From: Lucianopep Luciano
To: TekScopes@...
Sent: Friday, July 06, 2012 6:32 PM
Subject: Re: [TekScopes] Re: tektronix 2445 help







________________________________

Hello Tom What do you think? How about if I take once again the voltage
all pins of U800
and you send a photo as you set my Telk 2445?
The values ??that I have highlighted are those that determine the fault?
Thanks Tom. Luciano :-)


?
Here are the readings I get. I put them next to what you measured on your
scope.


pin 1 = -2,62 V -2.187
pin 2= -1233mV +1.164
pin3= +14,52 V +10.21
pin4= +8,30V +38.7 - hor plate
pin5= 0V 0
pin 6= + 78,7V +84.3
pin 7= +86,4V +86.3
pin 8= + 76,4 V +60.3
pin 9 =+73,7V +39.2 + hor plate
pin10 = +15,01V +14.98
pin 11= +3,95V +5.68 This one puzzles me. The measurement I got is what
I would expect.
pin12= +4,29V +4.27






pin13=+7,90 mV +0.296
pin 14= +4,96V +4.96
pin 15= 0V 0
pin 16= -1685mV -1.683
pin17= +230mV -0.306
pin18= -57,4mV -0.007
pin19= +4,95V -4.98
pin20= +24,7mV -.003
pin21= -41,2mV -0.032
pin 22= -1367mV +0 .035 H pos centered, yours is ok here.
pin 23= 0V 0
pin 24=+609mV -4.97 I need to review this one.

----- Original Message -----

From: Rob

To: TekScopes@...

Sent: Saturday, July 07, 2012 2:07 PM

Subject: RE: [TekScopes] Re: tektronix 2445 help

?

My take is the chip is bad because it has a piece of finger stuck to it? Buy a new chip sans finger and the scope will run again.
Rob
-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Alexandre Souza - Listas
Sent: Saturday, July 07, 2012 11:40 AM
To: TekScopes@...
Subject: Re: [TekScopes] Re: tektronix 2445 help

3847K file just showing something useless? Wake up to life, Luciano! :oP Why can't you host the picture online or compress it better? :oP

---
Enviado do meu Motorola PT550
Meu site:

----- Original Message -----
From: "Lucianopep Luciano" <lucianopep@...>
To: <TekScopes@...>
Sent: Saturday, July 07, 2012 1:34 PM
Subject: Re: [TekScopes] Re: tektronix 2445 help [2 Attachments]

________________________________
Hello Tom photo 4193 pin 18 U800 pin 16 non have trace..and test point 59
pin 9 u 735 see Photo 4195 ..4196
Probe X1 set.

hi ..luciano :-)

?
Can you put the good scope on U800 pins 18 (tp60), 16 (tp63), and test
point 59 (U735-9). Maybe take a quick picture of each.

The one measurement that has me puzzled is U800 pin 11. It is over 1.5
volts low and is a power input pin.

----- Original Message -----
>From: Lucianopep Luciano
>To: TekScopes@...
>Sent: Friday, July 06, 2012 6:32 PM
>Subject: Re: [TekScopes] Re: tektronix 2445 help
>
>
>
>
>
>
>
>________________________________
>
>Hello Tom What do you think? How about if I take once again the voltage
>all pins of U800
>and you send a photo as you set my Telk 2445?
>The values ??that I have highlighted are those that determine the fault?
>Thanks Tom. Luciano :-)
>
>
>?
>Here are the readings I get. I put them next to what you measured on your
>scope.
>
>
>pin 1 = -2,62 V -2.187
>pin 2= -1233mV +1.164
>pin3= +14,52 V +10.21
>pin4= +8,30V +38.7 - hor plate
>pin5= 0V 0
>pin 6= + 78,7V +84.3
>pin 7= +86,4V +86.3
>pin 8= + 76,4 V +60.3
>pin 9 =+73,7V +39.2 + hor plate
>pin10 = +15,01V +14.98
>pin 11= +3,95V +5.68 This one puzzles me. The measurement I got is what
>I would expect.
>pin12= +4,29V +4.27
>
>
>
>
>
>
>pin13=+7,90 mV +0.296
>pin 14= +4,96V +4.96
>pin 15= 0V 0
>pin 16= -1685mV -1.683
>pin17= +230mV -0.306
>pin18= -57,4mV -0.007
>pin19= +4,95V -4.98
>pin20= +24,7mV -.003
>pin21= -41,2mV -0.032
>pin 22= -1367mV +0 .035 H pos centered, yours is ok here.
>pin 23= 0V 0
>pin 24=+609mV -4.97 I need to review this one.
>
>
>
>>>
>
>

------------------------------------

Yahoo! Groups Links

----- Original Message -----

From: Tom Miller

To: TekScopes@...

Sent: Saturday, July 07, 2012 11:18 AM

Subject: Re: [TekScopes] Re: tektronix 2445 help

?

?

The best price I have seen for the U800 chip is about $150 and they are hard to find. There is also the issue of an in experienced person safely removing a 24 pin dip in a multilayer board.

?

We are going to take the discussion offline so as to not clutter the group.

?

Tom

?

?

?

----- Original Message -----

From: Rob

To: TekScopes@...

Sent: Saturday, July 07, 2012 2:07 PM

Subject: RE: [TekScopes] Re: tektronix 2445 help

?

My take is the chip is bad because it has a piece of finger stuck to it? Buy a new chip sans finger and the scope will run again.
Rob
-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Alexandre Souza - Listas
Sent: Saturday, July 07, 2012 11:40 AM
To: TekScopes@...
Subject: Re: [TekScopes] Re: tektronix 2445 help

3847K file just showing something useless? Wake up to life, Luciano! :oP Why can't you host the picture online or compress it better? :oP

---
Enviado do meu Motorola PT550
Meu site:

----- Original Message -----
From: "Lucianopep Luciano" <lucianopep@...>
To: <TekScopes@...>
Sent: Saturday, July 07, 2012 1:34 PM
Subject: Re: [TekScopes] Re: tektronix 2445 help [2 Attachments]

________________________________
Hello Tom photo 4193 pin 18 U800 pin 16 non have trace..and test point 59
pin 9 u 735 see Photo 4195 ..4196
Probe X1 set.

hi ..luciano :-)

?
Can you put the good scope on U800 pins 18 (tp60), 16 (tp63), and test
point 59 (U735-9). Maybe take a quick picture of each.

The one measurement that has me puzzled is U800 pin 11. It is over 1.5
volts low and is a power input pin.

----- Original Message -----
>From: Lucianopep Luciano
>To: TekScopes@...
>Sent: Friday, July 06, 2012 6:32 PM
>Subject: Re: [TekScopes] Re: tektronix 2445 help
>
>
>
>
>
>
>
>________________________________
>
>Hello Tom What do you think? How about if I take once again the voltage
>all pins of U800
>and you send a photo as you set my Telk 2445?
>The values ??that I have highlighted are those that determine the fault?
>Thanks Tom. Luciano :-)
>
>
>?
>Here are the readings I get. I put them next to what you measured on your
>scope.
>
>
>pin 1 = -2,62 V -2.187
>pin 2= -1233mV +1.164
>pin3= +14,52 V +10.21
>pin4= +8,30V +38.7 - hor plate
>pin5= 0V 0
>pin 6= + 78,7V +84.3
>pin 7= +86,4V +86.3
>pin 8= + 76,4 V +60.3
>pin 9 =+73,7V +39.2 + hor plate
>pin10 = +15,01V +14.98
>pin 11= +3,95V +5.68 This one puzzles me. The measurement I got is what
>I would expect.
>pin12= +4,29V +4.27
>
>
>
>
>
>
>pin13=+7,90 mV +0.296
>pin 14= +4,96V +4.96
>pin 15= 0V 0
>pin 16= -1685mV -1.683
>pin17= +230mV -0.306
>pin18= -57,4mV -0.007
>pin19= +4,95V -4.98
>pin20= +24,7mV -.003
>pin21= -41,2mV -0.032
>pin 22= -1367mV +0 .035 H pos centered, yours is ok here.
>pin 23= 0V 0
>pin 24=+609mV -4.97 I need to review this one.
>
>
>
>>>
>
>

------------------------------------

Yahoo! Groups Links

----- Original Message -----

From:

To:

Sent: Saturday, July 07, 2012 11:18 AM

Subject: Re: [TekScopes] Re: tektronix 2445 help

?

The best price I have seen for the U800 chip is about $150 and they are hard to find. There is also the issue of an in experienced person safely removing a 24 pin dip in a multilayer board.

We are going to take the discussion offline so as to not clutter the group.

Tom

----- Original Message -----

From:

To:

Sent: Saturday, July 07, 2012 2:07 PM

Subject: RE: [TekScopes] Re: tektronix 2445 help

My take is the chip is bad because it has a piece of finger stuck to it? Buy a new chip sans finger and the scope will run again.
Rob
-----Original Message-----
From: [mailto:] On Behalf Of Alexandre Souza - Listas
Sent: Saturday, July 07, 2012 11:40 AM
To:
Subject: Re: [TekScopes] Re: tektronix 2445 help

3847K file just showing something useless? Wake up to life, Luciano! :oP Why can't you host the picture online or compress it better? :oP

---
Enviado do meu Motorola PT550
Meu site:

----- Original Message -----
From: "Lucianopep Luciano" <lucianopep@...>
To: <TekScopes@...>
Sent: Saturday, July 07, 2012 1:34 PM
Subject: Re: [TekScopes] Re: tektronix 2445 help [2 Attachments]

________________________________
Hello Tom photo 4193 pin 18 U800 pin 16 non have trace..and test point 59
pin 9 u 735 see Photo 4195 ..4196
Probe X1 set.

hi ..luciano :-)

?
Can you put the good scope on U800 pins 18 (tp60), 16 (tp63), and test
point 59 (U735-9). Maybe take a quick picture of each.

The one measurement that has me puzzled is U800 pin 11. It is over 1.5
volts low and is a power input pin.

----- Original Message -- ---
>From: Lucianopep Luciano
>To: TekScopes@...
>Sent: Friday, July 06, 2012 6:32 PM
>Subject: Re: [TekScopes] Re: tektronix 2445 help
>
>
>
>
>
>
>
>________________________________
>
>Hello Tom What do you think? How about if I take once again the voltage
>all pins of U800
>and you send a photo as you set my Telk 2445?
>The values ??that I have highlighted are those that determine the fault?
>Thanks Tom. Luciano :-)
>
>
>?
>Here are the readings I get. I put them next to what you measured on your
>scope.
>
>
>pin 1 = -2,62 V -2.187
>pin 2= -1233mV +1.164
>pin3= +14,52 V +10.21
>pin4= +8,30V +38.7 - h or plate
>pin5= 0V 0
>pin 6= + 78,7V +84.3
>pin 7= +86,4V +86.3
>pin 8= + 76,4 V +60.3
>pin 9 =+73,7V +39.2 + hor plate
>pin10 = +15,01V +14.98
>pin 11= +3,95V +5.68 This one puzzles me. The measurement I got is what
>I would expect.
>pin12= +4,29V +4.27
>
>
>
>
>
>
>pin13=+7,90 mV +0.296
>pin 14= +4,96V +4.96
>pin 15= 0V 0
>pin 16= -1685mV -1.683
>pin17= +230mV -0.306
>pin18= -57,4mV -0.007
>pin19= +4,95V -4.98
>pin20= +24,7mV -.003
>pin21= -41,2mV -0.032
>pin 22= -1367mV +0 .035 H pos centered, yours is ok here.
>pin 23= 0V 0
>pin 24=+609mV -4.97 I need to review this one.
>
>
>
>>>
>
>

------------------------------------

Yahoo! Groups Links

?

?

I think a summary at the end would be much more helpful than following all the blind alleys.

On Sat, Jul 7, 2012 at 5:57 PM, Tom Jobe <tomjobe@...> wrote:

Hi Tom,
How could the discussion of this Tektronix 2445 repair be considered "clutter" to a Tektronix Scope Group?

----- Original Message -----

From: Patrick Wong

To: TekScopes@...

Sent: Saturday, July 07, 2012 11:00 PM

Subject: [TekScopes] Re: tektronix 2445 help

?

I believe the outcome is the OP found a good horizontal sweep signal being fed to the input of U800 (pin 18). Since the output (pins 4 & 9) is not correct, it is reasonable to assume that U800 has failed, especially since U800 is a known problem area.

The low voltage measured by the OP on pin 11 indicates the current flow to that pin is greater than normal (pin 11 receives voltage via a 330 ohm resistor connected to the +15V power supply.) I suppose that also is indicative of a failed U800.

Thanks,

Patrick Wong AK6C

--- In TekScopes@..., David DiGiacomo wrote:
>
> I think a summary at the end would be much more helpful than following all the blind alleys.
>
> On Sat, Jul 7, 2012 at 5:57 PM, Tom Jobe wrote:
>
> > Hi Tom,
> > How could the discussion of this Tektronix 2445 repair be considered "clutter" to a Tektronix Scope Group?

Hi Patrick,

Seeing the waveform on the input along with the DC component of 60 mV on pin 18 leads me to believe the chip is bad. I didn't want him to go through changing the chip unless I was sure that was the problem. It's no trivial task for a beginner to remove the main board just to get access to U800.

There are other failure modes that can cause the same symptoms.

Of course you or I could have arrived at that diagnosis within minutes but we are dealing with a language barrier as well as a time delay of a day between replies.

Rob has found two sources for U800 from $117 to $135 so that is very helpful. Now to find out if he can get some experienced help to change the chip.


Regards,
Tom




----- Original Message -----
From: Patrick Wong
To: TekScopes@...
Sent: Saturday, July 07, 2012 11:00 PM
Subject: [TekScopes] Re: tektronix 2445 help



I believe the outcome is the OP found a good horizontal sweep signal being fed to the input of U800 (pin 18). Since the output (pins 4 & 9) is not correct, it is reasonable to assume that U800 has failed, especially since U800 is a known problem area.

The low voltage measured by the OP on pin 11 indicates the current flow to that pin is greater than normal (pin 11 receives voltage via a 330 ohm resistor connected to the +15V power supply.) I suppose that also is indicative of a failed U800.

Thanks,

Patrick Wong AK6C

--- In TekScopes@..., David DiGiacomo <daviddigiacomo@> wrote:
>
> I think a summary at the end would be much more helpful than following all the blind alleys.
>
> On Sat, Jul 7, 2012 at 5:57 PM, Tom Jobe <tomjobe@> wrote:
>
> > Hi Tom,
> > How could the discussion of this Tektronix 2445 repair be considered "clutter" to a Tektronix Scope Group?

----- Original Message -----

From: victor_j_silva

To: TekScopes@...

Sent: Sunday, July 08, 2012 12:57 AM

Subject: [TekScopes] Re: tektronix 2445 help

?

I question whether replacing U800 on a 2445 is worth the labor and the cost of the device. I suppose if it's a beloved family heirloom would make it about the only reason to keep it working.

--- In TekScopes@..., "Tom Miller" wrote:
>
> Hi Patrick,
>
> Seeing the waveform on the input along with the DC component of 60 mV on pin 18 leads me to believe the chip is bad. I didn't want him to go through changing the chip unless I was sure that was the problem. It's no trivial task for a beginner to remove the main board just to get access to U800.
>
> There are other failure modes that can cause the same symptoms.
>
> Of course you or I could have arrived at that diagnosis within minutes but we are dealing with a language barrier as well as a time delay of a day between replies.
>
> Rob has found two sources for U800 from $117 to $135 so that is very helpful. Now to find out if he can get some experienced help to change the chip.
>
>
> Regards,
> Tom
>
>
>
>
> ----- Original Message -----
> From: Patrick Wong
> To: TekScopes@...
> Sent: Saturday, July 07, 2012 11:00 PM
> Subject: [TekScopes] Re: tektronix 2445 help
>
>
>
> I believe the outcome is the OP found a good horizontal sweep signal being fed to the input of U800 (pin 18). Since the output (pins 4 & 9) is not correct, it is reasonable to assume that U800 has failed, especially since U800 is a known problem area.
>
> The low voltage measured by the OP on pin 11 indicates the current flow to that pin is greater than normal (pin 11 receives voltage via a 330 ohm resistor connected to the +15V power supply.) I suppose that also is indicative of a failed U800.
>
> Thanks,
>
> Patrick Wong AK6C
>
> --- In TekScopes@..., David DiGiacomo wrote:
> >
> > I think a summary at the end would be much more helpful than following all the blind alleys.
> >
> > On Sat, Jul 7, 2012 at 5:57 PM, Tom Jobe wrote:
> >
> > > Hi Tom,
> > > How could the discussion of this Tektronix 2445 repair be considered "clutter" to a Tektronix Scope Group?
>

Well, he could most likely part out the good hybrids, attenuaters, power supply & fan, the A5 board, HV power supply, and the CRT for enough to buy a working 2465 and lunch. Especially in Italy. Or just keep it for spares.

:)

Tom



----- Original Message -----
From: victor_j_silva
To: TekScopes@...
Sent: Sunday, July 08, 2012 12:57 AM
Subject: [TekScopes] Re: tektronix 2445 help



I question whether replacing U800 on a 2445 is worth the labor and the cost of the device. I suppose if it's a beloved family heirloom would make it about the only reason to keep it working.

--- In TekScopes@..., "Tom Miller" <tmiller11147@> wrote:
>
> Hi Patrick,
>
> Seeing the waveform on the input along with the DC component of 60 mV on pin 18 leads me to believe the chip is bad. I didn't want him to go through changing the chip unless I was sure that was the problem. It's no trivial task for a beginner to remove the main board just to get access to U800.
>
> There are other failure modes that can cause the same symptoms.
>
> Of course you or I could have arrived at that diagnosis within minutes but we are dealing with a language barrier as well as a time delay of a day between replies.
>
> Rob has found two sources for U800 from $117 to $135 so that is very helpful. Now to find out if he can get some experienced help to change the chip.
>
>
> Regards,
> Tom
>
>
>
>
> ----- Original Message -----
> From: Patrick Wong
> To: TekScopes@...
> Sent: Saturday, July 07, 2012 11:00 PM
> Subject: [TekScopes] Re: tektronix 2445 help
>
>
>
> I believe the outcome is the OP found a good horizontal sweep signal being fed to the input of U800 (pin 18). Since the output (pins 4 & 9) is not correct, it is reasonable to assume that U800 has failed, especially since U800 is a known problem area.
>
> The low voltage measured by the OP on pin 11 indicates the current flow to that pin is greater than normal (pin 11 receives voltage via a 330 ohm resistor connected to the +15V power supply.) I suppose that also is indicative of a failed U800.
>
> Thanks,
>
> Patrick Wong AK6C
>
> --- In TekScopes@..., David DiGiacomo <daviddigiacomo@> wrote:
> >
> > I think a summary at the end would be much more helpful than following all the blind alleys.
> >
> > On Sat, Jul 7, 2012 at 5:57 PM, Tom Jobe <tomjobe@> wrote:
> >
> > > Hi Tom,
> > > How could the discussion of this Tektronix 2445 repair be considered "clutter" to a Tektronix Scope Group?
>