n4buq <n4buq@...> added the album 7B53N Rear Drum: Broken Rear Cam Drum
The following photos have been
uploaded to
the 7B53N Rear Drum album of the [email protected] group.
By:
n4buq <n4buq@...>
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Thanks, Stephen. I hope you find what's giving you the domino effect with yours. Wish could offer some advice.
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Stephen" <stephen.nabet@...>
To: "tekscopes" <[email protected]>
Sent: Saturday, December 18, 2021 3:15:40 PM
Subject: Re: [TekScopes] Type 106 On Sat, Dec 18, 2021 at 09:57 AM, n4buq wrote:
I think my 106 was simply angry with me for not cleaning it. Previous
owner(s) had stored it in a fairly dirty environment (along with the 184 and
191 I got with it) and I hadn't gotten around to cleaning it. All outputs are
now working ("working", not calibrated).
Not sure - perhaps something got reseated along the way. Whatever, it sure
looks a LOT better than it did.
Thanks,
Barry - N4BUQ Happy for you. Congratulations.
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I wouldn¡¯t necessarily call that upside down ¡ª the plate is still more positive than the cathode. I¡¯d call it level shifted...
Cheers
Tom
Sent from my iThing, so please forgive brevity and typos
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On Dec 18, 2021, at 14:52, saipan59 (Pete) <saipan1959@...> wrote:
On Sat, Dec 18, 2021 at 02:14 PM, Stephen wrote:
Just checked the plates of the EL84¡¯s¡ 0V and -6V after the 33ohm screen
grid resistors¡. Hmmmm Not sure I follow what you're measuring, but from the schematic, what I see is this (on any of EL84/7189A tubes):
All voltages wrt Ground.
Pin 3, cathode, -145V.
Pin 2, control grid, -151V.
Pin 6 or 9, screen grid, [some low-ish value, not marked on the schematic].
Pin 7, plate, -5V.
So, note that these tubes are powered "upside down" compared to most conventional circuits, where the Plate would be large-positive wrt Ground.
Pete
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On Sat, Dec 18, 2021 at 02:14 PM, Stephen wrote: Just checked the plates of the EL84¡¯s¡ 0V and -6V after the 33ohm screen
grid resistors¡. Hmmmm Not sure I follow what you're measuring, but from the schematic, what I see is this (on any of EL84/7189A tubes): All voltages wrt Ground. Pin 3, cathode, -145V. Pin 2, control grid, -151V. Pin 6 or 9, screen grid, [some low-ish value, not marked on the schematic]. Pin 7, plate, -5V. So, note that these tubes are powered "upside down" compared to most conventional circuits, where the Plate would be large-positive wrt Ground. Pete
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Re: OT: microwave oven blows fuse
Thanks, Ben.? I will see what I can do to get the interlock assembly.? Merry Christmas and Happy New Year to you and yours!? ? ?Jim?Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: "benwetzel via groups.io" <benwetzel@...> Date: 12/18/21 7:45 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] OT: microwave oven blows fuse You will need to replace the plastic bracket that holds all of the switches.? Or easier approach is to get the whole interlock assembly. Good luck sir.Ben
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Looks like you made some headway while I was writing my post. It still might be worthwhile to do the connection tests with the plastic probe just in case you shake/bump the chassis and the problems suddenly come back.
Regards
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Thought I would give you some alternative ideas since traditional troubleshooting is not leading you to a result.
There are a lot of directions you could take at this point and possibly it could be a transformer problem. Could be an intermittent/bad ground connection as well.
If you have some bench supplies, you might try removing the outputs of the existing supplies and use bench supplies instead. At a minimum you could use a +/- 9.1V supply in place of the +/- 10V rails.
Here is a different approach. Connect voltmeters to all the supply voltages, analog meters if you have them. Next take a plastic stick or probe and carefully shake or tap on the component leads and wires starting in the power supply section. There could be a cracked solder joint, poor ground or something similar. Check for anything conductive loose trapped within those connection strips which might move around as you turn the 106 around to work on it. I bring up this last idea as it seems that your problem is moving around as you work on the 106.
Also lightly tap the transformer sides a few times to see if internal shorts/opens could be triggered.
Regards
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On Sat, Dec 18, 2021 at 09:57 AM, n4buq wrote:
I think my 106 was simply angry with me for not cleaning it. Previous
owner(s) had stored it in a fairly dirty environment (along with the 184 and
191 I got with it) and I hadn't gotten around to cleaning it. All outputs are
now working ("working", not calibrated).
Not sure - perhaps something got reseated along the way. Whatever, it sure
looks a LOT better than it did.
Thanks,
Barry - N4BUQ Happy for you. Congratulations.
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Just checked the plates of the EL84¡¯s¡ 0V and -6V after the 33ohm screen grid resistors¡. Hmmmm
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I think my 106 was simply angry with me for not cleaning it. Previous owner(s) had stored it in a fairly dirty environment (along with the 184 and 191 I got with it) and I hadn't gotten around to cleaning it. All outputs are now working ("working", not calibrated).
Not sure - perhaps something got reseated along the way. Whatever, it sure looks a LOT better than it did.
Zen - your restoration video is quite amazing. I wish the insides of my 106 looked that nice. Maybe one day...
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Barry" <n4buq@...>
To: "tekscopes" <[email protected]>
Sent: Saturday, December 18, 2021 8:06:54 AM
Subject: Re: [TekScopes] Type 106 Hi Stephen,
I'm not sure my paper manual has that information so good to see it in the
scanned copy from TekWiki. Apparently they still used clip-in silicon Schottky
diodes which I don't find by that part number but that's pretty minor.
BTW, this document is of interest:
I particularly like the last two sentences on page 7 of that document. You
don't see that very much anymore.
Thanks,
Barry - N4BUQ
----- Original Message -----
From: "Stephen" <stephen.nabet@...>
To: "tekscopes" <[email protected]>
Sent: Saturday, December 18, 2021 1:44:49 AM
Subject: Re: [TekScopes] Type 106 On Fri, Dec 17, 2021 at 01:11 PM, n4buq wrote:
Speaking of a 106, anyone know anything about the GaAs diodes in the Fast Rise
outputs? I think one or two of mine are bad. The +OUTPUT works but not the
-OUTPUT. Input to the two diodes on the -OUTPUT side looks okay but at the
junction between the two, the signal is not correct and the output is not
correct at all.
I've never seen diodes constructed like these before and don't expect I'll
find direct replacements but am wondering could be used as replacements.
Thanks,
Barry - N4BUQ
If you look at the end of the manual, starting on page 96, you¡¯ll find the
replacement procedure and parts list for those obsolete GaAs diodes.
Hope this helps.
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BTW, I tested all the tubes, and they¡¯re all reading strong and ok, no shorts.
All filaments are lighting up just fine too.
Don¡¯t know what to think at this point¡
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On Sat, Dec 18, 2021 at 08:44 AM, saipan59 (Pete) wrote:
On Sat, Dec 18, 2021 at 12:41 PM, saipan59 (Pete) wrote:
I can't think of anything else that would kill the rectifiers... Correction: Power-rail short could certainly kill a single rectifier. But
having multiple die so easily makes me think of the transformer.
Pete
Well, all the voyages are correct. And I used to have quite nice outputs on all outputs. Current limiting bulbs are not lighting up either. So I don¡¯t think there is a shirt on the PT. Remember that this unit had quite a lot of issues. Maybe that stressed the old original rectifiers quit a bit over time. Once the unit was functioning at full power, the remaining original rectifiers gave under stress. That¡¯s my guess¡. The new ones seem to be holding up quite well, and again all required voltages are fine. I doubt they would be if any short was anywhere in the PT¡. Or I¡¯m missing something¡
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On Sat, Dec 18, 2021 at 12:41 PM, saipan59 (Pete) wrote: I can't think of anything else that would kill the rectifiers... Correction: Power-rail short could certainly kill a single rectifier. But having multiple die so easily makes me think of the transformer. Pete
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On Sat, Dec 18, 2021 at 08:34 AM, Stephen wrote: That thing is fighting me in any possible way! That¡¯s unbelievable!
All the rectifiers have been changed, not more mains fuse blowing. It turns
out the remaining 3 failed as well.
All the voltages are perfectly fine, but now I have no more output, nothing.
Neither on the high amplitude, nor on the fast rise. ZILCH!
Things seem to fail one after the other, in cascade¡. Fix one thing,
something else bad comes up¡
That thing doesn¡¯t want to cooperate¡
Any ideas? Perhaps an intermittent short in the primary side of the power transformer?? When the short kicks in, secondary-side voltages could go way higher than normal, frying lots of things. I can't think of anything else that would kill the rectifiers... Pete
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Re: Internal Drive Mechanism for 7B53N (et., al.) Sweep Speed Cam
On Fri, Dec 17, 2021 at 10:44 PM, Jim Adney wrote:
For the original poster: If the front knob does not turn the B drum, does it
turn the 1/8" B drum's shaft? If it does, but the B shaft does not turn the B
drum, then the drive dog has either shattered (most likely) or come loose from
the shaft.
This all looks very much like a rather frequent problem with 465- and 475-scopes, which have similar construction. A lot has been written about this on this Group, including the tricky - but successful for all who tried, AFAIK - glue method that I suggested. Look around in the Group's messages; I have no pointer nor the time currently to look them up, unfortunately. Raymond
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Re: 2247A problems (no power on)
All LV filter caps tested good. ESR on all was between 0.12 and 0.14 ohm, values withing 10%. Not bad for capacitors that have been in service since 1986 or so.
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When I replaced the sampling diodes in my 1S1, for each one I used a SOT23 part on a small carrier of FR-4. I made it in a T shape with the side-arms wrapped in small gauge bare wire-wrap wire. (The long arm of the T facilitates handling with tweezers.) These assemblies fit into the clips just like the original parts. Dave Wise From: [email protected] < [email protected]> On Behalf Of n4buq via groups.io Sent: Friday, December 17, 2021 6:55 PM To: tekscopes < [email protected]> Subject: Re: [TekScopes] Type 106 Thanks, Tom. The existing diodes are tiny glass(?) cylinders with metal ends that clip into small holders (much like the old fashioned clip-in fuses). I suppose I'll be doing some plumbing for whatever I find to replace them. Thanks, Barry - N4BUQ ----- Original Message ----- From: "Tom Lee" <tomlee@...<mailto:tomlee@...>>
To: "tekscopes" <[email protected]<mailto:[email protected]>>
Sent: Friday, December 17, 2021 7:14:57 PM
Subject: Re: [TekScopes] Type 106 Based on the fast-rise circuitry of the 106 and PG506 being similar and
having similar specs, you would seem to have several good Si-Schottky
candidates. A few that come to mind are:
MBD101
BAV17
HSMS-282x (15V breakdown makes these an upgrade over the stock diodes)
These have slightly higher capacitance than the GaAs originals, but it's
not enough to matter.
I'm sure others will chime in shortly with their recommendations.
-- Cheers
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
<> <snip>
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Re: 2247A problems (no power on)
Gave the HV connector another try and managed to separate it, and PS board is now out.
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Re: Internal Drive Mechanism for 7B53N (et., al.) Sweep Speed Cam
On Fri, Dec 17, 2021 at 09:05 PM, n4buq wrote: I will have to try removing that retaining ring and go from there. Yes, that's the only way to get to the bottom of this. Once the retaining ring is gone, the shaft should slide out the other end easily. Then you'll be left with a plastic dog that's either cracked into 2 parts, or busted into a dozen pieces. It will take some effort to get everything out of there, including the spring that won't be helping matters. Try to get an idea of the orientation of the dog as you get the pieces out. The dog body has a long and short end; that is, the actual drive dogs are closer to one end of the body. If the dog is simply broken into 2 halves, I suppose it might be possible to glue it back together on the shaft, but I hate to resort to fragile repairs on something so difficult to get to. That's why I went with the brass replacements.
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Re: OT: microwave oven blows fuse
You will need to replace the plastic bracket that holds all of the switches. Or easier approach is to
get the whole interlock assembly.
Good luck sir.
Ben
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saipan59 (Pete)
Raymond Domp Frank