Re: Tek 2215

Jay

Oh I found this page on rebuilding the switch too..
http://softsolder.com/2013/01/11/tektronix-2215a-oscilloscope-power-switch-rebuild/Also I need to find some info on rebuilding the power supply caps I have read they have alot of issues with ..

Re: 7603 weirdo inverted Z axis

Albert Otten

Hi David,

It seems that you forgot about R1155?
4.8 V across R1155 gives 0.48 mA. That 0.48 mA reduces the zener current and reduces the current via R1159 by the same amount.
I think you took 130 V across R1120 while it is about 128.4 V, this gives 0.21 mA less via R1120 and 0.21 mA more via R1159.
Together this yields 0.27 mA less via R1159 or 4.7 V lower output voltage. Then our results are the same.

Albert

---In TekScopes@..., <davidwhess@...> wrote :

On 24 Jan 2016 11:46:17 -0800, you wrote:

>Hi David,
>>With no input at Q1107, I calculate a 21 volt output at R1157 which agrees with your measurement and should blank the beam. That points to a problem in the DC restorer.
>
>I calculate it at 16 V, never mind.

I did not find a way to get 16 volts but my work can be checked:

With Q1107 disconnected there are three currents into or out of the
base of Q1156:

1. R1141 is -1.7mA
2. R1121 + R1122 is -1.15mA
3. R1120 is +2.3mA

The later two connect at the top of VR1148 but affect the base of
Q1107 the same way except for an offset of 11 volts.

2.3mA - 1.15mA - 1.7mA = -0.55mA

The amplifier is inverting and note that it does not care whether the
currents are applied to the top or bottom of VR1148 as long as VR1148
is conducting which R1141 guarantees so 0.55mA * 17.4k = 9.6V

The output is offset by VR1148 and the Vbe of Q1156 so:

9.6V + 11V + 0.6V = 21.2V

Re: Tek 2215

It looks like it is in pretty good shape. I think the handle can be
repaired and it is not difficult to remove once you pull the
oscilloscope chassis from the enclosure. I do not see any evidence of
the front panel controls being bent so they cannot be too damaged.

On Sun, 24 Jan 2016 21:33:41 +0000 (UTC), you wrote:

Thanks for such great info .. I will have to check out volt mod and see if the mod is done or needed to be done .. Oh also to clarify the handle locking tabs are broke and not the knobs ..The knobs are fine and the unit is pretty clean..I hope this works out but I got this for dirt cheap..

Here is the listing

http://www.ebay.com/itm/TEKTRONIX-2215-60MHz-oscilloscope-/321969604505?_trksid=p2047675.l2557&ssPageName=STRK%3AMEBIDX%3AIT&nma=true&si=wOUmi6rr6qZOZulXaqHvXtSpJJg%253D&orig_cvip=true&rt=nc

Re: 7603 weirdo inverted Z axis

Albert Otten

Typo in "I think you took 130 V across R1120 while it is about 128.4 V". Should read 130 V - 11.6 V = 118.4 V, not 128.4 V.
Albert

Re: Tek 2215

Jay

Thanks I hope so and for \$24 shipped we will see what happens and will post updates..

Re: Tek 2215

Tothwolf

On Sun, 24 Jan 2016, joe black jasontucker70@... [TekScopes] wrote:

Oh I found this page on rebuilding the switch too.. http://softsolder.com/2013/01/11/tektronix-2215a-oscilloscope-power-switch-rebuild/Also I need to find some info on rebuilding the power supply caps I have read they have alot of issues with ..
I didn't find it necessary to disassemble the switch apart from removing the add-on safety shield they added over the top of the switch. To remove it without cracking it, you have to slide it off the switch towards the back, and even then it can still crack.

While the power switch is the same, keep in mind that the main board in the 2213A/2215A is completely different from the board used in the 2213/2215.

When you get you scope, if it has the preregulator assembly, I can see about compiling a list of the parts I used for my scopes. Most of them will be the same but you would need to add the capacitors they used on the dual timebase board.

Re: Tek 2215

Jay

Ok thanks..
Are there alot of caps that should be replaced and any other mods that should be done ???

CL: Lot of 5 Tek 453's

John Clark

Re: 7603 weirdo inverted Z axis

On 24 Jan 2016 13:45:16 -0800, you wrote:

Typo in "I think you took 130 V across R1120 while it is about 128.4 V". Should read 130 V - 11.6 V = 118.4 V, not 128.4 V.

Albert
I have been going through your post and figured that was a typo. I
used 11.6 volts at the top of VR1148.

On 24 Jan 2016 13:40:48 -0800, you wrote:

Hi David,

It seems that you forgot about R1155?
Yep, I missed it. I might have designed it with an AC coupling
capacitor in series with R1155 but technically that is not needed. I
thought R1155 controlled the gain of Q1156 but the effect would be
very small. Who designed this thing?

Hmm, the later design used in the 7623A and 7633 lacks R1155 among
other minor changes and I had all of the schematics open when I did my
first analysis although I only scribbled on the correct schematic.

4.8 V across R1155 gives 0.48 mA. That 0.48 mA reduces the zener current and reduces the current via R1159 by the same amount.
I think you took 130 V across R1120 while it is about 128.4 V, this gives 0.21 mA less via R1120 and 0.21 mA more via R1159.
Together this yields 0.27 mA less via R1159 or 4.7 V lower output voltage. Then our results are the same.

Albert
4.8V / 10k [R1155] = +0.48mA
-15.6V / 9.1k [R1141] = -1.7mA
(130V - 11.6V) / 56k [R1120] = +2.1mA
-11.6V / 10.1k [R1121 and R1122] = -1.15mA
2.48mA - 2.85mA = -0.27mA
0.27mA * 17.4k [R1159] = 4.7V
4.7V + 11V = 15.7V

With Q1107 (a slow 2N3904???) removed on my 7603, the output at point
B is 14.8 volts which closely agrees with our current calculation so I
wonder if Marian's <public@...> measurement of 20 volts at the
output of the z-axis amplifier is significant and indicates a problem.
I get the same 14.8 volt output with Q1107 installed, the readout off,
and the intensity control turned to minimum.

I also measured the output at point B and as the intensity control is
turned fully clockwise, the output increases to about 28 volts
monotonically.

Re: Tek 2215

On Sun, 24 Jan 2016 16:02:14 -0600 (CST), you wrote:

While the power switch is the same, keep in mind that the main board in
the 2213A/2215A is completely different from the board used in the
2213/2215.
I consider them separate designs with the 2213/2215 (1982 to 1985)
being the beta test for the series which starts with the 2235/2236
(1984) and includes the 2213A/2215A (1986) as replacements for the
2213/2215. Besides differences in the overall design, the 2213/2215
has a 30pF input capacitance and 10kV acceleration while all of the
later models have a 20pF input capacitance and 14kV acceleration.

Re: CL: Lot of 5 Tek 453's

Chris Pierce

Yes I would like them, but I can't put the money together until Feb, 10 will try to get some money together Monday but I don't think I can put that much together. I live in Goose Creek call me Monday if you want to 8436702873

On Sunday, January 24, 2016 5:21 PM, "johnclark05@... [TekScopes]" <TekScopes@...> wrote:

Anyone in Charleston, SC area need some 453's? \$150 for 5 of 'em.

http://charleston.craigslist.org/ele/5417533394.html http://charleston.craigslist.org/ele/5417533394.html

[Non-text portions of this message have been removed]

Re: CL: Lot of 5 Tek 453's

John Clark

Oh, no, they're not mine. I just saw them pop up on Craigslist today.

John

To: TekScopes@...
From: TekScopes@...
Date: Sun, 24 Jan 2016 23:46:40 +0000
Subject: Re: [TekScopes] CL: Lot of 5 Tek 453's

Yes I would like them, but I can't put the money together until Feb, 10 will try to get some money together Monday but I don't think I can put that much together. I live in Goose Creek call me Monday if you want to 8436702873

On Sunday, January 24, 2016 5:21 PM, "johnclark05@... [TekScopes]" <TekScopes@...> wrote:

Anyone in Charleston, SC area need some 453's? \$150 for 5 of 'em.

http://charleston.craigslist.org/ele/5417533394.html http://charleston.craigslist.org/ele/5417533394.html

[Non-text portions of this message have been removed]

Recommendations / 2247A

John Dickens

I have my eye on a 2247A on Craigslist that looks very clean and appears to be fully functional.

Does anyone have any thoughts about this scope - reliable, repairable, etc.? It would be my first scope with a microprocessor. I also have a 7603 and a 2236 as well, not to mention a 503 in poor shape.

Thanks, John

Re: Tek 2215

Tothwolf

On Sun, 24 Jan 2016, jasontucker70@... [TekScopes] wrote:

Ok thanks..
Are there alot of caps that should be replaced and any other mods that should be done ???
As far as preventive maintenance parts goes, I replaced all of the electrolytic capacitors, the 5 Rifa brand safety capacitors, the 1M ohm carbon comp resistors in the high voltage divider, and some other misc resistors.

The 6 silver colored Mallory capacitors on the main board are an absolute must replace item, and if your 2215 still has the original parts installed, you'll probably find that they are beginning to leak from their bottom seals.

I used new manufacture carbon comp resistors for the 1M ohm resistors, however after the discussion on the list, I picked up some high voltage rated film parts that I plan to replace those with the next time I have the scopes opened up.

The difficulties I ran into with the 2213 scopes were that the component leads are bent down to hold the parts in before they were soldered, and the two small electrolytics on the front panel board were difficult to get to (I used some long tweezers to fit them).

While some people claim that the small 5mm and 6.3mm capacitors never fail, some of the small electrolytics in my scopes were visibly leaking or had corrosion on their leads which was only visible after removing them, so I think replacing them is a good idea.

I posted this link previously, but some photos of my scopes can be found here: http://strudel.ignorelist.com/~tothwolf/photos/Tektronix_2213/

Overall, the 2213/2215 isn't a scope I would recommend for a beginner, but if you have the patience and a vacuum soldering tool, they aren't that hard to service.

Re: Tek 2215

On Sun, 24 Jan 2016 18:56:02 -0600 (CST), you wrote:

On Sun, 24 Jan 2016, jasontucker70@... [TekScopes] wrote:

Ok thanks..
Are there alot of caps that should be replaced and any other mods that
should be done ???
....

I used new manufacture carbon comp resistors for the 1M ohm resistors,
however after the discussion on the list, I picked up some high voltage
rated film parts that I plan to replace those with the next time I have
the scopes opened up.

...
The Vishay VR25 and VR35 series high voltage film resistors are very
similar if not identical to the high voltage film resistors which
Tektronix used to replace the carbon composition resistors originally
used in the 22xx series focus chain. They are readily available and
inexpensive.

Re: Recommendations / 2247A

I do not have any complaints about mine. The 2247A duplicates the
universal timer/counter functions found in your 2236. Calibration is
*not* done digitally so there are no worries about dead batteries or
floating gate storage memory like with the 24xx oscilloscopes.

On Sun, 24 Jan 2016 18:45:59 -0600, you wrote:

I have my eye on a 2247A on Craigslist that looks very clean and appears to be fully functional.

Does anyone have any thoughts about this scope - reliable, repairable, etc.? It would be my first scope with a microprocessor. I also have a 7603 and a 2236 as well, not to mention a 503 in poor shape.

Thanks, John

Re: Recommendations / 2247A

Tom Jobe <tomjobe@...>

Hi John,
I have some 224x scopes and use a nice 2247A regularly. It's a wonderful
scope and I know it's very complicated, but I'm hoping all of you will
help me fix it if or when it does fail!
I'd say, go for it and worry about future in the future.
Ordinary things like re-capping the 224x power supply is a very simple
thing to do, and the details of it are well documented. Also the 2247A
probably came late in the 224x series so it probably has some
improvements they learned of earlier in the series.
tom jobe...

On 1/24/2016 4:45 PM, John Dickens jake_117_dickens@...
[TekScopes] wrote:

I have my eye on a 2247A on Craigslist that looks very clean and
appears to be fully functional.

Does anyone have any thoughts about this scope - reliable, repairable,
etc.? It would be my first scope with a microprocessor. I also have a
7603 and a 2236 as well, not to mention a 503 in poor shape.

Thanks, John

[Non-text portions of this message have been removed]

Re: Tek 2215

Jay

Why are you replacing the resistor that your listed ???

Re: Tek 2215

Jay

I have a hakko fx-888d iron and nice desoldering iron that works really good.I know I'm a noob to scopes but right now I have no scope cause I had a nice Rigol DS1054z but had to be sold in order to pay rent and a place for my family.. The scope is show in the pics working but will need further testing and why replace the resistors ... When I get the scopes is there anyway I could could post pics and you guys could show me what is needed to be replace or part# or something ???
About how much should the parts cost me for the rebuild here in the usa ???

Re: Tek 2215

Tothwolf

On Sun, 24 Jan 2016, David @DWH [TekScopes] wrote:
On Sun, 24 Jan 2016 18:56:02 -0600 (CST), you wrote:
On Sun, 24 Jan 2016, jasontucker70@... [TekScopes] wrote:

Ok thanks..
Are there alot of caps that should be replaced and any other mods that should be done ???
....

I used new manufacture carbon comp resistors for the 1M ohm resistors, however after the discussion on the list, I picked up some high voltage rated film parts that I plan to replace those with the next time I have the scopes opened up.

...
The Vishay VR25 and VR35 series high voltage film resistors are very similar if not identical to the high voltage film resistors which Tektronix used to replace the carbon composition resistors originally used in the 22xx series focus chain. They are readily available and inexpensive.
That's what I'm planning to install. I picked up 100 Vishay VR37000001004FR500 for \$13.60.