Re: 7000 ESD Safe dust cleaning
Doug, it's not one board but ALL PCB and parts.
As the 7904A is huge and complex, any removal of the connectors or boards is risky
Idea is to blow out or vacuum everything
A lot is not accessible to q tips, brushes.
For me, canned air is always problems as danger of damaging liquids and not nearly enough pressure or amount of air.
Enjoy
Jon
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Re: 7000 ESD Safe dust cleaning
I use a natural brush, like horse hair, to loosen and remove the bulk of the dust. Then I typically spray with compressed air (from air compressor) as it also compresses moisture in the air which will reduce the chance of a static charge. If it's a smaller board and the local humidity is high, like 70%, I might alternatively use an "air duster." If there is still dust after this, I might take cotton tipped swaps with alcohol and clean the electronics and PCB. You might want to insert some type of barrier between the electronics that you're spraying and any mechanical components, like pots, just on the extremely off chance that dust might enter them.
?
There are some smaller vacuum cleaners that are supposedly ESD-safe, but I still wouldn't use them on electronics, plus, they're pricey.
?
Doug
---------- Original Message ---------- From: "Froggie the Gremlin via groups.io" <jonpaul@...> To: [email protected]Subject: [TekScopes2] 7000 ESD Safe dust cleaning Date: Thu, 26 Dec 2024 02:51:23 -0800 Hello all, ??Have a 7904A, low SN, 1982, ?stored for ?decades. Usual cleaning of switches, contrlols, the CRT, bright and in focus. ?? But all surfaces, PCB, PS, HV, CRT arencoated with dust. Suggest I vacuum with brush nozzle, finish with compressed air? Which is better? Am Wary of Air, Vacuum ?ESD, damage, should I Use Metal nozzles , earthed? Many thanks, Have an absolutely fantastic day Jon
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7000 ESD Safe dust cleaning
Hello all, Have a 7904A, low SN, 1982, stored for decades.
Usual cleaning of switches, contrlols, the CRT, bright and in focus.
But all surfaces, PCB, PS, HV, CRT arencoated with dust.
Suggest I vacuum with brush nozzle, finish with compressed air? Which is better?
Am Wary of Air, Vacuum ESD, damage, should I Use Metal nozzles , earthed?
Many thanks, Have an absolutely fantastic day
Jon
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Re: Tektronix 577 Fraud Kleinanzeigen Germany
The problem, I think, is that people may not know the difference between eBay and kleinanzeigen - classifieds! With kleinanzeigen Germany , private sale, no money back if it's a scam
Ebay is not such a big risk as they will refund if it doesn't appear.?
Common sense usually find them out, offering to collect is a quick way to spot the scammers.?
?
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Re: Tektronix 577 Fraud Kleinanzeigen Germany
Ebay is not such a big risk as they will refund if it doesn't appear.?
Common sense usually find them out, offering to collect is a quick way to spot the scammers.?
?
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Re: Tektronix 577 Fraud Kleinanzeigen Germany
Thank you very much! I have just reported the ad, which is active again, as a scam! So that no one else gets scammed!
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Re: Tektronix 1503C EL Display...
Hi Burt,
I can¡¯t remember exactly what I had to do but I didn¡¯t need the service manual for it. ISTR that it¡¯s not even necessary to remove the lcd panel (completely).
?
Raymond
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Re: Tektronix 1503C EL Display...
Gang,
It's good to hear from you about replacing the EL portion of the display. You're kinda telling me what I suspected. Can any of you tell me about any "tricks" in removing the display from the instrument and what it takes to disassemble the display itself and actually replacing the EL portion. Step by step would be nice, if possible.
Thanks,
Burt, K6OQK
Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
biwa@...
K6OQK
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Re: Tektronix 1503C EL Display...
On Sat, Dec 21, 2024 at 02:25 AM, Raymond Domp Frank wrote:
On Mon, Dec 16, 2024 at 05:09 PM, Burt K6OQK wrote:
the display is very dim
Hi Burt,
This is a well-known phenomenon on 1502/1503's (B/C) that use an EL foil as backlighting. As long as there is some light, the power supply usually is ok. The panels just wear ou within a relatively short time.
EL foils can be purchased at various places, even at car tuning centers (where I bought mine 10 years ago or so, don't remember where): They are used to change the backlighting (color) on some car's dashboard instruments. Just google for electroluminescent (backlight) panel.
They are available at affordable prices in several colors, like greenish and blueish and in various sizes. They can simply be cut to shape, just making sure that a set of connection tabs (+ and -) remains available. Supply voltage doesn't matter much within a large range.
I purchased green foil for my 1502C and 1503B, cut them to size, shifted them in behind the LCD panel (after pulling the old ones out...), soldered them in and done. Very easy!
?
Raymond
?
I did exactly this with my J17 light meter, it worked great and wasn't too difficult to do at all.
?
?
?
Jared
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Re: Tektronix 1503C EL Display...
On 20 Dec 2024 12:25 pm, Raymond Domp Frank wrote: This is a well-known phenomenon on 1502/1503's (B/C) that use an EL foil as backlighting. That is why my 1502 and 1503 are the original models (not B/C) with CRTs. -- Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
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Re: Tektronix 1503C EL Display...
On Mon, Dec 16, 2024 at 05:09 PM, Burt K6OQK wrote:
the display is very dim
Hi Burt,
This is a well-known phenomenon on 1502/1503's (B/C) that use an EL foil as backlighting. As long as there is some light, the power supply usually is ok. The panels just wear ou within a relatively short time.
EL foils can be purchased at various places, even at car tuning centers (where I bought mine 10 years ago or so, don't remember where): They are used to change the backlighting (color) on some car's dashboard instruments. Just google for electroluminescent (backlight) panel.
They are available at affordable prices in several colors, like greenish and blueish and in various sizes. They can simply be cut to shape, just making sure that a set of connection tabs (+ and -) remains available. Supply voltage doesn't matter much within a large range.
I purchased green foil for my 1502C and 1503B, cut them to size, shifted them in behind the LCD panel (after pulling the old ones out...), soldered them in and done. Very easy!
?
Raymond
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Re: Tektronix 1503C EL Display...
Usually bad CFL lamp or HV transformer in lamp driver.
Check threads in on 1503 display replacement, also search EEVblog, tekscopes.
Jon
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Re: #tektronix475 No Beam, HV Test point @ -500V - 600V DC
#tektronix475
Read Z axis and CRT circuits theory in manual.
See Z axis schematics.
Jon
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Re: #tektronix475 No Beam, HV Test point @ -500V - 600V DC
#tektronix475
On Wed, Dec 18, 2024 at 02:18 AM, Jaden H. wrote:
After doing a bit of research I swapped out the multiplier for a NTE538 & a 0.01uf 7kv cap in-between, and I got high-voltage as well as a display on the screen! Even though their failure seems to be a bit contested, I decided to also grab enough transistors to replace the SKA6516's for a few dollars while I was at it. I was having some issues initially with the trace moving all over the place and not staying still, and while it seemed like doing this fixed it at the time, it seems like it may have instead just been the switch for the 10x magnification button being a bit stuck.
?
However, something is still clearly up with this but I haven't had much luck figuring out what yet. I wouldn't be surprised if many of the issues I am having are related, hopefully someone will recognize a through-line here. I've been seeing jittering and flickering of the trace, sometimes the trace shows up very blurry and I frequently see what looks like some kind of ghosting of the display. Its like the trace is mirrored vertically on top of itself though it's not as bright. The trace also has a very bright spot at the start of the line. Even when I sometimes get a clear defined line though, over time it seems to get noisier the longer the unit is left on.
?
I wasn't sure if some of this might be solvable with some calibrating, but I don't have another scope outside of a cheap handheld one or any kind of signal generator (at least so far) to perform many of the steps. Do I have a better way forward at the moment outside of just testing the various caps?
?
Best Regards,
Jaden
?
I tested just playing a sine wave over the probe and while I did get a fairly clean signal I'm still seeing the jitter, however I also saw a line drawn between each end the wave where there should be nothing. It seems to me that the CRT isn't blanking correctly, the cause of the "ghosting" and bright spot I was seeing before.
?
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Re: #tektronix475 No Beam, HV Test point @ -500V - 600V DC
#tektronix475
After doing a bit of research I swapped out the multiplier for a NTE538 & a 0.01uf 7kv cap in-between, and I got high-voltage as well as a display on the screen! Even though their failure seems to be a bit contested, I decided to also grab enough transistors to replace the SKA6516's for a few dollars while I was at it. I was having some issues initially with the trace moving all over the place and not staying still, and while it seemed like doing this fixed it at the time, it seems like it may have instead just been the switch for the 10x magnification button being a bit stuck.
?
However, something is still clearly up with this but I haven't had much luck figuring out what yet. I wouldn't be surprised if many of the issues I am having are related, hopefully someone will recognize a through-line here. I've been seeing jittering and flickering of the trace, sometimes the trace shows up very blurry and I frequently see what looks like some kind of ghosting of the display. Its like the trace is mirrored vertically on top of itself though it's not as bright. The trace also has a very bright spot at the start of the line. Even when I sometimes get a clear defined line though, over time it seems to get noisier the longer the unit is left on.
?
I wasn't sure if some of this might be solvable with some calibrating, but I don't have another scope outside of a cheap handheld one or any kind of signal generator (at least so far) to perform many of the steps. Do I have a better way forward at the moment outside of just testing the various caps?
?
Best Regards,
Jaden
?
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Disconnect the PSU jumpers. Test each rail individually
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Cap polarization backwards?
Dead cap?
Wrong V or C rating
J
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I have a puzzle. Just replaced 3 caps on the power supply. It's the common small refer caps. On powering up I see the scope cycle on and off repeatedly.? Any ideas Alan?
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Tektronix 1503C EL Display...
Greetings all and Merry Christmas.
?
I have a Tektronix 1503C TDR, the one with the EL display.? It works fine except that the display is very dim, dimmer than normal. My question is, has anyone here ever had experience replacing the illuminating portion of the display.? I don't want to experiment with my unit fearing I could make it worse by destroying the display altogether.? Any thoughts would be appreciated.
?
Burt, K6OQK
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Tek 7904A restoration tips?
Bonjour ¨¤ tous!
Just received a 7904A, little used in decades. So far, a fine CRT, all works but scratchy CRT controls and a few switches. Will CLA them.
Seeking advice and tips on typical weak points, e.g. tantalum capacitors.
Finally has anyone tried to reduce the fan speed?
Many thanks,
Have an absolutely fantastic day!
Jon
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Froggie the Gremlin
Philips 6500
Burt K6OQK
Jared Cabot
Dale H. Cook
Benjamin Badrakh