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Gary Robert Bosworth grbosworth@... [TekScopes] wrote: Use the chassis number to look for a manual. There are quite a few free service manual sites for consumer electronics.

The 454 is old enough that contact oxidation is a problem. The transistors are socketed and odd problems like a missing channel may be due to a poor contact. I've fixed more than one scope of that

Maybe it looks more promising if you know that the 454 contains no Tek-made ICs. See also http://www.reprise.com/host/scopes/scope_pick.asp http://www.reprise.com/host/scopes/scope_pick.asp Finding

Yes, that thing must be a real beast to handle and to work on. First, be aware that it can kill you if you screw up - there's the HV dangers, plus some or all of the circuitry may not be isolated from

I would say you have a number of bad capacitors. Check the caps in the power supply, around the flyback, and in the vertical circuit with an ESR meter if you have one. If you want to keep the TV,

It sure sounds like a power supply problem, maybe a high esr capacitor? But if it were me, I would just replace it with a LED LCD flat screen new TV and let the savings on the electric bill pay for

Good day. I'm having some trouble with my beloved Tektronix 465B and I'm hoping some gurus on this list may be able to assist me. Let me first say that I am a fledgling electronics hobbyist and have

Rich: I never worked on TVs, but numerous disimilar problems are usually associated with the power supply which supplies all the different circuit parts. I am surprised you cannot get a schematic

Ronan, I think you will find the 454 much easier to work on than a 485. The cover comes off easily, and many (not all) circuits can be accessed conveniently. --John Gord

Does changing the brightness also change the focus of the picture? If so the CRT may be conducting too much due to improper bias of the control and screen grids. Vertical fold-over can also be an

Dave, It is a B36A24Z. Thanks, rich!

Model number?

Hello all, I am having a problem with my Zenith 36" CRT TV. It goes into shutdown mode. When it is cold I have to start it up over and over before it will stay on. Also as the brightness of the

Thanks for the encouragement - I agree generally, it is just that my primary focus is to use test equipment in service/design,rather than to spend inordinate time repairing it. Having said that I

Ronan: There is a great amount of satisfaction in successfully repairing high-tech instrumentation. Some of my old equipment out-performs the latest offerings. Often it is worth the trouble to do

Hello! I've troubleshot my beloved 485, to the point I have to just let go -- I must send it to my scrap heap (spare parts shed) -- with the help of the service manual, I traced the problem to the

My first guess is that the full wave bridge for the -8 volt supply is dying. Replace it with the highest spec bridge that can be made to fit. The lead wire size of the full wave bridge is the

Hank: It is a slow pulsation as if it is a sinusoidal tied to the line frequency. It does not flash bright and dull. The trace never completely disappears. Someday I may find the time to go in

Gary, What kind of pulsating display does your 7904 have ?Is it worse at slower sweep speeds ?If so, the readout may be in "Gated" mode. ?HankC, Boston WA1HOS

Bert: I am sure you have heard of the 2 most common means of "smoking out" the cause. The first is to apply elevated heat levels to force the problem to surface long enough to trace it down. The