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Re: 7603 filter caps

tom jobe
 

Hello Scott,
Thanks for posting the link to the Anatek ESR comparison page.
I have both the EVB from Portugal, and the CapAnalyzer 88A that are on the
Anatek comparison page.
The EVB is another modern version of the famous Bob Parker design, and it is
my favorite everyday ESR meter.
It is a very durable unit, as I have not been able to kill it yet, and I
have done some very dumb things to it!
It does not care about polarity, and it just works.
I bought it directly from the fellow in Portugal who builds it, and he was a
treat to deal with.
I just followed the link on the Anatek ESR page to the EVB web site, and it
still is just $79 $ US delivered, which is 56 Euros.
This is not a kit, it is a finished ESR meter that you put a 9V battery in
and use.
The CapAnalyzer 88A is a full featured very nice ESR meter, but you will
have at least $200 US in it by the time it arrives. The downside to the 88A
is that it has a nice set of tweezers permanently attached (Pomona brand on
my 88A) but that limits what you can check, as the tweezer only open up a
little. The EVB does not come with any leads, so you supply (or make) some
test leads, and then you can check anything with two separate leads that can
be very far apart.
The 88A also requires that you have the polarity correct.
Working on this old equipment without an ESR meter of some kind, is very
foolish in my opinion.
Bad electrolytic capacitors are the number one failure in much of this old
gear, and the ESR meter will identify the bad caps in a few seconds.
tom jobe...

----- Original Message -----
From: "Scott McGrath" <mcgrath@...>
To: "Paul Kraemer" <elespe@...>; "Tek Scopes"
<TekScopes@...>
Sent: Wednesday, October 01, 2008 12:40 PM
Subject: Re: [TekScopes] 7603 filter caps



See this web page



- There is what is known as the 'Bob Parker' design this is a cheap
accurate ESR meter upon which countless commercial implementations have
been built upon. I use the BLUE meter myself it is more than accurate
enough for service work.

But read the information and decide for yourself

Paul Kraemer wrote:
ESR meter
Do you have a recommendation? Works well, cost effective.
Thanks
Paul

----- Original Message -----
*From:* Scott McGrath <mailto:mcgrath@...>
*To:* go_boating_fast@... <mailto:go_boating_fast@...>
*Cc:* Tek Scopes <mailto:TekScopes@...>
*Sent:* Wednesday, October 01, 2008 1:24 PM
*Subject:* Re: [TekScopes] 7603 filter caps

Using higher Voltage/Capacitance ratings usually is not a problem
especially since many of the old can type electrolytics were rated
-20/+40% of nominal rating.

Higher voltage is usually ok as long as the voltage differential
is not
extreme anything less than 3:1 is probably ok more than that and the
capacitor will not work effciently

Pay attention to temperature ratings and a ESR meter would be a good
investment

- Scott

Robert Simpson wrote:
> Hi folks,
> Thanks for all the tips in this forum. I am just stating to work
on a used 7603 with three plug-ins (7A18A, 7D15, 7B70) I acquired
cheap as a second scope with a 442 I got also got cheap (neither
working, both for $50, 442 now works)
> Thanks for the article on washing scopes as the 7603 really
needed it. With the plug-ins removed so they could be washed
separately, I used the siphon spray wand for my air hose with a
bucket of water with dish soap (avoiding the front panel). Rinsed
it off with the garden hose, blew it mostly dry with the air hose,
and then let it sit in the sun all afternoon. Then let it sit
inside overnight.
>
> It now turns on. And with no plug-ins installed gets a spot beam
in the center using the beam finder button. Most of the voltages
are within spec except for +5 which is 4.4V. All voltages except
130V have too much ripple; I am guessing filter cap problems.
>
> So, since exact replacement caps are hard to find and incredibly
expensive, I am thinking of using substitutes. For example, in
place of the 1800uf 75V caps I could get 2000uf 100V caps. Would
slightly larger specs work being they are used as filter caps?
>
>
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>



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