Re: Tektronix 2235 Oscilloscope Troubles

"Tony" <mrdevlin@xxxxxxxxxxxxx> wrote in
news:nvKdnfZK1afoiPXfRVn-uA@xxxxxxxxxxxxxxxx:

> Jim,
>
> If you're ever in the Chicagoland area - I owe you a cold one. I
> pulled the caps from the power supply and replaced them with brand new
> NTE replacements,

I hope you used low-ESR caps intended for switchers.(105 degF,low ESR)
Otherwise,they will not last long.


> and some NOS HV caps I had left over from a laser
> power supply project. I also replaced all of the 510K 1/2W resistors
> near the HV output stage since they looked like they were overheating
> and the epoxy coating was flaking off.
>

Good,they were a common problem for loss of focus;the carbon film resistors
would increase in value until they opened.They should be replaced with 0.5W
carbon composition types.

> I turned the unit on, and after a suspenseful second or two of
> silence, the unit powered up, the LEDs stayed lit, and I got a trace
> on the screen!
>
> I'm going to leave the unit on for a few hours to burn it in and see
> if it remains stable, but it appears you hit the bull's eye on this
> unit. Sometime this week, my Sencore LC75 analyzer should arrive in
> the mail from Florida, and I'll be able to determine exactly which
> part or parts were faulty.
>
> Thanks again!!

You're welcome,glad to be of help.

BTW,I use(and love) the Dick Smith ESR meter.
Hats off to it's inventor.

--
Jim Yanik
jyanik
at
kua.net
.

Relevant Pages

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