Bandpass problem with 7704A
Hi,
I have a 7704A that has a weak bandpass in the 40Mhz area on ch1 of both left and right vertical slots. Any ideas? Ch2 is okay. No other areas show a problem to 250Mhz(my teat limit).
Jerry Massengale
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Re: R7103 backplane repair
Be aware that not
all sprung metal contacts from differing donors are the same, even with the same
part number (131-0726-00 (straight)??& 131-0727-00 (offset)): some
are wider than others and have different shapes.? With work they all seem
to fit.? Also remember the plastic connector blocks for Vertical and
Horizontal ?are different.
How do I know this?
from having done a similar repair, but including connector block replacement, on
a 7904!
?
Chris
HJ
?
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--- In TekScopes@..., "scott_dixon" wrote:
Just got one of these and I'm trying to find an owners manual. I've checked the usual places online, did some Googling and asked Dave (Artekmedia) but no luck so far. I've found a brief service manual at tek.com but nothing else.
Anyone have a (preferably) electronic copy of the owners manual for this unit? Not that it seems that hard to figure out, but it never hurts to have the docs.
Thanks,
Scott
---------------
The Service Manual can be dowloaded from Tek's website. It is part of the manual called "Bench Test and Handheld Scopes Service". /H?kan
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Re: 7104 Horizontal Amplifier
FYI,
Found this HP description?of a TEK HYPCON connector
Bob
--- In TekScopes@..., "johncharlesgord" wrote: > > Chris, > > U1094 is held in contact by a frame and some sort of elastomeric pad. There are instructions starting at page 4-30 in the service manual (070-2314-00) on how to deal with this "HYPCON" connection. > > I suspect that the pin 3 connection has gone open, removing the main ground path to the chip. With luck, this connection break is not inside the hybrid but at the accessible HYPCON contacts. Following the manual directions, carefully remove the hybrid, clean the contacts with isopropyl alcohol (91% or more), dry, and reassemble. > > --John Gord > > --- In TekScopes@..., "chrismh_somenumber" wrote: > > > > Another Update: > > > > I've worked my way down the horizontal amplifier board, checking all voltages and waveform test points. Everything was looking good until I reached U1082. The voltages at many of the pins were high. > > > > Suspecting a problem with the readout, I removed Q1052 and Q1072, connecting the pads from emitter to collector with a wire. (This is recommended in the service manual, page 3-57, to remove the feedback path). > > > > More of the voltages around U1082 were OK after that change (15, 17, 18, 19 were still high), but TP1038 and TP1078 were still high. I lifted the collectors of Q1028 and Q1034 to remove the readout positioning, but that did not change TP1038 and TP1039. > > > > The voltages around U1094 are all wrong. Most read .5 to 1 volt high. Pins 13 and 14 read 4.5V high, and pin 3 reads 0V (it should be 4.2V). The output waveform going into the CRT (test points 5 and 6) is a flat line. > > > > I checked component values around U1094 and they seemed OK. The > > > > Is it likely that U1094 is bad? The U1014 OpAmp appears to be op-amping, and its supply voltage is OK. The voltages in that bit of circuitry utilizing U1094 are running a little high, but could that cause U1094 to not produce any output at all? > > > > Thanks, > > Chris > > > > > > --- In TekScopes@..., "chrismh_somenumber" wrote: > > > > > > My recently acquired 7104 has a problem, which I assume is something to do with the horizontal amplifier (please feel free to correct me...). > > > > > > When the scope starts up, I get a normal trace for about 3-5 minutes, then it changes to a compressed vertical line. It appears that the vertical is working since I can make the vertical line grow and shrink (vertically) by varying the v/div or by varying the input signal. However, the entire trace, and the readout, is compressed to a single vertical line. > > > > > > Thoughts? > > > > > > Thanks, > > > Chris > > > > > >
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Scope control via Android
This may interest some of you if you have a scope which can connect to the web:
http://www.tek.com/document/news-release/tektronix-launches-three-android-applications-use-oscilloscopes
HankC, Boston
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Re: 7104 Horizontal Amplifier
This is interesting. I was probing that exact pin on the chip last night and the scope all of a sudden started working. Maybe I jostled something enough to connect the ground.
Unfortunately, this morning it was back to not working.
I'll try cleaning the contacts.
Thanks,
CHris
toggle quoted message
Show quoted text
--- In TekScopes@..., "johncharlesgord" wrote:
Chris,
U1094 is held in contact by a frame and some sort of elastomeric pad. There are instructions starting at page 4-30 in the service manual (070-2314-00) on how to deal with this "HYPCON" connection.
I suspect that the pin 3 connection has gone open, removing the main ground path to the chip. With luck, this connection break is not inside the hybrid but at the accessible HYPCON contacts. Following the manual directions, carefully remove the hybrid, clean the contacts with isopropyl alcohol (91% or more), dry, and reassemble.
--John Gord
--- In TekScopes@..., "chrismh_somenumber" wrote:
Another Update:
I've worked my way down the horizontal amplifier board, checking all voltages and waveform test points. Everything was looking good until I reached U1082. The voltages at many of the pins were high.
Suspecting a problem with the readout, I removed Q1052 and Q1072, connecting the pads from emitter to collector with a wire. (This is recommended in the service manual, page 3-57, to remove the feedback path).
More of the voltages around U1082 were OK after that change (15, 17, 18, 19 were still high), but TP1038 and TP1078 were still high. I lifted the collectors of Q1028 and Q1034 to remove the readout positioning, but that did not change TP1038 and TP1039.
The voltages around U1094 are all wrong. Most read .5 to 1 volt high. Pins 13 and 14 read 4.5V high, and pin 3 reads 0V (it should be 4.2V). The output waveform going into the CRT (test points 5 and 6) is a flat line.
I checked component values around U1094 and they seemed OK. The
Is it likely that U1094 is bad? The U1014 OpAmp appears to be op-amping, and its supply voltage is OK. The voltages in that bit of circuitry utilizing U1094 are running a little high, but could that cause U1094 to not produce any output at all?
Thanks,
Chris
--- In TekScopes@..., "chrismh_somenumber" wrote:
My recently acquired 7104 has a problem, which I assume is something to do with the horizontal amplifier (please feel free to correct me...).
When the scope starts up, I get a normal trace for about 3-5 minutes, then it changes to a compressed vertical line. It appears that the vertical is working since I can make the vertical line grow and shrink (vertically) by varying the v/div or by varying the input signal. However, the entire trace, and the readout, is compressed to a single vertical line.
Thoughts?
Thanks,
Chris
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Mechanical switch on A7 Timing Board 475
Has anyone ever managed to dismantle and repair the long switch on the A7 timing board on a 475? The central grey knob pull switch on mine no longer springs back on its own when you release it. I took the aluminium cover off the long switch to reveal the red tumblers underneath, but could not see if a spring or something needed fixing. Any one else ever had this problem? Should I replace the whole switch, that is, if you can get them? Thanks.
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I replaced the U506 on the interface board, part number was MC1458N. I cleaned it as best I could with water and compressed air. It's not perfect but it doesn't smell nearly as bad when switched on now :)
The only thing still giving trouble are the volts/div selector switches. They do work but are very finicky. Calibration seems to be good enough for my purposes.
The storage part still works excellent to my surprise.
Thanks again,
toggle quoted message
Show quoted text
On 01/18/2013 12:41 AM, Tom Jobe wrote: Hi Ciphair,
Congratulations on the repair of your 468!
But what did you replace with what?
It has been awhile since you last reported on your progress.
tom jobe...
----- Original Message -----
From: Ciphair
To: TekScopes@...
Sent: Thursday, January 17, 2013 1:43 PM
Subject: Re: [TekScopes] Salty 468 update
Finally got around to replacing it today and it came back to live
immediately! +5v is spot on as well :)
Thanks for all the help
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A number of months ago I picked up a R7103 on ebay for a very good price as it didn't power up (shipping cost me as much as the purchase price). It seemed like something worth a gamble. I quickly found the problem to be the left vertical plug-in connector which was missing its outer plastic pieces, and the contacts were touching. A temporary piece of plastic inserted allowed the scope to power up and I happily found that the CRT was in excellent condition and the rest of the scope looked to be completely functional. I had to put it aside until I found my spare Tek parts and that happened a few days ago.
Unfortunately, on closer examination, I realized that most of the contacts in that connector were bent, doubled up, and even broken as someone had apparently jammed a plug-in in there at some point. I thought I would give it a shot to try and fix it...
I had a backplane from another rack mount 7k scope which I had parted out (don't cringe, it was unrecoverable due to a broken CRT and serious chassis damage courtesy of United Parcel Smashers).
To do the repair I had to remove the backplane from the scope, taking digital photos of all connections, routing, and mounting. I also wrote down where things went and labelled cables. I also removed and set aside the two boards attached to the backplane. I used ESD precautions.
Very fortunately, the special signal contacts were undamaged as that would have been a whole 'nother level of repair. I used a Pace desoldering station to salvage good contacts (there are two different types). These must be treated gently! I similarly removed the damaged ones from the 7103 backplane. I discovered that the plastic sides, which are required, grab on on the rear of the connector and that when soldering in replacement contacts you need to make sure that the contact is fully against the rear of the connector or the side piece will not stay in place as it can't latch.
After very careful inspection and mating tests with a plugin out in the open I reinstalled everything and double checked connections.
Problem: Intensity was uncontrollable and really bright. Unit went into protection. Checked power supplies, all EXACTLY on (as in, to 3 places after the decimal point). The manual showed Z-axis going through Peltrola connectors on the backplane so I disconnected and reconnected both of them (nothing looked wrong though?) and that was it, everything came up perfectly. I tried the operation of the repaired slot and it works perfectly. What an amazing scope.
I think it was worth the several hours it took me to do this repair, and it was something I think others can do as well even if for the first time, so don't despair if you find yourself in a similar situation, it is quite repairable if you can find a source of the contacts such as I did and have a little patience.
Peter
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Re: CATS software for 11302A
--- In TekScopes@..., "jlnhab" wrote:
Hi All,
I am seeking the CATS (Computer Aided Test System) program
for a 11302A.
Any clue?
Thanks for your time.
Bye,
Jean-Louis
Reply to me off list for a copy.
/H?kan
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Re: Looking for two parts from 53x or early 54x scope
I had meant to offer this to the forum earlier but your current dilemma reminded me. ? I recently acquired a significant amount of 1/4W-20W+ resistors in various Ohms from single digits to several Meg... A very high percentage these are carbon composite, old style ceramic etc. I would gladly go through these resistors and find suitable values and manufacturing style for forum members and send them if I have them. ? In this case. It sounds like the originals will not be something in the acquisition. However, I would think I can get you values and wattages that may fit the space you have. ? Just let me know if I an assist. Rob ? ? ?
toggle quoted message
Show quoted text
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Steve
Sent: Friday, January 18, 2013 1:31 AM
To: TekScopes@...
Subject: [TekScopes] Re: Looking for two parts from 53x or early 54x scope? ? --- In TekScopes@..., David Wise wrote:
>
> Better cobble up some temporary loads from standard resistors, until you're sure the surrounding circuit won't kill them. They'll work at moderate sweep speeds so you can test and debug.
>
> Dave Wise
>
Dave,
Thank you for the excellent suggestion.
I figured I can build a network from four 2 Watt carbon comp. resistors, physically arranged in a Z configuration. It looks like it will even fit in the existing space with some gap between each resistor. This should allow me to get nearly the full 8 watt possible dissipation. Since the horizontal BW is only 240 kHz, I don't think parasitic capacitance will be much of an issue, although the impedances are high so it is not insignificant.
I did some calculations that show the peak power dissipated in normal sweep operation or static movement of the beam when not triggered is within the 5 W rating of the existing resistors, but not by a large margin (4.67W for the 25 kOhm one.) However, the amplifier will be driven beyond this range when in the 5X sweep magnifier is used, or if a high amplitude external horizontal signal is applied to the input. There is no provision to clamp the tubes at a safe plate voltage. In addition to the potential to destroy the plate resistors, this condition will exceed the maximum plate current specification.
- Steve
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Re: Looking for two parts from 53x or early 54x scope
--- In TekScopes@..., David Wise wrote:
Better cobble up some temporary loads from standard resistors, until you're sure the surrounding circuit won't kill them. They'll work at moderate sweep speeds so you can test and debug.
Dave Wise
Dave, Thank you for the excellent suggestion. I figured I can build a network from four 2 Watt carbon comp. resistors, physically arranged in a Z configuration. It looks like it will even fit in the existing space with some gap between each resistor. This should allow me to get nearly the full 8 watt possible dissipation. Since the horizontal BW is only 240 kHz, I don't think parasitic capacitance will be much of an issue, although the impedances are high so it is not insignificant. I did some calculations that show the peak power dissipated in normal sweep operation or static movement of the beam when not triggered is within the 5 W rating of the existing resistors, but not by a large margin (4.67W for the 25 kOhm one.) However, the amplifier will be driven beyond this range when in the 5X sweep magnifier is used, or if a high amplitude external horizontal signal is applied to the input. There is no provision to clamp the tubes at a safe plate voltage. In addition to the potential to destroy the plate resistors, this condition will exceed the maximum plate current specification. - Steve
|
Re: 7104 Horizontal Amplifier
Chris,
U1094 is held in contact by a frame and some sort of elastomeric pad. There are instructions starting at page 4-30 in the service manual (070-2314-00) on how to deal with this "HYPCON" connection.
I suspect that the pin 3 connection has gone open, removing the main ground path to the chip. With luck, this connection break is not inside the hybrid but at the accessible HYPCON contacts. Following the manual directions, carefully remove the hybrid, clean the contacts with isopropyl alcohol (91% or more), dry, and reassemble.
--John Gord
toggle quoted message
Show quoted text
--- In TekScopes@..., "chrismh_somenumber" wrote:
Another Update:
I've worked my way down the horizontal amplifier board, checking all voltages and waveform test points. Everything was looking good until I reached U1082. The voltages at many of the pins were high.
Suspecting a problem with the readout, I removed Q1052 and Q1072, connecting the pads from emitter to collector with a wire. (This is recommended in the service manual, page 3-57, to remove the feedback path).
More of the voltages around U1082 were OK after that change (15, 17, 18, 19 were still high), but TP1038 and TP1078 were still high. I lifted the collectors of Q1028 and Q1034 to remove the readout positioning, but that did not change TP1038 and TP1039.
The voltages around U1094 are all wrong. Most read .5 to 1 volt high. Pins 13 and 14 read 4.5V high, and pin 3 reads 0V (it should be 4.2V). The output waveform going into the CRT (test points 5 and 6) is a flat line.
I checked component values around U1094 and they seemed OK. The
Is it likely that U1094 is bad? The U1014 OpAmp appears to be op-amping, and its supply voltage is OK. The voltages in that bit of circuitry utilizing U1094 are running a little high, but could that cause U1094 to not produce any output at all?
Thanks,
Chris
--- In TekScopes@..., "chrismh_somenumber" wrote:
My recently acquired 7104 has a problem, which I assume is something to do with the horizontal amplifier (please feel free to correct me...).
When the scope starts up, I get a normal trace for about 3-5 minutes, then it changes to a compressed vertical line. It appears that the vertical is working since I can make the vertical line grow and shrink (vertically) by varying the v/div or by varying the input signal. However, the entire trace, and the readout, is compressed to a single vertical line.
Thoughts?
Thanks,
Chris
|
Re: Bench Built Isolation Transformer
It's the fiddly little Test & Reset buttons on the front I'd like to somehow do away with. I like the Euro ones I've seen that are 2-pole and have a toggle handle. Thanks, Dave -=-=-=- On 17 January 2013, at 7:48 PM, n2ixk wrote: A real electrical supply house (not the big orange or blue box stores) should carry them. What you want is called a "dead front" GFCI.
Amazon.com has them, as well:
Bob -=-=-=- Where to find a 120vac RCD/GFI that is not a receptacle nor a circuit breaker (ie, not purpose-made to fit a load panel) for USA use?
240-mains countries have several nice in-line devices to choose from.
Thanks,
Dave
|
Re: Tektronix termination
On Thu, Jan 17, 2013 at 7:35 PM, David <dmacdonald@...> wrote: Hi Group,
Can someone kindly provide specs for a Tek through termination, 011-032 5XT. These things were not well specified, probably because they were not made by Tek, and they would change vendors from time to time. It's just a vanilla 5X attenuator.
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Re: AM-6565/U and some other 7K questions
On Thu, Jan 17, 2013 at 8:04 PM, Rob <rgwood@...> wrote: I know the number in the subject is a military 7000 series plug-in vertical.
I assume no readout. It is also single channel.
The question is which "normal" single channel vertical does it represent?
7A16, 7A15 or maybe 7A19? It's a 7A15AN11. I collect this kind of information and post it on my website: If anyone has some advice for how to go about finding such things out side
of E-bay searches, I would like to have an off line chat. Please feel free
to send me a note and I will reply. I am getting to where I prefer trading
things if possible. I am however not sure it is ok to post those kind of
request here. I think it's fine.
|
Re: AM-6565/U and some other 7K questions
Thank you David. I likely should have added the A after several of the verticals I mentioned. I sometimes have a tendency to run those two versions together in my mind. ?Your reply helps me a lot. The 7854 is one I have not worked on. I envy you somewhat. It may be the one to supplant my favorite 7844 if I ever get a chance to work on one. I hope this finds you well Thanks as always for the bandwidth. Rob ?
toggle quoted message
Show quoted text
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of David
Sent: Thursday, January 17, 2013 9:51 PM
To: TekScopes@...
Subject: Re: [TekScopes] AM-6565/U and some other 7K questions? ? On Thu, 17 Jan 2013 21:04:58 -0600, "Rob" rgwood@...>
wrote:
>I know the number in the subject is a military 7000 series plug-in vertical.
>I assume no readout. It is also single channel.
>
>The question is which "normal" single channel vertical does it represent?
>7A16, 7A15 or maybe 7A19?
The ones I have seen looked like 7A16A vertical amplifiers. The 7A16
is an older style that uses relays and push button switches instead of
slide switches and bipolar current switching.
>In the same vein, I had posted a question about 7D12 and associate M modules
>a week ago or so but didn't get any replies. Which leads me to believe they
>are relatively rare (or my questions were rude which if that is the case I
>apologize).
They are not very common.
>If anyone has some advice for how to go about finding such things out side
>of E-bay searches, I would like to have an off line chat. Please feel free
>to send me a note and I will reply. I am getting to where I prefer trading
>things if possible. I am however not sure it is ok to post those kind of
>request here.
My cursory watching has only seen one sell on Ebay and only a couple
more advertised. I passed them by since I have a 7854 and some other
DSOs.
|
Re: 7104 Horizontal Amplifier
Another Update:
I've worked my way down the horizontal amplifier board, checking all voltages and waveform test points. Everything was looking good until I reached U1082. The voltages at many of the pins were high.
Suspecting a problem with the readout, I removed Q1052 and Q1072, connecting the pads from emitter to collector with a wire. (This is recommended in the service manual, page 3-57, to remove the feedback path).
More of the voltages around U1082 were OK after that change (15, 17, 18, 19 were still high), but TP1038 and TP1078 were still high. I lifted the collectors of Q1028 and Q1034 to remove the readout positioning, but that did not change TP1038 and TP1039.
The voltages around U1094 are all wrong. Most read .5 to 1 volt high. Pins 13 and 14 read 4.5V high, and pin 3 reads 0V (it should be 4.2V). The output waveform going into the CRT (test points 5 and 6) is a flat line.
I checked component values around U1094 and they seemed OK. The
Is it likely that U1094 is bad? The U1014 OpAmp appears to be op-amping, and its supply voltage is OK. The voltages in that bit of circuitry utilizing U1094 are running a little high, but could that cause U1094 to not produce any output at all?
Thanks,
Chris
toggle quoted message
Show quoted text
--- In TekScopes@..., "chrismh_somenumber" wrote:
My recently acquired 7104 has a problem, which I assume is something to do with the horizontal amplifier (please feel free to correct me...).
When the scope starts up, I get a normal trace for about 3-5 minutes, then it changes to a compressed vertical line. It appears that the vertical is working since I can make the vertical line grow and shrink (vertically) by varying the v/div or by varying the input signal. However, the entire trace, and the readout, is compressed to a single vertical line.
Thoughts?
Thanks,
Chris
|
Re: Bench Built Isolation Transformer
Given the higher price, I would just go with the standard duplex GFCI since it is in the same form factor. The specialty items always seem to be priced for an unlimited budget. On Fri, 18 Jan 2013 03:48:00 -0000, "n2ixk" <bob.weiss@...> wrote: A real electrical supply house (not the big orange or blue box stores) should carry them. What you want is called a "dead front" GFCI.
Amazon.com has them, as well:
73,
Bob Weiss N2IXK
--- In TekScopes@..., Dave C wrote:
Where to find a 120vac RCD/GFI that is not a receptacle nor a circuit breaker (ie, not purpose-made to fit a load panel) for USA use?
240-mains countries have several nice in-line devices to choose from.
Thanks,
Dave
|
Re: AM-6565/U and some other 7K questions
On Thu, 17 Jan 2013 21:04:58 -0600, "Rob" <rgwood@...> wrote: I know the number in the subject is a military 7000 series plug-in vertical.
I assume no readout. It is also single channel.
The question is which "normal" single channel vertical does it represent?
7A16, 7A15 or maybe 7A19? The ones I have seen looked like 7A16A vertical amplifiers. The 7A16 is an older style that uses relays and push button switches instead of slide switches and bipolar current switching. In the same vein, I had posted a question about 7D12 and associate M modules
a week ago or so but didn't get any replies. Which leads me to believe they
are relatively rare (or my questions were rude which if that is the case I
apologize). They are not very common. If anyone has some advice for how to go about finding such things out side
of E-bay searches, I would like to have an off line chat. Please feel free
to send me a note and I will reply. I am getting to where I prefer trading
things if possible. I am however not sure it is ok to post those kind of
request here. My cursory watching has only seen one sell on Ebay and only a couple more advertised. I passed them by since I have a 7854 and some other DSOs.
|
zenith5106
David Hess