- Welcome to CPCWiki forum.
The ultimate Amstrad CPC community!
News:
Printed Amstrad Addict magazine announced, check it out here!
Recent posts
#1
Just in case any of you or your handyman friend dare to make the modifications, I will put here some recommendations.
Localise the 74HC138 and 74HC32 on the PCB. My TRH9000 version is v1.7, the one with SVideo and composite connectors at the side of the Dsub 15 pin connector. The chips are at the rear side, very near to the EDGE connector. I have seen pictures of other versions, and on all of them the chips are at the back side, but on different places.
Better destroy the two chips than damage the valuable PCB. Cut carefully all the legs while securely fasten the chip with a finger. The legs can then be easily removed one by one once the encapsulation is out of the PCB.
Once the two footprints are clean of surplus tin, put the new HCT chips on place(pay attention to the position of the dot or the stripe on the chips and their footprints) and try to solder two diagonal legs before continue. If you are not satisfied with the position you always can melt the tin on one leg and turn slightly the chip. The best results are using a fine point iron and 0,5mm tin.
Then continue soldering each individual leg with care to not touch the adjacent ones or add excessive tin. It is matter of rhythm and short touches, because you don't want to add excessive heat to the leg and damage the track or the chip itself...
In the case that two legs get joined by the tin, not all is lost. There are specialised tin suckers or cooper soldering mesh to remove the tin. But again remember, don't add excessive heat to the legs.
Maybe you also want to make the modification in the logic. At this moment I can't say if it was necessary or not... but is while you install the 74HCT32 chip when it is very easy to be done.
Just to re-assure, I don't know if all the TRH9000 versions use the chip 74HCT32 exactly the same, but we can check that. Look again at the TRH9000 schematics:
Put your tester in continuity mode and check in the 74HC32 footprint if pins 1-13 and 2-12 give continuity. Use this real pin-out instead:
If there is a match, before soldering the 74HTC32 chip, slightly bend up pins 12 and 13 together and leave them unsoldered. Solder all the rest of the legs like is explained above. Then prepare a short wire, and solder it from pin 3 to lifted pins 12 and 13 joined.
Pins 12 and 13 must not touch their footprints on the PCB.
Localise the 74HC138 and 74HC32 on the PCB. My TRH9000 version is v1.7, the one with SVideo and composite connectors at the side of the Dsub 15 pin connector. The chips are at the rear side, very near to the EDGE connector. I have seen pictures of other versions, and on all of them the chips are at the back side, but on different places.
Better destroy the two chips than damage the valuable PCB. Cut carefully all the legs while securely fasten the chip with a finger. The legs can then be easily removed one by one once the encapsulation is out of the PCB.
Once the two footprints are clean of surplus tin, put the new HCT chips on place(pay attention to the position of the dot or the stripe on the chips and their footprints) and try to solder two diagonal legs before continue. If you are not satisfied with the position you always can melt the tin on one leg and turn slightly the chip. The best results are using a fine point iron and 0,5mm tin.
Then continue soldering each individual leg with care to not touch the adjacent ones or add excessive tin. It is matter of rhythm and short touches, because you don't want to add excessive heat to the leg and damage the track or the chip itself...
In the case that two legs get joined by the tin, not all is lost. There are specialised tin suckers or cooper soldering mesh to remove the tin. But again remember, don't add excessive heat to the legs.
Maybe you also want to make the modification in the logic. At this moment I can't say if it was necessary or not... but is while you install the 74HCT32 chip when it is very easy to be done.
Just to re-assure, I don't know if all the TRH9000 versions use the chip 74HCT32 exactly the same, but we can check that. Look again at the TRH9000 schematics:
Put your tester in continuity mode and check in the 74HC32 footprint if pins 1-13 and 2-12 give continuity. Use this real pin-out instead:
If there is a match, before soldering the 74HTC32 chip, slightly bend up pins 12 and 13 together and leave them unsoldered. Solder all the rest of the legs like is explained above. Then prepare a short wire, and solder it from pin 3 to lifted pins 12 and 13 joined.
Pins 12 and 13 must not touch their footprints on the PCB.
#2
Technical support - Hardware related / Re: CPC 6128 - white screen, b...
Last post by McArti0 - Today at 12:02R124 but ROMDIS is enough as I checked mine.
Of course you won't see vertical bars.
Of course you won't see vertical bars.
#3
M
Technical support - Hardware related / Re: CPC 6128 - white screen, b...
Last post by mmldrm - Today at 11:14Quote from: McArti0 on Yesterday at 18:05https://www.cpcwiki.eu/forum/hardware-related/cpc-6128-white-screen-black-border/msg238468/#msg238468Thanks. I thought I had better connection points but couldn't remember where. Your memory is better than mine (and my CPC's).
nothing new
(Is there another for RAMDIS?)
#4
M
Technical support - Hardware related / Re: CPC 6128 - white screen, b...
Last post by mmldrm - Today at 11:12Quote from: Audronic on Today at 10:15@mmldrmScotland. Near Edinburgh.
Where in the world are you Located ?
#5
Technical support - Hardware related / Re: CPC 6128 - white screen, b...
Last post by Audronic - Today at 10:15 #6
Quote from: chinnyhill10 on Yesterday at 23:49The injection moulding would almost certainly be outsourced I'd guess but I think Trojan were quite capable of making up the boards themselves as they were fundamentally an electronics company. I'm not sure Amstrad would need someone like them just to essentially do assembly. Dunno thoughQuote from: dthrone on Yesterday at 01:02It's well established now that the cart manufacture was actually done by Trojan in Wales and the catalogue of Amstrad cock-ups is even more facepalm than was thought possible
It's strange because one of the problems cited (and I can't remember by who) was the long lead times on cartridges.
Perhaps Trojan were burning the ROM's and assembling them but Amstrad were having the boards and cart plastics made in Korea and then shipping them over? It would make more sense to have Orion handle the PCB work and injection moulding and then Trojan to do the 'finishing'. Burn the ROM, put it on a board, snap it into the case and slap a label on.
Unless Trojan had PCB and injection moulding facilities (or had access to them). But 'finishing' in the UK would fit with the way Amstrad worked with some of their other products at their Shoeburyness facility. Products like VCR's shipped over part finished.
#7
Welcome mate, nice to have you here 
#8
This time, with enough tests done, I can say that the PSU and voltage level and blah blah blah had nothing to do with the issue.
Now you can spit, ridicule and laugh at me....
This has happened to me before, I am excessively confident with the EDGE connectors, while they are almost all times the guilty ones, like the butler....
Today I have started to power the TRH9000 from 5v upwards, but arriving to 5,52v and beyond it still was refusing to react and prove that my latest theory was right....
Inexplicable... Then I have disconnected an re-connected every plug in the adapter and it has started to gloriously work...
Guess what? Then I slowly have returned to 5v and it has endured steadily.
So I have wasted more than a month thinking on why the HCT chips didn't work.
Sorry, sorry, sorry.
Now you can spit, ridicule and laugh at me....
This has happened to me before, I am excessively confident with the EDGE connectors, while they are almost all times the guilty ones, like the butler....
Today I have started to power the TRH9000 from 5v upwards, but arriving to 5,52v and beyond it still was refusing to react and prove that my latest theory was right....
Inexplicable... Then I have disconnected an re-connected every plug in the adapter and it has started to gloriously work...
Guess what? Then I slowly have returned to 5v and it has endured steadily.
So I have wasted more than a month thinking on why the HCT chips didn't work.
Sorry, sorry, sorry.
#9
Quote from: McArti0 on Yesterday at 08:39Mayby M4 board in CPCemu?
I do not have experience with CPCemu. I need to see how things are organized there.
#10
Welcome!