Tektronix 2465A repair: removal/reinstallation of A1 board

[Bill Woodbridge]

Apologies for opening another thread on this subject, but I’d be very grateful for advice please on one aspect I haven’t seen covered elsewhere – the physical removal and reinstallation of the main A1 board.

I’ve just finished a total recap with the excellent set of components supplied by Condor Audio, and have overcome the various physical challenges of disassembly so far.  The kit included several replacements for A1 board capacitors, and I managed to remove the mighty A1 board successfully in order to do this (following the sequence given in the Service Manual).

But now it’s time for reinstallation.  It’s a really tight fit and there are many potential obstructions with connectors, fixed pins to the HV board, soldered connections to the back panel, the power switch lever etc. so it’s sometimes difficult to see which of these is the critical part fouling the next few millimetres of the board’s insertion.  But I think I have cleared all these now and the board is sitting level and flush on its screw mount pillars ready for screwing in.  However, all the screw holes are slightly misaligned, by about 1mm, as the board seems to ‘need’ to push further towards the front panel.  The problem is it won’t budge, and I can’t see how it ever could as the Ch 1 and 2 attenuator casings are already hard up against the chassis at the front.  I’ve searched for any trapped leads, etc but can’t find anything.  I don't remember the board being under any stress from misaligned holes when I removed it (ie it didn't suddenly jump backwards when the screws were removed).

I could probably brute force the screws in with a bit of leverage to one side, but I feel that would be foolish and very much a last resort.

(I’m also dreading trying to reattach the X and Y plate push-on connectors at the bottom of the deep dark hole through the board and the u-metal shield, but that’s a problem for another day.)

Many thanks for any help anyone is able to give, and to all the contributions I've already read which encouraged me to undertake the project in the first place.

Bill

[4thDoctorWhoFan]

I had the same issue with my scope as far as being an extremely tight fit to both remove and install.  I just loosened some of the screws on the rear panel to give the board a little more room to slide into place.  It worked great and all the mounting then lined up to mount the board.

[Bill Woodbridge]

Thanks so much for your quick reply.  I couldn't see how easing off the rear panel screws would help push the board further towards the front panel, but I tried it (in fact I removed the rear panel altogether).

And weirdly that allowed a fraction more alignment on the A1 board screwholes, so I no longer felt nervous about just wiggling them in and tightening them down.  I think removing the rear panel must have allowed just that little bit more flex in the whole assembly, somehow.

So many thanks - a great tip.  Now for those X and Y plate connectors ...