CurtPalme.com Home Theater Forum

Ohmess · Joined: 11 Sep 2008 Posts: 242 Location: Vienna, VA

Question for you more experienced technicians out there. I'm thinking about acquiring an oscilliscope, both to help with the mods to the projector and because I was unable to isolate a problem with one of my amplifiers the other day.

How much scope does a hobbyist need to play with his projector and do the occassional stereo equipment repair?

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

Any 60mhz scope will do. Try to fins a dual probe scope. this comes in handy when you want to check a bad channel against a good one.
Techtronix makes a nice scope. i got a 300mhz one for 150 bucks.

Athanasios

Ohmess · Joined: 11 Sep 2008 Posts: 242 Location: Vienna, VA

Does dual probe mean it needs to have two channels?

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

yes.

RogueChili · Joined: 31 Mar 2008 Posts: 162 Location: Westfield, MA

In my opinion, and assuming serious data analysis, you should figure on a min band width of 4 times > then the highest bandwidth circuit you plan to analyze. This will allow you to view the circuit perfectly without interpolation. Another consideration is storage capability which is a must for digital bus and non periodic signals.

My favorite tool is a HP mixed signal oscilloscope (54645d). Very intuitive to use and very powerful, you can troubleshoot almost anything (digital / analog) with this type of scope, however being only 100 mhz bandwidth it's not ideal for the highest bandwidth circuits in a projector.

On the other hand, if your intention is to use the scope as a verification tool then a basic 100mhz dual channel will suffice and will be much less expensive.

Mark_A_W · Posted: Tue Jan 13, 2009 9:00 pm Post subject:

A 15mhz scope will do.

Unless you are Mike P, you aren't going to be looking at full bandwidth video signals.

I did a ground up mechanical white balance on a couple of NECs with a 15mhz scope - it's fine for that task. You are looking at levels, not waveform edges.

Spanky Ham · Joined: 22 Mar 2006 Posts: 5643 Location: Comedy Central

Tinman is the expert on scopes. I think he gave some recommendations here or at AVS. Do a search.

**AnalogRocks** · Posted: Wed Jan 14, 2009 5:59 am Post subject:

I like scope it tingles and leave my breath minty fresh Laughing

I need one too. I had a 120Mhz dual trace lined up last year and the Craiglist guy never showed Ba$tage!

Ohmess · Joined: 11 Sep 2008 Posts: 242 Location: Vienna, VA

Thanks Spanky -- I found some of tinman's prior posts and they are excellent.

**Curt Palme** · Posted: Wed Jan 14, 2009 3:31 pm Post subject:

My main scope is still a 35Mhz Leader, bought in oh... 1988 or so? It's failed once, bad solder joints in the power supply. WOrking strong still.

As stated above, unless you're doing video mods like Mike does, you can use almost any scope for troubleshooting. Usually it's a matter of making sure a signal is present rather than analyzing the waveform itself. Unless I'm looking at a crystal oscillator waveform in the Mhz, almost all waveforms I look at with CRT projectors max out at 67Khz, which is the H frequency of 1080p.

eBay is your friend. I bought a new in the box 100 Mhz scope about 3 years ago for $250-ish, some Korean brand, but I got the s/manual with it. On screen menus, analysis of the waveforms, etc. I figured I needed a new scope after 19 years. I've used it... maybe 10 times? For audio use BTW, not video. It's on my tape deck/amplifier bench. Go figure.

Ohmess · Joined: 11 Sep 2008 Posts: 242 Location: Vienna, VA

Here's what I bought:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350083009673&ru=http%3A%2F%2Fshop.ebay.com%3A80%2F%3F_from%3DR40%26_trksid%3Dm38%26_nkw%3D350083009673%26_sacat%3DSee-All-Categories%26_fvi%3D1

This is one of the scope's Tinman specifically recommended as having been designed for video. I'm hoping it comes with probes, but decided to take a risk on that since this thing works and appears to be relatively clean.

Tinman · Posted: Sat Jan 17, 2009 6:55 pm Post subject:

Hi,

That is a great scope. You just can't get a better beginner scope. Very simple to repair, as it mostly gets dirty. Probes can be had for $29 on the bay. Yes, it's made for troubleshooting video, but will do lots of other things.

If you need help with it, let me know. Should it require contact cleaning, talk to me first. Deoxit is a no-no on these.

Ohmess · Joined: 11 Sep 2008 Posts: 242 Location: Vienna, VA

Thanks for your offer to help Tinman. I may even seek assistance in getting my Teac reel to reel up and running.

A TEAC 4300 I bought back in the 1970 from a veteran who bought it in Japan during a break from one of his tours in Nam. I then bough a case of Maxell gold mastering tape and tapped into a buddy of mine's massive collection of vinyl. I've got a bunch of really nice jazz I haven't listened to in ages.