Re: Help with R7903 needed, some success...
Hi Keith,
As far as I know your Fluke 27 is average-based, not true RMS. Then the reading for square wave input will be higher than true RMS.
Albert
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I also wanted to make sure the CRT heater voltage was present- measured about 8 VAC RMS at pins 8 & 9 on P1704. A little high, but I guess that's OK.
Keith Ostertag
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Hi,
I have a Tek 468 analogue with digital display and storage. The problem: the scope works fine in analogue mode, however when digital mode is selected, the trace appears to be modulated at a higher frequency causing a blurred display. If the timebase x10 is used to expand the trace, it appears to be composed of a semi sinusoidal waveform.(Its not possible to determine the frequency as in the digital mode the timebase control doesnt seem to have much effect)and its not possible to re-create this effect in analogue mode. I have checked grounding connections, re-seated the i/cs etc all to no effect. My next step is to check the digital psu for excess ripple.
Has anyone come across this problem before or can anyone point me in the right direction?
Note: The digital functions seem to work ok,save, store etc.
Very often the 'scope will not 'POST (power on self test,) but will come on in analogue mode.
The digital LED display does work, and so do the cursors and they do measure, but the cursors are modulated in the same way as the trace.
Bill
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--- In TekScopes@..., "photo692002" <photo692002@...> wrote:
Is anyone aware of a supplier for the battery pack or the cells within? I want to sell this scope and would like to suggest to the buyer where a pack might be obtained.
Larry
Check this then Google on LCS-214 /H?kan
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Re: Video triggering of 'scopes in general
--- In TekScopes@..., David <davidwhess@...> wrote: [..]
My 2440 has the rare video triggering option. The only time I have
used it was when looking at a VGA output and it worked great. In the
case of the 2440, it includes features like field and line selection.
Oddly enough, worked correctly with 1050 and 1200 line video.
[..] Hi David, no real surprise here - at least for the Horizontal Sync extraction, those comparator circuits work nicely with a lot of different video standard-signals. Cheers, Magnus
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Re: Help with R7903 needed, some success...
Is the CRT filament drawing current?
Regards,
David Partridge
|
Re: 7854: Excessive stored trace brightness.
The readout in the 7854 is radically different - it is part of one of the logic boards.
Dave
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-----Original Message----- From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Rob Sent: 10 July 2012 02:49 To: TekScopes@... Subject: RE: [TekScopes] 7854: Excessive stored trace brightness. P.S. All the numbers above are for a 7904. I assume they are the same in a 7854.
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Re: Video triggering of 'scopes in general
? Having restarted this thread by mistake (I had intended my email to John directly but goofed) I will try to shed some light.? John' original comment on this thread (4 Mar 2011) did a good job of describing the NTSC signal and challenges of syncing a scope to the video stream with embedded V and H sync signals.
?
? Granted that VGA signals are similar in that they provide analog video signals, but they also provide H and V sync on the connector pins (not buried in the video stream).? So it is possible to setup the scope to trigger the 'A' Sweep with V sync and use the delayed sweep feature to effectively move down the computer screen and trigger the 'B' Sweep with H Sync and see an individual line of video.? Now, 'back in the old days' it was possible to connect a video monitor to the scope (524A) and see which line you were observing on the scope (it was brighter).? A trick I learned was to work my way down the monoscope resolution fan and adjust the focus by watching the HF amplitude increase as it got sharper (this was back in the days before computer generated images) when TV was Black and White.?
?
? While the Video option probably would do a good job of syncing the scope, the availability of the sync signals preclude the necessitity of the sync separator that the option provides.? Plus, since the VGA signal is progressive not interlaced all video fields are the same and there is not the need to identify them (NTSC on the other hand has four unique?fields, odd and even lines, 'A' frame and 'B' frame, which differ in burst phase polarity).? All of which is getting pretty deep into an antique video format (at least in some circles).? But, which leads me to answer Bob's question that I can't think of any other use for the video sync option.
Denis
?
?
From: David To: TekScopes@... Sent: Monday, July 9, 2012 12:13 PM Subject: Re: [TekScopes] Re: Video triggering of 'scopes in general
?
I have a broken 7B53A with the video option that I may get around to repairing some day. When I asked about it here, I was told that the mixed sweep feature of the 7B53A is particularly useful for examining video. My 2440 has the rare video triggering option. The only time I have used it was when looking at a VGA output and it worked great. In the case of the 2440, it includes features like field and line selection. Oddly enough, worked correctly with 1050 and 1200 line video. On Mon, 09 Jul 2012 17:52:43 -0000, "Robert" < mailto:go_boating_fast%40yahoo.com> wrote: >Some 7B53As have video sync. I have two. Don't really use that feature but they work fine anyway. Might check those manuals as well. >Also, Is that feature good for anything else? >Bob > >--- In
mailto:TekScopes%40yahoogroups.com, Denis wrote: >> >> John, >> ?? I would like to request a copy of the 453 Mod 127C Schematic.?? I still have some NTSC gear around and want to see how Tek implemented sync separation, for possible inclusion into a 453A. >> ??Thanks, >> Denis >> >> >> ________________________________ >> From: John S >> To: mailto:TekScopes%40yahoogroups.com >> Sent: Friday, March 4, 2011 9:21 AM >> Subject: [TekScopes] Video triggering of 'scopes in general >> >> >> ?? >> - All the old TV
standards adopted around the world have an odd numbers of lines in a "complete" picture, which is defined as a TV Frame. (25Hz Europe, c.30Hz USA) >> - To conserve RF bandwidth, the signal is transmitted in sequential Fields, each of which contains half the lines (odd lines Field 1, even lines Filed 2 etc), as required to assemble the full TV Frame. >> - This is known as interlace scanning, and gives rise to display artefacts such as line-twitter on strong horizontal black-white transitions. >> - As the odd number of lines is clearly not divisible by 2, odd fields terminate (theoretically) half way through a line, and even fields commence similarly. >> - The problem confronted by TV engineers is to get the 'scope to trigger stably (ideally) at the FRAME rate, which is half the field rate. This allows a 'scope with a good dual-time-base delayed sweep to select a particular line. (The line can be a bit dim, as the
'scope is only writing for c. 60uS in every c. 40mS). >> - I have a 453 with TV triggering ( MOD127C ): Tek used to supply special graticules (which I also have) based around standardised TV test & measurement waveforms. >> - broadcasters use a few of the "blank" lines in the field blanking area* to transmit the test waveforms so an entire transmission chain can be quality monitored >> >> I can supply a copy of the MOD127C 453 handbook description to anyone who's interested. >> >> John >> >> * the "field blanking" lines contain synchronising pulses which are "broader" than on normal video lines, and the shift in DC level is used by the sync separators in the TV to lock the frame oscillator to field rate. They were kept free of video in order to allow the CRT scan time to return to the top of the screen without losing active picture content. >> >> --- In
mailto:TekScopes%40yahoogroups.com, Gala Dragos wrote: >> > >> > Hi! >> > >> > I've worked with a TD2002B recently. It had a trigger mode named "Video". It was used to display PAL/SECAM/NTSC video signals and lines. How do I do that with Tektronix 475 or 465 ? >> > >> > Thanks. >> > >> >
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Re: Help with R7903 needed, some success...
On Tue, 10 Jul 2012 02:36:22 -0000, "keithostertag" <keitho@...> wrote: TP1635 measures about -30mV. Probably ok given that it is a 741 operational amplifier although I wonder about their choice of 470kOhms for the bias current compensation resistor. Maybe they used that to introduce a deliberate offset. TP1876 measures about 16.5 volts, should be 7.6 volts. It may be worth checking it with an oscilloscope as described in the z-axis adjustment procedure in the manual. If you check TP1801 and TP1805 (bottom left corner of schematic 11), then I think you can rule out a problem earlier in the z-axis signal chain. If needed I can post a clean scan from my 7904 manual. There were two of those 47uF tantalums on the z-axis board- they checked OK but I figure I might as well get them out. Looking at the SM they were supposed to have been replaced by 220uF caps soon before my serial number, so that's what I replaced them with. I usually do not replace the tantalums until one actually fails and then I replace all of the similar ones. Electrolytic replacements tend to be 2 to 4 times larger in value to achieve similar ESR depending on how good the electrolytic is. I also wanted to make sure the CRT heater voltage was present- measured about 8 VAC RMS at pins 8 & 9 on P1704. A little high, but I guess that's OK. I would consider 8 volts too high if it is suppose to be 6.3 volts. Is the filament open or shorted to the cathode?
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Re: I have a type 585 oscope how much is it worth
I overheard a guy at the DeAnza flea market a few years ago tell about how he would wipe the markings off tubes and remark with a marker so the hard core tube vultures wouldn't want the scopes/tubes he was selling, but the people who would actually use the scopes wouldn't care.
Seemed kind of extreme...
-Dave
From: "mattko87" To: TekScopes@... Sent: Monday, July 9, 2012 9:20:32 PM Subject: [TekScopes] Re: I have a type 585 oscope how much is it worth
?
--- In TekScopes@..., "casey" wrote:
>
> Hello this is Casey Berg from Scotts Mills.
>
> I recently obtained a type 585 oscope. It works but I think it needs some calibration. are there any interested buyers.
>
> It also comes with a cart.
>
> Please add me to skype my user id is caseyberg88
>
Hi
Don?t sell him over eBay and other plattform, because audio people will killing them for 6DJ8. In Germany are selling many 585 to this idiots.
You can pull out 6Dj8, put russia 6922 into 585.
You will seeing, interested buyer will be reduced, because some are a tube vulture ;-)
Regards
matt
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Re: I have a type 585 oscope how much is it worth
--- In TekScopes@..., "casey" <caseycberg@...> wrote:
Hello this is Casey Berg from Scotts Mills.
I recently obtained a type 585 oscope. It works but I think it needs some calibration. are there any interested buyers.
It also comes with a cart.
Please add me to skype my user id is caseyberg88
Hi Don?t sell him over eBay and other plattform, because audio people will killing them for 6DJ8. In Germany are selling many 585 to this idiots. You can pull out 6Dj8, put russia 6922 into 585. You will seeing, interested buyer will be reduced, because some are a tube vulture ;-) Regards matt
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Re: 453 EHT and CRT: trouble-shooting advice
John,
? Have you considered letting the filament winding float and supplying the CRT filament with a separate transformer winding biased to the minus 2KV supply.? That way?any intermittent short would not impact the EHT supply.? Not having played EHT supplies I don't know if it would take kindly to the change in loading (removal of the filament load) and you might replace it with a load resistor (not connected to the -2KV rail).
?
? I have seen toroid transformers with 3500V insulation ratings for about $10 + Shipping.
?
? The 453 and 454 to me are very fine instruments and worth the effort to maintain?(even to the point of altering the CRT filament supply.)? I especially like to sharp trace that I see on them and the 'A' versions.
Denis
From: John S To: TekScopes@... Sent: Monday, July 9, 2012 2:45 PM Subject: [TekScopes] Re: 453 EHT and CRT: trouble-shooting advice
?
Well, as there has been no response, I've bitten the bullet and found that it's fine to power the EHT section with the anode and tube base disconnected. I think the problem lay in the EHT transformer: circumstantial evidence suggests an intermittent insulation break-down between the CRT heater winding and the "cold" end of another winding. John --- In mailto:TekScopes%40yahoogroups.com, "John S" wrote: > > > I'm attempting to bring a 453 (FET's) back to life. There is no trace, nor sign of an "off-screen" glow. Both sets of deflection plates are at the correct potentials, and the heater is not O/c. > > Initially, the EHT section did give the correct regulated outputs (-1.96/+8kV), but this must have been a transient condition, as it refuses (for the most
part) to produce any EHT at all. After a prod around and the odd component substitution, I can see the start of an oscillation in the driver Q930, but this gently subsides over a second or two as the scope warms up. This has happened several times. > > This suggests a possibility there is one secondary which is being loaded to the extent that the oscillator formed around the transformer does not have a loop gain of >1. I'd like to disconnect the EHT secondaries one-by-one, but I'm nervous at leaving the CRT connected in case the grid end up +ve..... > > 1. is it OK to remove the CRT base connector with the anode still hooked up? > 2. Is it OK to remove both the CRT base and the final anode connection whilst powering the EHT section? > > Cheers > > John >
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Re: Just got a tek 555 for free, and in need of some advice!
The scope carts have storeage for two plug-ins.? These are not wired in any way.
?
I go have spare cover clamps.
?
Keith
|
--- On Mon, 7/9/12, dutchbosstard wrote:
From: dutchbosstard
Subject: [TekScopes] Re: Just got a tek 555 for free, and in need of some advice!
To: TekScopes@...
Date: Monday, July 9, 2012, 4:03 AM
?
ill look into 3-in-one oil, i think ive seen some before around the machine shop at my university.
I see that you painted the carts of your 555 scopes? this might come off as another dumb question, but are the two provisions for plug-ins on the 555 cart just there as a holding rack for 2 extra plug-ins, or is it actually possible to somehow connect those plugins on the cart to the actual scope?
I appreciate your offer, and as it turns out, i might actually need a part. the day i turned it on, at my friends house, I dropped one of the white little things that the outside panel screws get screwed into, i just tried to find it in the parts list, but I dont know what their exact name is.
-Robby
--- In , Keith Knox
wrote:
>
> Hi Robby,
> ??
> At the present time I am working on 4 Tek 555 scopes. I have 3 of them working, 555 #4 is not working yet but will be soon.
> ??
> As for the fans I use a drop of 3-in-ONE oil and find that it works very well. Fans must spin freely or they will not run or they will run slowly.
> ??
> Test points for LV power supplys are on the bottom of power supply unit.
> ??
> Because the Tek 555 is a dual beam scope, there are two -1350 HV adjustments. One for each cathode.?? The HV Anode lead that plugs into the CRT will provide about +8650 volts.
> This totals out to 10KV accelerating voltage.
> ??
> When you get your Tek 555 working,?? remember that the upper beam will only write to the upper 4 cm of the crt and the lower beam will only write to the lower 4 cm of the crt.
> ??
> I have some spare
parts for 555 scopes.?? Let me know if there is anything you need.
> ??
> Have attached??photos of my three working 555 scopes.
> ??
> Keith
>
>
> --- On Fri, 7/6/12, dutchbosstard >
>
> From: dutchbosstard
> Subject: [TekScopes] Re: Just got a tek 555 for free, and in need of some advice!
> To:
> Date: Friday, July 6, 2012, 10:01 PM
>
>
>
> ??
>
>
>
> awesome. so when i get it back to my house ill carefully hit it with 40 psi. im guessing that shouldnt damage any tubes as long as im careful. My air compressor is sanborn reciprocating compressor -
ive never noticed any oil in the lines, only a small bit of moisture from when i drain the tank all the way. it also has a air filter on the input.
>
> so i guess ill just utilize a dry cloth until i get the scope back to my house.
>
> a few questions about the test points - when the time comes that i power up the scope, where are the test points for the low voltages from the power supply? are they in the PSU box? or are they somewhere inside the scope? also, when i opened up the case yesterday i found the -1350V test point for the CRT, but I was under the impression that the total accelerating voltage for the crt is 10kV. where is that test point located, and should i worry about it?
>
> also what fuses should i see for the main fuse, and the filament fuse in the PSU box?
>
> thanks,
>
> Robby
>
> --- In , tubesnthings@ wrote:
> >
> >
> > Valid concerns! Set air pressure no higher than necessary, say below 40
> > psi.
> > Use caution and common sense - 40 year old dust doesn't belong in your
> > lungs - do it outside and wear a mask.
> >
> >
> >
> > In a message dated 7/6/2012 1:43:15 P.M. Pacific Daylight Time,
> > childwhereugo@ writes:
> >
> > since i have an air compressor at home, should i try blowing out all the
> > dust? Ive heard that you can do this to electronic equipment, but i am kinda
> > terrified to do this since i dont want to have anything become
> > unconnected, or cause anything to short out, or worse yet
- damage a tube.
> >
> > are these valid concerns, or am i overacting? my air compressor is usually
> > set to 100 PSI.
> >
>
|
Oops.? Looks like these packs are not appropriate for the 224.? Sorry.
|
--- On Mon, 7/9/12, KeepIt SimpleStupid wrote:
From: KeepIt SimpleStupid
Subject: Re: [TekScopes] 224 Battery Pack
To: TekScopes@...
Date: Monday, July 9, 2012, 8:03 PM
?
It should be the same as the 211, 212 scope I think.? There was some discussion on Tekscopes that there are actually two different cup holders that have slightly different dimensions.
I bought the paks, less connectors, from www.bulbtronics.com.? Their part #, 5149.? You need two pack at a total cost for two of about $30.? Their order # is BAMED4149.? Note the 5 changed to a 4.
The part is hard to find on their website.? Look under medical batteries Siemens.
--- On Mon, 7/9/12, photo692002 wrote:
From: photo692002
Subject: [TekScopes] 224 Battery Pack
To: TekScopes@...
Date: Monday, July 9, 2012, 7:19
PM
?
Is anyone aware of a supplier for the battery pack or the cells within? I want to sell this scope and would like to suggest to the buyer where a pack might be obtained.
Larry
|
|
Re: Help with R7903 needed, some success...
TP1635 measures about -30mV.
TP1876 measures about 16.5 volts, should be 7.6 volts.
There were two of those 47uF tantalums on the z-axis board- they checked OK but I figure I might as well get them out. Looking at the SM they were supposed to have been replaced by 220uF caps soon before my serial number, so that's what I replaced them with.
I also wanted to make sure the CRT heater voltage was present- measured about 8 VAC RMS at pins 8 & 9 on P1704. A little high, but I guess that's OK.
Tomorrow I will begin looking around why TP1876 is high.
Further ideas?
Thanks,
Keith Ostertag
|
Re: 7854: Excessive stored trace brightness.
I have had to bugger around in the readout circuits in my exploits a bit. I
am no expert but a couple of things I have learned (I wish on my own but I
plagiarized some). In addition, I cannot address the brightness issue and
you may be right they may be related. If they are however, I bet it is a
noise/power supply issue. I suspect a bad cap on the readout board perhaps.
Anyway, if it is readout only:
Given that it's units only missing in the words.
Does the Identify display correctly or is it missing letters (it should
display if the vertical is in a horizontal as well)?
If you remove Q-2225 (at least that is the number in a 7904 double check for
a 7854) do all 40 zeros show? (should be a row of 40 across the top and
bottom).
Depending on the answers to those questions you will know if you have a
character generation problem or not.
If it is a character problem you can move U1251-U1255 around to isolate the
bad chip.
If it isn't you are in a data collection place (the identify should likely
have had letters in all places but misspelled perhaps).
This is U1130,1170 which you can switch to see if it changes channels....
Probably vertical...
If Identify misspelled really bad or symptoms don't change swapping above.
Check U1166 or U1186
I hope this helps
Rob
P.S. All the numbers above are for a 7904. I assume they are the same in a
7854.
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Show quoted text
-----Original Message----- From: TekScopes@... [mailto:TekScopes@...] On Behalf Of David Holland Sent: Monday, July 09, 2012 7:30 PM To: TekScopes@... Subject: Re: [TekScopes] 7854: Excessive stored trace brightness. Yeah, I've a 7B85 down in the basement. I'll plug things in and fiddle with them (probably tomorrow) and see what shows up. (Or doesn't.) Before running to far down the rabbit hole, I should probably describe the readout symptoms. AFACT, the readout doesn't display units. I get a number in the correct locations, that will change depending on the settings of the plugins, but there's no units associated with them. Perhaps its related, perhaps not. Anyways, thank you for the pointers. David On Mon, Jul 9, 2012 at 1:08 PM, David <davidwhess@...> wrote: Do you have a dual time base, a 7B87, or a 7B80/7B85 (or equivalent)
which you could use to check if the A intensified by B display is
correct?
I wonder if your readout troubles are related. The stored trace
intensify command could be controlled through the readout or from the
same place the readout is controlled from. Verifying it should be as
simple as disabling that function by pulling a transistor but I did a
cursory search of the service manual and did not find out it.
You might try fiddling with the contrast adjustment on the front of
the oscilloscope to see if that affects anything. I know mine has
trouble with the intensified display when using some dual time bases.
On Mon, 9 Jul 2012 12:36:13 -0400, David Holland
<david.w.holland@...> wrote:
Yup. Blanking looks good to me...
I'll double check the pot, and make certain its smooth. It looks
like I have some reading to do in the manual....(this is certainly
going to be umm.. interesting)
David
On Mon, Jul 9, 2012 at 11:32 AM, <larrys@...> wrote:
Are the parts that are supposed to be blanked getting blanked?
-ls-
David Holland <david.w.holland@...> wrote:
Hello all,
I'm kind of getting around to poking at my 7854 scope.
The stored trace brightness is excessive, and the adjustment won't go
down any further. I'm reasonably certain the pot is good, since
it'll smoothy vary over what range it does have. (From "too bright",
to "cr*p, I'd better turn that down before the CRT gets burnt").
Normal display, and readout's are of a more reasonable intensity, and
have goodly range. (Readout isn't working correctly, but that's
not the problem I want to concentrate first on.)
Before I crack the covers, any suggestions of which parts of the
service manual would be most relevant to read...
thanks in advance...
David
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|
Re: 7854: Excessive stored trace brightness.
The readout problem is straightforward although it may not be easy to find the specific fault and access may be limited. I am sure it is not related to the intensity problem unless Tektronix did something really weird. On Mon, 9 Jul 2012 20:30:20 -0400, David Holland <david.w.holland@...> wrote: Yeah, I've a 7B85 down in the basement. I'll plug things in and
fiddle with them (probably tomorrow) and see what shows up. (Or
doesn't.)
Before running to far down the rabbit hole, I should probably describe
the readout symptoms.
AFACT, the readout doesn't display units. I get a number in the
correct locations, that will change depending on the settings of the
plugins, but there's no units associated with them.
Perhaps its related, perhaps not.
Anyways, thank you for the pointers.
David
On Mon, Jul 9, 2012 at 1:08 PM, David <davidwhess@...> wrote:
Do you have a dual time base, a 7B87, or a 7B80/7B85 (or equivalent)
which you could use to check if the A intensified by B display is
correct?
I wonder if your readout troubles are related. The stored trace
intensify command could be controlled through the readout or from the
same place the readout is controlled from. Verifying it should be as
simple as disabling that function by pulling a transistor but I did a
cursory search of the service manual and did not find out it.
You might try fiddling with the contrast adjustment on the front of
the oscilloscope to see if that affects anything. I know mine has
trouble with the intensified display when using some dual time bases.
On Mon, 9 Jul 2012 12:36:13 -0400, David Holland
<david.w.holland@...> wrote:
Yup. Blanking looks good to me...
I'll double check the pot, and make certain its smooth. It looks
like I have some reading to do in the manual....(this is certainly
going to be umm.. interesting)
David
On Mon, Jul 9, 2012 at 11:32 AM, <larrys@...> wrote:
Are the parts that are supposed to be blanked getting blanked?
-ls-
David Holland <david.w.holland@...> wrote:
Hello all,
I'm kind of getting around to poking at my 7854 scope.
The stored trace brightness is excessive, and the adjustment won't go
down any further. I'm reasonably certain the pot is good, since
it'll smoothy vary over what range it does have. (From "too bright",
to "cr*p, I'd better turn that down before the CRT gets burnt").
Normal display, and readout's are of a more reasonable intensity, and
have goodly range. (Readout isn't working correctly, but that's
not the problem I want to concentrate first on.)
Before I crack the covers, any suggestions of which parts of the
service manual would be most relevant to read...
thanks in advance...
David
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
------------------------------------
Yahoo! Groups Links
|
Hi Larry,
I faced the same dilemma recently and found another fellow who had
substituted individual SLA cells.?? I am using the EnerSys Cyclon 2V
2.5AH "D" CELL batteries in both my 222A and 224.
EnerSys part number is 0810-0004, although I could never find the
battery on either their site, or their
"Specialty Battery Site", .
Mouser part number 846-0810-0004 showing over 250 available right
now, at $11.20 each.? Not cheap, but made my scopes portable again,
and with a decent run time.
Some plastic removal is necessary, but it's not major surgery.? I
just took a photo of my 222A so you can see what it looks like.?
Another option.
scotto
On 7/9/2012 4:19 PM, photo692002 wrote:
toggle quoted message
Show quoted text
?
Is anyone aware of a supplier for the battery pack or the
cells within? I want to sell this scope and would like to
suggest to the buyer where a pack might be obtained.
Larry
|
Re: 7854: Excessive stored trace brightness.
Yeah, I've a 7B85 down in the basement. I'll plug things in and
fiddle with them (probably tomorrow) and see what shows up. (Or
doesn't.)
Before running to far down the rabbit hole, I should probably describe
the readout symptoms.
AFACT, the readout doesn't display units. I get a number in the
correct locations, that will change depending on the settings of the
plugins, but there's no units associated with them.
Perhaps its related, perhaps not.
Anyways, thank you for the pointers.
David
toggle quoted message
Show quoted text
On Mon, Jul 9, 2012 at 1:08 PM, David <davidwhess@...> wrote: Do you have a dual time base, a 7B87, or a 7B80/7B85 (or equivalent)
which you could use to check if the A intensified by B display is
correct?
I wonder if your readout troubles are related. The stored trace
intensify command could be controlled through the readout or from the
same place the readout is controlled from. Verifying it should be as
simple as disabling that function by pulling a transistor but I did a
cursory search of the service manual and did not find out it.
You might try fiddling with the contrast adjustment on the front of
the oscilloscope to see if that affects anything. I know mine has
trouble with the intensified display when using some dual time bases.
On Mon, 9 Jul 2012 12:36:13 -0400, David Holland
<david.w.holland@...> wrote:
Yup. Blanking looks good to me...
I'll double check the pot, and make certain its smooth. It looks
like I have some reading to do in the manual....(this is certainly
going to be umm.. interesting)
David
On Mon, Jul 9, 2012 at 11:32 AM, <larrys@...> wrote:
Are the parts that are supposed to be blanked getting blanked?
-ls-
David Holland <david.w.holland@...> wrote:
Hello all,
I'm kind of getting around to poking at my 7854 scope.
The stored trace brightness is excessive, and the adjustment won't go
down any further. I'm reasonably certain the pot is good, since
it'll smoothy vary over what range it does have. (From "too bright",
to "cr*p, I'd better turn that down before the CRT gets burnt").
Normal display, and readout's are of a more reasonable intensity, and
have goodly range. (Readout isn't working correctly, but that's
not the problem I want to concentrate first on.)
Before I crack the covers, any suggestions of which parts of the
service manual would be most relevant to read...
thanks in advance...
David
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Yahoo! Groups Links
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Yahoo! Groups Links
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It should be the same as the 211, 212 scope I think.? There was some discussion on Tekscopes that there are actually two different cup holders that have slightly different dimensions.
I bought the paks, less connectors, from www.bulbtronics.com.? Their part #, 5149.? You need two pack at a total cost for two of about $30.? Their order # is BAMED4149.? Note the 5 changed to a 4.
The part is hard to find on their website.? Look under medical batteries Siemens.
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--- On Mon, 7/9/12, photo692002 wrote:
From: photo692002
Subject: [TekScopes] 224 Battery Pack
To: TekScopes@...
Date: Monday, July 9, 2012, 7:19
PM
?
Is anyone aware of a supplier for the battery pack or the cells within? I want to sell this scope and would like to suggest to the buyer where a pack might be obtained.
Larry
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Is anyone aware of a supplier for the battery pack or the cells within? I want to sell this scope and would like to suggest to the buyer where a pack might be obtained.
Larry
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zenith5106
David C. Partridge
David Hess