I have a Hickok 440 curve tracer that I am having difficulty troubleshooting, even though it is a relatively simple circuit.

The base generator staircase is not stable, and will not stay in calibration. It looks like noise comes and goes and distorts it. I have replaced most of the semiconductors. The 15v power supply is a bit low at about 13.9v, though the regulator transistor and zeners have been replaced.

I have the manual, schematic, parts and usual test equipment.

Thank you,
Don

On 2019/06/25 6:54 a.m., Don Brown wrote:
I have a Hickok 440 curve tracer that I am having difficulty troubleshooting, even though it is a relatively simple circuit.

The base generator staircase is not stable, and will not stay in calibration. It looks like noise comes and goes and distorts it. I have replaced most of the semiconductors. The 15v power supply is a bit low at about 13.9v, though the regulator transistor and zeners have been replaced.

I have the manual, schematic, parts and usual test equipment.

Thank you,
Don


Have you replaced any and all electrolytic capacitors and verified that
the resistors are on spec?

Capacitors are bigger suspects than the semiconductors...

John :-#)#

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(Please post followups or tech inquiries to the USENET newsgroup)
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"Old pinballers never die, they just flip out."

On Tuesday, June 25, 2019 at 6:54:49 AM UTC-7, Don Brown wrote:
I have a Hickok 440 curve tracer that I am having difficulty troubleshooting, even though it is a relatively simple circuit.

The base generator staircase is not stable, and will not stay in calibration. It looks like noise comes and goes and distorts it. I have replaced most of the semiconductors. The 15v power supply is a bit low at about 13.9v, though the regulator transistor and zeners have been replaced.

I have the manual, schematic, parts and usual test equipment.

Thank you,
Don

I changed the two electrolytics in the 15v supply, and one polyester that is used in the base generator section (though it tested OK out of circuit). I did a quick run through on the resistors while in circuit, and they test within spec with nothing unusual.

In article ,
says...

Have you replaced any and all electrolytic capacitors and verified that
the resistors are on spec?

Capacitors are bigger suspects than the semiconductors...




In older equipment it is always to suspect the electrolytic capacitors
first. For older tube equipment the 1/2 and 1 watt carbon resistors
often seem to go up in value and are the next thing after the capacitors
I check for equipment that is sort of working,but not up to
specifications.

On Tuesday, June 25, 2019 at 6:54:49 AM UTC-7, Don Brown wrote:
I have a Hickok 440 curve tracer that I am having difficulty troubleshooting, even though it is a relatively simple circuit.

The base generator staircase is not stable, and will not stay in calibration. It looks like noise comes and goes and distorts it. I have replaced most of the semiconductors. The 15v power supply is a bit low at about 13.9v, though the regulator transistor and zeners have been replaced.

I have the manual, schematic, parts and usual test equipment.

Thank you,
Don

So the short answer is Yes.

On 2019/06/25 8:09 a.m., Don Brown wrote:
On Tuesday, June 25, 2019 at 6:54:49 AM UTC-7, Don Brown wrote:
I have a Hickok 440 curve tracer that I am having difficulty troubleshooting, even though it is a relatively simple circuit.

The base generator staircase is not stable, and will not stay in calibration. It looks like noise comes and goes and distorts it. I have replaced most of the semiconductors. The 15v power supply is a bit low at about 13.9v, though the regulator transistor and zeners have been replaced.

I have the manual, schematic, parts and usual test equipment.

Thank you,
Don

So the short answer is Yes.

OK, caps and resistors all good.

Then I'd scope the existing power supply to make sure it is clean & stable.

If you have a good bench power supply see if using a different +15VDC
source clears up the issue.

John :-#)#

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(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

On Tuesday, June 25, 2019 at 8:50:33 AM UTC-7, John Robertson wrote:
On 2019/06/25 8:09 a.m., Don Brown wrote:
On Tuesday, June 25, 2019 at 6:54:49 AM UTC-7, Don Brown wrote:
I have a Hickok 440 curve tracer that I am having difficulty troubleshooting, even though it is a relatively simple circuit.

The base generator staircase is not stable, and will not stay in calibration. It looks like noise comes and goes and distorts it. I have replaced most of the semiconductors. The 15v power supply is a bit low at about 13.9v, though the regulator transistor and zeners have been replaced.

I have the manual, schematic, parts and usual test equipment.

Thank you,
Don

So the short answer is Yes.

OK, caps and resistors all good.

Then I'd scope the existing power supply to make sure it is clean & stable.

If you have a good bench power supply see if using a different +15VDC
source clears up the issue.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

I can do both. I did not think of an external power supply, will report back and post results.

Thank you

On Tuesday, June 25, 2019 at 6:54:49 AM UTC-7, Don Brown wrote:
I have a Hickok 440 curve tracer that I am having difficulty troubleshooting, even though it is a relatively simple circuit.

The base generator staircase is not stable


Typically, there's a monostable making a current pulse into a capacitor for each step.
If the capacitor is an electrolytic, it may be leaky now (but run the staircase
overnight before you replace parts, it may be that some ON-time will reform
the oxide layer). If the monostable has a capacitor, it is also a suspect (unstable times).

Resetting the staircase there's a charge-dump (transistor?) that could be leaky, or its
drive might be picking up noise. Hanging an o-scope probe onto the step generator
to show the rise/plateau qualities will tell where the problem lies.

On Wednesday, June 26, 2019 at 2:46:50 AM UTC-7, whit3rd wrote:
On Tuesday, June 25, 2019 at 6:54:49 AM UTC-7, Don Brown wrote:
I have a Hickok 440 curve tracer that I am having difficulty troubleshooting, even though it is a relatively simple circuit.

The base generator staircase is not stable


Typically, there's a monostable making a current pulse into a capacitor for each step.
If the capacitor is an electrolytic, it may be leaky now (but run the staircase
overnight before you replace parts, it may be that some ON-time will reform
the oxide layer). If the monostable has a capacitor, it is also a suspect (unstable times).

Resetting the staircase there's a charge-dump (transistor?) that could be leaky, or its
drive might be picking up noise. Hanging an o-scope probe onto the step generator
to show the rise/plateau qualities will tell where the problem lies

Yes, this is the way it works. I should attach the schematic and circuit description. It charges a ceramic non electrolytic capacitor, with a diode in line that keeps it from discharging each pulse. But since ceramics rarely fail I did not change it, but maybe I should. And from previous scope probing I saw various qualities of pulses but did not really understand what was normal and what was not.

Thank you.

You can't attach things here. Bama probably has it but I can't confirm it right now because of this wonky MODEM that is going back to SBC with stab wounds, three bullet holes and half burned by a Bernzomatic torch. I am seriously about to jump ship but the only other thing I can get here is Hughesnet and in this area since there is a temporary rain forest to the south every year it is going to drop when it rains south of here just like the Dish TV thing.

But you probably got it online, just throw up a link.

I suppose I don't have to tell you to scrutinize every small signal PNP in there right ?

Nice thing is they all work the same. You should be able to put a low value resistor on the base drive and derive current that way. the noise and whatever have to be there. You can leave that on one channel of the scope and just start going backwards with the other. Unless you already have, if you are sure it is at the beginning of the "chain".

Nice to have it localised of course but when things get old they get weird failure modes. I have seen PC boards that worked for more than a decade and then came to me and looking for a bad connection on the board bending things a huge piece of solder simply came off the copper. It wasn't clean enough when they wave soldered it but it took all that time to manifest itself.

I think on this unit you are probably down to the small caps. some of them like to be a piece of wire sometimes.

More later, I am going to go shoot the MODEM. Don't worry I got another one..

On 6/26/19 2:59 PM, Jeff Urban wrote:
Bama probably has it but I can't confirm it right now

They don't.
http://bama.edebris.com/manuals/hickok/

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

On Wednesday, June 26, 2019 at 1:51:20 PM UTC-7, Fox's Mercantile wrote:
On 6/26/19 2:59 PM, Jeff Urban wrote:
Bama probably has it but I can't confirm it right now

They don't.
http://bama.edebris.com/manuals/hickok/

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

I looked everywhere for it and ended up buying the hard copy. So I need to scan it and link it.

On Wednesday, June 26, 2019 at 1:53:53 PM UTC-7, Don Brown wrote:
On Wednesday, June 26, 2019 at 1:51:20 PM UTC-7, Fox's Mercantile wrote:
On 6/26/19 2:59 PM, Jeff Urban wrote:
Bama probably has it but I can't confirm it right now

They don't.
http://bama.edebris.com/manuals/hickok/

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

I looked everywhere for it and ended up buying the hard copy. So I need to scan it and link it.

Here is a photo gallery that I created with the schematic and circuit description: http://www.edfredcorp.com/Hickok/httphotos/index.html

On Wednesday, June 26, 2019 at 1:53:53 PM UTC-7, Don Brown wrote:
On Wednesday, June 26, 2019 at 1:51:20 PM UTC-7, Fox's Mercantile wrote:
On 6/26/19 2:59 PM, Jeff Urban wrote:
Bama probably has it but I can't confirm it right now

They don't.
http://bama.edebris.com/manuals/hickok/

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

I looked everywhere for it and ended up buying the hard copy. So I need to scan it and link it.

Here is a photo gallery that I created with the schematic and circuit description: http://www.edfredcorp.com/Hickok/httphotos/index.html

And an enlarged schematic link:
http://www.edfredcorp.com/Hickok/htt...0Schematic.jpg

On Wednesday, June 26, 2019 at 1:53:53 PM UTC-7, Don Brown wrote:
On Wednesday, June 26, 2019 at 1:51:20 PM UTC-7, Fox's Mercantile wrote:
On 6/26/19 2:59 PM, Jeff Urban wrote:
Bama probably has it but I can't confirm it right now

They don't.
http://bama.edebris.com/manuals/hickok/

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

I looked everywhere for it and ended up buying the hard copy. So I need to scan it and link it.

Here is a photo gallery that I created with the schematic and circuit description: http://www.edfredcorp.com/Hickok/httphotos/index.html

And here is a link for a high resolution schematic: http://www.edfredcorp.com/Hickok/htt...0Schematic.jpg

On Wednesday, June 26, 2019 at 3:42:36 PM UTC-7, Don Brown wrote:
On Wednesday, June 26, 2019 at 1:53:53 PM UTC-7, Don Brown wrote:
On Wednesday, June 26, 2019 at 1:51:20 PM UTC-7, Fox's Mercantile wrote:
On 6/26/19 2:59 PM, Jeff Urban wrote:
Bama probably has it but I can't confirm it right now

They don't.
http://bama.edebris.com/manuals/hickok/

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

I looked everywhere for it and ended up buying the hard copy. So I need to scan it and link it.

Here is a photo gallery that I created with the schematic and circuit description: http://www.edfredcorp.com/Hickok/httphotos/index.html

And here is a link for a high resolution schematic: http://www.edfredcorp.com/Hickok/htt...0Schematic.jpg

By temporarily reducing the resistance of R22 & R23 in the 15+ & 15- I was able to bring up voltages to exactly 15v.That does heat up the zeners, which I upgraded from 1/2W to 15v 1W. No change on stability issue.

On 2019/06/26 3:42 p.m., Don Brown wrote:
On Wednesday, June 26, 2019 at 1:53:53 PM UTC-7, Don Brown wrote:
On Wednesday, June 26, 2019 at 1:51:20 PM UTC-7, Fox's Mercantile wrote:
On 6/26/19 2:59 PM, Jeff Urban wrote:
Bama probably has it but I can't confirm it right now

They don't.
http://bama.edebris.com/manuals/hickok/

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

I looked everywhere for it and ended up buying the hard copy. So I need to scan it and link it.

Here is a photo gallery that I created with the schematic and circuit description: http://www.edfredcorp.com/Hickok/httphotos/index.html

And here is a link for a high resolution schematic: http://www.edfredcorp.com/Hickok/htt...0Schematic.jpg


Hi Dan,

The Heathkit IT-1121 curve tracer is somewhat similar to your schematic.
Have you read that manual?

Pretty sure you can download it from www.tech-systems-labs.com - use
web.archive.org and look in 2007 archives...

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

On Wednesday, June 26, 2019 at 8:06:47 PM UTC-7, John Robertson wrote:
On 2019/06/26 3:42 p.m., Don Brown wrote:
On Wednesday, June 26, 2019 at 1:53:53 PM UTC-7, Don Brown wrote:
On Wednesday, June 26, 2019 at 1:51:20 PM UTC-7, Fox's Mercantile wrote:
On 6/26/19 2:59 PM, Jeff Urban wrote:
Bama probably has it but I can't confirm it right now

They don't.
http://bama.edebris.com/manuals/hickok/

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

I looked everywhere for it and ended up buying the hard copy. So I need to scan it and link it.

Here is a photo gallery that I created with the schematic and circuit description: http://www.edfredcorp.com/Hickok/httphotos/index.html

And here is a link for a high resolution schematic: http://www.edfredcorp.com/Hickok/htt...0Schematic.jpg


Hi Dan,

The Heathkit IT-1121 curve tracer is somewhat similar to your schematic.
Have you read that manual?

Pretty sure you can download it from www.tech-systems-labs.com - use
web.archive.org and look in 2007 archives...

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

I will review the Heathkit manual. I am new to curve tracers and have several manuals to study and plenty to learn.

My problem is intermittent. Cannot find what causes it yet. It does not change with length of time on (heat), case open or closed, switch movements or settings, tapping components. Maybe she is like me, getting old and not consistently useful.

I took some photos of when it is at it's best:

Here is a sample curve trace - http://www.edfredcorp.com/Hickok/htt... 0Working.jpg

Here is the calibration screen, fairly normal I think with two steps per division as expected - http://www.edfredcorp.com/Hickok/htt...0 Working.jpg

On Wednesday, June 26, 2019 at 9:10:30 PM UTC-7, Don Brown wrote:
On Wednesday, June 26, 2019 at 8:06:47 PM UTC-7, John Robertson wrote:
On 2019/06/26 3:42 p.m., Don Brown wrote:
On Wednesday, June 26, 2019 at 1:53:53 PM UTC-7, Don Brown wrote:
On Wednesday, June 26, 2019 at 1:51:20 PM UTC-7, Fox's Mercantile wrote:
On 6/26/19 2:59 PM, Jeff Urban wrote:
Bama probably has it but I can't confirm it right now

They don't.
http://bama.edebris.com/manuals/hickok/

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

I looked everywhere for it and ended up buying the hard copy. So I need to scan it and link it.

Here is a photo gallery that I created with the schematic and circuit description: http://www.edfredcorp.com/Hickok/httphotos/index.html

And here is a link for a high resolution schematic: http://www.edfredcorp.com/Hickok/htt...0Schematic.jpg


Hi Dan,

The Heathkit IT-1121 curve tracer is somewhat similar to your schematic..
Have you read that manual?

Pretty sure you can download it from www.tech-systems-labs.com - use
web.archive.org and look in 2007 archives...

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

I will review the Heathkit manual. I am new to curve tracers and have several manuals to study and plenty to learn.

My problem is intermittent. Cannot find what causes it yet. It does not change with length of time on (heat), case open or closed, switch movements or settings, tapping components. Maybe she is like me, getting old and not consistently useful.

I took some photos of when it is at it's best:

Here is a sample curve trace - http://www.edfredcorp.com/Hickok/htt... 0Working.jpg

Here is the calibration screen, fairly normal I think with two steps per division as expected - http://www.edfredcorp.com/Hickok/htt...0 Working.jpg

OK, it has been stable for hours. I repeatedly cleaned and worked all switches and adjusted component clearances to avoid possible touching to case. Also gently flexed the pc board looking for sources of intermittent signs.

Maybe the non electrolytic capacitors needed time to reform, though I did not think it mattered to those.

At this point I did not address the 13v-14v power supply deficit, since it seems to be working. If anybody thinks I should address that for better precision, I will.

Also now have the Heathkit manual for review.

Thanks for all the tips from everybody.