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Messages - John Fante

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Hardware / NOOB recap question :-)
« on: 2020.September.12. 19:50:19 »
I am in the proces of recapping my Egyptian EP64 board.

I am out of horisontal 10 ferrit caps so I have to switch to vertical.

However I am a bit unsure if I am putting them in correctly.

In short my questions is if the end with the curve on the Phillips caps on a EP64 are +.

As far as I can see from my research it is but I want to be sure before I test.

The old cap is here. The end with the curve is in the bottom of the picture.

Thank you in advance. Judge have posted a picture of his recapped board but I must confess that I can't really see what end is + on his caps. I am a cap NOOB :)

Great! :) Thank you!

Yes :ds_icon_cheesygrin:
Meanwhile John solved it. If the C9 failed, then it is kill TR2, as it is also happened there. Another capacitors not a "life-critical", but good idea replace all avoid signal noise problems.

Cool :lol:  Just to be sure for the rest of the recap: On the vertical philips capacitors the line in one end is 0 (zero), right? Just so I don't - by mistake -  turn a capacitor the wrong way. The standing one has a big 0 on one side so they are easy enough.

I have allready written to http://www.commodoreszerviz.hu/billentyuzet_folia.htm regarding new membrames. Thank you very much for the tip/link :)

I have planed to continue replacing the caps while I wait for the keyboard membrame. Was just wondering if the "noise" problem was a known issue.

It is alive :ds_icon_cheesygrin: :ds_icon_cheesygrin: :ds_icon_cheesygrin: :ds_icon_cheesygrin: Replacing TR2 brought it back to life.

The keymembrame is dead (simply fell apart) and need replacement and I have a little noise on the picture but otherwise it seems to be functioning.

I have - so far - only replaced three caps so maybe the noise problem is there but it this a known problem? Besides the noise the picture seems rock solid (and better that an my old 128)

I managed (I think) to find the 78L regulator and have measured it :smt050 .

It shows 6,8 volt on the output pin and 8,3 on the input. I figure that that is not the correct value :)

I have changed the C9 capacitor and that did not make a difference so is the way forward to replace TR2 and maybe 78L12?

If the 5V is fine, have you got a volt meter and checked the 12V coming out of the 78L12 regulator? It could be that you're not getting 12V to the motherboard. Apparently the most common fix with 12V is to replace TR2 and C9.

I have not checked the 12V. Where is "78L12 regulator" more precisely located? :)

And thank you for the tip :)

Great to hear! Thank you for the feed back/review :)

@gflorez: Thank you for your - as allways - huge help :) I will start soldering .... :smt068

Well! This is certainly not my sommer when it comes to EP :( . First I managed to mess my EP128 when I tried to fix a video problem. Now I can not get my "new" Egyptian EP64 to start. More on that later.

First: Are there anybody - besides ZoZo who is a bit out of the loop at the moment - who does EP repair work? I can solder a bit but I do not have the equipment or knowledge to fix major issues. I will ofcourse pay for the time, postage etc. I would highly appreciate it if anybody are willing to give it a go!

Secondly. The Egyptian EP64 problem (the 128 problem is described in the thread linked to above). The machine I recieved is in VERY good condition. Clean an clearly not used. The red led lights when I power it on and you can hear very low static in the speaker so there is some kind of activity. However there is no video output and there is no click when I press the keys so it is not booting.

There is also some kind of signal comming out of the RGB port. My OSSC registers this but no picture. Normally the frequency should be like this.

My first instinct would be the two voltage regulators (7805) to see if the machine is getting enough power. They are however fine. The next would be to recap the machine. Capacitors does not age well.

It would be a very big challenge for me to do a recap. Does anybody here has some advice on doing it and does anybody have a complete list of the replacement capacitors I need?  

Or is there any other suggestions/advice?

I have done a first check of the motherboard and it looks fine. You can see it here and a closeup of the power section here.

Sorry for taking your time with my issues. This has really been an EP sommer from hell. Instead of playing with my Symbiface3 as planned I have been bogged down with technical issues.

I hope someone will be able to help so I can get at least one of the machines up and running.

Thank you in advance!

And about leaving your "old EP" without the internal ROM, you say that you plan to inject it with the SF3.

Ok, remember to put on the INI file the line

Code: [Select]
and the line

Code: [Select]
ROM[#00]  =SD:EXOS2.4.ROM
Remember that your old EP will only start with the SF3 connected.

Thank you :)

So an INI file like this should do the trick for an EP64 with the old rom removed?

Code: [Select]
*      SF3 INI FILE                                        
*Wifi settings.  Up to 5 wifi providers can be put here,  
*                the first has the gratest priority


*TMTnet settings




* The Roms can be in any place of the SD or on a web page

ROM[#00]  =SD:ROMS/exos24uk.ROM
*ROM[#64]  =SD:ROMS/epd19uk.rom
*ROM[#66]  =SD:forth.rom

*ROM[#67] =HTTP:www.tmtlogic.com/cyrus.rom

* Audio settings SYMAMP for symbos audio

Thank you for all the great advise :)

Just one thing. On my present machine the ROM is not wired to the expansion port but to the U6 chip. See here.

The wire to the expansion port is wired like this.

Is this an alternative way of doing it?

In the english monarchy you use the expression "An heir and a spare" when you have an extra son if the heir is killed in battle.

I now have an spare. Or to be more precise an Egyptian EP spare :)

I have so far not found a solution to my frequency problem. Hopefully it will show up soon but until then I will use the Ep64 I have just bought in Egypt. If it works that is ... I just could not wait and hopefully the "new" machine does not have the same artifact problem that started all this.

I am considering moving my Exos 2.4 rom from my present nonfunctioning machine to the new one. I understand that I also need to solder a ekstra wire besides moving the ROM. Can anybody direct my to a more precise description?

But first I will use my Symbiface to inject the ROM (and remove the present exos2.0). Does anybody have a link to the latest EXOS2.4 ROM with IS basic etc.?

Thank you in advance!

I have gotten a (small) bit further :)

When I alter the settings on C43 and L2 I get changes in the output signal that the OSSC recieves. It therefore looks like they are working - at least a bit - but are not configures correctly.

Does anybody know how to configure C43 and L2 and what the correct settings are?

Thank you in advance!

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