Re: Tek 576 Curve Tracer HV Transformer winding
Chuck Harris <cfharris@...>
Just remember the ferrite is a ceramic mixture,
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so it was once heated much hotter than your oven will ever go. Good gloves so you don't burn yourself, don't worry about the winding. Soak it in the oven, and then remove it and with two hands give the top half and the bottom half a twist, like you were removing a jar lid. If that doesn't work, up the temperature. If you break it, don't cry. A drop of thin crazy glue, and carefully aligning it back together, and you will never know you did it... electrically. A dry trial fit is a good idea, and a little compressed air to remove any extra bits of ferrite sand that may be in the way of a good fit. -Chuck Harris Mlynch001 wrote:
John,
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Re: 2465 DVS Repair - was; Re: [TekScopes] Wanted; Person to repair Tektronix 2465 DVS
Assuming TP46 is the PCB edge side of R567 It has about 1VAC 60hz maybe a 20 ms dc offset. It doesn't change as I exit the error message or _fiddle_ with the triggering adjustments.
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- Jeff
On 9/15/2019 6:39 AM, Chuck Harris wrote:
The power inside of the 2465 supplies is pretty dirty from
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Re: Tek 576 Curve Tracer HV Transformer winding
ykochcal
There are practice cores in most old electronics, which are everywhere
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around here if you look. In particular Old PC power supplies typically have one of similar size but the wrong orientation. I am under the opinion that if you break the core it may still be useable. They have by design a fair gap in the center leg. If you break the core you will most lily break off one side of the E Then you just need to break the other side to match (that happened to me anyway). Then glue back together with very slow epoxy using a machinist vise and clamp to keep it square while squeezing it so the gap is as small as possible. I ended up with a gap in each leg that I thought was about less then 20% or so of the gap in the center. The core seemed to work well, but after awhile that attempt failed due to a short. I think that I did not put in added space when the winding went from two wires to one at the end of the coil which doubled the voltage difference per layer. Haven't tried to rewind after that attempt John
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Mlynch001 Sent: Sunday, September 15, 2019 10:51 AM To: TekScopes@groups.io Subject: Re: [TekScopes] Tek 576 Curve Tracer HV Transformer winding John, I will try this again at a higher temp. You are very certainly right about this. I have not done any "practice" since I don't have anything to practice on. I guess this is my "practice" piece? I'm going to cut the rest of the coil off and then go from there. I appreciate Chuck's offer, but I really feel the need to try to do this on my own. I may break the core, I may be successful or, in the end, I may give up and send it to Chuck. If I break these ferrite cores, I may come crying to Chuck or others for a replacement set. I appreciate your advice and insight. One way or the other, I will get this thing fixed. It is a shame that one stupid part has disabled an otherwise functioning instrument. Before it "cuts off", it works beautifully. Sincerely -- Michael Lynch Dardanelle, AR
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Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest
Dave Daniel
Yes, after perusing my copy of "Oscilloscope Development, 1943-57" by Peter D. Hiscocks, I realize that one cannot beat a 511 as the earliest 'Tektronix 'scope.
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When I was much younger, I had a Dumont 'scope that was given to me by an uncle who worked for Fisher Scientific. It did not have calibrated amplifier controls, which, at age 11 or so, confused me. I do not remember the model of that 'scope and I have wondered for years how old it was. The original 511 was made available in 1948. DaveD
On 9/15/2019 9:56 AM, Chuck Harris wrote:
The 310 is close, but no cigar.
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Re: AM700
Hi,
Wow! I waiting for your flash image very happy. Do you know if this flash simm are commercial type? In this days I continued capacitors check, I find some through hole capacitors that just start leak (green oxide on leg and smell when desolder). I am start to change all capacitors before is to late.
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Re: 11801 NVRAM
Reginald Beardsley
I'm very interested in how to derive and store the correction terms. There has been discussion of a command to write them, but it appeared not to work when attempted IIRC.
It would be very helpful to know where they are stored in the NVRAM. I've got a programmer, but no idea where to put the data. My Keysight 33622A is specified as <1 ps jitter. That's less than the 4 ps jitter specified for the 11801. I think I'll play with that a bit and see if I can persuade the 11801 to tell me what the uncalibrated errors are. Having just built a GPIB-USB adapter using an Uno and AR488 I think I need to read the programming manual for my 11801 to see if I can get digits out via the GPIB port. That would allow removing the NVRAM one time to load the correction values. Have Fun! Reg
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Re: Tek 576 Curve Tracer HV Transformer winding
John,
I will try this again at a higher temp. You are very certainly right about this. I have not done any “practice” since I don’t have anything to practice on. I guess this is my “practice” piece? I’m going to cut the rest of the coil off and then go from there. I appreciate Chuck’s offer, but I really feel the need to try to do this on my own. I may break the core, I may be successful or, in the end, I may give up and send it to Chuck. If I break these ferrite cores, I may come crying to Chuck or others for a replacement set. I appreciate your advice and insight. One way or the other, I will get this thing fixed. It is a shame that one stupid part has disabled an otherwise functioning instrument. Before it “cuts off”, it works beautifully. Sincerely -- Michael Lynch Dardanelle, AR
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Re: Tek 576 Curve Tracer HV Transformer winding
ykochcal
I have split a number of transformers, A few thoughts
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1, You should take Chuck up on the offer 2, But how are you getting the number 260F? oven dials can be way off and the temp inside an oven can very considerably depending where you measure I found the epoxy strength has a fairly quick transition, so its possible that it's not hot enough. Also a transformer cools very quickly and gets strong again so I would have gloves, open oven, grab and give a quick twist, if it did not split, back in and add a few more degrees. I would call the move a shearing twist. I too was a bit hesitant then practiced on some old power supply and TV cores to get the hang of it, although clearly different epoxies are used that break at different temps. John
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Chuck Harris Sent: Sunday, September 15, 2019 7:08 AM To: TekScopes@groups.io Subject: Re: [TekScopes] Tek 576 Curve Tracer HV Transformer winding Michael, The cores are universal among tekscopes. I have never had one stick like you are describing. Epoxy just isn't that good. Send it to me, and I will remove it. If, in my zeal I should happen to break it, I will send you another core. I have two examples of the 576 EHT right on my desk, one black, and one brown. Both were removed in the way I described. -Chuck Harris Mlynch001 wrote: Chuck,definitely bad and I need to attempt to rewind. People are all saying "no problem, just heat them up and pull them apart". Well this is not working for me. The bobbin and windings are loose on the core, they are not the problem. The problem is that the core halves on my 576 HV Transformer are stuck tight and I mean TIGHT! I have heated for an hour @ 260F, hot enough that the epoxy just peeled off the windings, but those 2 halves of the core are not budging. It is like they are welded or silver soldered. I can see the split between the two halves of the core, but I'll be darned if they will come apart. I have put some small chips in the cores, so I stopped trying for now. The winding part does not scare me, but breaking the only cores that I have scares the crap out of me. Any Ideas? rewind of the old one.
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Re: 2465 DVS Repair - was; Re: [TekScopes] Wanted; Person to repair Tektronix 2465 DVS
Tony Fleming
Very well and detail explanation!
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Thank you Chuck.
On Sun, Sep 15, 2019 at 8:39 AM Chuck Harris <cfharris@erols.com> wrote:
The power inside of the 2465 supplies is pretty dirty from
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Re: Tek 576 Curve Tracer HV Transformer winding
Chuck,
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Leave it to me to have the “odd ball” of the group. I have seen many others that look the same or very similar. I may take you up on your offer and contact you off list for an address. Sincerely, Michael Lynch From My I-Phone mlynch003@yahoo.com 479-477-1115
On Sep 15, 2019, at 9:08 AM, Chuck Harris <cfharris@erols.com> wrote:
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Re: Tek 576 Curve Tracer HV Transformer winding
Chuck Harris <cfharris@...>
Michael,
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The cores are universal among tekscopes. I have never had one stick like you are describing. Epoxy just isn't that good. Send it to me, and I will remove it. If, in my zeal I should happen to break it, I will send you another core. I have two examples of the 576 EHT right on my desk, one black, and one brown. Both were removed in the way I described. -Chuck Harris Mlynch001 wrote:
Chuck,
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Re: Thermal Insulator question
Chuck Harris <cfharris@...>
Be careful here!
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Sometimes, the screw passes through the heatsink to a socket, and the screw is the electrical connection to the tab. Other times the screw screws into the heatsink, and must be isolated from the tab. Be sure what your situation is. The schematic may be a more clear indication of the need for isolation. -Chuck Harris Mlynch001 wrote:
Chuck,
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Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest
Chuck Harris <cfharris@...>
The 310 is close, but no cigar.
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The 511 was the original Tek scope, the 511AD was a later refined model, with a distributed vertical amplifier. My working (?) 513D is probably older than Alan's 511AD. I give it a ? because although I went over it completely about 30 years ago, it has the selenium rectifiers, which tend to turn into insulators. According to Stan G's book: 511 last catalog 1952 511AD last catalog 1955 513 last catalog 1953 513D last catalog 1953 310 last catalog 1958 310A last catalod 1971 -Chuck Harris Dave Daniel wrote:
Hmmm.. I have (and had back in 2014) a working 310.
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Re: 2465 DVS Repair - was; Re: [TekScopes] Wanted; Person to repair Tektronix 2465 DVS
Chuck Harris <cfharris@...>
The power inside of the 2465 supplies is pretty dirty from
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an RF point of view. It is pretty quiet from a 2x60Hz point of view. How can you tell the difference? The RF noise is composed of sliver thin spikes that ride on the top and bottom of the supply's DC waveform. They look like a fuzzy caterpillar. The 2x60Hz ripple will stand still when the scope is triggered using the line mode. Tek recommends you use the scope in bandwidth limit mode for making these measurements. The other failure that can happen to cause the Test05 Fail XX failures is in the MUX and Sample and hold gates that the A5 board uses to feed the threshold signals to the trigger hybrid. Typically one of three things happens (In approximately the order of likelihood): The MUX has an output that gets stuck high, or low (the message gives a clue), or, The sample and hold op amp gets stuck high or low, or, The sample and hold capacitor gets leaky. Trace back the TLA and TLB signals from the trigger hybrid to the two sample and hold OPAMPS, and from there to the MUX. And, it is conceivable that the AC Line signal that is supposed to go from the power supply to the CHN5 input to the trigger hybrid could be missing, or stuck... TP46 is your friend. -Chuck Harris jhalbrecht wrote:
O.K. tried without success to improve the ripple signal on the DC test points. I
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Re: Thermal Insulator question
Chuck Harris <cfharris@...>
Thermal Conductivity
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-------------------- Mica = 0.75W/mK Silicone/fiberglass = 1.3-3.0W/mK The unit of thermal conductivity is Watts per milliKelvin temperature rise. So, higher W/mK is better conductivity. Dielectric Strength ------------------- Silicone/fiberglass dielectric strength is typically 300-400V/mil. Mica dielectric strength is typically 5000KV/inch, or 5000V/mil. Where 1 mil = 0.001 inch. Mica was used at first because it was all we had. Later advances in material science brought us the silicone-fiberglass composites, and their improvement in thermal transfer. In addition, the incompressibility of silicone rubber, and its tendency to flow, improves thermal contact with irregular surfaces. The silicone rubber flows into the voids. Mica's biggest advantages are very high dielectric strength and very high temperature capability. Silicone/fiberglass pads biggest advantages are ease of use, and high thermal conductivity. Thermal greases, such as silicone grease, or the white zinc-oxide/ silicone greases, are used to fill any air gaps between the device being cooled, and the heatsink. The zinc-oxide was added to silicone grease because it has a slightly better thermal conductivity. In some applications, beryllium oxide ceramic powder, silver powder, or ??? powder is added to silicone grease improve thermal conductivity even more. Rule of thumb: The higher the thermal conductivity, the lower the electrical resistance. IF you want super high thermal conductivity, bolt the device directly to the heatsink. -Chuck Harris Dale H. Cook wrote:
As a rule I use silicone thermal pads only when heat dissipation needs are relatively
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Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest
Dave Seiter
Did the contest apply to only Tek scopes? Sadly, my 511A and 514AD don't work (The HV assemblies (I think) on both are dead- both had puddles of melted stuff around the assembly just above the main chassis-if my memory is correct). I cleaned them up, but never went further. I was waiting until I knew more before attempting anything.
I think my DeForrest Training scope is the oldest I have that works. The father of some good friends built it as a young man in the midwest many years ago. -Dave On Saturday, September 14, 2019, 11:26:14 PM PDT, Dennis Tillman W7PF <dennis@ridesoft.com> wrote:
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Re: 11801 NVRAM
Albert Otten
/
/ The challenge would be how to iteratively adjust the NVram constants without removing the NVram chips a thousand times. I don't know of any GPIB way / to SET the value of each NVram cal constant, maybe there's some tribal knowledge regarding that ?? / Perhaps you haven't seen this message https://groups.io/g/TekScopes/message/159274 and the previous ones in that topic? Albert
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Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest
Hi Jamie,
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AFAIK Alan Ainslie is alive and well since he posted a message this past May but since he receives TekScopes in full digest form he may not be aware of this until tomorrow. Dennis Tillman W7PF
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jamie Ostrowski Sent: Saturday, September 14, 2019 7:59 PM Does anyone know if there are any photos of Alan Ainslie's Tek oscilloscope collection? I read he had around 400 of them. It would be a pity if a collection of that size were not photographed! I was unable to find anything. On Sat, Sep 14, 2019 at 8:37 PM Dave Daniel <kc0wjn@gmail.com> wrote: Hmmm.. I have (and had back in 2014) a working 310. -- Dennis Tillman W7PF TekScopes Moderator
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Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest
Jamie Ostrowski
Does anyone know if there are any photos of Alan Ainslie's Tek oscilloscope
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collection? I read he had around 400 of them. It would be a pity if a collection of that size were not photographed! I was unable to find anything.
On Sat, Sep 14, 2019 at 8:37 PM Dave Daniel <kc0wjn@gmail.com> wrote:
Hmmm.. I have (and had back in 2014) a working 310.
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Re: From 2014: Tektronix Announces Winner of Europe’s Oldest Working Oscilloscope Contest
Dave Daniel
Hmmm.. I have (and had back in 2014) a working 310.
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As cool as an MDO would be, and not that I want a 'scope that I can't repair when (not if) it breaks, but there have to be hundreds of owners of vintage Tektronix 'scopes out there that own working 'scopes that are older than the 511 cited in the post, Europe or not. I don't recall hearing of this "contest". It is weird that it did not come to light while it was in progress. Does anyone have any information about the the contest itself? DaveD
On 9/14/2019 6:43 PM, Dennis Tillman W7PF wrote:
Craig Sawyers found this announcement from 2014 by accident. It was never mentioned on TekScopes prior to today.
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