Two Rev B ST's with different shifter bodges

General discussions or ideas about hardware.
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Two Rev B ST's with different shifter bodges

Post by Steve »

Hi people,

I've got two faulty ST's, both Rev B ST's. On the rear of the shifter socket they both have different resistor/capacitor bodges, can anyone here clear up which is correct for this revision?

Code: Select all

Image 1:
Shifter: C025914-38 / PH23-023 CAP
1k resistor (Shifter pin 1 to GND)
capacitor: yellow violet black gold black (Shifter pin 21 to GND)

Image 2:
Shifter: C025914-38A / PH23-024
capacitor: yellow violet black gold black (Shifter pin 11 to GND)
Thanks,
Steve

For orientation, ram is at the bottom of each photo.

PXL_20210811_170657698.jpg
PXL_20210811_170657698.jpg (522.22 KiB) Viewed 2211 times
PXL_20210811_170645496.jpg
PXL_20210811_170645496.jpg (469.98 KiB) Viewed 2211 times
User avatar
frank.lukas
Posts: 660
Joined: Fri Jan 19, 2018 11:52 am

Re: Two Rev B ST's with different shifter bodges

Post by frank.lukas »

Image1: a single resistor 1k or 10k? and a capacitor
Image 2: only one capacitor

I think original Atari factory hardware mod ...

What are the Shifter Pin numbers? IMP or normal chipset?
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Re: Two Rev B ST's with different shifter bodges

Post by Steve »

Thanks @frank.lukas
Ah yes.. sorry I always forget these are capacitors.

Image 1:
Shifter: C025914-38 / PH23-023 CAP
1k resistor (Shifter pin 1 to GND)
capacitor: yellow violet black gold black (Shifter pin 21 to GND)

Image 2:
Shifter: C025914-38A / PH23-024
capacitor: yellow violet black gold black (Shifter pin 11 to GND)
User avatar
frank.lukas
Posts: 660
Joined: Fri Jan 19, 2018 11:52 am

Re: Two Rev B ST's with different shifter bodges

Post by frank.lukas »

See the schematics ...
User avatar
exxos
Site Admin
Site Admin
Posts: 23499
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Two Rev B ST's with different shifter bodges

Post by exxos »

Steve wrote: Thu Aug 12, 2021 11:14 am 1k resistor (Shifter pin 1 to GND)
Seem normal (10K on the H5 in fact)
Steve wrote: Thu Aug 12, 2021 11:14 am capacitor: yellow violet black gold black (Shifter pin 21 to GND)
BLUE bit 2... Odd to have capacitors in the blue line like that, maybe it was just inherently more noisy on that colour :shrug:

Steve wrote: Thu Aug 12, 2021 11:14 am capacitor: yellow violet black gold black (Shifter pin 11 to GND)
/LOAD. Again probably noise.

Overall by the looks of it, these bodies are probably just tailored to whatever board has whatever problem after manufacture.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
User avatar
frank.lukas
Posts: 660
Joined: Fri Jan 19, 2018 11:52 am

Re: Two Rev B ST's with different shifter bodges

Post by frank.lukas »

capacitor: yellow violet black gold black

4 7 x1 5% ?

47pF
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Re: Two Rev B ST's with different shifter bodges

Post by Steve »

Ok, thank you guys. So it seems they're perfectly fine to keep as-is.
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Re: Two Rev B ST's with different shifter bodges

Post by Steve »

Just as a follow up to this thread I decided to try these capacitors on another ST with poor video output:

PXL_20210817_184633045.jpg
PXL_20210817_184633045.jpg (495.78 KiB) Viewed 2068 times
PXL_20210817_180336995.jpg
PXL_20210817_180336995.jpg (251.48 KiB) Viewed 2068 times
PXL_20210817_184808206.jpg
PXL_20210817_184808206.jpg (424.23 KiB) Viewed 2068 times

But even after applying these capacitors nothing changed and the video output is still poor, with all those vertical white and black dotted lines. Does anyone have more suggestions on what else I could try to smooth out the image quality / reduce noise?
User avatar
exxos
Site Admin
Site Admin
Posts: 23499
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Two Rev B ST's with different shifter bodges

Post by exxos »

Its a inherent problem which a lot of early STs suffer from :? All you can do is add something like 10uf ceramics on the power on the shifter and rgb drivers and 47pf from RGB on the video connector to gnd.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Steve
Posts: 2570
Joined: Fri Sep 15, 2017 11:49 am

Re: Two Rev B ST's with different shifter bodges

Post by Steve »

exxos wrote: Tue Aug 17, 2021 8:32 pm Its a inherent problem which a lot of early STs suffer from :? All you can do is add something like 10uf ceramics on the power on the shifter and rgb drivers and 47pf from RGB on the video connector to gnd.
Okay cool, just to clarify for my feeble mind:
  • 10uf ceramic on Shifter 5v pin to GND
  • RGB drivers, are these Q5,Q4,Q3,Q2 transistors? If so am I connecting 10uf from base/or/collector/or/emitter to gnd on each one?
  • With the 47pf, is that three 47pf's, one on each line R,G,B connected to gnd. At the video connector.
thx
Post Reply

Return to “HARDWARE DISCUSSIONS”