Tektronix 2246

You'll have to wait until Jim Yanik comes around for comfiration, but I suspect the CRT.

Actually, that is not bad luck, IIRC there are some very hard to get ICs for Tektronix scopes. Think it was the horizontal amp. Your problem has nothing to do with that, so hopefully either you have ICs for another scope or can find a CRT for yours.

Once sure of the problem, ESI in Cleveland OH has alot of Tek stuff. You might try Skycraft in Orlando FL but they don't have as much, or didn't last time I was there. Other than that there is always eBay. There are other places, I just don't know of them.

Good luck with it.

JURB

Thanks for reply. Glad to hear about availability of TEK CRT's. In the meantime of Jim advice's I'll use my 2213. Not the same feeling, definitively.

Daniel

snipped-for-privacy@swing.be wrote in news: snipped-for-privacy@z34g2000cwc.googlegroups.com:

TEK puts a couple of neon lamps between the CRT cathode and grid to limit the voltage difference between them to less than ~130v to protect the CRT;pins 2,3 are CRT cathode and grid.(P1,14 are filaments)

I do not have access to any TEK manuals anymore.

snipped-for-privacy@swing.be wrote in news: snipped-for-privacy@e56g2000cwe.googlegroups.com:

I have a 2213,too. Nice scope,built it myself,from boards and parts other techs didn't fix.

snipped-for-privacy@swing.be wrote in news: snipped-for-privacy@z34g2000cwc.googlegroups.com:

BTW,the DC restorer diodes could be breaking down intermittently under HV. They're part of the CRT brightness circuit.

That reminds me of the old Johnny Cash song, "I got it one piece at a time". ;-)

"Michael A. Terrell" wrote in news: snipped-for-privacy@earthlink.net:

The first TEK scope I built from old boards was a 5 Mhz 221 mini-scope,but it had problems in the 4 layer PCBs,I had to jumper too many runs,so I traded it for boards for my 2213. It's CRT was too small for much use,anyways.

What's the next model, the 321? I still have one of those that more or less works (or at least it did the last time I tried it a couple years ago). Some of the design of that is strange. I have to power cycle mine a few times before the trace appears, and only at full brightness. I think I concluded it was fault in the CRT because everything else checked out.

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Sam Goldwasser wrote in news: snipped-for-privacy@saul.cis.upenn.edu:

An entirely different class. The 200 series were a group of handheld,battery-powered scopes with really small CRTs.

The 300 series (after the 321) were from Sony-TEK. The 321 was first sold in 1960,BTW.It was TEK's first solid-state scope(and also battery-powered). The 211,the first 200 series scope,came into being in 1972.

I recommend you check for a couple of failure possibilities:

First: DC restorer diodes might be damaged, as Jim says. If ok, check for cold solder joints near insity pot (cracked due to mechanical stess, cold solder, etc.9. If ok: I suspect CRT (had this 3 times), but CRT seldom fails to my experience in the 2213/2215 sereis scopes.

hth, Andreas

The 221 etc. series scopes still run fine nowadays. You need a calm hand and a lot of experience to keep them healthy. But in the end, for using in field service at a customer site, I like these small scopes. The BW is low (0.5 up to 1 MHz, depending on model). But most times enough for the things I have to do in field: get a quick impression of where the fault is, these scopes are real helpful.

The battery and the plastic molded case gives my most time problems when I get these units for repair.

Personally, the 213 with the integrated DMM is what I enjoy most. It's a good combination, and still useful in 99% of my service work. If you take a little bit of care, and handle these analog scopes well, they last real long.

Andreas

TEK2246.

Thanks to all for inputs.

I have made a cleaning and resoldering job around diodes and high voltage caps under the HV plastic covers. I think it was never cleaned since 20 years as it was a quite dirty area. Now trace and readout are stable again and the neon bulbs doesn't flashes anymore. Maybe it's fixed. It's working fine since two days now.

BTW as I do not have the diagrams are those diodes (MSC 152-0242-00632) the DC restorer one's?

Daniel

"Andreas Tekman" wrote in news: snipped-for-privacy@i40g2000cwc.googlegroups.com:

The plastic pins in both case halves are important,they retain the circuit board's position,keeps the interconnect pins from spreading the receptacles open and the tiny leaf spring from falling out and shorting things.They caused a few meltdowns,with those NiCds.

snipped-for-privacy@swing.be wrote in news: snipped-for-privacy@u72g2000cwu.googlegroups.com:

Good!

the proper TEK part number would be 152-0242-00,and they would be the DC restorer diodes. I don't have the specs or cross references.