Repairs to a Heath WH19 Terminal
Looking for some advice on getting a Heath WH19 terminal going again. First, some schematics: http://www.rsp-italy.it/Electronics/Kits/_contents/Heathkit/Kits/Heathkit%20... My annotations on the x-ray view: https://goo.gl/photos/PF8N7wRDPLc1czUU7 What I observed: When first powering the terminal it did nothing. The fast blow 1A fuse was open, the wire was broken. As it was handled it broke more, suggesting it could have simply failed from vibration? The manual said that a 2A slow blow fuse is appropriate for 120v operation. I replaced the fuse with the smallest one I had on hand, a 4A slow blow, connected the terminal to a current meter, and powered it up. It beeped :) But was drawing 5A :( and then there was a little smoke :( :( I quickly powered it off. R263, a 1.2 ohm 2W resistor had cracked. R263 supplies the +53v rail to the horizontal section. C228 seems to be good (open resistance, correct mfd), D208 and D211 seem to be good (.5v one way, open the other), C229 isn't shorted but my meter can't measure its capacitance. I replaced R263 with a 4w 1.2 ohm resistor I had on hand, and powered up again. Still too much current draw, and more smoke in the area of Q217. Does this suggest Q217, the HOT, is bad? I pulled it out and did the diode test on it, it seemed to test OK? It's a BU500, and I see some NOS ones on ebay. I'm unsure what my next step should be. Thanks for your input! -- Jason Perkins 313 355 0085
Jason, Pull the HOT and try to power it on, and see what the current draw is then. Sent from my iPhone
On Mar 12, 2017, at 12:37 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Looking for some advice on getting a Heath WH19 terminal going again.
First, some schematics:
http://www.rsp-italy.it/Electronics/Kits/_contents/Heathkit/Kits/Heathkit%20...
My annotations on the x-ray view: https://goo.gl/photos/PF8N7wRDPLc1czUU7
What I observed: When first powering the terminal it did nothing. The fast blow 1A fuse was open, the wire was broken. As it was handled it broke more, suggesting it could have simply failed from vibration? The manual said that a 2A slow blow fuse is appropriate for 120v operation.
I replaced the fuse with the smallest one I had on hand, a 4A slow blow, connected the terminal to a current meter, and powered it up. It beeped :) But was drawing 5A :( and then there was a little smoke :( :( I quickly powered it off.
R263, a 1.2 ohm 2W resistor had cracked. R263 supplies the +53v rail to the horizontal section.
C228 seems to be good (open resistance, correct mfd), D208 and D211 seem to be good (.5v one way, open the other), C229 isn't shorted but my meter can't measure its capacitance.
I replaced R263 with a 4w 1.2 ohm resistor I had on hand, and powered up again. Still too much current draw, and more smoke in the area of Q217.
Does this suggest Q217, the HOT, is bad? I pulled it out and did the diode test on it, it seemed to test OK? It's a BU500, and I see some NOS ones on ebay.
I'm unsure what my next step should be.
Thanks for your input!
-- Jason Perkins 313 355 0085
Ok, I removed the HOT, and the short / overload is still present. If the flyback is unplugged the extra load goes away. I found that with flyback pin 3, the red wire, unhooked the extra load goes away too. Unplugging the yolk makes no change. There aren't many things on that ground return from the flyback, I'll take them out one at a time till I find the shorted part. -J On Sun, Mar 12, 2017 at 1:15 PM, Matt Patoray via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Jason,
Pull the HOT and try to power it on, and see what the current draw is then.
Sent from my iPhone
On Mar 12, 2017, at 12:37 PM, Jason Perkins via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Looking for some advice on getting a Heath WH19 terminal going again.
First, some schematics:
http://www.rsp-italy.it/Electronics/Kits/_contents/ Heathkit/Kits/Heathkit%20H-19%20video%20terminal.pdf
My annotations on the x-ray view: https://goo.gl/photos/ PF8N7wRDPLc1czUU7
What I observed: When first powering the terminal it did nothing. The fast blow 1A fuse was open, the wire was broken. As it was handled it broke more, suggesting it could have simply failed from vibration? The manual said that a 2A slow blow fuse is appropriate for 120v operation.
I replaced the fuse with the smallest one I had on hand, a 4A slow blow, connected the terminal to a current meter, and powered it up. It beeped :) But was drawing 5A :( and then there was a little smoke :( :( I quickly powered it off.
R263, a 1.2 ohm 2W resistor had cracked. R263 supplies the +53v rail to the horizontal section.
C228 seems to be good (open resistance, correct mfd), D208 and D211 seem to be good (.5v one way, open the other), C229 isn't shorted but my meter can't measure its capacitance.
I replaced R263 with a 4w 1.2 ohm resistor I had on hand, and powered up again. Still too much current draw, and more smoke in the area of Q217.
Does this suggest Q217, the HOT, is bad? I pulled it out and did the diode test on it, it seemed to test OK? It's a BU500, and I see some NOS ones on ebay.
I'm unsure what my next step should be.
Thanks for your input!
-- Jason Perkins 313 355 0085
-- Jason Perkins 313 355 0085
You were right, the big .22 600v cap C232 was shorted. I've placed an order from DigiKey, hopefully the impending snow doesn't delay things too badly. -J On Sun, Mar 12, 2017 at 6:55 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 12, 2017 at 05:43:22PM -0400, Jason Perkins via vcf-midatlantic wrote:
There aren't many things on that ground return from the flyback, I'll
take
them out one at a time till I find the shorted part.
The caps to ground look like the most obvious path to create a short.
-- Jason Perkins 313 355 0085
On 03/12/2017 11:25 PM, Jason Perkins via vcf-midatlantic wrote:
You were right, the big .22 600v cap C232 was shorted. I've placed an order from DigiKey, hopefully the impending snow doesn't delay things too badly.
-J
On Sun, Mar 12, 2017 at 6:55 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 12, 2017 at 05:43:22PM -0400, Jason Perkins via vcf-midatlantic wrote:
There aren't many things on that ground return from the flyback, I'll
take
them out one at a time till I find the shorted part.
The caps to ground look like the most obvious path to create a short.
Queue eerie Twilight Zone Music: http://hackaday.com/2017/03/13/raspberry-pi-hitches-ride-inside-vintage-term... ... but he quickly determined that a bad cap was shorting out the -12VDC rail ... hehe -- 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
Man what a small world... My other big not-work time investment is TDIClub, looks like the OP of that article is into TDIs a bit as well! On Mon, Mar 13, 2017 at 11:56 AM, Neil Cherry <ncherry@linuxha.com> wrote:
On 03/12/2017 11:25 PM, Jason Perkins via vcf-midatlantic wrote:
You were right, the big .22 600v cap C232 was shorted. I've placed an order from DigiKey, hopefully the impending snow doesn't delay things too badly.
-J
On Sun, Mar 12, 2017 at 6:55 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 12, 2017 at 05:43:22PM -0400, Jason Perkins via
vcf-midatlantic wrote:
There aren't many things on that ground return from the flyback, I'll
take
them out one at a time till I find the shorted part.
The caps to ground look like the most obvious path to create a short.
Queue eerie Twilight Zone Music:
http://hackaday.com/2017/03/13/raspberry-pi-hitches-ride-ins ide-vintage-terminal/
... but he quickly determined that a bad cap was shorting out the -12VDC rail ...
hehe
-- 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
-- Jason Perkins 313 355 0085
Replacing the shorted cap and blown current limiting resistors results in signs of life! https://goo.gl/photos/nk5kvxuCT2VGztgf6 Good: The terminal works! https://goo.gl/photos/TPoPQ1c8QajthkZM7 (yes, I tested with a loopback adapter, then with a usb to RS232 adapter before hooking it up to the Lisa :) ) The terminal draws 51 watts running. Nothing inside seems to be getting unusually hot. Problems: The display has a major wave. https://goo.gl/photos/wXKydMr5syKU1SWd7 Guessing there are more bad caps in the video section. The 65V input, and 53V rail in the monitor have .5v of ac ripple. Perhaps the big 1500uf electrolytic is going bad... The keyboard didn't work very well at first, but after typing on it for a bit it now works perfectly. -J On Mon, Mar 13, 2017 at 12:10 PM, Jason Perkins <perkins.jason@gmail.com> wrote:
Man what a small world... My other big not-work time investment is TDIClub, looks like the OP of that article is into TDIs a bit as well!
On Mon, Mar 13, 2017 at 11:56 AM, Neil Cherry <ncherry@linuxha.com> wrote:
On 03/12/2017 11:25 PM, Jason Perkins via vcf-midatlantic wrote:
You were right, the big .22 600v cap C232 was shorted. I've placed an order from DigiKey, hopefully the impending snow doesn't delay things too badly.
-J
On Sun, Mar 12, 2017 at 6:55 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 12, 2017 at 05:43:22PM -0400, Jason Perkins via
vcf-midatlantic wrote:
There aren't many things on that ground return from the flyback, I'll
take
them out one at a time till I find the shorted part.
The caps to ground look like the most obvious path to create a short.
Queue eerie Twilight Zone Music:
http://hackaday.com/2017/03/13/raspberry-pi-hitches-ride-ins ide-vintage-terminal/
... but he quickly determined that a bad cap was shorting out the -12VDC rail ...
hehe
-- 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
-- Jason Perkins 313 355 0085 <(313)%20355-0085>
-- Jason Perkins 313 355 0085
Jason, That is great news! That is also too much AC on a DC rail, I would suspect those caps and get replacements, 1500 uF would be hard to find but a 2200 would be ok in this case, remember those older electrolytics may have a tolerance of -20% +85% and modern caps are all +- 20% or better. Sent from my iPhone
On Mar 15, 2017, at 10:17 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Replacing the shorted cap and blown current limiting resistors results in signs of life!
https://goo.gl/photos/nk5kvxuCT2VGztgf6
Good: The terminal works! https://goo.gl/photos/TPoPQ1c8QajthkZM7 (yes, I tested with a loopback adapter, then with a usb to RS232 adapter before hooking it up to the Lisa :) ) The terminal draws 51 watts running. Nothing inside seems to be getting unusually hot.
Problems: The display has a major wave. https://goo.gl/photos/wXKydMr5syKU1SWd7 Guessing there are more bad caps in the video section. The 65V input, and 53V rail in the monitor have .5v of ac ripple. Perhaps the big 1500uf electrolytic is going bad...
The keyboard didn't work very well at first, but after typing on it for a bit it now works perfectly.
-J
On Mon, Mar 13, 2017 at 12:10 PM, Jason Perkins <perkins.jason@gmail.com> wrote:
Man what a small world... My other big not-work time investment is TDIClub, looks like the OP of that article is into TDIs a bit as well!
On Mon, Mar 13, 2017 at 11:56 AM, Neil Cherry <ncherry@linuxha.com> wrote:
On 03/12/2017 11:25 PM, Jason Perkins via vcf-midatlantic wrote:
You were right, the big .22 600v cap C232 was shorted. I've placed an order from DigiKey, hopefully the impending snow doesn't delay things too badly.
-J
On Sun, Mar 12, 2017 at 6:55 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 12, 2017 at 05:43:22PM -0400, Jason Perkins via
vcf-midatlantic wrote:
There aren't many things on that ground return from the flyback, I'll
take
them out one at a time till I find the shorted part.
The caps to ground look like the most obvious path to create a short.
Queue eerie Twilight Zone Music:
http://hackaday.com/2017/03/13/raspberry-pi-hitches-ride-ins ide-vintage-terminal/
... but he quickly determined that a bad cap was shorting out the -12VDC rail ...
hehe
-- 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
-- Jason Perkins 313 355 0085 <(313)%20355-0085>
-- Jason Perkins 313 355 0085
So I had some more time to look into this. I swapped in some caps I removed from some computer power supplies as a test... no change. I then added the original cap in parallel... it made some improvement: down to .3v AC ripple on the monitor supply rail and a less distorted display. When I was trying to find the short circuit I fried 2 of the bridge diodes, and replaced them with some modern computer PSU takeouts.I swapped all 4 out with new 1N4004's, no change. This is such a simple circuit I'm having trouble understanding where the ripple could be coming from. If I use a light bulb as a load on the circuit the ripple is the same (the monitor draws about half an amp, and a 70w 120v light bulb works as a good stand in). Any other suggestions? Thanks, -J On Thu, Mar 16, 2017 at 12:07 AM, Matt Patoray via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Jason,
That is great news! That is also too much AC on a DC rail, I would suspect those caps and get replacements, 1500 uF would be hard to find but a 2200 would be ok in this case, remember those older electrolytics may have a tolerance of -20% +85% and modern caps are all +- 20% or better.
Sent from my iPhone
On Mar 15, 2017, at 10:17 PM, Jason Perkins via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Replacing the shorted cap and blown current limiting resistors results in signs of life!
https://goo.gl/photos/nk5kvxuCT2VGztgf6
Good: The terminal works! https://goo.gl/photos/TPoPQ1c8QajthkZM7 (yes, I tested with a loopback adapter, then with a usb to RS232 adapter before hooking it up to the Lisa :) ) The terminal draws 51 watts running. Nothing inside seems to be getting unusually hot.
Problems: The display has a major wave. https://goo.gl/photos/wXKydMr5syKU1SWd7 Guessing there are more bad caps in the video section. The 65V input, and 53V rail in the monitor have .5v of ac ripple. Perhaps the big 1500uf electrolytic is going bad...
The keyboard didn't work very well at first, but after typing on it for a bit it now works perfectly.
-J
On Mon, Mar 13, 2017 at 12:10 PM, Jason Perkins <perkins.jason@gmail.com
wrote:
Man what a small world... My other big not-work time investment is TDIClub, looks like the OP of that article is into TDIs a bit as well!
On Mon, Mar 13, 2017 at 11:56 AM, Neil Cherry <ncherry@linuxha.com> wrote:
On 03/12/2017 11:25 PM, Jason Perkins via vcf-midatlantic wrote:
You were right, the big .22 600v cap C232 was shorted. I've placed an order from DigiKey, hopefully the impending snow doesn't delay things too badly.
-J
On Sun, Mar 12, 2017 at 6:55 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 12, 2017 at 05:43:22PM -0400, Jason Perkins via
vcf-midatlantic wrote:
> > There aren't many things on that ground return from the flyback, I'll > take
> them out one at a time till I find the shorted part. > > The caps to ground look like the most obvious path to create a short.
Queue eerie Twilight Zone Music:
http://hackaday.com/2017/03/13/raspberry-pi-hitches-ride-ins ide-vintage-terminal/
... but he quickly determined that a bad cap was shorting out the -12VDC rail ...
hehe
-- 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
-- Jason Perkins 313 355 0085 <(313)%20355-0085>
-- Jason Perkins 313 355 0085
-- Jason Perkins 313 355 0085
Check the actual voltage of the B+ rail. It may be a bit too high. If so, then suspect your voltage regulator transistor/transistors. It's possible to have a bad voltage regulator, but still have things almost working, but there will be too much ripple and you won't be able to get rid of it with capacitors. -Ian On Sun, Mar 26, 2017 at 12:41 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
So I had some more time to look into this.
I swapped in some caps I removed from some computer power supplies as a test... no change. I then added the original cap in parallel... it made some improvement: down to .3v AC ripple on the monitor supply rail and a less distorted display.
When I was trying to find the short circuit I fried 2 of the bridge diodes, and replaced them with some modern computer PSU takeouts.I swapped all 4 out with new 1N4004's, no change.
This is such a simple circuit I'm having trouble understanding where the ripple could be coming from. If I use a light bulb as a load on the circuit the ripple is the same (the monitor draws about half an amp, and a 70w 120v light bulb works as a good stand in).
Any other suggestions?
Thanks,
-J
On Thu, Mar 16, 2017 at 12:07 AM, Matt Patoray via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Jason,
That is great news! That is also too much AC on a DC rail, I would suspect those caps and get replacements, 1500 uF would be hard to find but a 2200 would be ok in this case, remember those older electrolytics may have a tolerance of -20% +85% and modern caps are all +- 20% or better.
Sent from my iPhone
On Mar 15, 2017, at 10:17 PM, Jason Perkins via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Replacing the shorted cap and blown current limiting resistors results in signs of life!
https://goo.gl/photos/nk5kvxuCT2VGztgf6
Good: The terminal works! https://goo.gl/photos/TPoPQ1c8QajthkZM7 (yes, I tested with a loopback adapter, then with a usb to RS232 adapter before hooking it up to the Lisa :) ) The terminal draws 51 watts running. Nothing inside seems to be getting unusually hot.
Problems: The display has a major wave. https://goo.gl/photos/wXKydMr5syKU1SWd7 Guessing there are more bad caps in the video section. The 65V input, and 53V rail in the monitor have .5v of ac ripple. Perhaps the big 1500uf electrolytic is going bad...
The keyboard didn't work very well at first, but after typing on it for a bit it now works perfectly.
-J
On Mon, Mar 13, 2017 at 12:10 PM, Jason Perkins <perkins.jason@gmail.com
wrote:
Man what a small world... My other big not-work time investment is TDIClub, looks like the OP of that article is into TDIs a bit as well!
On Mon, Mar 13, 2017 at 11:56 AM, Neil Cherry <ncherry@linuxha.com> wrote:
On 03/12/2017 11:25 PM, Jason Perkins via vcf-midatlantic wrote:
You were right, the big .22 600v cap C232 was shorted. I've placed an order from DigiKey, hopefully the impending snow doesn't delay things too badly.
-J
On Sun, Mar 12, 2017 at 6:55 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 12, 2017 at 05:43:22PM -0400, Jason Perkins via > vcf-midatlantic wrote: > >> >> There aren't many things on that ground return from the flyback, I'll >> > take > >> them out one at a time till I find the shorted part. >> >> The caps to ground look like the most obvious path to create a short. >
Queue eerie Twilight Zone Music:
http://hackaday.com/2017/03/13/raspberry-pi-hitches-ride-ins ide-vintage-terminal/
... but he quickly determined that a bad cap was shorting out the -12VDC rail ...
hehe
-- 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
-- Jason Perkins 313 355 0085 <(313)%20355-0085>
-- Jason Perkins 313 355 0085
-- Jason Perkins 313 355 0085
I noticed the schematic I linked in the first post doesn't match this terminal exactly. This one does: https://stacks.stanford.edu/file/druid:vg695gp5537/vg695gp5537.pdf A picture of the video PSU section we're looking at here: https://goo.gl/photos/Lu8YTcNhE6NpyztB9 Before the regulator I measure 66 volts DC w/ .25v of ripple at 120hz. After the regulator I measure 61.5 volts DC w/ .35v to .41v of ripple at 60hz. - sounds like it's not regulating much Reading the manual more, it doesn't use an integrated voltage regulator (page 33): "The unregulated 65-volts DC from the power supply circuit board enters the video circuit board at plug P202, pins 2 and 3. Assume that the Terminal has just been turned on and the output of the +53-volt regulator is at zero volts. The base current of Q209 is supplied through resistors R201,R202, and R203. The collector current of Q209 causes Q211 to turn on and supply current to the base of Q213. As the output voltage at the emitter of Q213 rises, D204 begins to supply current to zener diode D203 through resistor R202. D203 stabilizes at 12.8 volts and provides a reference for the output voltage. The divider formed by resistors R207 and R208 samples the output voltage as it continues to rise, and applies a fraction of the voltage to the emitter of Q209. When the emitter voltage of Q209 reaches 12.15volts (12.8 -.65), its collector current is reduced to a value that keeps the output voltage stabilized at +53 volts." Q209's emitter measures 13.71V. D203's cathode measures 12.8V. So the PSU is regulating some, but not enough? Any suggestions where I should check next? - - - - Now that the terminal is running the next problem shows itself... after it's been on for ~10 minutes the keyboard stops working. All the supply rails on the logic board are fine when this happens (no change between working and not). Power cycling the terminal will get the keyboard working again for a short while. The reset key combo (right shift + reset) always works. -J On Sun, Mar 26, 2017 at 1:48 PM, Ian Primus via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Check the actual voltage of the B+ rail. It may be a bit too high. If so, then suspect your voltage regulator transistor/transistors. It's possible to have a bad voltage regulator, but still have things almost working, but there will be too much ripple and you won't be able to get rid of it with capacitors.
-Ian
On Sun, Mar 26, 2017 at 12:41 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
So I had some more time to look into this.
I swapped in some caps I removed from some computer power supplies as a test... no change. I then added the original cap in parallel... it made some improvement: down to .3v AC ripple on the monitor supply rail and a less distorted display.
When I was trying to find the short circuit I fried 2 of the bridge diodes, and replaced them with some modern computer PSU takeouts.I swapped all 4 out with new 1N4004's, no change.
This is such a simple circuit I'm having trouble understanding where the ripple could be coming from. If I use a light bulb as a load on the circuit the ripple is the same (the monitor draws about half an amp, and a 70w 120v light bulb works as a good stand in).
Any other suggestions?
Thanks,
-J
On Thu, Mar 16, 2017 at 12:07 AM, Matt Patoray via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Jason,
That is great news! That is also too much AC on a DC rail, I would suspect those caps and get replacements, 1500 uF would be hard to find but a 2200 would be ok in this case, remember those older electrolytics may have a tolerance of -20% +85% and modern caps are all +- 20% or better.
Sent from my iPhone
On Mar 15, 2017, at 10:17 PM, Jason Perkins via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Replacing the shorted cap and blown current limiting resistors results in signs of life!
https://goo.gl/photos/nk5kvxuCT2VGztgf6
Good: The terminal works! https://goo.gl/photos/TPoPQ1c8QajthkZM7 (yes, I tested with a loopback adapter, then with a usb to RS232 adapter before hooking it up to the Lisa :) ) The terminal draws 51 watts running. Nothing inside seems to be getting unusually hot.
Problems: The display has a major wave. https://goo.gl/photos/wXKydMr5syKU1SWd7 Guessing there are more bad caps in the video section. The 65V input, and 53V rail in the monitor have .5v of ac ripple. Perhaps the big 1500uf electrolytic is going bad...
The keyboard didn't work very well at first, but after typing on it for a bit it now works perfectly.
-J
On Mon, Mar 13, 2017 at 12:10 PM, Jason Perkins < perkins.jason@gmail.com
wrote:
Man what a small world... My other big not-work time investment is TDIClub, looks like the OP of that article is into TDIs a bit as well!
On Mon, Mar 13, 2017 at 11:56 AM, Neil Cherry <ncherry@linuxha.com> wrote:
> On 03/12/2017 11:25 PM, Jason Perkins via vcf-midatlantic wrote: > > You were right, the big .22 600v cap C232 was shorted. I've placed an > order > from DigiKey, hopefully the impending snow doesn't delay things too > badly. > > -J > > On Sun, Mar 12, 2017 at 6:55 PM, David Gesswein via vcf-midatlantic < > vcf-midatlantic@lists.vintagecomputerfederation.org> wrote: > > On Sun, Mar 12, 2017 at 05:43:22PM -0400, Jason Perkins via >> vcf-midatlantic wrote: >> >>> >>> There aren't many things on that ground return from the flyback, I'll >>> >> take >> >>> them out one at a time till I find the shorted part. >>> >>> The caps to ground look like the most obvious path to create a short. >> > Queue eerie Twilight Zone Music:
http://hackaday.com/2017/03/13/raspberry-pi-hitches-ride-ins ide-vintage-terminal/
... but he quickly determined that a bad cap was shorting out the -12VDC rail ...
hehe
-- 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
-- Jason Perkins 313 355 0085 <(313)%20355-0085>
-- Jason Perkins 313 355 0085
-- Jason Perkins 313 355 0085
-- Jason Perkins 313 355 0085
On Sun, Mar 26, 2017 at 04:51:30PM -0400, Jason Perkins via vcf-midatlantic wrote:
After the regulator I measure 61.5 volts DC w/ .35v to .41v of ripple at 60hz. - sounds like it's not regulating much
Reading the manual more, it doesn't use an integrated voltage regulator "The unregulated 65-volts DC from the power supply circuit board enters the video circuit board at plug P202, pins 2 and 3. Assume that the Terminal has just been turned on and the output of the +53-volt regulator is at zero volts.
Didn't have time to look at the schematic but if you are reading 61.5V on the 53V output the regulator probably isn't regulating so its not filtering the ripple. Are you able to understand the circuit to see how it should be regulating and that the correct output should be close to 53 volts?
With some extra off-list help from Dave I found that the main power transistor Q213 is leaky. Now the challenge will be to find one of those, or something that can sub, without having to pay $50 in shipping! -J On Sun, Mar 26, 2017 at 4:58 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 26, 2017 at 04:51:30PM -0400, Jason Perkins via vcf-midatlantic wrote:
After the regulator I measure 61.5 volts DC w/ .35v to .41v of ripple at 60hz. - sounds like it's not regulating much
Reading the manual more, it doesn't use an integrated voltage regulator "The unregulated 65-volts DC from the power supply circuit board enters
the
video circuit board at plug P202, pins 2 and 3. Assume that the Terminal has just been turned on and the output of the +53-volt regulator is at zero volts.
Didn't have time to look at the schematic but if you are reading 61.5V on the 53V output the regulator probably isn't regulating so its not filtering the ripple. Are you able to understand the circuit to see how it should be regulating and that the correct output should be close to 53 volts?
-- Jason Perkins 313 355 0085
Jason, what is the transistor model? on the schematic that just looks like a house part number? On Sun, Mar 26, 2017 at 11:57 PM, Jason Perkins via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
With some extra off-list help from Dave I found that the main power transistor Q213 is leaky.
Now the challenge will be to find one of those, or something that can sub, without having to pay $50 in shipping!
-J
On Sun, Mar 26, 2017 at 4:58 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 26, 2017 at 04:51:30PM -0400, Jason Perkins via vcf-midatlantic wrote:
After the regulator I measure 61.5 volts DC w/ .35v to .41v of ripple
at
60hz. - sounds like it's not regulating much
Reading the manual more, it doesn't use an integrated voltage regulator "The unregulated 65-volts DC from the power supply circuit board enters the video circuit board at plug P202, pins 2 and 3. Assume that the Terminal has just been turned on and the output of the +53-volt regulator is at zero volts.
Didn't have time to look at the schematic but if you are reading 61.5V on the 53V output the regulator probably isn't regulating so its not filtering the ripple. Are you able to understand the circuit to see how it should be regulating and that the correct output should be close to 53 volts?
-- Jason Perkins 313 355 0085
-- Matt Patoray Owner, MSP Productions KD8AMG
It's an MJ2841 https://goo.gl/photos/LwghHKBZXx3GxGN1A I ordered one from eBay. We'll see what the tracking says. If it won't get here in time I can pick up an NTE-284 tomorrow at a local place. -J On Mon, Mar 27, 2017 at 11:49 AM, Matt Patoray via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Jason, what is the transistor model? on the schematic that just looks like a house part number?
On Sun, Mar 26, 2017 at 11:57 PM, Jason Perkins via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
With some extra off-list help from Dave I found that the main power transistor Q213 is leaky.
Now the challenge will be to find one of those, or something that can sub, without having to pay $50 in shipping!
-J
On Sun, Mar 26, 2017 at 4:58 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 26, 2017 at 04:51:30PM -0400, Jason Perkins via vcf-midatlantic wrote:
After the regulator I measure 61.5 volts DC w/ .35v to .41v of ripple
at
60hz. - sounds like it's not regulating much
Reading the manual more, it doesn't use an integrated voltage regulator "The unregulated 65-volts DC from the power supply circuit board enters the video circuit board at plug P202, pins 2 and 3. Assume that the Terminal has just been turned on and the output of the +53-volt regulator is at zero volts.
Didn't have time to look at the schematic but if you are reading 61.5V on the 53V output the regulator probably isn't regulating so its not filtering the ripple. Are you able to understand the circuit to see how it should be regulating and that the correct output should be close to 53 volts?
-- Jason Perkins 313 355 0085
-- Matt Patoray Owner, MSP Productions KD8AMG
-- Jason Perkins 313 355 0085
New power transistor, and now B+ is spot on and stable. No more wobbles! -J On Sun, Mar 26, 2017 at 11:57 PM Jason Perkins <perkins.jason@gmail.com> wrote:
With some extra off-list help from Dave I found that the main power transistor Q213 is leaky.
Now the challenge will be to find one of those, or something that can sub, without having to pay $50 in shipping!
-J
On Sun, Mar 26, 2017 at 4:58 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 26, 2017 at 04:51:30PM -0400, Jason Perkins via vcf-midatlantic wrote:
After the regulator I measure 61.5 volts DC w/ .35v to .41v of ripple at 60hz. - sounds like it's not regulating much
Reading the manual more, it doesn't use an integrated voltage regulator "The unregulated 65-volts DC from the power supply circuit board enters
the
video circuit board at plug P202, pins 2 and 3. Assume that the Terminal has just been turned on and the output of the +53-volt regulator is at zero volts.
Didn't have time to look at the schematic but if you are reading 61.5V on the 53V output the regulator probably isn't regulating so its not filtering the ripple. Are you able to understand the circuit to see how it should be regulating and that the correct output should be close to 53 volts?
-- Jason Perkins 313 355 0085
-- Jason Perkins 313 355 0085 Sent from my iPhone
Awesome! Always good when another piece of gear is saved! Sent from my iPhone
On Mar 27, 2017, at 7:34 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
New power transistor, and now B+ is spot on and stable. No more wobbles!
-J
On Sun, Mar 26, 2017 at 11:57 PM Jason Perkins <perkins.jason@gmail.com> wrote:
With some extra off-list help from Dave I found that the main power transistor Q213 is leaky.
Now the challenge will be to find one of those, or something that can sub, without having to pay $50 in shipping!
-J
On Sun, Mar 26, 2017 at 4:58 PM, David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On Sun, Mar 26, 2017 at 04:51:30PM -0400, Jason Perkins via vcf-midatlantic wrote:
After the regulator I measure 61.5 volts DC w/ .35v to .41v of ripple at 60hz. - sounds like it's not regulating much
Reading the manual more, it doesn't use an integrated voltage regulator "The unregulated 65-volts DC from the power supply circuit board enters
the
video circuit board at plug P202, pins 2 and 3. Assume that the Terminal has just been turned on and the output of the +53-volt regulator is at zero volts.
Didn't have time to look at the schematic but if you are reading 61.5V on the 53V output the regulator probably isn't regulating so its not filtering the ripple. Are you able to understand the circuit to see how it should be regulating and that the correct output should be close to 53 volts?
-- Jason Perkins 313 355 0085
-- Jason Perkins 313 355 0085 Sent from my iPhone
participants (5)
-
David Gesswein -
Ian Primus -
Jason Perkins -
Matt Patoray -
Neil Cherry