Thank you George,
For the best 22xx tip of the year, from a chronic offender of your excellent advice about installing that extra screw on the right hand side in the back!
Your advice is applicable to many 22xx scopes, such as the 2213A, 2215A, 2235, 2236 and many others.
tom jobe...
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On 11/21/2018 4:59 PM, george edmonds via Groups.Io wrote:
Hi Chris
I have a beyond repair 2235 here, it has blown up the smpsu transformer. ?I keep it as a spare parts mule for my two 2236's which are my standard bench scopes. ?I have had the Tek IEC mains input filter emit the magic smoke on a number of occasions, not quite as bad as a Selenium rectifier for smell, but, close.
One thing I have found with the 223X scopes is that people leave out the rear right hand side case screw which deprives the power supply heat sink of some of the case cooling.
CATS is always a good rally for prices as it is the last South of England rally until Canvey on the 3rd February next year, some of the traders do not wish to hold stock until then. ?I will be at Canvey next year, again as a trader.
73 George ?G6HIG
On Thursday, November 22, 2018 12:11 AM, Chris Smith via Groups.Io <chrisjsmithuk@...> wrote:
Hi,
At the CATS rally (South London) a Tek 465B with the DM module sold for ?30 it was clean, complete and had a very sharp focus.? I would have purchased it, but, I have now moved on to the next generation of Tek scopes.? I did buy a 2430A with a power supply fault for ?25.
Good luck with your 475A, a lot of users consider it the best portable scope that Tek made.
73 George G6HIG, now living in Dover
Small world! I actually went to the CATS rally as well. I saw that 465B. I skipped that as I¡¯d just grabbed a ¡°working" 2235 for a respectable ?25 with a hope that I will end up with at least one working analogue scope!? Unfortunately the power supply in it was rather unhealthy. I replaced literally everything suspicious in it i.e. electrolytic caps, RIFAs and the Schaffner filter but unfortunately the main switching MOSFET decided to let go after an hour. I think the design of the 2235 power supply is somewhat marginal. The SOA on the IRF710 that was in it was very tight! Replacement bits arriving tomorrow for that as well. Hopefully it hasn¡¯t caused any transformer damage. Cost a new (better) MOSFET, diode and driver transistor. SMPS controller still works by the looks.
Hope your 2430A doesn¡¯t give you as much trouble or stink the house out with magic smoke!
Best regards,
Chris M0XTE
