Re: DC503 Not Working


I got to working on bit on this unit today again. I rechecked all the voltages, and they’re all good.
For good measure, I replaced all the tantalums on the lower board. 2 with electrolytics, the 15uF/50V and the 6.8uF, which I couldn’t find. And of course nothing has changed, I yet have to find time to modify the JAMMA extender. After all that has been changed, there is close to no improvement...

Re: Message to satbeginner and Saroj Pradhan re: Tektronix 2230


Hi Chuck,
The first thing I can say is I always appreciate you input.

I did receive a complaint about it so I took a closer look. What I saw was an awful lot of messages with only two individuals involved. I was concerned that others might find it annoying.

It was a judgement call. But since many others indicate they are benefitting from it please accept my apology.

Dennis W7pF

-----Original Message-----
From: [] On Behalf Of Chuck Harris
Sent: Monday, August 03, 2020 6:55 PM
Subject: Re: [TekScopes] Message to satbeginner and Saroj Pradhan re: Tektronix 2230


Are you serious? Why is the 2230 not worthy of long threads, but every damn thing else is?

Yes, it is bit of a chit/chat fest, but the messages all seem to me on topic. Bandwidth (ha ha!) is minimal, perhaps less than 40K for the entire thread.

I admit that I care nothing for the 2230, but others do.

So, why?

-Chuck Harris

Dennis Tillman W7pF wrote:
You are creating an excessive amount of unnecessary message traffic, consuming significant bandwidth, and taking up precious storage on TekScopes.
I believe the best way for you to explore your mutual interests regarding the 2230 is to communicate directly to each other rather than through TekScopes.
If you need further assistance please contact me directly.
Thank you,
Dennis Tillman W7pF

Dennis Tillman W7pF
TekScopes Moderator

Re: 7834 Missing Trace


Alright, good news. Turning R2135 about 1/8 of a turn to the right brought the trace back. Thank you! Both time bases seem to work properly. Unfortunately this is the only scope I own, I've only used them at school before; if I really need another one I might be able to take it to a lab at my college when I go back at the end of the month, but I'm not sure if they'd let me use one for personal purposes. Is there more checking I need to do with regards to the trace issue? Not sure what would cause it to suddenly go out of adjustment like that. I also don't know the proper calibration procedure.

With regards to the storage controls, I've never used a storage analog scope before so I'm not sure if I'm using them correctly and I'm a bit afraid of burning the CRT with them. They all seem to turn the screen green at varying intensities, some at a worrying brightness.

Thanks again,


Re: 7834 Missing Trace

Roger Evans

Turn the readout intensity fully anticlockwise, there should be a detent to turn the readout function off.

You need to turn R2135 slowly since if it does brighten up the missing trace you don't want to overdo it and damage the very rare 7834 storage CRT. It's probably clockwise to brighten the trace but if not try turning it slowly anti clockwise. You may see nothing at all or a trace with both X and Y signals or a dot or a line, it just depends on which of the X, Y and Z signals are missing by the time they get to the CRT. Make sure to return R2135 to its original position, you can do a final adjustment when everything is working. There are X, Y and Z signals to drive the readout, they clearly do get through to the CRT so the problem is to find the point where the main signals go missing.

Were both time bases working before the right one was removed?

Do you have a second scope for troubleshooting?


Re: Tektronix 2230


Hi Saroj,

It looks like the FET gate signal is good now.
I would not worry too much about the Vpp of 19V, because both the rise and falling flank show quite some overshoot.
It would not surprise me if that is caused by the probe not compensated optimally.

I would look into the temperature: my recent 2215A repair showed a long run temperature of 59 Celsius, the higher temperatures you are seeing worry me.

On the other hand, your scope is a 2230, so a higher current would be expected.

Some questions:

Is the FET you are using a plastic one?
What is the specified On-Resistance?
Are you able to use a TO-220 heatsink on both sides of the metal mounting plate?
Did you use heat conducting compound when you mounted the FET?

You're getting close I think.


Re: Message to satbeginner and Saroj Pradhan re: Tektronix 2230

Greg Muir

I’ll probably take some flak over this.

Yes, on-topic discussions are fine as far as I am concerned but it seems to be the nature of others to predictably wander off the path and start discussions about the creation of the universe, different brands of steel wool, the effectiveness of lawn fertilizer, swimming pool maintenance and other comparable dribble.

It would be nice if everyone kept in the back of their minds that these sites are created to share pertinent information related to the topic at hand, not as a “chat room” in which to wander on through the idiosyncrasies about the meaning of life. We’re here to share our technical knowledge to help others learn and, in return, find answers to our own questions in a semi-professional way.

I do understand that there may be a share of members who seen to be hopelessly trapped in their homes due to the ongoing pandemic but if the urge strikes one to post unrelated thoughts it best be done via off-list contact with the person you wish to share those thoughts with.

I may be wrong but I feel that Dennis may have developed a little impatience from looking at the entire picture, not just only the posts between “satbeginner” and Saroj Pradhan. I, myself see on goings in many posts every week that allude to unrelated conversation when a topic finally jumps the rails and ends up continuing for dozens more postings of no relational value whatsoever.

Dennis may have happened to reach that “point” where he felt it was time to say something. We all exhibit that behavior when something finally irritates the devil out of us and we finally have to take action and say something.

As for myself, I do receive the digest mode via email and seldom go to the website because of the numerous OT posts that follow. It gives me a quick indication as to when to stop looking at topics when they veer off course – which seems to be quite frequently. I personally do not have untold amounts of time to waste.


PS – Maybe it is time to create a “”



The spectrum analyzer 7L5 contains two 155-0035-00 quad op amps. One of the four was faulty. No direct replacement was available. Therefore, I disconnected the three affected pins, then piggy-backed a LM324 in place with ±15V lines attached to the 115-0035 and added three wires for the socket. The remaining three op amps in the LM324 are not used.
Works nicely. The gain/bandwidth product of the LM324 is much smaller, but that does not affect the performance.

Re: FG502

Colin Herbert

Now I've tried it on my FG 503, I can see that it enables much better setting of the frequency.
Couldn't a static Lissajous pattern be obtained more simply by connecting the two function generators via "trigger out" and "gate in"? Maybe not....

-----Original Message-----
From: [] On Behalf Of Roger Evans via
Sent: 04 August 2020 15:56
Subject: Re: [TekScopes] FG502

The fine adjustment knob gives about a factor of ten improvement in the precision with which you can set the frequency measured against a DC503 counter. The only reason that comes immediately to mind is that it would help to give an almost static Lissajous figure in XY mode against some other generator. Any other ideas?


Re: 7834 Missing Trace


Ok, sorry for my inexperience. Just to make sure, you're saying turn the readout knob all the way to the left to turn it off, then try twisting R2135 back and forth? Should I just move it a little or all the way? And I'm looking for something to appear on the display?

Thanks for the help,


Re: FG502


On Tue, Aug 4, 2020 at 03:56 AM, Roger Evans wrote:

The fine adjustment knob gives about a factor of ten improvement in the
precision with which you can set the frequency measured against a DC503
counter. The only reason that comes immediately to mind is that it would help
to give an almost static Lissajous figure in XY mode against some other
generator. Any other ideas?


Hummm... Interesting. If only my FG503 was working...
I have to find the time to get back to it..

Re: AWG2005 Issues and Repair Question.


On Tue, Aug 4, 2020 at 03:55 AM, Michael W. Lynch wrote:

Yes, I have a 2440 and that is one of the scopes that must be constantly
cooled to prevent overheating of the A/D Converters and the CCD Hybrids. I
think that Martin makes a good point.
Yep. Very good piece of advice indeed.
I don’t personally know that series, but I trust you guys on that.

Re: Tektronix 2230

Saroj Pradhan

Hi satbeginner
Now it is double checked.
Oscilloscope probe itself has attenuation factor of 10 and default setting of probe in oscilloscope has gain of 10.
I have attached the photos.
It seems measurement voltage is little in higher side. And when ever you measured the voltage with respect to tp950 that 43 v dc also superimposed in the waveform.
And for the temperature it reached to 68 degree Celsius after 20 minutes.
After 25 minutes it reached upto 69 degree Celsius.
To day, for the first time I run the oscilloscope for 1 hour and the temperature reached upto 72 degree Celsius.
I saw temperature stabalised at 72 degree after 40 minutes.

Re: 7834 Missing Trace

Roger Evans

It's my turn to be the idiot! I had forgotten that the readout is still working. If the readout is in the right place and in good focus then all the high voltages are in good order and the X and Y amplifiers are working OK. You then need to check the sweep and unblanking signals are getting through so I would still say, turn the readout off completely, and tweak the grid bias. Beyond that a second scope really would be an asset.


Re: Why would you do this?

Richard R. Pope

Hello all,
. . . . I use!
GOD Bless and Thanks,

On 8/4/2020 9:43 AM, Michael W. Lynch via wrote:
On Tue, Aug 4, 2020 at 09:28 AM, Dick Wilson at DiLette Sales wrote:

In case anyone is unaware, eBay has now cut Paypal out and is forcing it's
members to give their financial info to a foreign company or the accounts will
be closed.
When or If this happens to me, I will also be out. I am only a "small potatoes" seller, but I will not submit my information to a foreign bank, just to stay on E-Bay. PayPal is its own boatload of pirates, but they are my pirates. E-Bay has become more and more difficult to justify as a seller over the years. The rules of use are indeed arbitrary and in some cases even draconian.

Re: 7834 Missing Trace

Roger Evans

Sorry for the idiot level reply, it just seemed too much of a coincidence that you unplug a timebase and the sweep disappears.

Do you have another scope, also a high voltage DC probe capable of measuring 2kV?

A quick test which should spot a problem in the Z axis / unblanking circuitry is to locate R2135, CRT bias, on the high voltage board. Note its position, turn it slowly in each direction looking for anything on screen, and return it to its original position. I had a 7623A with several storage board problems but they did not affect non-store mode, that is not to say that there might be some issue on the storage board that would affect non-store mode. I would try the various storage modes and also the reduced scan to see if anything interesting happens and also simply to exercise switches which may be a slightly contaminated.



Re: 7834 Missing Trace


Actually, I just checked again and I see what you mean now Roger. While I still have not trace, if I switch to gated with the trigger light on the readout stays on. Thanks for the tip! Maybe this rules out the CRT as the problem?


Re: Tektronix 2230


On Sun, Jun 28, 2020 at 06:19 PM, Saroj Pradhan wrote:
Hi Leo
I made myself a old style transformer type power supply to connect to the
inverter section. Here are my findings.
1. Un loaded external power supply out put voltage---44v
2. Loaded external power supply voltage--- 38.7v
3. Got the trace

Sorry to barge in so late in this thread, and have not even read it all the way to the end, but it reminded me when back in 2004 got my first Tek scope, a 2213A with the typical tic-tic-tic sound and flashing power LED. It was from a customer that had several of these scopes and wanted me to try and repair it, but after I ended up putting a lot of time and effort into it he ended up stating to just keep it if I eventually managed to fix it. Back then I actually turned for the first time to Tekscopes for advice, and was lucky enough to get help from Denis Cobley that helped a lot and really went out of his way (same as he always did help everyone) with lots of quick back and forth messages over a period of several weeks at that time, if not longer, just like Satbeginner is doing here. I also used a linear power supply (actually putting two 24V supplies in series and adjusting one for a 43V combined output) to bypass the scope Prereg, which is what rocked my memory. But unfortunately for me that did not help much as I had problems in both in the Prereg and main inverter. But after replacing all the blown parts it would still not work, even after replacing every single even mildly suspect component that I had on hand (small Elco caps, power resistors, semis, etc), quite a few late nights, and many many diagnostic measurements and hand drawn schematics all over the place (only had the plain 2213 service manual, which in terms of power supply is somewhat different). Then after finally making some progress on the Prereg of course made the customary single brief but fatal mistake and almost every power semi I had replaced was once again shorted or plain blown up, and put me right back to square one. But I was really determined to fix this scope and started suspecting that the problem was a part for which I did not have a replacement for a test. In the end eventually it turned out that the problem was a shorted T948, most probably in the HV secondary, and after replacing it I was finally greeted by a steady light from the green power LED. I managed to get a replacement transformer when another kind member of Tekscopes (sorry his name escapes me now), and that I assume was also following the repair thread, Fedexed me for free a whole 2213A scrapped main board but that was still almost fully populated. And as they say, the rest is history, and the helpful experience was so positive that so far I never have once considered getting any other used ("it was working the last time I used it") scopes but from Tek. Anyhow, good luck with the repair and I think this is a nice and very educative thread for any future 22xx newcomers!

Re: 7834 Missing Trace


Unfortunately the problem is just that. I can get a trigger light on both of the horizontals, with the display set to either CH1/CH2 or chop, but there is still no trace. With the side panels off I made a cursory inspection of the boards and the only thing unusual I could find was a capacitor with a strange glassy blue substance on top of it. I presume it is leakage, but I haven't seen one leak like this before. It is on the A25 storage board just behind the fan, so I'm not sure if that could be related. From what I can tell from the troubleshooting manual I think the problem is either in the CRT, the horizontal, or the PSU. I did notice the night before that in certain settings the display would flicker a bit, but as it warmed up the problem seemed to dissipate. Hoping the whole scope didn't become trash the day after I bought it, haha.

Here is an image of the capacitor:


Re: Preventing SPAM from new members

Tom Gardner

The occasional spam doesn't bother me, so I'd encourage Dennis (et al?) to choose whatever mechanism is least work for themselves.

It isn't just mask guys; electronic components as well :(  I've seen them ask questions with appropriate terms and sentences, but with paragraphs that indicate either complete beginner or not an English speaker.

Their followups to responses are either non-existent or complete rubbish.

On 04/08/20 15:01, Vince Vielhaber wrote:
These mask guys have been doing this on other groups.  Dennis is 100% correct in his new policy.  They ask some question, usually a how-to, and get approved.  Then after they're approved here it comes.  I've seen them in machining groups asking the same questions but using terms that are more apropos to the group.

Vince - K8ZW.

On 08/04/2020 04:37 AM, David C. Partridge wrote:
I didn't raise the point at the time, and 'm really not trying to tell you
"how to suck eggs":   Did you check with the person involved? It is
possible that his email had been hi-jacked, and that he wasn't the spammer.

Why do I say this - it happened to me a long time ago to a different email
from the one I now use.   Not much spam was sent and I was not (luckily)
banned anywhere.


-----Original Message-----
From: [] On Behalf Of Dennis
Tillman W7pF
Sent: 04 August 2020 01:24
Subject: [TekScopes] Preventing SPAM from new members

Prior to the SPAMMER I accepted and approved as a member a few weeks ago
anyone who wanted to post a message to TekScopes had to be approved by me. I
read each of their pending messages to be sure they passed my "smell" test.
If they did, then I approved them as a member and unmoderated them at the
same time.
Unfortunately spammers are now getting better at hiding their intentions and
it is becoming harder to separate them from legitimate future members.
From this point forward I will no longer be un-moderating new members
automatically. I apologize in advance for any inconvenience this may cause
new members.
Thanks to the member who alerted me to that spammer he was immediately
banned, all of his posts were removed, and all of the posts by others in
response the topic(s) he initiated were removed.

Dennis Tillman W7pF

Re: Why would you do this?

Michael W. Lynch

On Tue, Aug 4, 2020 at 09:51 AM, Paul Amaranth wrote:

What are the alternatives? Ebay was great in the early days; I got a ton of
useful equipment. Not so great these days and I'd love to go somewhere

Me Too!

A "needs repair" 465 with no trace, busted up knobs and that looks like it came out of a dumpster; priced at $200 + $100 shipping is too rich for me.

Viable Alternates anyone?

Michael Lynch
Dardanelle, AR