egg?
Or am I just supposed to let the ADM sit unplugged for a few weeks and just assume it self discharged?
Just when I thought I was finished with this project and was going to move onto my TI silent rebuild.
Thanks, Cheers, Corey
corey cohen uǝɥoɔ ʎǝɹoɔ
-- Normal Person: Hey, it seems that you know a lot. Geek: To be honest, it's due to all the surfing I do. Normal Person: So you go surfing? Normal Person: But I don't think that has anything to do with knowing a lot... Geek: I think that's wrong on a fundamental level. Normal Person: Huh? Huh? What?
I would say yes. As long as not removing the rubber anode cup, the tube connector on the end and/yoke can be removed without discharging the tube. I had removed/swapped around several early Mac tubes without discharging the monitor. On Thu, Feb 8, 2018 at 8:51 AM corey cohen <coreyvcf@gmail.com> wrote:
Ok. Well then let me ask you and Ian this..
Can I safely disconnect the plug at the end of the CRT neck without discharging?
That would make it easier to take the tube out while the anode wire is still connected and then in can discharge the tube with a screwdriver.
Also is the best place to clip onto the implosion bracket since the ADM doesn’t really have a metal chassis?
Thanks, Corey
*corey cohen*
*uǝɥoɔ ʎǝɹoɔ*
On Feb 8, 2018, at 12:01 AM, Joseph Oprysko via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I’ve done the screwdriver trick myself. Because often, even after waiting a few weeks, there can still be enough voltage to make your hair stand on end. LOL
On Wed, Feb 7, 2018 at 7:05 PM Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I don't remember any particular trick or real difficulty in doing it.
Maybe you needed to get the tube loose to get the screwdriver in
there? But I thought it would fit in there without too much problem. I
know I've done it a whole bunch of times and nothing sticks out at me
as being out of the ordinary about working on the 3A. Remember you
don't need to disconnect the anode connection right away, just
discharge it.
If you're doing a lot of work on one of those monitors, sometimes you
do need to get a bit creative though:
https://i.imgur.com/k2wPmw3.jpg
https://i.imgur.com/UwU3gek.jpg
-Ian
On Wed, Feb 7, 2018 at 6:29 PM, corey cohen via vcf-midatlantic
<vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
So I was about to swap out my ADM5 for my ADM3a with my ALTAIR and
realized while I did replace the electrolytic and tantalum caps on the main
board, I didn’t change the electrolytic caps on the analog board behind the
tube.
No big deal except that the rubber cup is on the top where I can’t get
to it without removing the tube and you aren’t really supposed to remove
the tube till you discharge it under the rubber cup. So chicken or the
egg?
Or am I just supposed to let the ADM sit unplugged for a few weeks and
just assume it self discharged?
Just when I thought I was finished with this project and was going to
move onto my TI silent rebuild.
Thanks,
Cheers,
Corey
corey cohen
uǝɥoɔ ʎǝɹoɔ
-- Normal Person: Hey, it seems that you know a lot. Geek: To be honest, it's due to all the surfing I do. Normal Person: So you go surfing? Normal Person: But I don't think that has anything to do with knowing a lot... Geek: I think that's wrong on a fundamental level. Normal Person: Huh? Huh? What?
-- Normal Person: Hey, it seems that you know a lot. Geek: To be honest, it's due to all the surfing I do. Normal Person: So you go surfing? Normal Person: But I don't think that has anything to do with knowing a lot... Geek: I think that's wrong on a fundamental level. Normal Person: Huh? Huh? What?
On 02/08/2018 08:51 AM, corey cohen via vcf-midatlantic wrote:
Ok. Well then let me ask you and Ian this..
Can I safely disconnect the plug at the end of the CRT neck without discharging?
My opinion is NO! Ian?
Also is the best place to clip onto the implosion bracket since the ADM doesn’t really have a metal chassis?
Not know much about the bracket. I can't say. We had our ground on a know cold water pipe. -- Linux Home Automation Neil Cherry ncherry@linuxha.com http://www.linuxha.com/ Main site http://linuxha.blogspot.com/ My HA Blog Author of: Linux Smart Homes For Dummies
On Thu, Feb 8, 2018 at 9:48 AM, Neil Cherry via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Can I safely disconnect the plug at the end of the CRT neck without discharging?
My opinion is NO! Ian?
It's perfectly safe to disconnect that. That's not in any way connected to the second anode.
Also is the best place to clip onto the implosion bracket since the ADM doesn’t really have a metal chassis?
Not know much about the bracket. I can't say. We had our ground on a know cold water pipe.
The cold water pipe is not part of the circuit, or even the terminal. Try draining a car battery by connecting the positive terminal to the cold water pipe. You're not "grounding", the tube, you're discharging it. You have to short out the capacitor formed by the picture tube itself. Connecting the clip to some random other external ground might do something, you might get a spark, but since there's no complete circuit, you haven't fully discharged it. That's a really unsafe thing to attempt to do. -Ian
On 02/08/2018 10:15 AM, Ian Primus via vcf-midatlantic wrote:
On Thu, Feb 8, 2018 at 9:48 AM, Neil Cherry via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Can I safely disconnect the plug at the end of the CRT neck without discharging?
My opinion is NO! Ian?
It's perfectly safe to disconnect that. That's not in any way connected to the second anode.
You are correct, sorry I'm not paying enough attention to the email. Sorry, I'll go hide in the corner. My reference for the cold water pipe was for use with the screw driver to ground. Thanks for correct my bad information. -- Linux Home Automation Neil Cherry ncherry@linuxha.com http://www.linuxha.com/ Main site http://linuxha.blogspot.com/ My HA Blog Author of: Linux Smart Homes For Dummies
On Feb 8, 2018, at 11:08 AM, Neil Cherry via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
My reference for the cold water pipe was for use with the screw driver to ground.
Well, the cold water pipe will connect to EARTH ground, which if your house is wired correctly should be the same as ground on your power outlets. But since you're doing this with the system unplugged (you're doing this with the system unplugged, right?), it has no connection to the tube/chassis ground, which is what you really want. In general, you want the shortest path possible to short it anyway; like Ian said, your best bet is to discharge the anode terminal straight to the other end of the capacitor that is the CRT glass by connecting to something metal directly connected to the glass (like the metal ears or the spring leads). Remember also that glass does have a fair amount of electrical hysteresis; charges migrate slowly through it. You may want to wait a few minutes and do a second discharge after the first to clear up any remaining charge. - Dave
On 02/08/2018 12:12 PM, David Riley via vcf-midatlantic wrote:
Remember also that glass does have a fair amount of electrical hysteresis; charges migrate slowly through it. You may want to wait a few minutes and do a second discharge after the first to clear up any remaining charge.
I'm pretty sure that's dielectric absorption at work there, not quite the same thing. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
You would have lost. Screen removed and board almost recapped. Missing one 47uf 50v cap. Looks like my problem was my giant insulated screwdriver. It was too big. Moving to a smaller one I could get under the cap while the tube was still in the cabinet and discharge it. Kinda pissed I have to wait till I get the missing cap to put it all back together. I only had 25v versions not 50v or more. corey cohen uǝɥoɔ ʎǝɹoɔ
On Feb 8, 2018, at 1:22 PM, Evan Koblentz via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Over/under on Corey getting zapped? :)
On Feb 8, 2018, at 1:20 PM, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On 02/08/2018 12:12 PM, David Riley via vcf-midatlantic wrote:
Remember also that glass does have a fair amount of electrical hysteresis; charges migrate slowly through it. You may want to wait a few minutes and do a second discharge after the first to clear up any remaining charge.
I'm pretty sure that's dielectric absorption at work there, not quite the same thing.
Sorry, you're right, I had a brain fart and conflated it with magnetic hysteresis, which is of course a completely different thing in a different application. - Dave
On 02/08/2018 12:12 PM, David Riley wrote:
On Feb 8, 2018, at 11:08 AM, Neil Cherry via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
My reference for the cold water pipe was for use with the screw driver to ground.
Well, the cold water pipe will connect to EARTH ground, which if your house is wired correctly should be the same as ground on your power outlets. But since you're doing this with the system unplugged (you're doing this with the system unplugged, right?), it has no connection to the tube/chassis ground, which is what you really want.
Very good point. I don't recall if it was unplugged. I don't think it was but I can't recall. I do know we worked on live systems with the scope (Isolated). -- Linux Home Automation Neil Cherry ncherry@linuxha.com http://www.linuxha.com/ Main site http://linuxha.blogspot.com/ My HA Blog Author of: Linux Smart Homes For Dummies
Yeah, of course - you can disconnect the neck without discharging the tube. There's no danger there. You can clip on to any part of the metal mounting ears of the tube, the implosion band, or that spring that stretches across the bell of the tube. That's all connected to dag ground. -Ian On Thu, Feb 8, 2018 at 8:51 AM, corey cohen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Ok. Well then let me ask you and Ian this..
Can I safely disconnect the plug at the end of the CRT neck without discharging?
That would make it easier to take the tube out while the anode wire is still connected and then in can discharge the tube with a screwdriver.
Also is the best place to clip onto the implosion bracket since the ADM doesn’t really have a metal chassis?
Thanks, Corey
corey cohen uǝɥoɔ ʎǝɹoɔ
On Feb 8, 2018, at 12:01 AM, Joseph Oprysko via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I’ve done the screwdriver trick myself. Because often, even after waiting a few weeks, there can still be enough voltage to make your hair stand on end. LOL
On Wed, Feb 7, 2018 at 7:05 PM Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I don't remember any particular trick or real difficulty in doing it. Maybe you needed to get the tube loose to get the screwdriver in there? But I thought it would fit in there without too much problem. I know I've done it a whole bunch of times and nothing sticks out at me as being out of the ordinary about working on the 3A. Remember you don't need to disconnect the anode connection right away, just discharge it.
If you're doing a lot of work on one of those monitors, sometimes you do need to get a bit creative though:
https://i.imgur.com/k2wPmw3.jpg https://i.imgur.com/UwU3gek.jpg
-Ian
On Wed, Feb 7, 2018 at 6:29 PM, corey cohen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
So I was about to swap out my ADM5 for my ADM3a with my ALTAIR and realized while I did replace the electrolytic and tantalum caps on the main board, I didn’t change the electrolytic caps on the analog board behind the tube.
No big deal except that the rubber cup is on the top where I can’t get to it without removing the tube and you aren’t really supposed to remove the tube till you discharge it under the rubber cup. So chicken or the egg?
Or am I just supposed to let the ADM sit unplugged for a few weeks and just assume it self discharged?
Just when I thought I was finished with this project and was going to move onto my TI silent rebuild.
Thanks, Cheers, Corey
corey cohen uǝɥoɔ ʎǝɹoɔ
-- Normal Person: Hey, it seems that you know a lot. Geek: To be honest, it's due to all the surfing I do. Normal Person: So you go surfing? Normal Person: But I don't think that has anything to do with knowing a lot... Geek: I think that's wrong on a fundamental level. Normal Person: Huh? Huh? What?
Is it a good idea to unhook the tube from the chassis / electronic ground before discharging? On Thu, Feb 8, 2018 at 10:10 AM, Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Yeah, of course - you can disconnect the neck without discharging the tube. There's no danger there. You can clip on to any part of the metal mounting ears of the tube, the implosion band, or that spring that stretches across the bell of the tube. That's all connected to dag ground.
-Ian
On Thu, Feb 8, 2018 at 8:51 AM, corey cohen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Ok. Well then let me ask you and Ian this..
Can I safely disconnect the plug at the end of the CRT neck without discharging?
That would make it easier to take the tube out while the anode wire is still connected and then in can discharge the tube with a screwdriver.
Also is the best place to clip onto the implosion bracket since the ADM doesn’t really have a metal chassis?
Thanks, Corey
corey cohen uǝɥoɔ ʎǝɹoɔ
On Feb 8, 2018, at 12:01 AM, Joseph Oprysko via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I’ve done the screwdriver trick myself. Because often, even after waiting a few weeks, there can still be enough voltage to make your hair stand on end. LOL
On Wed, Feb 7, 2018 at 7:05 PM Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I don't remember any particular trick or real difficulty in doing it. Maybe you needed to get the tube loose to get the screwdriver in there? But I thought it would fit in there without too much problem. I know I've done it a whole bunch of times and nothing sticks out at me as being out of the ordinary about working on the 3A. Remember you don't need to disconnect the anode connection right away, just discharge it.
If you're doing a lot of work on one of those monitors, sometimes you do need to get a bit creative though:
https://i.imgur.com/k2wPmw3.jpg https://i.imgur.com/UwU3gek.jpg
-Ian
On Wed, Feb 7, 2018 at 6:29 PM, corey cohen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
So I was about to swap out my ADM5 for my ADM3a with my ALTAIR and realized while I did replace the electrolytic and tantalum caps on the main board, I didn’t change the electrolytic caps on the analog board behind the tube.
No big deal except that the rubber cup is on the top where I can’t get to it without removing the tube and you aren’t really supposed to remove the tube till you discharge it under the rubber cup. So chicken or the egg?
Or am I just supposed to let the ADM sit unplugged for a few weeks and just assume it self discharged?
Just when I thought I was finished with this project and was going to move onto my TI silent rebuild.
Thanks, Cheers, Corey
corey cohen uǝɥoɔ ʎǝɹoɔ
-- Normal Person: Hey, it seems that you know a lot. Geek: To be honest, it's due to all the surfing I do. Normal Person: So you go surfing? Normal Person: But I don't think that has anything to do with knowing a lot... Geek: I think that's wrong on a fundamental level. Normal Person: Huh? Huh? What?
-- Jason Perkins 313 355 0085
You don't have to, no. It really doesn't matter. You're just discharging the tube. You can if you want to, provided you are very sure you are attaching the clip directly to the metal mounting ears, implosion band, or that spring strap that actually contacts the bell of the tube, and not to any other metal chassis work in the monitor that might be connected only to electronic ground and may have become disconnected. It's always safe to clip onto that spring strap on the bell of the tube. You're shorting out the capacitor formed by the picture tube. The one plate of this capacitor is the inside coating - which is attached to that connector that's hidden under the suction cup. The other plate of this capacitor is the conductive gray aquadag coating on the bell of the tube. The spring strap connects this to the metal ears/implosion band of the tube, and the ground wire that attaches to the chassis. -Ian On Thu, Feb 8, 2018 at 10:12 AM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Is it a good idea to unhook the tube from the chassis / electronic ground before discharging?
On Thu, Feb 8, 2018 at 10:10 AM, Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Yeah, of course - you can disconnect the neck without discharging the tube. There's no danger there. You can clip on to any part of the metal mounting ears of the tube, the implosion band, or that spring that stretches across the bell of the tube. That's all connected to dag ground.
-Ian
On Thu, Feb 8, 2018 at 8:51 AM, corey cohen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Ok. Well then let me ask you and Ian this..
Can I safely disconnect the plug at the end of the CRT neck without discharging?
That would make it easier to take the tube out while the anode wire is still connected and then in can discharge the tube with a screwdriver.
Also is the best place to clip onto the implosion bracket since the ADM doesn’t really have a metal chassis?
Thanks, Corey
corey cohen uǝɥoɔ ʎǝɹoɔ
On Feb 8, 2018, at 12:01 AM, Joseph Oprysko via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I’ve done the screwdriver trick myself. Because often, even after waiting a few weeks, there can still be enough voltage to make your hair stand on end. LOL
On Wed, Feb 7, 2018 at 7:05 PM Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I don't remember any particular trick or real difficulty in doing it. Maybe you needed to get the tube loose to get the screwdriver in there? But I thought it would fit in there without too much problem. I know I've done it a whole bunch of times and nothing sticks out at me as being out of the ordinary about working on the 3A. Remember you don't need to disconnect the anode connection right away, just discharge it.
If you're doing a lot of work on one of those monitors, sometimes you do need to get a bit creative though:
https://i.imgur.com/k2wPmw3.jpg https://i.imgur.com/UwU3gek.jpg
-Ian
On Wed, Feb 7, 2018 at 6:29 PM, corey cohen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
So I was about to swap out my ADM5 for my ADM3a with my ALTAIR and realized while I did replace the electrolytic and tantalum caps on the main board, I didn’t change the electrolytic caps on the analog board behind the tube.
No big deal except that the rubber cup is on the top where I can’t get to it without removing the tube and you aren’t really supposed to remove the tube till you discharge it under the rubber cup. So chicken or the egg?
Or am I just supposed to let the ADM sit unplugged for a few weeks and just assume it self discharged?
Just when I thought I was finished with this project and was going to move onto my TI silent rebuild.
Thanks, Cheers, Corey
corey cohen uǝɥoɔ ʎǝɹoɔ
-- Normal Person: Hey, it seems that you know a lot. Geek: To be honest, it's due to all the surfing I do. Normal Person: So you go surfing? Normal Person: But I don't think that has anything to do with knowing a lot... Geek: I think that's wrong on a fundamental level. Normal Person: Huh? Huh? What?
-- Jason Perkins 313 355 0085
Adm-3a follow up question: The raster on mine is rotated slightly. I had to center it by rotating the ring magnets. I did this powered on with insulated tools (chopsticks). I was planning on discharging the tube before I loosened the yoke and rotated it. Any thoughts or tips on rotating the yoke? Eric
I just loosen the screw holding the yoke clamped in place so it can be rotated. Then, turn the monitor on, and rotate the yoke with my hand until the raster is level. Shut it off, then use your screwdriver to tighten the yoke in place. Tighten the screw down until the picture tube implodes, then back it off a quarter turn. :) But, seriously, don't crank it down super tight, just enough to hold it snug. When rotating the yoke, don't touch the terminals where the windings are connected. Those will give you a very painful shock. Avoid touching the windings themselves if possible - just grab it by the plastic part. Technically, you can loosen/tighten the yoke clamp with the power on, but there is no reason to, always a chance to drop the screwdriver into it. Similarly, the windings are insulated with enamel - you can touch them, but I avoid it because there is no reason to touch them and any crack or damage in the insulation will certainly be noticed. You don't need to discharge the tube unless you plan to disconnect or otherwise touch that second anode connection. The bell of the tube is grounded, and the yoke itself is insulated wire on a piece of plastic. The neck of the tube is just clear glass and has no electrical properties. -Ian On Fri, Feb 9, 2018 at 5:22 PM, E.M.F. via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Adm-3a follow up question: The raster on mine is rotated slightly. I had to center it by rotating the ring magnets. I did this powered on with insulated tools (chopsticks). I was planning on discharging the tube before I loosened the yoke and rotated it. Any thoughts or tips on rotating the yoke?
Eric
On Fri, 9 Feb 2018, Ian Primus via vcf-midatlantic wrote:
I just loosen the screw holding the yoke clamped in place so it can be rotated. Then, turn the monitor on, and rotate the yoke with my hand until the raster is level. Shut it off, then use your screwdriver to tighten the yoke in place. Tighten the screw down until the picture tube implodes, then back it off a quarter turn. :)
Love it! "Tighten until the bolt strips, then hack of a quarter turn." :-) Mike Loewen mloewen@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/
On Fri, 9 Feb 2018, Ian Primus via vcf-midatlantic wrote:
I just loosen the screw holding the yoke clamped in place so it can be rotated. Then, turn the monitor on, and rotate the yoke with my hand until the raster is level. Shut it off, then use your screwdriver to tighten the yoke in place. Tighten the screw down until the picture tube implodes, then back it off a quarter turn. :)
Love it! "Tighten until the bolt strips, then back off a quarter turn." :-) Mike Loewen mloewen@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/
On Feb 9, 2018, at 6:12 PM, Mike Loewen via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Fri, 9 Feb 2018, Ian Primus via vcf-midatlantic wrote:
I just loosen the screw holding the yoke clamped in place so it can be rotated. Then, turn the monitor on, and rotate the yoke with my hand until the raster is level. Shut it off, then use your screwdriver to tighten the yoke in place. Tighten the screw down until the picture tube implodes, then back it off a quarter turn. :)
Love it!
"Tighten until the bolt strips, then back off a quarter turn." :-)
Mike Loewen mloewen@cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/
Wait that was sarcasm, I just imploded my tube!!! Not!!! Amazon just dropped off my missing cap (and a dvd of idiocracy as an prime add-on). Swapped out the cap and all looks good.
On Feb 9, 2018, at 5:34 PM, Ian Primus via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I just loosen the screw holding the yoke clamped in place so it can be rotated. Then, turn the monitor on, and rotate the yoke with my hand until the raster is level. Shut it off, then use your screwdriver to tighten the yoke in place. Tighten the screw down until the picture tube implodes, then back it off a quarter turn. :) But, seriously, don't crank it down super tight, just enough to hold it snug.
When rotating the yoke, don't touch the terminals where the windings are connected. Those will give you a very painful shock. Avoid touching the windings themselves if possible - just grab it by the plastic part.
Technically, you can loosen/tighten the yoke clamp with the power on, but there is no reason to, always a chance to drop the screwdriver into it. Similarly, the windings are insulated with enamel - you can touch them, but I avoid it because there is no reason to touch them and any crack or damage in the insulation will certainly be noticed.
You don't need to discharge the tube unless you plan to disconnect or otherwise touch that second anode connection. The bell of the tube is grounded, and the yoke itself is insulated wire on a piece of plastic. The neck of the tube is just clear glass and has no electrical properties.
-Ian
Awesome. Thanks for the help! I have to work on making a lower character rom next. eric
On Feb 9, 2018, at 10:58 PM, E.M.F. via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Feb 9, 2018, at 5:34 PM, Ian Primus via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I just loosen the screw holding the yoke clamped in place so it can be rotated. Then, turn the monitor on, and rotate the yoke with my hand until the raster is level. Shut it off, then use your screwdriver to tighten the yoke in place. Tighten the screw down until the picture tube implodes, then back it off a quarter turn. :) But, seriously, don't crank it down super tight, just enough to hold it snug.
When rotating the yoke, don't touch the terminals where the windings are connected. Those will give you a very painful shock. Avoid touching the windings themselves if possible - just grab it by the plastic part.
Technically, you can loosen/tighten the yoke clamp with the power on, but there is no reason to, always a chance to drop the screwdriver into it. Similarly, the windings are insulated with enamel - you can touch them, but I avoid it because there is no reason to touch them and any crack or damage in the insulation will certainly be noticed.
You don't need to discharge the tube unless you plan to disconnect or otherwise touch that second anode connection. The bell of the tube is grounded, and the yoke itself is insulated wire on a piece of plastic. The neck of the tube is just clear glass and has no electrical properties.
-Ian
Awesome. Thanks for the help! I have to work on making a lower character rom next.
eric
For the lower character rom you have some options before you resort to a 2716 with an adapter. The Apple II and earlier II plus used the same character generator and there were lowercase adaption solutions for the Apple II where you can get a lower case rom. Also if you get a different rom and it’s not mapping correctly, the ADM taps the address lines for the lowercase rom from an inverted output and uses the regular output for the uppercase rom. You can tap off the vias near the uppercase rom that have all 6 non-inverted address lines or you can hide a 7404 underneath the chip in a socket. Just be careful of clearance as you can’t fit too high of a chip stack in that part of the board. Cheers, Corey
One of my "shorter list" projects is laying out a proper Batten & Allen lower character ROM for the ADM-3A. I've got 50K Batten & Allen pins on order for various ROM replacement projects. It'll be something like this, a DS1244 replacement I recently built: https://imgur.com/a/1qNfP Obviously with EEPROM instead of a battery-backed SRAM :) Thanks, Jonathan On Sat, Feb 10, 2018 at 6:45 AM, corey cohen via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Feb 9, 2018, at 10:58 PM, E.M.F. via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Feb 9, 2018, at 5:34 PM, Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I just loosen the screw holding the yoke clamped in place so it can be rotated. Then, turn the monitor on, and rotate the yoke with my hand until the raster is level. Shut it off, then use your screwdriver to tighten the yoke in place. Tighten the screw down until the picture tube implodes, then back it off a quarter turn. :) But, seriously, don't crank it down super tight, just enough to hold it snug.
When rotating the yoke, don't touch the terminals where the windings are connected. Those will give you a very painful shock. Avoid touching the windings themselves if possible - just grab it by the plastic part.
Technically, you can loosen/tighten the yoke clamp with the power on, but there is no reason to, always a chance to drop the screwdriver into it. Similarly, the windings are insulated with enamel - you can touch them, but I avoid it because there is no reason to touch them and any crack or damage in the insulation will certainly be noticed.
You don't need to discharge the tube unless you plan to disconnect or otherwise touch that second anode connection. The bell of the tube is grounded, and the yoke itself is insulated wire on a piece of plastic. The neck of the tube is just clear glass and has no electrical properties.
-Ian
Awesome. Thanks for the help! I have to work on making a lower character rom next.
eric
For the lower character rom you have some options before you resort to a 2716 with an adapter. The Apple II and earlier II plus used the same character generator and there were lowercase adaption solutions for the Apple II where you can get a lower case rom.
Also if you get a different rom and it’s not mapping correctly, the ADM taps the address lines for the lowercase rom from an inverted output and uses the regular output for the uppercase rom. You can tap off the vias near the uppercase rom that have all 6 non-inverted address lines or you can hide a 7404 underneath the chip in a socket. Just be careful of clearance as you can’t fit too high of a chip stack in that part of the board.
Cheers, Corey
participants (11)
-
corey cohen -
Dave McGuire -
David Riley -
E.M.F. -
Evan Koblentz -
Ian Primus -
Jason Perkins -
Joseph Oprysko -
Mike Loewen -
Neil Cherry -
systems_glitch