SdriveMax on 600XL Problem

[AirKon]

Hello
I have a small problem with Sdrive-max and the 600XL.
I made a Sdrive max, with UNO with chip on socket, Schottky diode and external power supply.
It works well on my 800xl, on my 2 XEGS, on my 130xe but it refuses to work on 2 of my 3 600XL.
I unsoldered the 3 capacitors ( in, out & command ), but no better.
The motherboard of the 600xl on which it works is slightly different from the 2 others (not the same capacitor). 

Is this a known problem ? 
Do you have an idea ? 
Thanks

//

 

bonjour
J'ai un petit probleme avec Sdrive-max and le 600XL.
J'ai fabriqué un Sdrive max, avec UNO avec puce sur socket, diode Schottky et alimantation exterieur.
Il fonctionne bien sur mon 800xl, sur mes 2 XEGS, sur mon 1300xe mais il refuse de fonctionner sur 2 de mes 3 600XL.
J'ai dessoudé les 3 condensateurs ( in, out & command ) , mais pas mieux.
LA carte mere du 600xl sur lequel  il fonctionne est legerment differentes des 2 autres ( pas les meme condensateur ). 

C'est un probleme connu ? 
Vous auriez une idée ? 
Merci

Edited May 11, 2021 by AirKon

[Gavin1968]

Hi,

What is the problem you are having with it? I have built and sold more than 1000 SDRive-MAX's and have not had anyone say they have had any problems with the 800XL. No one has modified their computer to use the SDrive that I know of either, that is the whole point of it, you don't have to do anything other than plug it in. 

 

Gavin

 

[AirKon]

no problem with my 800xl/130xe/xegs but with 2 of 3 600xl.

[flashjazzcat]

Do all the 600XLs have 64K RAM upgrades? The SDrive loader won't work in 16K, as I recall.

[AirKon]

7 hours ago, flashjazzcat said:

Do all the 600XLs have 64K RAM upgrades? The SDrive loader won't work in 16K, as I recall.

Yes, with 2 4464 and some wire . 

[+orpheuswaking]

15 hours ago, AirKon said:

no problem with my 800xl/130xe/xegs but with 2 of 3 600xl.

Yes, but what is the nature of the problem... What happens? Giving specifics can help with troubleshooting. 

[AirKon]

Well that's the problem, nothing happens.
The sdrive is well turned on, sio connected, D1 with DOS 2.5 . I turn on the 600xl and it behaves as if the sdrive was not there.
With a real 1050 the 600xl works fine.
With an oscilloscope the "COMMAND" frame is sent but no DataOut or DataIn signal.

[+Stephen]

16 minutes ago, AirKon said:

Well that's the problem, nothing happens.
The sdrive is well turned on, sio connected, D1 with DOS 2.5 . I turn on the 600xl and it behaves as if the sdrive was not there.
With a real 1050 the 600xl works fine.
With an oscilloscope the "COMMAND" frame is sent but no DataOut or DataIn signal.

Hmm - I was going to ask how the 5V line on the SIO port was, but then I see you are using external power.

[archeocomp]

Did you try it with 1050 connected or only with SDrive and nothing else? Even if 1050 was not on.

[Mazzspeed]

Pull up resistors on the 1050 acting as pull down resistors with the SDrive connected? I'm not too sure if that's an issue on the A8, it happens on my C64 with an SD2IEC. The SD2IEC either becomes invisible or I get data 'reflections' causing double characters and corruption.

 

Have you tried connecting the SDrive by itself with nothing else on the SIO bus?

Edited May 14, 2021 by Mazzspeed

[AirKon]

Hello,
I think I found the problem.
The output (SIO5) is too low ( 2 volts ) and very noisy.
I replaced the 4.7 k resistor by a 1.5 k one to reduce the noise and an AOP (x2) to raise the signal.
Now it works.
Could it come from the POKEY which would start to get tired ? 

[archeocomp]

Where is that Opamp circuit schema from? It is 2x amplifier so it would make 4V out of 2V

Edit: now I see it in the screenshot. Output does not correspond to 2x amplification

Edited May 16, 2021 by archeocomp

[AirKon]

1 hour ago, archeocomp said:

now I see it in the screenshot. Output does not correspond to 2x amplification

you are sur ??
 

[archeocomp]

I mean output as shown in the screenshot. Blue signal is not 2x yellow. Something is wrong there.

 

I would not use opamp there as that SIO line is supposed to be pulled down by other devices.

 

Can you try Pokey from working 600XL?

Edited May 16, 2021 by archeocomp

[AirKon]

1 hour ago, archeocomp said:

I mean output as shown in the screenshot. Blue signal is not 2x yellow. Something is wrong there.

Ha yes ok  

1 hour ago, archeocomp said:

I would not use opamp there as that SIO line is supposed to be pulled down by other devices.

I placed the AOP inside the SDRIVE.
I did not modify the 600xl.

1 hour ago, archeocomp said:

Can you try Pokey from working 600XL?

I will do some tests next week with my other 600xl

 

[ijor]

On 5/15/2021 at 2:37 PM, AirKon said:

Hello,
I think I found the problem.
The output (SIO5) is too low ( 2 volts ) and very noisy.
I replaced the 4.7 k resistor by a 1.5 k one to reduce the noise and an AOP (x2) to raise the signal.
Now it works. Could it come from the POKEY which would start to get tired ? 

 

Pokey has nothing to do with this. Pokey outputs are open drain and then it doesn't control the signal at the high state.

 

You normally get low voltage when the bitrate is too high and also depends on the capacitor. Are you sure you removed the correct capacitor? Which frequency/bitrate you were using at that scope capture?

 

I'm not sure it is a good idea to replace the pullup with such a strong one. You might damage Pokey. At least you are certainly going out of specs for the max current.

@tf_hh recently posted an issue with 600XL because they lack in line resistors. Not sure this is related to your problem though.

[AirKon]

I installed the POKEY on another 600XL and the problem is still there.
So I think the pokey is very tired.