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Re: Falcon B52803000012 service blog
Posted: 25 Apr 2021 19:27
by Steve
Cleaned floppy drive heads and cleaned/relubed gliders:

- PXL_20210425_173117542.jpg (359.81 KiB) Viewed 4588 times

- PXL_20210425_173131521.jpg (294.01 KiB) Viewed 4588 times
Format floppy to get the drive exercising:

- PXL_20210425_174553015.jpg (409.09 KiB) Viewed 4588 times
Remove wait states to increase system performance now we have a fast ROM:

- PXL_20210425_174153933.jpg (346.17 KiB) Viewed 4588 times
Do a quick benchmark:

- PXL_20210425_180517232.MP.jpg (446.85 KiB) Viewed 4588 times
The result is dragged down a bit by the old MC68881FN16B FPU but otherwise the entire system is a little bit quicker.
Re: Falcon B52803000012 service blog
Posted: 25 Apr 2021 20:12
by Steve
Damn this was a very tough Dallas clock to remove. Every pin was fully desoldered and loose but it wouldn't budge. So I protected the area with kapton tape and used my hot air gun and after a little while it gently fell out :)

- PXL_20210425_190728598.jpg (460 KiB) Viewed 4580 times
Re: Falcon B52803000012 service blog
Posted: 26 Apr 2021 08:30
by stween
Steve wrote: 25 Apr 2021 19:27Do a quick benchmark:
PXL_20210425_180517232.MP.jpg
The result is dragged down a bit by the old MC68881FN16B FPU but otherwise the entire system is a little bit quicker.
You have the
same RAM access performance as I have :) (I haven't gotten back to looking at this yet!)
Re: Falcon B52803000012 service blog
Posted: 27 Apr 2021 21:57
by Steve
Re: Falcon B52803000012 service blog
Posted: 27 Apr 2021 22:09
by photonstorm
Looking beautiful :dualthumbup: - can't wait to get this back and start playing with it!
Re: Falcon B52803000012 service blog
Posted: 27 Apr 2021 22:20
by exxos
:bravo: :2k2:
Re: Falcon B52803000012 service blog
Posted: 05 May 2021 17:55
by centuriontech
While I am not a big fan of radial caps in axial caps designed application (for many reasons), I must admit the job is nice and tidy.
Just a side note about your fan installation:
There is a _very_ good reason, why fans are not connected on main power rail with rest of the system, by design. They are rather powered from either entirely dedicated power supply, or at least from secondary/utility power rail - just like in Falcon. This design rule is golden especially for digital processing applications, RF applications and audio devices. So pretty much everywhere ;) The reason is motors induce a lot of electric noise back into the power rail, resulting in whole bunch of issues. If the system design limitations otherwise enforce DC motor on main power rail, it is always connected through properly calculated low-pass filter (L-C, C-L-C,...). Still, it is always suboptimal, because no filter can filter out entire frequency spectrum in all motor operating conditions.
Re: Falcon B52803000012 service blog
Posted: 05 May 2021 18:05
by Steve
@centuriontech thanks Pavel, so it would be best for me to connect it back to its dedicated 12v and put a resistor in-line to reduce its speed. I'll do that, thanks I appreciate the advice!