Tek 2215 Repair

[jdragoset]

Another 2215 up.
Ch 1 & 2 position top half of screen and beyond, no beam find.
Found R 388 (1/2 W 340 ohm, 1% film, looks like 1 W) open circuit, Q 387 had been changed, but not the two series collector resistors, 680 ohms total.

[lordvader88]

How hard is it to get replacement parts for these? Is there any rare chips ? I have 1, overall I think it's working ok, just need some contact cleaner and tightening of stuff.

[bd139]

Switches, focus pot and HT are the risks on them.

Any old scope you need two of. I’ve got a BER 2235 from the same series here.

[jdragoset]

I don't know if "brand-naming" is allowed on this forum but
Hosa F100L-L25C CAIG DeoxIT F100L 100% 25ml FADERLUBE - NEW - PERFECT CIRCUIT
works on the switch contacts.
The 5% spray can be injected through the pot shaft anulus' for noisy pots.
Most of the rest of components (not switches, pots, knobs, plugs, etc.) other than HF transformer and HV multiplier are on ebay.
Later series have the custom/rare chips.

[David Hess]

Another 2215 up.
Ch 1 & 2 position top half of screen and beyond, no beam find.
Found R 388 (1/2 W 340 ohm, 1% film, looks like 1 W) open circuit, Q 387 had been changed, but not the two series collector resistors, 680 ohms total.

That is part of the collector load resistance for the vertical CRT amplifier output transistors and a common failure with enough hours because they run hot.  Later models used six resistors to distribute the heat better.  All of them should have been changed when the first one was.  Mouser had replacements last time I needed some.

How hard is it to get replacement parts for these? Is there any rare chips ? I have 1, overall I think it's working ok, just need some contact cleaner and tightening of stuff.

There are no custom ICs in these but that does not necessarily make replacement parts easy to get.

Switches, focus pot and HT are the risks on them.

Failure of the carbon composition resistors in the focus resistor chain might be responsible for the focus pot failure.  These resistors were replaced with high voltage film resistors in later models.

I’ve got a BER 2235 from the same series here.

There are a lot of similarities but the 2213/2215 are really their own series but might be considered prototypes to the 2235 series which includes the 2213A/2215A which replaced the 2213/2215.

[jdragoset]

David,
Thanks,
340 ohms isn't much available But 330 is, in 2 Watt rating.
Alternative is 680 ohm in 3 Watt rating.
I've got both on the way, metal film, 1%
Any preference?

[jdragoset]

David,
On another note, although I can fully appreciate Tektronix/military's desire to have scopes that will accept multiple AC supply (90-250 volts,48-440 Hz), the trickle-down to civilian use (from Ebay, etc.) may better be served by a 50 watt 240/120 volt control transformer power adapter mock-up.
Not much different than a laptop supply cord.

[David Hess]

340 ohms isn't much available But 330 is, in 2 Watt rating.
Alternative is 680 ohm in 3 Watt rating.
I've got both on the way, metal film, 1%
Any preference?

Don't use a single resistor as a replacement.  One reason multiple resistors in series are used is for lower capacitance.

The originals were only 1/2 watt and I would stick with that.  Larger resistors will have different high frequency characteristics.

https://www.mouser.com/Passive-Components/Resistors/Through-Hole-Resistors/Metal-Film-Resistors/_/N-7h7zbZ1yzvvqx?P=1z0wngzZ1z0wljoZ1yzbppyZ1ytork2&FS=True

When you replace them, use something like the shaft of a cotton swab to space the resistors bodies above the printed circuit board.

[David Hess]

David,
On another note, although I can fully appreciate Tektronix/military's desire to have scopes that will accept multiple AC supply (90-250 volts,48-440 Hz), the trickle-down to civilian use (from Ebay, etc.) may better be served by a 50 watt 240/120 volt control transformer power adapter mock-up.
Not much different than a laptop supply cord.

The 2225 series were built like that.

Another option if you are rebuilding one is to use a 48 volt DC power supply and adjust it down to about 43 volts to power the inverter.