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
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On 12/17/2021 16:11, 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
----- Original Message -----
From: "saipan59 (Pete)" <saipan1959@...>
To: "tekscopes" <[email protected]>
Sent: Friday, December 17, 2021 4:24:27 PM
Subject: Re: [TekScopes] Type 106
Ah, so your earlier "my bad" message meant to say that nothing is actually wrong
with the +/-10 rails. Got it.
However, regarding:
"Instead of checking voltages between chassis ground and directly at both
emitters, I probed between ground and + C215/ C218. According to the
schematic, this should be the same. But apparently not"
You MUST get the same values at the Emitters and at +C215 and -C218 ! If you
don't, you've got a measurement problem, OR those caps are not actually
connected like they should be.
Note that those rails *may* appear to work fine, even if C215 and C218 are
missing...
Pete
|
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
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----- Original Message ----- From: "saipan59 (Pete)" <saipan1959@...>
To: "tekscopes" <[email protected]>
Sent: Friday, December 17, 2021 4:24:27 PM
Subject: Re: [TekScopes] Type 106 Ah, so your earlier "my bad" message meant to say that nothing is actually wrong
with the +/-10 rails. Got it.
However, regarding:
"Instead of checking voltages between chassis ground and directly at both
emitters, I probed between ground and + C215/ C218. According to the
schematic, this should be the same. But apparently not"
You MUST get the same values at the Emitters and at +C215 and -C218 ! If you
don't, you've got a measurement problem, OR those caps are not actually
connected like they should be.
Note that those rails *may* appear to work fine, even if C215 and C218 are
missing...
Pete
|
Re: Recommended ventilation clearance around a 2465 scope
Nothing better than a fan AND a heat sink for the Horizontal Chip. Digikey
has one but you have to drill your own holes in it. Part Number HS273-ND
|
On Fri, Dec 17, 2021 at 11:00 AM, saipan59 (Pete) wrote:
What about D213 and D216? You can simply measure the voltage at the cathode of
D213, and the anode of D216 (or at the Base of the associated transistor, if
that's easier to get to). Should be around 10V.
If the diodes are open, the output voltage would be just about what you are
seeing (around 16 to 18V).
It pretty much HAS TO BE either the transistors, the Zener diodes, or an
external short across the transistors (both of them).
Pete
Yes, but no. Everything is fine. As you understood, I was not probing at the right place. I was misled by the +/- 9.1V beneath the capacitors, so I probed there because it was an easy access.
|
Ah, so your earlier "my bad" message meant to say that nothing is actually wrong with the +/-10 rails. Got it.
However, regarding:
"Instead of checking voltages between chassis ground and directly at both emitters, I probed between ground and + C215/ C218. According to the schematic, this should be the same. But apparently not"
You MUST get the same values at the Emitters and at +C215 and -C218 ! If you don't, you've got a measurement problem, OR those caps are not actually connected like they should be.
Note that those rails *may* appear to work fine, even if C215 and C218 are missing...
Pete
|
Yes, you¡¯re right. But weirdly enough the +/- 9.1 are also mentioned at the capacitors. Which is misleading.
That¡¯s why I expected that when I checked there, but nope¡
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The voltages taken directly at the emitters read + and - 9.7V. All within specs.
|
One other note: Even though the two rails are named "+10" and "-10", note that the schematic shows that the REAL values are +9.1 and -9.1.
Pete
|
What about D213 and D216? You can simply measure the voltage at the cathode of D213, and the anode of D216 (or at the Base of the associated transistor, if that's easier to get to). Should be around 10V.
If the diodes are open, the output voltage would be just about what you are seeing (around 16 to 18V).
It pretty much HAS TO BE either the transistors, the Zener diodes, or an external short across the transistors (both of them).
Pete
|
Re: Internal Drive Mechanism for 7B53N (et., al.) Sweep Speed Cam
Yes, it's clearly been a long time since I've had to work on one of these. I was thinking that pulling the drive dog forward would disengage the drive dogs from the rear drum, but that bothered me, as something in the back of my mind kept saying, "A Sweep in front, B Sweep in back."
So the interlocking is done by the knobs and the drive dogs continue to turn the rear drum even when its shaft is pulled forward.
Thanks, that makes more sense.
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. You'll have to remove that retaining washer from the shaft to get it apart. That can be tricky, or you can destroy the washer and buy a new one at your local hardware store.
Does anyone have a better name for that kind of retaining washer? It looks like an internal star lockwasher, but the inside spikes flare in one direction so that it can be pushed on but can't be easily pulled off. McMaster-Carr calls them Push-On External Retaining Rings.
|
Re: Wanted: Feet for TDS6xx scope..
Hello Lyle.
If you can't locate a replacement set, have you considered 3D printing a set?
J
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Re: Recommended ventilation clearance around a 2465 scope
Thanks everyone for your valuable feedback.
Thank you for the heat sink suggestion avtek2. Reading through the various threads about "horizontal output IC" cooling, there seems to be an even split between those that advocate installing a heat sink, and those that say the original engineering took "horizontal output IC" cooling into account. The fan in my particular scope was dead, and the prior owner apparently had been successfully using the 2465 that way ... "ouch"! I've replaced the scope with a new fan with the same specs rather than repair the old fan. For cooling, other than the fan replacement, I still haven't quite decided what do do about adding the heat sink.
I've finally finished 3D printing the rear feet for my scope. Luckily someone had already posted a model on Thingiverse, so I only had to tweak the CAD to lift it up a bit more than the original design. I'm also going to 3D print new front feet with a smidgen more height for ventilation per M Yachad's reply above. Hopefully these will give me more than enough clearance on the bottom of the scope.
Thanks again for all the help,
J
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Hi Pete.
They are not shorted. I have checked all the transistors in the power supply with a dedicated transistor checker. They are fine and within specs.
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My bad. I wasn¡¯t probing the right places. Instead of checking voltages between chassis ground and directly at both emitters, I probed between ground and + C215/ C218. According to the schematic, this should be the same. But apparently not¡
|
Re: Looking for a replacement Tunnel Diode for a 7B53N
My current understanding is capacitance directly plays in to rise time. Lower capacitance faster the rise time. I would expect this to be fine. But for D180 in a 284 capacitance is a HUGE deal .
Zen
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of n4buq Sent: Friday, December 17, 2021 2:36 PM To: tekscopes < [email protected]> Subject: Re: [TekScopes] Looking for a replacement Tunnel Diode for a 7B53N A follow-on question: How critical is the total capacitance for this TD? Specs state 8pF but the TekWiki page states that as a maximum and I presume less would work. I found a 10mA 2pF and am wondering if that will be suitable. Thanks, Barry - N4BUQ ----- Original Message ----- From: "Barry" <n4buq@...>
To: "tekscopes" <[email protected]>
Sent: Wednesday, December 15, 2021 9:43:43 PM
Subject: Looking for a replacement Tunnel Diode for a 7B53N One of the tunnel diodes in my 7B53N is bad. It is a TEK P/N
152-0140-01 (10mA, 8pF).
Does anyone know where I could get a replacement? I've been looking
at the Russian TDs on eBay and I think some of those might work but am
wondering if other folks have tried those as replacements.
Thanks,
Barry - N4BUQ
|
Re: Looking for a replacement Tunnel Diode for a 7B53N
A follow-on question: How critical is the total capacitance for this TD? Specs state 8pF but the TekWiki page states that as a maximum and I presume less would work. I found a 10mA 2pF and am wondering if that will be suitable.
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Barry" <n4buq@...>
To: "tekscopes" <[email protected]>
Sent: Wednesday, December 15, 2021 9:43:43 PM
Subject: Looking for a replacement Tunnel Diode for a 7B53N One of the tunnel diodes in my 7B53N is bad. It is a TEK P/N 152-0140-01 (10mA,
8pF).
Does anyone know where I could get a replacement? I've been looking at the
Russian TDs on eBay and I think some of those might work but am wondering if
other folks have tried those as replacements.
Thanks,
Barry - N4BUQ
|
Also some of the supplies in this unit are unregulated. Check the
transformer for correct line voltage. The line voltage have moved up I the
world sence these were built it is normal for some of the supplies to be
elevated here in the US these were made for 115vac. And they are now seeing
125 vac at the line. This will elevate some of the supplies. It might be
fine.
Eric
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On Fri, Dec 17, 2021, 2:17 PM saipan59 (Pete) <saipan1959@...> wrote: Hi Stephen,
My first thought is that the series regulators on +/-10 are not regulating.
Most obvious issue would be Q213 and Q217 are shorted, and/or D213 and
D216 are open.
Check the 27VAC at the transformer, and verify that you see about 14VAC
between each side and Ground.
Given all the problems you already found and fixed, perhaps the unit was
exposed to a "catastrophic" event, such as being powered by 230V when the
switch was set to 115V.
Pete
|
Hi Stephen,
My first thought is that the series regulators on +/-10 are not regulating.
Most obvious issue would be Q213 and Q217 are shorted, and/or D213 and D216 are open.
Check the 27VAC at the transformer, and verify that you see about 14VAC between each side and Ground.
Given all the problems you already found and fixed, perhaps the unit was exposed to a "catastrophic" event, such as being powered by 230V when the switch was set to 115V.
Pete
|
On Fri, Dec 17, 2021 at 07:56 PM, Stephen wrote:
However, 1 is referenced to chassis ground, and it should be + and - 10V +/-
1.5V, but I read very high at +16.73V and -16.59V.
The manual tells you to check the voltages, but not how to correct them when
they¡¯re not within specs.
Can anyone help? Thanks.
That's a very simple circuit with two main causes for your problem, although a bit surprising the two separate supplies are both bad: 1. D213 and D216 open. Check if they carry +10V and -10V aginst GND. 2. Q213 and Q217 shorted between C and E or open B. Depending on how the instrument is constructed (I don't have one), some connections could be open. Should be easy to check with your DMM. The voltages are shown in the Manual. Raymond
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Hi all,
I finally found the time to repair the Type 106 I bought back almost a year ago¡
A few months ago I had offline help from 2 very nice people here.
That thing had shorts everywhere. A few blown transistors, 3 out of 5 shorted bridge rectifiers, burned resistors, shorted and opened diodes, the whole shebang¡. In other words, it drove me crazy¡
It¡¯s now finally back from the dead, and working quite well, except for a few voltage issues.
3 voltages are referenced to what they call the ¡°A SUPPLY¡±: +150 +/- 15V, -150V +/- 15V, -20V +/- 2V.
All check within specs at +153.7, -150.72, and although the -20V reads a bit low at 18.73V, it¡¯s still ok.
However, 1 is referenced to chassis ground, and it should be + and - 10V +/- 1.5V, but I read very high at +16.73V and -16.59V.
The manual tells you to check the voltages, but not how to correct them when they¡¯re not within specs.
Can anyone help? Thanks.
|
saipan59 (Pete)
Raymond Domp Frank