Topics

Tektronix 222 mini scope repair, looking for schematics

satbeginner
 

Hi all,

A friend gave me 222, because it was a Tek and he knew "I have a thing" for Tektronix.
It's almost mint!, But... The readout is clearly visible, but there is no trace?
I tried inputting a signal, but I never got the triggered light to come on, nor did I got something visible but the readout.

It will be another 5 days before I get home, but meanwhile I want to think about the problem.
I looked for a manual including the schematics, but found nothing.

After the recent submerge of the microfiche set, could they be in there?
Is there anything available?

Un saludo,

Leo

johncharlesgord
 

Leo,

Qservice has a pdf of the 224 manual, which includes schematics. The 224 and 222 are quite similar.

--John Gord

On Sun, Oct 20, 2019 at 01:55 PM, satbeginner wrote:


Hi all,

A friend gave me 222, because it was a Tek and he knew "I have a thing" for
Tektronix.
It's almost mint!, But... The readout is clearly visible, but there is no
trace?
I tried inputting a signal, but I never got the triggered light to come on,
nor did I got something visible but the readout.

It will be another 5 days before I get home, but meanwhile I want to think
about the problem.
I looked for a manual including the schematics, but found nothing.

After the recent submerge of the microfiche set, could they be in there?
Is there anything available?

Un saludo,

Leo

ArtekManuals
 

Leo

We have the full service manual with schematics for the 222A which I am told ( though I have no personal experience in using it to service a 222)
There are only minor  differences between the 222 and the 222A

Contact me off list for details
Dave
manuals@...

On 10/20/2019 5:26 PM, johncharlesgord via Groups.Io wrote:
Leo,

Qservice has a pdf of the 224 manual, which includes schematics. The 224 and 222 are quite similar.

--John Gord

On Sun, Oct 20, 2019 at 01:55 PM, satbeginner wrote:

Hi all,

A friend gave me 222, because it was a Tek and he knew "I have a thing" for
Tektronix.
It's almost mint!, But... The readout is clearly visible, but there is no
trace?
I tried inputting a signal, but I never got the triggered light to come on,
nor did I got something visible but the readout.

It will be another 5 days before I get home, but meanwhile I want to think
about the problem.
I looked for a manual including the schematics, but found nothing.

After the recent submerge of the microfiche set, could they be in there?
Is there anything available?

Un saludo,

Leo
--
Dave
Manuals@...
www.ArtekManuals.com
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

GerryR
 

I just received a manual for an older Wavetek Pulse Generator, from Artek Manuals, on CD. Very high quality and complete. I have no affiliation with them, but definitely recommend them. The sections that I printed out were very clear, including the schematics.

GerryR

----- Original Message -----
From: "ArtekManuals" <manuals@...>
To: <TekScopes@groups.io>
Sent: Sunday, October 20, 2019 5:42 PM
Subject: Re: [TekScopes] Tektronix 222 mini scope repair, looking for schematics


Leo

We have the full service manual with schematics for the 222A which I am told ( though I have no personal experience in using it to service a 222)
There are only minor differences between the 222 and the 222A

Contact me off list for details
Dave
manuals@...

On 10/20/2019 5:26 PM, johncharlesgord via Groups.Io wrote:
Leo,

Qservice has a pdf of the 224 manual, which includes schematics. The 224 and 222 are quite similar.

--John Gord

On Sun, Oct 20, 2019 at 01:55 PM, satbeginner wrote:

Hi all,

A friend gave me 222, because it was a Tek and he knew "I have a thing" for
Tektronix.
It's almost mint!, But... The readout is clearly visible, but there is no
trace?
I tried inputting a signal, but I never got the triggered light to come on,
nor did I got something visible but the readout.

It will be another 5 days before I get home, but meanwhile I want to think
about the problem.
I looked for a manual including the schematics, but found nothing.

After the recent submerge of the microfiche set, could they be in there?
Is there anything available?

Un saludo,

Leo
--
Dave
Manuals@...
www.ArtekManuals.com


--
This email has been checked for viruses by Avast antivirus software.
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guy232
 

Not the answer for your question but maybe it is of interest: Mr Carlson has a ~30 min video of tear down/repair/battery fabrication for the 224 on youtube. Just sharing this because I see someone mentioned it is similar to the 222. A quality video, especially in regards to the battery.

https://youtu.be/nLWVTFj_Yik

ken chalfant
 

Greetings Leo,

Dave at Artekmanuals.com lists the service manual for the Tek 222.

It should be available for download or available as a CD.

His prices are extremely fair and his service is fantastic.

Good troubleshooting!

Regards,

Ken

On 20Oct, 2019, at 2:55 PM, satbeginner <@satbeginner> wrote:

Hi all,

A friend gave me 222, because it was a Tek and he knew "I have a thing" for Tektronix.
It's almost mint!, But... The readout is clearly visible, but there is no trace?
I tried inputting a signal, but I never got the triggered light to come on, nor did I got something visible but the readout.

It will be another 5 days before I get home, but meanwhile I want to think about the problem.
I looked for a manual including the schematics, but found nothing.

After the recent submerge of the microfiche set, could they be in there?
Is there anything available?

Un saludo,

Leo


Miguel Work
 

Thanks!

I ´have complete service manual for 222 and 222A. Is more easy to modify scope charger circuit to charge lithium battery. All my old NI-CD gadgets, like my THS730, TEK 222, 221, 213, 214, now are working with lithium batteries with minimum modifications.

Regards

Miguel




-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de guy232
Enviado el: lunes, 21 de octubre de 2019 1:09
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Tektronix 222 mini scope repair, looking for schematics

Not the answer for your question but maybe it is of interest: Mr Carlson has a ~30 min video of tear down/repair/battery fabrication for the 224 on youtube. Just sharing this because I see someone mentioned it is similar to the 222. A quality video, especially in regards to the battery.

https://youtu.be/nLWVTFj_Yik

Dave Voorhis
 

On 21 Oct 2019, at 10:23, Miguel Work <harrimansat@...> wrote:

I ´have complete service manual for 222 and 222A. Is more easy to modify scope charger circuit to charge lithium battery. All my old NI-CD gadgets, like my THS730, TEK 222, 221, 213, 214, now are working with lithium batteries with minimum modifications.
What were your modifications?

BTW, at least the 222 was originally lead-acid gel, not NiCad.

Miguel Work
 

Hi Dave!


The trick is modify charger to Supply 4,2 volt max for element, and modify main power supply to work with voltages at lithium range, 3.2 to 4.2, 6.4 to 8.4, 9.6 to 12.6 and so on.

The Tektronix 222 has a lead battery, and it haves a lead voltage temperature compensation that must be cancelled to work with lithium.

For security I only use batteries with internal protection.

Regards

Miguel



-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Dave Voorhis
Enviado el: lunes, 21 de octubre de 2019 11:27
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Tektronix 222 mini scope repair, looking for schematics

On 21 Oct 2019, at 10:23, Miguel Work <harrimansat@...> wrote:

I ´have complete service manual for 222 and 222A. Is more easy to modify scope charger circuit to charge lithium battery. All my old NI-CD gadgets, like my THS730, TEK 222, 221, 213, 214, now are working with lithium batteries with minimum modifications.
What were your modifications?

BTW, at least the 222 was originally lead-acid gel, not NiCad.

Colin Herbert
 

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of satbeginner
Sent: 20 October 2019 21:56
To: TekScopes@groups.io
Subject: [TekScopes] Tektronix 222 mini scope repair, looking for schematics

Hi all,

A friend gave me 222, because it was a Tek and he knew "I have a thing" for Tektronix.
It's almost mint!, But... The readout is clearly visible, but there is no trace?
I tried inputting a signal, but I never got the triggered light to come on, nor did I got something visible but the readout.

It will be another 5 days before I get home, but meanwhile I want to think about the problem.
I looked for a manual including the schematics, but found nothing.

After the recent submerge of the microfiche set, could they be in there?
Is there anything available?

Un saludo,

Leo

ArtekManuals
 

True that copy is better than nothing ....BUT... the schematic scans are barely readable, it is not electronically bookmarked and it is not text searchable

The ArtekManuals scan is much better, is text searchable and has an electronic table of contents.

as my father used to say; " if you want good clean oats they cost a bit more than the oats that have already been through the horse"

Dave
manuals@...

On 10/21/2019 8:49 AM, Colin Herbert via Groups.Io wrote:
Tried TekWiki?

http://w140.com/tekwiki/wiki/222

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of satbeginner
Sent: 20 October 2019 21:56
To: TekScopes@groups.io
Subject: [TekScopes] Tektronix 222 mini scope repair, looking for schematics

Hi all,

A friend gave me 222, because it was a Tek and he knew "I have a thing" for Tektronix.
It's almost mint!, But... The readout is clearly visible, but there is no trace?
I tried inputting a signal, but I never got the triggered light to come on, nor did I got something visible but the readout.

It will be another 5 days before I get home, but meanwhile I want to think about the problem.
I looked for a manual including the schematics, but found nothing.

After the recent submerge of the microfiche set, could they be in there?
Is there anything available?

Un saludo,

Leo





--
Dave
Manuals@...
www.ArtekManuals.com
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

tekscopegroup@...
 

On Mon, Oct 21, 2019 at 02:52 AM, Miguel Work wrote:
The trick is modify charger to Supply 4,2 volt max for element, and modify
main power supply to work with voltages at lithium range, 3.2 to 4.2, 6.4 to
8.4, 9.6 to 12.6 and so on.
The ideal configuration seems to be using 2x 16850 Lithium cells. I have a 222 and mounted a 2-cell holder into the battery cavity and it fits quite well with room to spare. By mounting the holder first on a purpose size cut PC board I am able to make it press-fit securely just right so no screws or new holes where needed. The mounting on the PC board was actually an afterthought because I had to cut the battery holder in half in order to stretch it a bit so the battery cells with build-in protection that are slightly longer would fit into it lengthwise. For a time some years ago there was a seller on ebay that was offering a 2-cell battery pack kit specifically for the 22x scopes and included detailed instructions on how to implement the charging process internally at the correct voltage by modifying a couple of resistors. But I don't think it has been available any longer for a good amount of time. In any case its very easy to do it yourself.

The Tektronix 222 has a lead battery, and it haves a lead voltage temperature
compensation that must be cancelled to work with lithium.
For security I only use batteries with internal protection.
To maximize scope run time on the new batteries, the automatic cut-off voltage needs to be reset to a lower value than the factory setting for the original Lead-Acid battery, which is about ~7.2-7.5V. With Lithium batteries to cut-off at that level it is too early as there will still be usable power left in the cells without harming them. The scope cut-off point is determined by a simple two resistor voltage divider that feeds the CPU and comprised of two 100K SMD resistors. The cut-off happens when the CPU input pin sees 3.6V (after the divider). The desired new specific cut-off point depends on the type of Lithium battery chemistry that you choose, as nominal cell voltages vary a bit. But basically all that is needed is to adjust the top 100K resistor of the divider with a somewhat higher value to lower the cut-off point.

I still have not finished this project (its been on hold now for the better part of 2 years) and only got as far as installing the battery holder and to take the voltage readings in order to figure out how the internal low voltage cut-off circuit behaves. I also put a special Schottky "smart diode" with only 0.22V drop-out voltage in series with the battery to prevent the scope from directly charging the batteries, as I initially intended to keep things simple to recharge each cell individually on an external charger. So I have yet to modify the resistor of the voltage divider in my scope, but I intend to set it to cut-off when the new Li battery pack reaches 6.0 (3.0V/cell) which is still well clear of the 2.45V low voltage trip point of the protection circuit build into each cell. I have over time learned more about Li batteries and have revised my plans and will eventually install a 2S (2-cell) charging board which I already have received some weeks ago for an unrelated project and that will allow the scope to automatically charge the batteries directly when plugged into AC. Said charging boards (and cell protector) boards are both widely available off ebay and very easy to implement. Maybe this thread is what I needed to revive interest in finishing this project.

Alex

greenboxmaven
 

Will the power supply in the scope be damaged by the lower voltage? In an effort to maintain full output, a fixed wattage, with a lower supply voltage, the current in the transformer primary and switching transistors will rise.

Bruce, KA2IVY

On 10/21/19 11:21 AM, tekscopegroup@... wrote:
On Mon, Oct 21, 2019 at 02:52 AM, Miguel Work wrote:
The trick is modify charger to Supply 4,2 volt max for element, and modify
main power supply to work with voltages at lithium range, 3.2 to 4.2, 6.4 to
8.4, 9.6 to 12.6 and so on.
To maximize scope run time on the new batteries, the automatic cut-off voltage needs to be reset to a lower value than the factory setting for the original Lead-Acid battery, which is about ~7.2-7.5V. With Lithium batteries to cut-off at that level it is too early as there will still be usable power left in the cells without harming them. The scope cut-off point is determined by a simple two resistor voltage divider that feeds the CPU and comprised of two 100K SMD resistors. The cut-off happens when the CPU input pin sees 3.6V (after the divider). The desired new specific cut-off point depends on the type of Lithium battery chemistry that you choose, as nominal cell voltages vary a bit. But basically all that is needed is to adjust the top 100K resistor of the divider with a somewhat higher value to lower the cut-off point.


Henry Hopkinson
 

If the 222 TEK is the DSO 222 you can download the users manual from this
website.
bama.edebris.com/manual.
Henry

On Sun, Oct 20, 2019 at 5:43 PM ArtekManuals <manuals@...>
wrote:

Leo

We have the full service manual with schematics for the 222A which I am
told ( though I have no personal experience in using it to service a 222)
There are only minor differences between the 222 and the 222A

Contact me off list for details
Dave
manuals@...

On 10/20/2019 5:26 PM, johncharlesgord via Groups.Io wrote:
Leo,

Qservice has a pdf of the 224 manual, which includes schematics. The
224 and 222 are quite similar.

--John Gord

On Sun, Oct 20, 2019 at 01:55 PM, satbeginner wrote:

Hi all,

A friend gave me 222, because it was a Tek and he knew "I have a thing"
for
Tektronix.
It's almost mint!, But... The readout is clearly visible, but there is
no
trace?
I tried inputting a signal, but I never got the triggered light to come
on,
nor did I got something visible but the readout.

It will be another 5 days before I get home, but meanwhile I want to
think
about the problem.
I looked for a manual including the schematics, but found nothing.

After the recent submerge of the microfiche set, could they be in there?
Is there anything available?

Un saludo,

Leo
--
Dave
Manuals@...
www.ArtekManuals.com


--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus




tekscopegroup@...
 

On Mon, Oct 21, 2019 at 10:22 AM, greenboxmaven wrote:
Will the power supply in the scope be damaged by the lower voltage? In
an effort to maintain full output, a fixed wattage, with a lower supply
voltage, the current in the transformer primary and switching
transistors will rise.

Bruce, KA2IVY
I never saw or felt any problems when I extensively ran the scope on the Lithium batteries to determine approximate run times, shut off voltages, etc. After all where are talking about running the scope between 8.4 - 6V, compared to 9.5 to 7.5V with the original battery. If there is any difference in current it seems to be small enough that the circuit can easily handle it without any complaints. I seems silly not to take full advantage of the capacity of the new batteries to extend run times. However I did not take a deep dive into this issue nor at the time did I even think about it being a potential problem, so if anybody has recommendations in regards to it, would be good to know.

Miguel Work
 

The main problem with lithium and 222 is that the DC converter core is a TL594, is connected directly to VBAT, and his min. operational voltage is 7V but it works well with 6.5V

Regards

Miguel

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de tekscopegroup@...
Enviado el: martes, 22 de octubre de 2019 18:40
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Tektronix 222 mini scope repair, looking for schematics

On Mon, Oct 21, 2019 at 10:22 AM, greenboxmaven wrote:
Will the power supply in the scope be damaged by the lower voltage?
In an effort to maintain full output, a fixed wattage, with a lower
supply voltage, the current in the transformer primary and switching
transistors will rise.

Bruce, KA2IVY
I never saw or felt any problems when I extensively ran the scope on the Lithium batteries to determine approximate run times, shut off voltages, etc. After all where are talking about running the scope between 8.4 - 6V, compared to 9.5 to 7.5V with the original battery. If there is any difference in current it seems to be small enough that the circuit can easily handle it without any complaints. I seems silly not to take full advantage of the capacity of the new batteries to extend run times. However I did not take a deep dive into this issue nor at the time did I even think about it being a potential problem, so if anybody has recommendations in regards to it, would be good to know.

satbeginner
 

Hi all,

Thanks for all links, files an suggestions!
We will be driving back to Spain coming Friday, so next week I can dive in my unit.

Still not sure if the 222A schematics can be used for my 222, but I will update on the matter next week.

Un saludo,

Leo

Miguel Work
 

8.3.2 Undervoltage Lockout
The TL594 has circuitry to provide an undervoltage-lockout functionality. A minimum recommended VCC voltage
of 7 V is recommended for operation, but if the VCC voltage drops below 6 V during operation, then the device
shuts off. See Electrical Characteristics for additional information regarding the undervoltage lockout circuitry.

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de tekscopegroup@...
Enviado el: martes, 22 de octubre de 2019 18:40
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Tektronix 222 mini scope repair, looking for schematics

On Mon, Oct 21, 2019 at 10:22 AM, greenboxmaven wrote:
Will the power supply in the scope be damaged by the lower voltage?
In an effort to maintain full output, a fixed wattage, with a lower
supply voltage, the current in the transformer primary and switching
transistors will rise.

Bruce, KA2IVY
I never saw or felt any problems when I extensively ran the scope on the Lithium batteries to determine approximate run times, shut off voltages, etc. After all where are talking about running the scope between 8.4 - 6V, compared to 9.5 to 7.5V with the original battery. If there is any difference in current it seems to be small enough that the circuit can easily handle it without any complaints. I seems silly not to take full advantage of the capacity of the new batteries to extend run times. However I did not take a deep dive into this issue nor at the time did I even think about it being a potential problem, so if anybody has recommendations in regards to it, would be good to know.

tekscopegroup@...
 

On Tue, Oct 22, 2019 at 11:11 AM, satbeginner wrote:
Still not sure if the 222A schematics can be used for my 222, but I will
update on the matter next week.
Leo I do have a good PDF copy of the plain (non-A) 222 SM (070-7459-00) if you need it let me know. Its 84 pages and about 24MB. Can't remember now where I got it from. I also have the 222A and 224A SMs that I purchased from Artek some time ago and I would highly recommend getting from them as the quality is excellent as usual.
Alex

 

On Wed, Oct 23, 2019 at 03:45 PM, <tekscopegroup@...> wrote:


Leo I do have a good PDF copy of the plain (non-A) 222 SM (070-7459-00) if you need it let me know.
This one is also on TekWiki and does not contain schematics.

I have the Component Level Manual with schematics for internal use and I just scanned it.
It could be found here for some time: www.hakanh.com/dl/temp/222_Component_Level_Service.pdf
The original print isn't as good as a normal manual but better than nothing.

/Håkan