Date   

Re: 7104 SMPS no start troubleshooting

Bob Albert
 

Cangratulations!  I like when stuff is easy.
Bob

On Friday, August 9, 2019, 09:49:01 PM PDT, <sdturne@q.com> wrote:

Happy ending: the problem was the fan wiring all along. I rearranged it before I inserted the SMPS for the last time, and we have life.


LOOKING FOR TEK485 FUSEHOLDER;PLASTIC 352-0326-00

 

Hi :

I have a 485 working after repair , but there are missing parts of fuse-holder p/n :352-0326-00, plastic.

Anyone can help ? I am locate in Hong Kong.

Regard
Tony Cheung
Aug 10 2019


Re: 7104 SMPS no start troubleshooting

Sean Turner
 

Happy ending: the problem was the fan wiring all along. I rearranged it before I inserted the SMPS for the last time, and we have life.


Re: Tektronix 577 Regular board capacitor question

DW
 


Re: oh yeah?

Kevin Oconnor
 

I use to have half a dozen working tdr plugins with mix of pulse gens & samplers in imperial and metric.
Long gone on eBay, but do they count?😆
Kevin, KO3Y

Sent from kjo iPhone


Re: 7104 SMPS no start troubleshooting

Sean Turner
 

It's the fan. If I pull on the power leads that go to the fa, the SMPS will start. Maybe something's rubbed up in there. Have to take a look.


Re: 7104 SMPS no start troubleshooting

Sean Turner
 

So I had a considerable breakthrough. While I still don't know WHAT is shorting out, I have determined that there is no electrical problem as far as I can tell. It's mechanical. I "fixed" it with my tinkering...then it started clicking again when the SMPS module was reinstalled in the mainframe. Thinking something is pushing on something in there when the module is installed.


Re: oh yeah?

Jim Ford
 

Yes, I have 7S11 and 7S12 plug-ins and two S-4 sampling heads, S-51 trigger countdown head, S-52 pulse generator head, and two S-53 trigger recognizer heads.  I'm sure others in the group have more extensive collections.Nice score with the S-42.  Several decades ago I had a CSA803 scope at work with at least one SD-24 sampling/TDR head.  I can't remember what we used for OE conversion, maybe just the fiber optic receivers themselves.  Kind of lost interest in F/O though.I find the 7S12 + 7S11 + S-4 combo very cumbersome to get to work properly.  Hard to even get a stable trace on the screen.  Maybe I'm doing something wrong?JimSent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "snapdiode via Groups.Io" <snapdiode=yahoo.com@groups.io> Date: 8/9/19 5:57 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] oh yeah? It's a sampling head, not really a plugin, but plugs into a plugin, I guess. I was in such a rush to gloat I used the wrong terminology. I am being punished, the thing is shipping Fedex, I didn't even check that. I will be destroyed by the customs charges.An expensive trinket to be sure. I have no fiber optics to plug into it.


Re: oh yeah?

snapdiode
 

It's a sampling head, not really a plugin, but plugs into a plugin, I guess. I was in such a rush to gloat I used the wrong terminology. I am being punished, the thing is shipping Fedex, I didn't even check that. I will be destroyed by the customs charges.
An expensive trinket to be sure. I have no fiber optics to plug into it.


Re: oh yeah?

Jim Ford
 

Well, if that's your only plug-in, no.I do have the S-42 on my wish list, though.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "snapdiode via Groups.Io" <snapdiode=yahoo.com@groups.io> Date: 8/9/19 4:37 PM (GMT-08:00) To: TekScopes@groups.io Subject: [TekScopes] oh yeah? oh yeah.https://www.ebay.ca/itm/Tektronix-S-42-Optical-Sampling-Head/133059541970?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649I am the king of rare and obscure plugins.Prove me wrong! :)


Re: 7104 SMPS no start troubleshooting

Bob Koller <testtech@...>
 

Most, if not all, of the boards have "harmonica connectors" for the supply input. When I am faced with this, I connect the ohmmeter at the PSU perhaps, and, noting the resistance, remove the connectors one-by-one, checking to see if the resistance reading jumps up a bit. If it does, you have likely found the board with the shorted cap. From there it is usually a simple matter to check the resistance across the caps on the board.
It usually is about this simple, especially on the 7000 series. It is also possible that the short is in the PSU proper, again, disconnecting it from the main scope should reveal the location.


oh yeah?

snapdiode
 


Re: 7104 SMPS no start troubleshooting

John Griessen
 

On 8/9/19 5:47 PM, sdturne@q.com wrote:
On Fri, Aug 9, 2019 at 03:39 PM, John Griessen wrote:
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...
Input it where?
Right where the 5V is made, at its SMPS source. or rectifier and caps, (I have not looked at a 7104 schematic today), and relative to a ground point that is the 5V return.

So, that way, as you probe along in the 5V loads, and/or hold up caps, one will be more of a short than the whole
and you will notice that lowness.

If you no longer suspect the 5V and switch, *DO* switch the return GND point also to be related to the new suspect.


Re: 7104 SMPS no start troubleshooting

Sean Turner
 

On Fri, Aug 9, 2019 at 03:39 PM, John Griessen wrote:


On 8/9/19 4:42 PM, sdturne@q.com 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...
Input it where?

I've been poring over the schematics trying to map out in my head where everything is.


Re: 7104 SMPS no start troubleshooting

John Griessen
 

On 8/9/19 4:42 PM, sdturne@q.com 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...


7104 SMPS no start troubleshooting

Sean Turner
 

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


Re: 577 CT Collector Voltage Knob needed.

Mlynch001
 

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.

--
Michael Lynch
Dardanelle, AR


Re: 577 CT Collector Voltage Knob needed.

Vince Vielhaber
 

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.

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..


Re: 577 CT Collector Voltage Knob needed.

Mlynch001
 

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


Re: 577 CT Collector Voltage Knob needed.

Dave Daniel
 

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

On Aug 9, 2019, at 14:12, Mlynch001 <mlynch002@gmail.com> 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.


--
Michael Lynch
Dardanelle, AR


28501 - 28520 of 187119