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de-soldering
Paul Kraemer
I just happened to think
Now that I no longer have 5 extra bodies around here, I don't really need to keep their tools either I do have an extra Ungar / Weller 4624 Solder / de-solder station I could send to a new home It does better on small leads and pads than on the larger pads Not the best not the worst Gauranteed ok If interested contact me off net and I'll see if I have any extra tips and such and send pictures. Hopefully we can make a deal we can both live with. Paul |
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2235 Oscilloscope Trace Problem
I have acquired a 2235 Option 01 oscilloscope that displays the
following symptoms.... 1) The "A" intensity control changes the intensity of both "A" & "B" traces...the "B" intensity control does nothing. 2) The traces (both A & B) do not fill up the entire screen from left to right..... The traces right end point can only be moved as far as the 6th graticule from the left using the Horizontal Position control. This is with the Horizontal Position control 80% full clockwise. Moving the Horizontal Position Control farther clockwise only compresses the signal into a vertical line near the 6th graticule. The start of both traces can be moved off of the screen to the left using the Horizontal Position control. I have measured the -8.6vdc, 5vdc, 8.6vdc, 30vdc and 100vdc on the main circuit board and they seem to be fine (I don't have a second scope to measure the ripple on these signals). I do not have a meter that has a working range to measure the 2500vdc signal to the crt. 3) With the timebase set to x/y, and both probes connected to the probe adjust signal available at the front panel, channel 1 set to 0.1v/div and channel 2 set to 0.1v/div the trace (diagonal line) that is made on the screen is 5 graticules high but only 1.6 graticules long. The scope seems to behave normally otherwise but the timebase measurements are incorrect. Are there any other suggestions of things to check?.... |
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Re: unsoldering tricks
Yes, that's what I just did with a board from a Dyna dm2400 cnc m/c. The L295 solenoid driver ( used as a stepper driver) had gone down with a few diodes gone with it. Not having sophisticated equipment snipping the leads is the way to go. Board now works a treat and the owner is well pleased - he bought it cheap on fleabay as it was faulty.
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I remember the weller attachment, my dad made me something similar in work - it went between the pins and was a solid block without holes - worked well. Geoff. Paul Kraemer wrote: A fellow from plant engineering at an auto plant told me how they repaired boards at the plant, where down time is really expensive. They cut the ic from the leads, remove the leads one at a time and then put in a new ic. |
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Re: unsoldering tricks
Stefan Trethan
The best tool i have found is this one:
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<> I would not want to work without it any more. When we got it, the first thing we tried it on was the rear connector of a dead CDROM drive (the 40 pin IDE plus power puls audio plus jumpers all in one molded connector). After sucking the solder from all the joints, the connector dropped right out and was as good as new, the board too. It is a little harder when the holes are a too small, but still works OK. If you do any amount of throughhole de-soldering, you really want this tool. I actually prefer to take parts from used boards instead of new ones now, because de-soldering is easier and faster than bending and cutting the leads. Sadly it is a little too expensive for the occassional use at home. I have seen a chinese copy on ebay for roughly 100USD, but i do not know how well it works. There were some negative comments about rusting tips in the feedback so i did not get one. ST On Mon, Sep 22, 2008 at 3:40 PM, Paul Kraemer <elespe@...> wrote:
A fellow from plant engineering at an auto plant told me how they repaired |
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Re: unsoldering tricks
Paul Kraemer
A fellow from plant engineering at an auto plant told me how they repaired boards at the plant, where down time is really expensive. They cut the ic from the leads, remove the leads one at a time and then put in a new ic.
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It is fast and doesn't damage the board. Of course there isn't any old chip left. Paul ----- Original Message -----
From: Tim Phillips To: tekscopes@... Sent: Monday, September 22, 2008 3:02 AM Subject: [TekScopes] unsoldering tricks From Tim P (UK) further to the discussion on removing components from boards, I remember Weller produced a device for de-soldering ICs which was like a metal IC socket on a soldering iron, which went over all 16 pins. I think it's main problem was that the molten solder would then short out adjacent pads, needing careful clean-up. Tim |
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Re: CG551AP Low SAC Uncal
OK I have done some further testing and found the following:
With the output of U1311 (pin 6) disconnected and the inverting input at -13V and the non-inverting input at -4.5V the out still remains at -13V. Disconnecting pins 1 and 8 offset null adjustment does not change this. Disconnecting the frequency compensation components R1301 and C1301 allows the output to swing to 14V (what it should be). Addition of external frequency components of the same value applied to pin 5 does not force the output back to -13V Conclusion one of the frequency compensation components is faulty replacing C1301 has so far confirmed this as it is now working properly. This has been a really hard problem to find! Has anyone encountered this issue before with the external frequency components forcing the output of an OP-amp to go the wrong way? I can't seem to measure anything that indicates that the capacitor is stuffed either. Has anyone found any issues with the green axial capacitors that Tek used in this vintage stuff? --- In TekScopes@..., "cmbath" <cmbath@...> wrote: driven to -12.5V, after some stuffing around I have found that the outputpositive saturation rather than what appears to be negative saturationgiven that the voltage of the inverting input is below that of the noncompensation components going out of spec. |
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Re: [TekScopes2] Re:Replacing caps
Jerry Massengale
Greetings,
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? I bought a Madell 850B SMD Rework Station last year. I do not use it as much as I thought I would but it is great to have around. I use it to preheat ground planes that my small irons cannot handle. ? jerry --- On Mon, 9/22/08, d.seiter@... <d.seiter@...> wrote:
From: d.seiter@... <d.seiter@...> Subject: Re: [TekScopes] Re: [TekScopes2] Re:Replacing caps To: TekScopes@... Date: Monday, September 22, 2008, 12:58 AM So I'm not the only one makes weird soldering tips. I had to make a .5" wide one a while back that worked great. I also made one with a 2.5" wide blade for a DC/DC converter that was really stubborn- it worked, but not very well. -Dave ------------ -- Original message ------------ --------- - From: "Jonathan Thornton" <Jonathanthornton@ bulldoghome. com> Hi everybody[Non-text portions of this message have been removed] [Non-text portions of this message have been removed] |
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unsoldering tricks
Tim Phillips
From Tim P (UK)
further to the discussion on removing components from boards, I remember Weller produced a device for de-soldering ICs which was like a metal IC socket on a soldering iron, which went over all 16 pins. I think it's main problem was that the molten solder would then short out adjacent pads, needing careful clean-up. Tim |
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Re: [TekScopes2] Re:Replacing caps
So I'm not the only one makes weird soldering tips. I had to make a .5" wide one a while back that worked great. I also made one with a 2.5" wide blade for a DC/DC converter that was really stubborn- it worked, but not very well.
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-Dave -------------- Original message ----------------------
From: "Jonathan Thornton" <Jonathanthornton@...> Hi everybody |
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Re: THM565 rear connector
--- In TekScopes@..., "gehp01" <rodd@...> wrote:
Why not get six standard alkaline AA cells and run it as it was intended ? /H?kan |
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wanted- 485
Dave_s
Hi,
I am very close to replacing my 475 scope with another 465. Having a little trouble deciding between replacing my 475 with another 475 or a 475A or 485. Just doing a little more checking. What are the sources for a good working 485 scope? Has any 485 owner ever used the 'fast rise time' of the built in 'probe calibrator' to check coax cables for defects like a TDR? I think the 485 'probe calibrator' has a fairly fast rise or fall time. Is it wise to buffer the probe calibrator output when using the calibrator to test coax cable? Regards, 73, W6MIK, Dave |
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CG551AP Low SAC Uncal
I have 1 CG551AP which is having issues with its Low SAC that I
can't seem to understand. The output of the Low SAC is being driven to -12.5V, after some stuffing around I have found that the output of U1311 which provides offset adjustment for the Low SAC has is output at about -13V despite the inverting input (roughly -13V) sitting well below the non-inverting input (roughly -4.5V). I have tried removing U1311 which allows the Low SAC to function normally apart from there being an offset which is unable to be corrected for. I have also tried replacing both U1311 (LM725) and U1211 (LF356) which did not help at all. The big mystery for me is why the output of U1311 is not at positive saturation rather than what appears to be negative saturation given that the voltage of the inverting input is below that of the non inverting input. The input voltages appear to be in the specified range for the supply voltage being used i.e. +/-13.5V (worst case) for a supply of +/-15V. I am even considering the possibility that the circuit may be going unstable due to the frequency compensation components going out of spec. Has anyone experienced this problem before with the Low SAC in the CG551AP or had similar issues with OP-Amps? |
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Re: [TekScopes2] Re:Replacing caps
Jonathan Thornton
Re: [TekScopes2] Re:Replacing caps
Hi everybody Hurrah, I just got my TDS 544A working, usual acq fault, replaced all the electrolytics on the acquisition PCB - still same fault, so I replaced all the double and quad SOIC op.amps (TL 02/04 )--fault finding by attrition I removed the caps by making a 2 pronged fork out of wire for the tip of the soldering iron, to unsolder both sides of the cap simultaneously. You can alternate the iron from one side of the cap to the other whilst lifting the cap, but there a serious risk of pulling a pad off. For the ICs I made a U shaped tip for the end of the iron out of brass sheet, which with a bit of adjustment gripped the IC and unsoldered both sides at the same time, very quick. I then cleaned up all the pads with desoldering (the spellcheck tried to change this to 'disordering' braid) and cleaned the board with isopropyl alchohol. For replacement i used solder paste and a very fine iron tip, all helped enormously by a great purchase on XXXX, a nearly new Leica StereoZoom 4 binocular microscope for under $180, it's one of those things you don't know how you managed without Finally a wash in the dishwasher. Jonathan -- I am using the free version of SPAMfighter for home users. SPAMfighter has removed 12850 spam emails to date. Paying users do not have this message in their emails. Get the free SPAMfighter here: |
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Re: [TekScopes2] Re:Replacing caps
Jonathan Thornton
Hi everybody
Hurrah, I just got my TDS 544A working, usual acq fault, replaced all the electrolytics on the acquisition PCB - still same fault, so I replaced all the double and quad SOIC op.amps (TL 02/04 )--fault finding by attrition I removed the caps by making a 2 pronged fork out of wire for the tip of the soldering iron, to unsolder both sides of the cap simultaneously. You can alternate the iron from one side of the cap to the other whilst lifting the cap, but there a serious risk of pulling a pad off. For the ICs I made a U shaped tip for the end of the iron out of brass sheet, which with a bit of adjustment gripped the IC and unsoldered both sides at the same time, very quick. I then cleaned up all the pads with desoldering (the spellcheck tried to change this to 'disordering' braid) and cleaned the board with isopropyl alchohol. For replacement i used solder paste and a very fine iron tip, all helped enormously by a great purchase on XXXX, a nearly new Leica StereoZoom 4 binocular microscope for under $180, it's one of those things you don't know how you managed without Finally a wash in the dishwasher. Jonathan -- I am using the free version of SPAMfighter for home users. SPAMfighter has removed 12850 spam emails to date. Paying users do not have this message in their emails. Get the free SPAMfighter here: |
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TDS460A display intensity?
Just acquired a TDS460A.
Display intensity seems low (I have is set to 100)?and the contrast adjustment does nothing (on both internal and external monitor). Is this a common problem? ? Is there an hours counter on it somewhere? wondering if the CRT is going out or some other problem. Seems to work perfectly otherwise. ? Thanks, ? David. ? [Non-text portions of this message have been removed] |
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THM565 rear connector
Folks,
I bought two Tektronix THM565 portable scopes at a local surplus dealer for a very cheap price. However, the units came without batteries. I could download the operating manual and found that there is an ac adapter for this model, the THM5AC, but the only source I could find for them was charging a modest value of $365.00 for one. Since I do not even know if the units are operational, it makes no sense trying to buy one. Does anybody knows the pin assignment for the THM565 rear connector in order to allow me to build a DIY power supply and test the units. Thanks in advance for any help. Roger |
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Re: Somewhat OT: HP 8553B/8443A system needs new home (Los Angeles area)
All of the items are now taken.
--John Gord --- In TekScopes@..., "johncharlesgord" <johngord@...> wrote: California.)
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Re: Type 111 Pretrigger Pulse Generator not up to speed
Craig Sawyers
I have heard thatThat is one of the reasons that I prefer scopes from the steam age. What you see is generally what is happening, rather than something that has been digitised and processed using a process I have no control over. Mostly I'm just glad it works at all, actually, I shouldn'tYeah - that sounds a good move. The 111 is actually a really nice pulser, and should do nicely. I also have a very odd avalanche pulser of more recent vintage that fits in a TM5xx series power unit. The part number is not marked on the front, and by all accounts there are several variants of this rather rare, and somewhat prototypic beast - I've only heard of another two, and all three are different. Over 4 years ago I put some pics on the tekscopes gallery, including some sampler traces of the rise time, which measures an aberration-free 250ps on an S6 sampling head (<30ps rise) - it is a fast beastie. Gallery is called "Wierd TM500 plug in". Craig |
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