Booster V4sm problem

[zfrenchy]

I follow all tuto to installed the STE Booster but still have some ramdom issue.

The STE start when the computer was left OFF for a long time, but do not start after a RESET, or an ON/OFF toggle, both show a white screen, no bomb, no message.

All SILS are correct (see photo below with yellow marking) and also on the Booster (all 472). A 22uF/16V biggybacked the 10uF/50V (C100), U405 is 74F257.
NO ISSUE when switch to 8Mhz (1.62 or 2.06 FAST TOS).

I ordered the DMA FIX board, but not sure that will fix the behavior.

Note:
I was needed to sanded (very small amount) of the dummy CPU (white plain) to fit the socket, without sanding the Booster will not get in without bending pin.

IMG_6572.JPG (321.98 KiB) Viewed 123 times

[exxos]

It would help if you take a picture of your motherboard and how you have installed the 32 megahertz wire.

[zfrenchy]

here it is
yellow wires are to swith 8/32Mhz

20251129_161026.jpg (393.57 KiB) Viewed 95 times

[exxos]

Your 32MHz wire is way to long and you need to remove the parity chip..

See this older post

viewtopic.php?p=41199#p41199

Not sure what PSU your using but possibly a factor?

[zfrenchy]

the original PSU was replaced by a MeanWell RD50A

What is the party chip, U ?

[zfrenchy]

if is an issue with reset timimg, should the wire path be better like this ?

32mhz line.jpg (582.71 KiB) Viewed 90 times

[rubber_jonnie]

if is an issue with reset timimg, should the wire path be better like this ?


32mhz line.jpg

The image you've posted has the preferred route for the wire on it, just follow the thin black wire back from the booster, you may need to zoom in.

Yours seems to be mostly routed correctly up to U401, however it is way too long after that and needs to be shortened after it comes round the corner of U401 and the wire needs to almost be pulled as tight as possible so it can be as short as possible. Use dabs of hot glue and route it tightly, waiting for each dab to set before moving on to the next. You can see where the dabs of hot glue are on the image.

I would say my own are routed similarly to the yellow line (They were amongst the first to be done a long time ago and are soldered in) and that route works for me, but that was a long time ago and recommendations change.

However, you should follow the recommended route in the image as it is tried and tested and done that way for a reason.

As for parity RAM, you have 3 chip SIMMS, so likely 2x 4 bit wide RAM IC's and 1x 1 bit wide RAM IC, giving 8 bits + 1 bit of parity. You can either remove the 1 bit parity IC or simply replace your SIMMS for non-parity types with 8 RAM IC's, or 2 RAM IC's. I recommend 8 IC SIMMs, they are cheap and plentiful.

EDIT - Just to add, simply removing the parity IC may not be enough as there may be some configuration pads on the SIMMs so I would suggest replaments are the best way to go.

[exxos]

Also note, some STE's may have a 74S257chip for U405. This chip does not output correct TTL voltages to drive the booster. As such the machine will likely be unstable or not boot. This IC should be replaced with a 74F257 IC.

You should replace the caps in the reset circuit as well.

The 32MHz wire needs to be short and not taped down to he motherboard as it causes interference.

[Steve]

@zfrenchy as Exxos says, see the thin black wire? Also notice something important: it is raised above the motherboard surface, using glue-gun to secure on the outside edge of the shifter PLCC socket, and on the top of a few IC's.

This was taken during my tests. Don't route by the RAM as you indicated, I tried this initially but found noise from the RAM was effecting the clock line.