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Author Topic: Capacitors - wrong orientation? (Read 1529 times)

Offline Judge

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Re: Capacitors - wrong orientation?
« Reply #30 on: 2020.October.05. 20:14:16 »
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Offline elmer

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Re: Capacitors - wrong orientation?
« Reply #31 on: 2020.October.06. 02:07:34 »
I found it here...

Cool, eBay to the rescue! ;)

It looks like you can get the smaller voltage ones here.

Offline Judge

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Re: Capacitors - wrong orientation?
« Reply #32 on: 2020.October.06. 10:56:05 »
It looks like you can get the smaller voltage ones here.

Damn it!  :evil:  I didn't find this. It doesn't matter now. Thanks!  :lol:
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Offline BruceTanner

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Re: Capacitors - wrong orientation?
« Reply #33 on: 2020.October.06. 14:46:53 »
I ordered these from eBay UK: https://www.ebay.co.uk/itm/Nichicon-UEP-EP-6-3V-100V-0-47uF-6800uF-Bi-Polarized-Bipolar-105-C-Capacitors/183792363878. By coincidence this is the same make as all the other electrolytics in my EP, so they match :mrgreen::lol:. (I don't have the blue sort, but they look original, the solder joints look un-disturbed. :?: Also TR2 looked original.)

Anyway it is working fine. No difference that I could see on the start-up oscilloscope traces that I posted before.

It was easy to fit the radial capacitor in the same space as the original axial capacitor:

25546-0 25548-1

I don't know if this has fixed the C9 / TR2 weak point, but I have turned mine off and on 50 times and it is still working!

Offline Judge

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Re: Capacitors - wrong orientation?
« Reply #34 on: 2020.October.06. 15:21:40 »
It was easy to fit the radial capacitor in the same space as the original axial capacitor:

Yes! I did the same. On this motherboard, all capacitors are originally radial.

25550-0
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Offline elmer

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Re: Capacitors - wrong orientation?
« Reply #35 on: 2020.October.10. 05:13:49 »
Thanks. On my EP it was 6.3V, but of course these are prone to failure and might have been replaced in the past, so it might not have been the original original! :lol:

FYI, I finally opened up my EP64, serial #71370 (so fairly late manufacture), and it also uses 6.3V 100uF capacitors for C9, C11 and C12.

In this case they are all old-style axial, and Unicon brand (another decent-quality Japanese manufacturer).

That is on an issue 4 motherboard, which unfortunately has 300ns video RAM, so I presumably won't be able to change to a 6MHz clock unless I replace those. :(

Offline dangerman

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Re: Capacitors - wrong orientation?
« Reply #36 on: 2020.October.10. 10:49:20 »
That is on an issue 4 motherboard, which unfortunately has 300ns video RAM, so I presumably won't be able to change to a 6MHz clock unless I replace those. :(

Often chips are faster than the official rating, so you might be lucky.

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Re: Capacitors - wrong orientation?
« Reply #37 on: 2020.October.10. 11:21:36 »
Hello Elmer.

About serial numbers, I don't know if you have took a look to the inventory of machines from Zozo's page.

On it you can observe how the EP64 numerations are different from the EP128 ones. You also can see how there are very big gaps on the EP64 list.

EP64 numbers 2000~30000, probably all expanded to 128KB by the Enterprise company, that could explain why there are so many issue 4 and 5 PCBs mixed with issue 6 ones, the usual on the 128KB EP.(There are also some issue 6 EP64s, probably refurbished in Germany and then sold to the Egypt dealer).

EP64 numbers 40000~70000...., I have a theory for this gap... at that time they were selling less Enterprise units than expected and, incrementing artificially the serials, then could give to the public impression that they had manufactured a huge amount.

I think that they restarted the serial count for the EP128 model, now lineal, the first units being mounted with the rest of old issue 4 and 5 PCBs with the defective Nick(mine for example), and then all the rest issue 6 PCBs with the improved Nick.

Offline John Fante

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Re: Capacitors - wrong orientation?
« Reply #38 on: 2020.October.10. 17:46:59 »
This is a bit of topic but what is the difference between the different issues?

And I can confirm that the Egyptian EP64's are issue 6. At least my Egyptian EP64 is issue 6 :)

Offline Wolfgang

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Re: Capacitors - wrong orientation?
« Reply #39 on: 2020.October.10. 18:46:41 »
This is a bit of topic but what is the difference between the different issues?

And I can confirm that the Egyptian EP64's are issue 6. At least my Egyptian EP64 is issue 6 :)
You are lucky then. My three EPs from Egypt are all issue 4 with the problematic NICK :(

Online gflorez

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Re: Capacitors - wrong orientation?
« Reply #40 on: 2020.October.10. 19:23:10 »
Zozo can say all about that.

What I have read from him is that ALL EP PCBs share the same circuit layout, with minor differences on the "fingers" of the EDGE connectors.



Starting from bottom, issue 3, 4 and 5 on the middle, and 6 the upper one.

The Issue 3 EDGE fingers were totally wrong, with excessive width, prone to cause short-circuits if not correctly aligned with the female connector . A bigger gap was added on issues 4 and 5 to fix that, and on issue 6 some of the unused pins of the Video connector were populated and gained a solder point, the planed use unknown.

There are also some differences on the custom chips mounted. Issue 3 were test EP64s fitted with Korean made Nick and Dave, first batches of chips that turned out to be malfunctioning, needing an external PCB to correct the behaviour. There are very few of these, almost all distributed to developers, not to open public.  

Issues 4 and 5 mount the first batches of Austrian made custom chips, but it happened that the advanced designs were years ahead of the contemporary manufacturing techniques, and then the new Nick also didn't worked as intended. It showed bad colours on some intensive screen modes(and probably bad external colour input), some units worse than others. The cooper heat sink over Nick was then added to minimize the failure, worse on high temperature.

The new fixed Nick was introduced with the Issue 6 PCBs or a little earlier on last Issue 5.

There are other curiosities about the Enterprise PCBs, the most evident is the black lead from the Z80 to the cartridge port that can be seen on the upper side... the same cooper track already exist on the PCB, but cut on two places(on all EPs), a modification probably made to fix some insidious signal interference.
« Last Edit: 2020.October.10. 20:10:53 by gflorez »

Offline Zozosoft

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Re: Capacitors - wrong orientation?
« Reply #41 on: 2020.October.10. 21:02:47 »
ISSUE 3 only the first 100 non final machine which are sent to the developers and magazines. (Marked as "Not for resale")
These are not have a internal speaker circuit on the board, it is on a additional piggyback pcb.
Using Made in Korea Nick, which are very faulty.

ISSUE 4 board are originaly at the early 64K machines. But! at this time many lot of manufacturing problems. Boards which are not passed the quality check, later are repaired, and putted back to the production line. Then randomly can found ISSUE 4 board at later EP64 and also at EP128 machines.
The main interesting point of ISSUE 4 boards: these are have a FLAN company, name which are only used for a short time.
R208 and C215 missing from the PCB, soldered in the air at the modulator. Two unused pins are missing from the monitor connector.
Using Made in Austria Nick, 08-04, which are much better than the Korean version, but still have a problems. Heat shink reduce the problem. Good idea check the heat shink, because the ~35 years glue start fall apart at many machines.
This ISSUE using the bad Philips capacitors

ISSUE 5 the most common at EP64 machines. Currently never see it at EP128.
It is have a Enterprise company name. R208 and C215 placed to the pcb. The two unused monitor pins still missing.
Also using 08-04 Nick. But using the better capacitos (I'm not sure about all ISSUE 5, but what I see used the good caps).

ISSUE 6 same with ISSUE 5, just the two unused pins putted back as spare at monitor connector.
This version used mostly at 128K machines, only few 64K machines (randomly) have it.
Possible both are 08-04 and 08-47 Nick chips. Not a 100%, but usually the dark green ones have a 08-04 and the light green have a 08-47, but exist a exceptions for a both. In a few ISSUE 6 EP64 I found a 08-47.

Offline Ep128

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Re: Capacitors - wrong orientation?
« Reply #42 on: 2020.October.10. 23:10:17 »
It hasn’t left me calm for many years to see what the Issue 1 and 2 motherboards might have been like.

Online gflorez

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Re: Capacitors - wrong orientation?
« Reply #43 on: 2020.October.10. 23:17:34 »
If the Issue 3 were only 100... maybe these were the prototypes, no more than 10 or so.

Offline Ep128

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Re: Capacitors - wrong orientation?
« Reply #44 on: 2020.October.11. 23:58:47 »
If the Issue 3 were only 100... maybe these were the prototypes, no more than 10 or so.
But we would have at least 1 photo of them... :-)