Author Topic: Me and my Schneider CPC 464 again.  (Read 2360 times)

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Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #25 on: 18:09, 05 February 19 »
I got it to work!! "This side up" on the adaptor made a fool out of me!!! argh!! :doh:

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #26 on: 21:12, 06 February 19 »
After 1.5 days of playing and careful observations, my main (and only) concern is the whistle. It definitely comes from the speaker, and volume of the whistle corresponds to volume of other sounds. Yesterday, when i was playing games, only the loudest volume was hearable. Few hours into gaming, i could also locate a sweet spot somewhere at 40% volume (the rest was still unhearable). Today all volumes worked, but the whistling did not stop, and i wouldn't lie if i said that it got louder. So, the state of speaker isn't stable, the fact that it got better by time is just dumb luck. Also, i tried to plug in old headphones, but it did not stop playing on the speaker and the headphones were silent. I can record a video of this to diagnose it further if needed. Cheers

Offline Bryce

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Re: Me and my Schneider CPC 464 again.
« Reply #27 on: 09:26, 07 February 19 »
Inserting the headphones doesn't cut off the internal speakers, it plays both in parallel, so you have to turn down the speaker yourself. It's also not a headphone socket, it's an audio out, so non-amplified headphones would probably be very quiet if they are high impedance.

The whistling is hard to judge without hearing it. There was always a slight buzz from the CPC speaker, but the aging capacitors on the amplifier board may have made this worse. You could also try cleaning the volume potentiometer and see if that helps.

Bryce.

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #28 on: 15:09, 07 February 19 »
The whistle is very simmilar to kettle whistling:

https://www.youtube.com/watch?v=YQXvFOYhwssMy phone introduced sharp cuts in the audio for some reason, in reality the volume is gradual, never stops and always corresponds to the value on potentiometer.Also, one of the capacitors on the board had a yellow gunk under it. It kind of looked like it was applied deliberately, but i thought it was worthwhile to mention it.
« Last Edit: 15:26, 07 February 19 by twox »

Offline Bryce

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Re: Me and my Schneider CPC 464 again.
« Reply #29 on: 15:43, 07 February 19 »
Oh, that's not the normal whistle, I suspect a capacitor or two need changing on the amplifier board. A picture of the "gunk" under the capacitor might also help to determine whether it's leakage or mastic.

Bryce.

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #30 on: 16:04, 07 February 19 »
It was very hard to make a good quality photo without removing the board completely, but i guess i will need to do so anyways.Here are two photos that i managed to snap, sorry for bad quality. The capacitor in question is the one in middle.

https://imgur.com/a/DhbFoFg
EDIT:
Here are some more photos

https://imgur.com/a/lGjf8Qi

The thinnier one (part number c308) is 25v (althought service manual says its 10v), 22uf. The bulkier one (part number c322) is 10v, 470uf. Both are not swollen at all, or unnoticeably so.
Also, if i were to replace the bigger capacitor, i would need to completely remove the board. There are like 12 different cables fixed to the board, would i need to disassemble the whole tape assembly or is there a magic trick to do it better?
LATE NIGHT EDIT:
I found a photo of the board, and it also has this substance in the very same spots:
https://www.genesis8bit.fr/archives/index.php?news_id=907
So i guess those capacitors are not faulty.. But, i just noticed that one of L302 (Relay) solders have a brown outline (kind of). From what i browsed on english, french, russian, devilish evil sites this relay's business is related to tapes, which work fine in my CPC so i am confused. All other parts look fine to me.
« Last Edit: 03:51, 08 February 19 by twox »

Offline Bryce

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Re: Me and my Schneider CPC 464 again.
« Reply #31 on: 10:03, 08 February 19 »
That gunk is mastic, not something that came out of the capacitor. The voltage of capacitors isn't that critical as long as it's higher than the voltage being applied to it, without being crazy high. ie: For a 5V system, anything above 5V, maybe up to 50V would be fine, but a 2000V capacitor would be too much. The capacitors probably could do with a swap anyway just due to age.

The relay is what starts/stops the motor. If the tape motor is turning on/off the relay is fine.

Bryce.

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #32 on: 15:03, 08 February 19 »
Hmm. So i am changing capacitors all the way from C301 to C314? Do you suggest changing from C301 to C314 or vice versa?BTW.. Isn't the whole ordeal grounded using the two screws that attach the board? When i dissasembled it i noticed that i have only one screw.
« Last Edit: 15:17, 08 February 19 by twox »

Offline Bryce

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Re: Me and my Schneider CPC 464 again.
« Reply #33 on: 15:29, 08 February 19 »
Change all electrolytics, ceramics don't need to be changed as they don't age. The circuit is grounded through the 6pin connector too. Without a ground it wouldn't work at all.

Bryce.

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #34 on: 18:18, 08 February 19 »
I'll go buy some of those tomorrow. For now i will play with a speaker system (it is amplified as far as im aware).Your IC desoldering tutorial on wiki says its unsafe to desolder ICs from bottom. Is it also the case with those caps (yes IK caps arent ICs)? All cap replacement tutorials i watched showed desoldering from bottom, so i am confused. Cheers
EDIT:
Just plugged in an amplified speaker. The default speaker is at zero, but now i hear the same whine from my auxiliary speakers. Is the audio-out connected in any way to the speaker/tape board or it goes straight out the AY?I also noticed, that when loading tapes this whine isn't occuring. If the AY output is supressed during loading, it is another thing that points to AY.
« Last Edit: 20:13, 08 February 19 by twox »

Offline Bryce

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Re: Me and my Schneider CPC 464 again.
« Reply #35 on: 18:21, 09 February 19 »
The reason I say that is because the pins are soldered on the top too. If you haven't removed all the solder from the top and pull the chip, you end up tearing the traces off the PCB. This is unlikely to happen on capacitors, and either way, the tape deck PCB is single sided, so there aren'T any traces to destroy on the top.

That's starting to look more like an AY issue, the Aux output doesn't go via the amplifier.

Bryce.

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #36 on: 19:58, 09 February 19 »
Now that is a problem.. I heard that getting this chip specifically means alot of trouble. Especially for a guy who doesn't have Paypal and doesnt want to pay a ridicolous price of 50$ to ship from china. There arent any of those locally (and by locally i meant whole Poland) to buy. For some reason arduino users have over-abundance of those, but i havent been able to discover how. They suspiciously die of internal hemorrhage when i try to ask them (and the AY's disappear). I guess i just need to keep on trying. Cheers

Offline Bryce

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Re: Me and my Schneider CPC 464 again.
« Reply #37 on: 21:57, 09 February 19 »
No, the AY is pretty easy to find on ebay and other sources. Make sure you socket the new one though.


Bryce.

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #38 on: 20:07, 12 February 19 »
Do you have some of those AY's laying around? I happen to have a spare 40010, confirmed working, and i thought about a little exchange... Those things go around for 4x as much as AY's so you definitely wont be lossy :P And you will have a better use for it than me, if it were to stay at my, in some distant future it could be the last available replacement GA in the whole world. And it would be forgotten. Yuck.
If you accept, my private message box is open as it ever was.
Cheers

Offline Bryce

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Re: Me and my Schneider CPC 464 again.
« Reply #39 on: 10:48, 13 February 19 »
I'll check tonight and send you a PM later.

Bryce.

Offline LambdaMikel

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Re: Me and my Schneider CPC 464 again.
« Reply #40 on: 20:37, 13 February 19 »
Do you have some of those AY's laying around? I happen to have a spare 40010, confirmed working, and i thought about a little exchange...


Oh, if Bryce doesnt have one, I'll sure trade you! That's a VERY BAD DEAL (for you!) I should say. But I think you know that...

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #41 on: 20:48, 13 February 19 »

Oh, if Bryce doesnt have one, I'll sure trade you! That's a VERY BAD DEAL (for you!) I should say. But I think you know that...
Not to worry, i'll make sure that he at least includes a DIP28 socket!I am very well aware that its not the best deal for me, but even if i wanted to sell the damned thing most propably i couldn't. I dont even really have a bank account of my own, let alone a Paypal or Ebay account. Moreover, if you peek(the right places) you still can source GA's for a fair price. I think i bought my one from CentPourCent, for under 10$. If i were to buy AY from Ebay, id pay just about the same amout of money.And, i dont want this GA to lay around in the dirts of my desk, when it could be the difference between one CPC working and not.
Also, with the availability of 40010 schematics, it can be reproduced on FPGA's. Then, it is a case of making a board to connect the different pinouts. Stuff like this isn't very expensive (in retail), and BOOM. We have a supply of replacement GA's. BTW, i just recently learned about all this FPGA stuff and it completely blew my mind. What if we were to allow a neural network to work on a shitload of FPGA's? And allow it to change the logic gates? And allow it to overwrite it's own program memory?
« Last Edit: 21:04, 13 February 19 by twox »

Offline LambdaMikel

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Re: Me and my Schneider CPC 464 again.
« Reply #42 on: 21:17, 13 February 19 »
Also, with the availability of 40010 schematics, it can be reproduced on FPGA's. Then, it is a case of making a board to connect the different pinouts.

I'm afraid it is a bit more complicated than that  ;)  For starters, the schematics don't help that much - it would be good to a least have a netlist... unless you want to place a couple thousand gates by hand. See, the guy that created the Monster 6502 CPU at least hat the netlist from the Javascript 6502 Simulator, for example.


But it is a good question - do FPGA Amstrad cores (MIST FPGA) actually implement the GA on a Register-Transfer Level at least?


However, it is of course also possible to specify the GA logic by means of logic equations (functional specification), and then let the Verilog / VHDL compiler figure it out... not sure that's good enough though. Curious to learn how MIST FPGA Amstrad Core does that!
« Last Edit: 21:24, 13 February 19 by LambdaMikel »

Offline LambdaMikel

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Re: Me and my Schneider CPC 464 again.
« Reply #43 on: 21:23, 13 February 19 »
What if we were to allow a neural network to work on a shitload of FPGA's?


Google for it and you will find a lot of FPGA-based implementations of neural networks... not sure they are using a s***l*** though, I was thinking more like Silicon  :laugh:
« Last Edit: 21:25, 13 February 19 by LambdaMikel »

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #44 on: 21:26, 13 February 19 »
I'm afraid it is a bit more complicated like that  ;)  For starters, the schematics don't help that much - it would be good to a least have a netlist... unless you want to place a couple thousand gates by hand. See, the guy that created the Monster 6502 CPU at least hat the netlist from the Javascript 6502 Simulator, for example.


But it is a good question - doe FPQA Amstrad's cores (MIST FPGA) actually implement the GA on a Register-Transfer Level at least?


However, it is of course also possible to specify the GA logic by means of logic equations (functional specification), and then let the Verilog / VHDL compiler figure it out... not sure that's good enough though. Curious to learn how MIST FPGA Amstrad Core does that!
Well, from my message it is not hard to deduct that i am not an expert on the topic ::)

I just found this (in Polish):
https://www.speccy.pl/forum/index.php?topic=3663.0
Basically, they were talking about the exact same thing that came to my mind - a FPGA GA replacement. Apparently some guy was prototyping a FPGA GA. I wouldn't be suprised if the guy was registered here. The post was linking to some facebook page but unfortunately i dont have a facebook account so i cant investigate it myself. Im sure you will have a nice research thought (if you have a facebook account, that is).

Offline LambdaMikel

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Re: Me and my Schneider CPC 464 again.
« Reply #45 on: 17:26, 14 February 19 »
But it is a good question - do FPGA Amstrad cores (MIST FPGA) actually implement the GA on a Register-Transfer Level at least?


However, it is of course also possible to specify the GA logic by means of logic equations (functional specification), and then let the Verilog / VHDL compiler figure it out... not sure that's good enough though. Curious to learn how MIST FPGA Amstrad Core does that!
Seem that this effor is already on the way... but probably still a long way to go:

http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/gate-array-decapped!/200/


Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #46 on: 19:49, 14 February 19 »
Id give it a year or two.I already seen a AY-8912A FPGA replacement for original Speccy's, based on Atmega8 (a very small 5v chip). 100% working, without weird cables sticking out of chassy, althought admitedly the sound quality isn't the best.
The experimental FPGA GA that i found had those weird cables sticking all around, and that was what vexed me.

Offline LambdaMikel

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Re: Me and my Schneider CPC 464 again.
« Reply #47 on: 23:54, 14 February 19 »

Id give it a year or two.I already seen a AY-8912A FPGA replacement for original Speccy's, based on Atmega8 (a very small 5v chip). 100% working, without weird cables sticking out of chassy, althought admitedly the sound quality isn't the best.
The experimental FPGA GA that i found had those weird cables sticking all around, and that was what vexed me.


Probably still under development / cables for the programmer etc.
You usually use a development board for FPGA before you "go live" with your chip.


There is also a plug-in replacement for various Commodore chips, for example SID:
https://www.c64-wiki.com/wiki/SwinSID

Similar hardware exists for the BBC Micro (eg, the Speech Chip).

Offline Bryce

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Re: Me and my Schneider CPC 464 again.
« Reply #48 on: 09:22, 15 February 19 »
Id give it a year or two.I already seen a AY-8912A FPGA replacement for original Speccy's, based on Atmega8 (a very small 5v chip). 100% working, without weird cables sticking out of chassy, althought admitedly the sound quality isn't the best.
The experimental FPGA GA that i found had those weird cables sticking all around, and that was what vexed me.

Well it's not an FPGA replacement if it uses an ATmega8. It's an ATmega replacement :D . The AY would also be much easier to implement than a GA, just like the SID, the SPO256 and other chips have been made.

Bryce.

Offline twox

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Re: Me and my Schneider CPC 464 again.
« Reply #49 on: 19:27, 20 February 19 »
My AY arrived today. I'll be replacing tomorrow, because in my fucking village, which looks and feels like it just switched from thatching to tiles, there are no shops to buy desoldering wick.