Products > Test Equipment
Is my Tektronix 7104 irreparably damaged?
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bottlegardener:
Hi folks,
I'm not an EE, just a hobbyist who uses (used) his scope for audio equipment repair and calibration (e.g. adjusting the azimuth of analog tape machines).
Recently my Tek 7104 mainframe started billowing a small amount of smoke and its trace shrunk considerably (like it was only a couple inches and very bunched up).
I was just wondering if this is a common failure mode and if anyone could let me know what's up? I took apart the PSU and nothing was visible burnt.
If the mainframe is toast, would it be reasonable to hope the plugins (Tektroniix 7A18 Dual Trace Amplifier; Tektroniix 7B53A dual time base Dual Trace Amplifier; Tektroniix 7A26 Dual Trace Amplifier; and Tektroniix 7B92 Dual Trace Amplifier) escaped unscathed? I shut it down fairly quickly...
Thanks,
Peter
VintageTekFan:
Sounds to me like a problem in the HV supply. There is a metal shield protecting it. Be careful! There are some high voltages that could still be lingering.
Orange:
Probably a tantalum capacitor. This can be in the mainframe or in one of the plug-ins....
Measure the power-supply rails for shorts. Hopefully it is in one of the plugins, that is the easiest to repair.
bottlegardener:
Thanks for the tips folks. I'll check for shorts.
edavid:
--- Quote from: bottlegardener on October 10, 2013, 02:14:06 pm ---Hi folks,
I'm not an EE, just a hobbyist who uses (used) his scope for audio equipment repair and calibration (e.g. adjusting the azimuth of analog tape machines).
Recently my Tek 7104 mainframe started billowing a small amount of smoke and its trace shrunk considerably (like it was only a couple inches and very bunched up).
I was just wondering if this is a common failure mode and if anyone could let me know what's up? I took apart the PSU and nothing was visible burnt.
If the mainframe is toast, would it be reasonable to hope the plugins (Tektroniix 7A18 Dual Trace Amplifier; Tektroniix 7B53A dual time base Dual Trace Amplifier; Tektroniix 7A26 Dual Trace Amplifier; and Tektroniix 7B92 Dual Trace Amplifier) escaped unscathed? I shut it down fairly quickly...
Thanks,
Peter
--- End quote ---
No, not a common failure mode.
Doesn't sound particularly like a shorted cap, but it's possible.
The plugins are probably OK, but you're only talking $60 worth of plugins there anyway.
As long as the CRT is good, it's definitely worth repairing. It doesn't sound like you need the 7104's MCP CRT for anything, so you could probably trade your broken 7104 for a working mainframe of a different model.
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