Re: Tek 2215

Tothwolf
 

On Mon, 25 Jan 2016, David @DWH [TekScopes] wrote:

I only have the later 2230 and 2232 models and Tektronix used film resistors for the focus resistor chain in them.

I would have expected there to be a clean cutoff date for when they changed resistors in the focus resistor chain but that apparently is not the case. The 2235, released in 1984, used carbon composition resistors but the 2236 which was released at the same time used film resistors and the 2213A and 2215A which were released later, both in 1986, used carbon composition resistors.
Tektronix revised the type of resistors used in the high voltage divider in the 2213/2215 at least several times too. All of my 2213 scopes are late model scopes which already had the preregulator option installed. None of the scopes appeared to have ever been serviced and these are the resistors I found installed:

B0228xx [scope #2]
R877 - 18K 1/4W carbon film (in spec)
R878, R879, R880, R881, R882, R884 - 1M 1/2W carbon film [red dot on body]

B0229xx [scope #1]
R877 - 18K 1/4W carbon comp (in spec, measured dead on 18K)
R878, R879, R880, R881, R882, R884 - 1M 1/2W carbon comp [standard]

B0233xx [scope #3]
R877 - 18K 1/4W carbon comp (out of spec, measured as 22K)
R878, R879, R880, R881, R882, R884 - 1M 1/2W carbon comp [mil spec]

The B0228xx and B0229xx scopes are only 21 digits apart on their serial
numbers.

There was another resistor change Tektronix made and I think it was for reliability. The 2213 and 2215 use two 1/2 watt 1% metal film resistors in series for the collector loads at the output of the vertical amplifier. These resistors run hot making them unreliable and were the first 2213/2215 repair that I made and I know of two other instances where they had to be replaced. The later models used 3 resistors in series for each collector load to distribute the heat better.

The collector load resistors are not difficult to replace so I would change them also.
Are those the 4 resistors mounted to the board plus the two inline with V+ and V- on the left side of the board in this photo? One of my scopes has one carbon comp and one carbon film for the two inline resistors. I'm planning to replace the two inline resistors with Vishay CCF6015R0FKE36 and the 18K R877 with a Vishay CCF0718K0GKE36. I hadn't planned to replace the 4 resistors on the board, but they look like they might be 1W parts. I've seen photos of these boards where the board is discolored badly from heat around those 4 resistors.

http://strudel.ignorelist.com/~tothwolf/photos/Tektronix_2213/Tektronix_2213_3/1600/IMG_9288.1600.jpg

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