CurtPalme.com Home Theater Forum

bfeils · Joined: 23 Apr 2006 Posts: 166 Location: Phoenix

I'm looking for a cheap used scope to play around with and learn some things with. What would you guys recommend? I find myself wanting to probe around with some of my spare projectors.

Mark_A_W · Posted: Wed Feb 14, 2007 3:52 am Post subject:

I was looking for a 100mhz CRO when a 15mhz one fell in my lap. It's done everything I've needed so far, including an XG white balance.

What I think is important:

- Robust sync circuit, a borrowed 35mhz tek was giving me a wrong value

- Big screen

- Bright screen, dim just won't allow you so see some subtle stuff in video waveforms

Bandwidth seems relatively unimportant in practice.

Tinman is the expert BTW - he fixes them for a living I think.

Mark

bfeils · Joined: 23 Apr 2006 Posts: 166 Location: Phoenix

The bandwidth thing was one of the questions i had regarding how it applies to crt use. By the way, how did that white balance end up? It looks like a real pita from the way the manual reads.

Tinman · Posted: Wed Feb 14, 2007 4:26 am Post subject:

This will do everything you need. EASY to fix and maintain, great video sync, great little scope. I still have one, even with my later 300Mhz scopes.

ebay 180083991195

Tek T935. Also a T922 is good. The T935 is: You guessed it, 35Mhz AND a delaying timebase. Good price for it.

The T9XX scopes were specially made for video service.

Marc

Mark_A_W · Posted: Wed Feb 14, 2007 4:37 am Post subject:

T935 (or very similar) is the one I had trouble with.

My Cathode drive levels were reading 0.3-0.4 Vpp (target 0.7Vpp). Fiddled around with sync for AGES. I could tell that 0.4v reading was actually way to high as the image went ballistic.

Got the Trio scope, hooked it up and I was reading in the 0.6-0.75Vpp range - Bingo.

I have NFI what was going wrong.

Both have TV sync. Maybe I was using it wrong on the Tek and it was syncing/triggering in the wrong part of the waveform.

I'm a total scope newbie..

Tinman · Posted: Wed Feb 14, 2007 4:38 am Post subject:

Then there is Hitachi V1XXX series. These are all CPU controlled scopes. Some even have a frequency counter in the readout. All have on-screen readouts. The best part is that they have an AUTO function that will select the best speed for signal display. TV sync is standard. I use one as my everyday bench scope. VERY EASY to use, but hard to fix. So don't buy a busted one. However, these are WAYYY under-rated, so can be had cheap on ebay most of the time.

Ebay 150091180110

Good luck.

Marc

Tinman · Posted: Wed Feb 14, 2007 4:39 am Post subject:

Mark_A_W · Posted: Wed Feb 14, 2007 4:42 am Post subject:

Yeah..maybe...

Every other reading in the procedure was fine. And it measured DC voltages fine (an EE owns it, and another EE at worked checked it out).

Anyway, I have my Trio scope now, and I'm happy Smile

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

bfiels, make sure you get an *analog* scope. Most digital scopes don't do well with video signals, unless they have special video-capture circuitry. (Right Marc?)

jask · Joined: 17 Mar 2006 Posts: 10187 Location: kamloops BC

so what about a 2246 like this one ebay 160083804000 close to you and ends pretty soon

bfeils · Joined: 23 Apr 2006 Posts: 166 Location: Phoenix

Thanks for all the replies guys. And I thought this was just a crt forum. Very Happy

Heywood Jablome · Joined: 12 Mar 2006 Posts: 1548

Tinman · Posted: Wed Feb 14, 2007 4:18 pm Post subject:

**AnalogRocks** · Posted: Sat Apr 12, 2008 8:00 am Post subject:

My turn. I need a scope. I found one locally. It's a HP 1740A 100Mhz Dual trace. Any good for doing CRT work? What probe(s) would I need to buy for it?

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

I just got an Sillyscope and sooo glad I did: i got a textronics: this one to be exact

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=230229745957&ssPageName=STRK:MEWN:IT&ih=013

It really helped out diagnosing some blown mosfets in my marquees focus board.

Athanasios

**AnalogRocks** · Posted: Sat Apr 12, 2008 5:02 pm Post subject:

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

You can just solder wire to the places you want to check and have the wire come out so you can probe it. I bought a set on ebay these are cool because they have little hooks that come out when you slide back the plastic shield then it springs back after you conect to the pin your testing. On my Marquee focus board the spots I wanted to probe allowed the board to be slid back into place so I didnt have to solder any wires.....but its not like that for all cases. It takes time to do the soldering method but if you dont have the $300 dollar extension board set to raise the boards out of their slots you have to do it that way.

Here is the set i bought, their not bad They also have a swithc for 1X or 10X use.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=380006868882&ssPageName=STRK:MEWN:IT&ih=025
Athanasios

**AnalogRocks** · Posted: Sat Apr 12, 2008 10:08 pm Post subject:

Hmmm the local that's selling the HP 'scope doens't have the lead's for it. So, I'll have to look into some.

I'd still like to know if the HP 1740A 100Mhz Dual trace scope will work for CRT stuff?? Anyone?