Re: 7104 SMPS no start troubleshooting
On 8/9/19 4:42 PM, [email protected] wrote: I believe the issue lies in either the +5V rail Seems likely. Can you rig a little current to flow through a resistance to be mild like 20 milliamps total, then do you have a 6 or 7 digit voltmeter? Probing will show dropping volts along power rails until you get next to the offending tantalum cap, then not change much if probing farther along than that...
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7104 SMPS no start troubleshooting
Hi all,
Scored a very nice condition 7104 and plugins at auction for a great price. Long story short it was working during the item viewing hours the day before the auction. Got it home this morning and it's clicking...anyway...
I believe the issue lies in either the +5V rail or the +/-15 V rails. However, specifically, the manual says the typical resistance for the +5V rail when everything is connected up is 0.005 Kohm. I'm measuring 3 ohms. Is there any chance that is a typo and it should be 0.050 Kohm and not 0.005 Kohm? It's the former for 7904 mainframes.
Here's my readings:
With the mainframe circuits connected:
+50 is at 1.82 kohm
+15 is at 73 ohm
+5 is at 3 ohm
-15 is at 84 ohm
-50 is at 4.494 kohm
With the mainframe circuits disconnected:
+50 is 9.28 kohm
+15 is 154 ohm
+5 is 7.53 kohm
-15 is 8.55 kohm
-50 is 30.2 kohm
Thanks,
Sean
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Re: 577 CT Collector Voltage Knob needed.
Sadly, I don¡¯t have anything to use as a pattern. The entire plastic part of the knob is gone. One of these days I will try that casting material, it sounds like it would do the trick if you had a pattern.
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Michael Lynch
Dardanelle, AR
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Re: 577 CT Collector Voltage Knob needed.
I didn't see Chuck's post, but you can get plastic in liquid form from Smooth-On.com. Wear an shop apron or old shirt when mixin, don't ask how I know! SmoothCast 300 should do the job fine. 1:1 mixing, you have a few minutes to mix and pour, whether it's a few drops or something large, cured and ready in about 15-20 mins.
I've made many knobs and feet with it and repaired many things that glue just wouldn't hold. If you're using it for something external, you can color it.
Vince.
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On 08/09/2019 03:29 PM, Mlynch001 wrote: Dave,
Yes, I read Chuck's post about repairing knobs. I wish I had some plastic to work with. I did refer to that 366-RPR on TEKWIKI and found that the Knob that I am looking for is not very common. Used on 576, 577 and several TV/Video products and a few plotters. That RPR section is an excellent resource for those who have not yet used it. Tons of great information, I have just scratched the surface of that section of TEKWIKI..
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K8ZW
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Re: 577 CT Collector Voltage Knob needed.
Dave,
Yes, I read Chuck's post about repairing knobs. I wish I had some plastic to work with. I did refer to that 366-RPR on TEKWIKI and found that the Knob that I am looking for is not very common. Used on 576, 577 and several TV/Video products and a few plotters. That RPR section is an excellent resource for those who have not yet used it. Tons of great information, I have just scratched the surface of that section of TEKWIKI..
--
Michael Lynch
Dardanelle, AR
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Re: 577 CT Collector Voltage Knob needed.
Michael,
Ok. I wrote because Chuck Harris recently posted a method for repairing the plastic part of a knob and then melting the aluminum core back into the knob.
I think that there are master parts lists for various categories of Tektronix parts available online, perhaps on this forum. Having been involved in moving for about a year, I haven¡¯t paid much attention to them but perhaps they list the instruments which use each part. I know that there is a parts list for knobs; search the forum for ¡°rpr¡±.
DaveD
Sent from a small flat thingy
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On Aug 9, 2019, at 14:12, Mlynch001 <mlynch002@...> wrote:
On Fri, Aug 9, 2019 at 11:55 AM, Dave Daniel wrote:
Is the one on your 577 missing og broken? If broken, what is ¡°broken¡±
about it.
DaveD
Sent from a small flat thingy
Dave,
Appreciate the reply. The plastic outer "knob" has broken off the aluminum hub. So I still have the aluminum part of the knob attached to the shaft. This is the typical old TEKTRONIX knob failure. At this point, this is purely cosmetic, but for aesthetic reasons, I would like it to be a good knob.
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Michael Lynch
Dardanelle, AR
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Re: 577 CT Collector Voltage Knob needed.
On Fri, Aug 9, 2019 at 11:55 AM, Dave Daniel wrote:
Is the one on your 577 missing og broken? If broken, what is ¡°broken¡±
about it.
DaveD
Sent from a small flat thingy
Dave, Appreciate the reply. The plastic outer "knob" has broken off the aluminum hub. So I still have the aluminum part of the knob attached to the shaft. This is the typical old TEKTRONIX knob failure. At this point, this is purely cosmetic, but for aesthetic reasons, I would like it to be a good knob. -- Michael Lynch Dardanelle, AR
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Re: 577 CT Collector Voltage Knob needed.
Is the one on your 577 missing og broken? If broken, what is ¡°broken¡± about it.
DaveD
Sent from a small flat thingy
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On Aug 9, 2019, at 12:14, Mlynch001 <mlynch002@...> wrote:
On Fri, Aug 9, 2019 at 10:59 AM, tom jobe wrote:
Are any of these knobs what you are looking for?
On 8/9/2019 7:33 AM, Mlynch001 wrote:
I am looking for the collector voltage control knob for a Type 577 curve tracer. P/N is 366-1026-00. Does anyone have a spare one that they would be
willing to part with? Let me know if you can help.
Thanks!
Tom,
I saw those in my search, Unfortunately, not what I need. The one that I need is the collector voltage adjust on the left side of the instrument, directly below the CRT . I searched E-bay, Sphere, Qservice and came up with nada. I did search the forum here as well as all the usual sources before I posted this request.
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Michael Lynch
Dardanelle, AR
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Re: 577 CT Collector Voltage Knob needed.
On Fri, Aug 9, 2019 at 10:59 AM, tom jobe wrote:
Are any of these knobs what you are looking for?
On 8/9/2019 7:33 AM, Mlynch001 wrote:
I am looking for the collector voltage control knob for a Type 577 curve tracer. P/N is 366-1026-00. Does anyone have a spare one that they would be
willing to part with? Let me know if you can help.
Thanks!
Tom, I saw those in my search, Unfortunately, not what I need. The one that I need is the collector voltage adjust on the left side of the instrument, directly below the CRT . I searched E-bay, Sphere, Qservice and came up with nada. I did search the forum here as well as all the usual sources before I posted this request. -- Michael Lynch Dardanelle, AR
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Re: Tektronix 577 Regular board capacitor question
That is correct.? A rating of -10%/+75% is indeed a capacitance tolerance specification.? For a while they used GMV as a tolerance, meaning Guaranteed Minimum Value.? When bypassing, tolerance isn't very important.? But price is.? The wider the tolerance, the fewer rejects and the easier testing becomes.
Bob
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On Friday, August 9, 2019, 09:00:49 AM PDT, Mlynch001 <mlynch002@...> wrote: On Fri, Aug? 9, 2019 at 10:27 AM, DW wrote:
Thanks, and if I understand right +75-10? is 75C tempature and 10% tolerance.
Any idea what the manual is referring to when it is describing a capacitor
under the parts list by CER DIR, seems like the CER might be ceramic but DI I
am not sure
In my experience, that rating is +75% -10% (capacitance) and most Tektronix caps are rated at 85C or occasionally better. -- Michael Lynch Dardanelle, AR
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Re: Tektronix 577 Regular board capacitor question
On Fri, Aug 9, 2019 at 10:27 AM, DW wrote: Any idea what the manual is referring to when it is describing a capacitor
under the parts list by CER DIR, seems like the CER might be ceramic but DI I
am not sure
I do not have a 577 in front of me, But I am thinking that "CIR DI" stands for "Ceramic Disc". -- Michael Lynch Dardanelle, AR
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Re: Tektronix 577 Regular board capacitor question
On Fri, Aug 9, 2019 at 10:27 AM, DW wrote:
Thanks, and if I understand right +75-10? is 75C tempature and 10% tolerance.
Any idea what the manual is referring to when it is describing a capacitor
under the parts list by CER DIR, seems like the CER might be ceramic but DI I
am not sure
In my experience, that rating is +75% -10% (capacitance) and most Tektronix caps are rated at 85C or occasionally better. -- Michael Lynch Dardanelle, AR
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Re: 577 CT Collector Voltage Knob needed.
Are any of these knobs what you are looking for?
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On 8/9/2019 7:33 AM, Mlynch001 wrote: I am looking for the collector voltage control knob for a Type 577 curve tracer. P/N is 366-1026-00. Does anyone have a spare one that they would be willing to part with? Let me know if you can help.
Thanks!
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Re: 2712 SA that thinks it is a 2714
Eureka! I have found it!
R882, a 10 ohm resistor on the PSU/Mother board selects the 2712/2714 bit. This area is located on A15A1 Sh 6, of the 2712 service manual.
Thanks for the help!
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Re: Tektronix 577 Regular board capacitor question
Thanks, and if I understand right +75-10? is 75C tempature and 10% tolerance.
Any idea what the manual is referring to when it is describing a capacitor under the parts list by CER DIR, seems like the CER might be ceramic but DI I am not sure
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577 CT Collector Voltage Knob needed.
I am looking for the collector voltage control knob for a Type 577 curve tracer. P/N is 366-1026-00. Does anyone have a spare one that they would be willing to part with? Let me know if you can help.
Thanks!
--
Michael Lynch
Dardanelle, AR
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Re: Tektronix 577 Regular board capacitor question
I haven't opened up a 577, but those are likely the typical Sprague capacitors
used by Tektronix in that era. They may still be good; I'd check them with a
good capacitor and esr meter before removing them.
If you need to replace them, the neatest repair is one I use in 4xx and 7K scopes - use
a small carrier board to mate the footprint to a commonly available snapcap. This
provides the jumpers that Tek used and the footprint for the new cap. Use
105C caps as replacements. You can find these on ebay and there are gerbers floating
around if you want to send them to a board house yourself. You can also etch them
yourself of course.
Some purists might restuff the cans with a new snapcap.
Paul
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On Fri, Aug 09, 2019 at 07:15:33AM -0700, DW wrote: I decided I would replace the electrolytic on the regulator board as I noticed the capacitors appear quite old.
On removing the board and looking at some of the radial style capacitors I noticed they are not your standard capacitors. The bigger capacitors have 4 metal feet towards the rim that seem to serve two purposes, hold the capacitor in place and serve as a electrical connection. And then there is a a 5th connector towards the middle.
I am thinking if I replace these I will need to come up with some kind of retrofit unless they stock similar capacitors like these.
And thoughts? Thanks
!DSPAM:5d4d801167228766950437!
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Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix & Windows
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Tektronix 577 Regular board capacitor question
I decided I would replace the electrolytic on the regulator board as I noticed the capacitors appear quite old.
On removing the board and looking at some of the radial style capacitors I noticed they are not your standard capacitors. The bigger capacitors have 4 metal feet towards the rim that seem to serve two purposes, hold the capacitor in place and serve as a electrical connection. And then there is a a 5th connector towards the middle.
I am thinking if I replace these I will need to come up with some kind of retrofit unless they stock similar capacitors like these.
And thoughts? Thanks
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Too good to live long....
Kevin, KO3Y
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On 09/08/19 02:51, Dave Casey wrote: All scopes are in the Dallas, TX area and are priced for local sale It would have been considerate of most people's time if you had put "Dallas" in the subject.
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Mlynch001