开云体育

The recent "design ideas" discussion led me to an announcement of a IGBT that does not require a snubbing circuit
when used in the typical offline flyback PS.
Supposedly it handles this on chip and to me this is one of those "why doesn't everyone do it this way?" moments.
Searching on the listed part number led nowhere.
Has anyone worked with these?

Thanks,
Bert

Hi, Thanks.

I was able to peel off the top plastic cover using a xacto knife, and some of the hard 'nylon' stuff surrounding it. It in acetone now, hopefully it will make it work again. We use that technique to "fix" 80017A ICs and it works many times.

any one have saved that 517A ?

one of the greatest Tek ever build, I would love to have one !

- Martin -

From: mailto:TekScopes@...
Sent: Sunday, October 12, 2014 8:18 PM
To: TekScopes@...
Subject: [TekScopes] Tektronix 517A and 535A on Michigan Craigslist


If I collected vacuum tube equipment I'd be all over this.



$5 for the 517A and $10 for the 535A + some plugins

--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows





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

John,

As Albert said there is a lot of good information on the 576 repair in general and the HV transformer in previous posts. As you read through those posts you will learn that the HV transformer in the 576 is unique, the ones potted in the brown epoxy fail often, the ones potted in the later black silicon are still running, the cut off is around 3000000 (not sure if I put enough zeros in the serial number… but starting around the ones that start with a 3 in the first digit was when the black silicone ones started showing up). As far as repair goes… there is some data on the web on how to gently remove the old brown epoxy, however, rewinding is a chore and most on here will tell you "impossible" at worst, and "maybe if I ever finish my home made winder" at best. So I decided to find a company that would make a new one for me. With the help of others on this board, I was able to secure a transformer winding and specification drawing, then I found a company willing to make one for me, if I purchased five of them. It turned out to be a less than optimum economical repair (though still much much less than a working and calibrated one on eBay), however, it was also a really good and rewarding learning experience bringing a 576 that was sold "for parts" back to life.


I was on eBay about a week ago and noticed that someone was selling the entire HV unit with the newer version of the transformer as well as the entire readout display (another part with unobtanium parts (ICs)) for what I thought were very reasonable prices. I was tempted to pick them up… then changed my mind as they would be really helpful for someone else struggling to get their 576 going again. I actually was planning to get on here and let others know about it ... I have not checked if they are still there.


Finally, if the one on eBay is gone… I have a few transformers for sale that were left of the five I bought for the initial run. It does not look like either of the OEM transformers, but it works very well and will fit in the original location easily.


Dave

I bought my Manual online .. dont remember where right now ...

Hope you find your problem ...

My 2336YA had *a **155-0219-00 go bad ... affected both channels


*
On 12/13/2014 04:01 PM, system100m@... [TekScopes] wrote:

Hi everybody ! I just bought a Tek 2335 which has some issues with
channel 1 it appears... At first once I powered it up, the vertical
line would wobble until it would totally disappear after a few
minutes. I tried to detect the bad component and found that spraying
some freeze spray on the vertical amplifier (marked 155-0220-00)
ceramic chip/IC, had made it go back. Now, it doesn't disappear at all
anymore, only wobbles very little the first 1-2 minutes it on, and
becomes stable... I wonder if anyone knows whether its the vertical
amplifier which is bad ? or any other known issue or component which
would need checking ?


If anyone has the service manual for any of the Tek 2335/2336/2337 I'd
be very thankful...


Thanks !

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

--
Mike KC7NOA



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

On 12/13/2014 6:02 PM, henasau@... [TekScopes] wrote:

I acquired DC508 counter Opt1. It works fine from direct input but 75-1GHz input is not connected to the circuit. I couldn't find DC508 1GHz manual. I downloaded DC508A 1.3GHZ instead. The DC508A appears to have x3 PCB's: main board, resolution multiplier and prescaler.

My unit only have two boards:main board and resolution multiplier board. The 75-1GHz BNC connector is not connected to anything. I wonder maybe the difference between DC508 and 508A is in the prescaler board hence 1GHz vs 1.3GHz, just guessing.

Can anyone please confirm if this the case or I am missing the prescaler board in my unit. The main boards appeares to be nearly identical.

Henryk,

I have a DC508A here, and it is a very nice counter by the way. I don't see that the 508 version could exist without the pre-scaler; with the technology of the day 100 MHz was about the upper limit for direct counting so a pre-scaler would have been essential. There would have been no point in making a version without the pre-scaler so I'd guess yours has been removed for some reason.

Option 1 ( and7 ) in the A version has an OCXO timebase.

Good luck!

Dan

The method would depend on the materials used in that hybrid, which is
something I don't know.

But yes, there are some things that can be fixed (I'm thinking of internet
examples of reflowing BGAs on XBOX and PC motherboards) in a conventional
household oven if you know the recipe (or have nothing to lose by trying
to derive it).

Dave Casey

I acquired DC508 counter Opt1. It works fine from direct input but 75-1GHz input is not connected to the circuit. I couldn't find DC508 1GHz manual. I downloaded DC508A 1.3GHZ instead. The DC508A appears to have x3 PCB's: main board, resolution multiplier and prescaler.


My unit only have two boards:main board and resolution multiplier board. The 75-1GHz BNC connector is not connected to anything. I wonder maybe the difference between DC508 and 508A is in the prescaler board hence 1GHz vs 1.3GHz, just guessing.


Can anyone please confirm if this the case or I am missing the prescaler board in my unit. The main boards appeares to be nearly identical.


Henryk

Hi, thanks ! I was able to narrow it down to that IC, switching between the same IC on the two channel and verifying the problem does "move" to the second channel once switching them. I was able to source on for 35$, but as well was wondering if the IC itself can be repaired. It's an hybrid, the top is a plastic cover while the bottom of the part has some kind of transparent "glue", protecting the inner board. What would you suggest to be able to remove this protection layer and cover, and hopefully to 'repair' that unit ? and what 'baking' means ? does it mean literally having it heated in an oven ?

There's an old trick fixing a similar type of IC named 80017A (which is a synthesizer part). The trick is sinking it in acetone over night and then taking all vinyl layer off, 'cleaning' it. That does the trick most of the times...

Is it a ceramic DIP IC or a ceramic hybrid (like a little white vertical
PCB with leads, or a larger flat package)? If it's one of the hybrids,
then the fault could be in the connections of components to the etches on
the ceramic substrate and not between the hybrid and the scope board.
You still might be able to repair it by removing the hybrid and baking it
to reflow, but I would leave that as one of the very last things to try
and then only if you can source a replacement.

Dave Casey

I thought about it too, but now I read here that these are "plug in" modules ? meaning you are able to pull them in and out ? I'm not sure about this and how they are soldered in if at all... also how can they be pulled or pushed in without causing any damage.. might be a simple contact issue.

Maybe you should try reflowing the solder on that amplifier IC?

Dave Casey

Hi everybody ! I just bought a Tek 2335 which has some issues with channel 1 it appears... At first once I powered it up, the vertical line would wobble until it would totally disappear after a few minutes. I tried to detect the bad component and found that spraying some freeze spray on the vertical amplifier (marked 155-0220-00) ceramic chip/IC, had made it go back. Now, it doesn't disappear at all anymore, only wobbles very little the first 1-2 minutes it on, and becomes stable... I wonder if anyone knows whether its the vertical amplifier which is bad ? or any other known issue or component which would need checking ?


If anyone has the service manual for any of the Tek 2335/2336/2337 I'd be very thankful...


Thanks !

Definitely McMaster-Carr (www.mcmaster.com) I've bought lots of Delrin from them over the years....

Tom

@Tom

I try the "Cycle Test" with "ALL PASS" as a result. Also make the error clear process. Nothing change!
The manual says cause if you have some error there, a diagonal line on the screen appear.
I haven't any diagonal line on my case.




@iamachine


Every dot is one of the lower part of character, in exact place in between groups at bottom of screen, who text disappear. All the characters appear in place of dots (not left or right), when some button pressed. For example ch3 or ch4 or ch2 or 20 Mhz bw limit etc.


Panos.

Thanks for the tip. I also found it at eplastics.com for half the cost and in lengths less than 5 feet (I only need a small length). Don't know about shipping yet, but no doubt it'll be more than the material <g>!

I think tinkerer suggested this test as a diagnostic, not a repair, reset or fix. If these dots are in tyhe same position as some of the screen text, it will point one way and if not maybe another.

Yeah, that's the idea.
I'd be very surprised if EAROM failure manifested this way. I'd expect the scope to fail POST with 04-level errors, as there's checksumming over the EAROM contents.
In your video, you're turning the scope on, and it's not failing self tests, which leads me to believe the error is not in the EAROM, nor in any of the other myriad things that the power on self tests (POSTs) cover.
Come to think of it, there is a POST for the readout RAM (see test 03), where the CPU writes to the character RAM and then reads back to check the RAM.
So, if this is a readout board error, it's presumably downstream from the readout character ROM.


Since you have a 2445 with a compatible readout board, why not try to swap them, see what happens?
$5 says your error is going to vanish :).

Hi sadosp Try again and look closely; are the characters you turned on with ch 3,4 positioned exactly over the dots?

I think tinkerer suggested this test as a diagnostic, not a repair, reset or fix. If these dots are in tyhe same position as some of the screen text, it will point one way and if not maybe another.


Also it isn't clear; did the dots in-between groups of screen text disappear when the text was displayed?

Hi Tom. Just see your message. I will try it, and respond back here.


Panos.

Yes nice. Grrr... I have an IR thermometer but now I also need an IR camera!
Albert


=====
Nice thermal IR picture of a 576 EHT in message 15:

< >

John