Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

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Zarchos
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Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

Postby Zarchos » Wed Oct 15, 2014 6:18 pm

Hi Acorn lovers !

I'd like to repair a faulty IFEL A3010 4 Mbyte RAM upgrade and as I'm not good at electronics and there are some experts here, I ask your help.

I've got several questions.

The board has 2 memory chips HY5118160.
Is there a way to test these chips (voltage pins or ?) to know if 1 or both are faulty ?

The board also has a surface mount capacitor where I can read
47
16S
8M3

I undesrtand 47 is for micro Farads, 16S I'd say it's 16 Volts (but why is that an 'S' and not a 'V' ?) and for the 8M3 I've got no clue.
Any idea ?
These are impossible to find on Ebay, and it worries me.

There are also 4 surface mount yellow chips and I'd say these are resistors, but help on these would be highly appreciated.

I've already ordered some memory chips from an Ebay US seller, in case the chips on my board would be faulty, and who knows if one day I decided to create my own PCBs to have some home made 4 Mbyte expansion boards for my other A3010s ...


A picture of the board :
DSC00005.jpg

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1024MAK
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Re: Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

Postby 1024MAK » Wed Oct 15, 2014 11:43 pm

Zarchos wrote:The board has 2 memory chips HY5118160.
Is there a way to test these chips (voltage pins or ?) to know if 1 or both are faulty ?
Not really, the best way is with a special RAM test program. If this board electrically completely replaces the standard motherboard mounted RAM, this could be difficult. If the system has some working RAM, then the special RAM test program can run from the good RAM and test the bad RAM.
Zarchos wrote:There are also 4 surface mount yellow chips and I'd say these are resistors, but help on these would be highly appreciated.
These are small value ceramic capacitors, used to decouple the +V and 0V supply for the chips (they act like small, but very fast batteries to supply the rapid current spikes that the chips require).

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munchausen
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Re: Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

Postby munchausen » Thu Oct 16, 2014 5:50 am

I'd say it's unlikely the caps have died, perhaps C1 which you should be able to replace by a non-SMD one if necessary. I have another IFEL RAM expansion (this one http://chrisacorns.computinghistory.org.uk/32bit_UpgradesH2Z/IFEL_A3010_MA104B4MB.html) so I'm a little suprised there is no jumper wire coming from it (it looks so much simpler than the one I have!)

Are there any components on the back? Are you sure you installed the jumpers correctly when installing it and it was really firmly pressed down (mine needs quite a lot of force to install correctly)? It took me ages to get mine working correctly!

I think this does replace the whole RAM (it has 4MB RAM on the expansion) so running a test program might be impossible.

There is no other simple way to test the RAM unfortunately, unless the jumper settings allow you to have part of the expansion RAM connected along with part of the on board RAM, but I'm not sure that's possible (I haven't seen a clear explanation of what the jumpers do, though I suppose there are always the schematics to refer back to...)

The easiest way to repair it is probably put it in the oven, take it out and quickly tap it on a hard surface to remove all the components, then replace everything. Soldering those tiny pitch caps is going to be really tricky though! I'd use through hole components and solder them to the vias I think.

If you do go this route, it might be useful to take some hi-res scans of both sides of the boards with the components removed.

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roland
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Re: Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

Postby roland » Thu Oct 16, 2014 6:17 am

You can check the voltage on the power pins of the memory ic's:

VCC: pins 1, 6, 21 (+)
VSS: pins 22, 37, 42 (0V)

If the voltage is not correct one of the caps might be faulty or check the socket on the main board. If the voltage is correct, it doesn't tell you anything about the condition of the ic.

Did you test the IFEL in one of your other A3010's? Maybe the A3013 is faulty?

The easiest way to repair it is probably put it in the oven, take it out and quickly tap it on a hard surface to remove all the components, then replace everything.


At what temperature should you bake the pcb? A soldering iron gets over 300 degrees Celcius but my oven doesn't reach that temperature.

Another way to remove the ic's is to cut it out with a dremel and desolder the pins one by one. You need a steady hand for that because you must not damage the board. The advantage is that the heating is very short and very local so the pcb will not be damaged by the desoldering process.
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Zarchos
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Re: Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

Postby Zarchos » Thu Oct 16, 2014 7:01 am

Thanks to all of you for your help.

Replies to your questions :
- Memory board was tested on 2 different A3010s, yes I checked it was correctly inserted and did try all jumpers configurations (after the one described for the other IFEL 4 Mbyte expansion board on the Acorn Chris pages, and as this memory expansion board was received in a working, configured A3010 sent from the UK (but damaged during transportation) I had the right jumpers configuration).

- There are no ICs on the other side (only 4 tracks).

- What voltages should I get please (and between which pins) ?

-Using the Dremmel is sthing I thought of (alone, without the oven), as I've got one. What a useful tool btw.
And yes I'll take pictures of both sides for future use.

A3010 4 Mbyte expansion boards are very difficult to find, and as noticed here this model is very nice and neat, with memory chips you can still find in quantities (I got 80 of them for less than 200 € including shipping).

It could be a nice community project to produce some, don't you think so ?

- What's the value of the tiny yellow capacitors ?


Thanks again for your help, I appreciate.

I'm still curious to know why the capacitor is labelled '16S' and not '16V' and what '8M3' stands for.
Explanations welcome.

Xavier.

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roland
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Re: Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

Postby roland » Thu Oct 16, 2014 5:20 pm

While I was waiting for Linux to install I did some research for you:

Schermafbeelding 2014-10-16 om 19.17.47.png


The S has nothing to do with the voltage, it's just an identifier for the serie. The last number is a lot number. You can find the complete datasheet at http://industrial.panasonic.com/www-dat ... 000CE2.pdf
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Zarchos
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Re: Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

Postby Zarchos » Fri Oct 17, 2014 7:13 am

Ta ! :)

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roland
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Re: Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

Postby roland » Fri Oct 17, 2014 4:15 pm

You don't wanna know how many ads I have seen for capacitors in the last 24 hours :lol:
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Re: Attempt to repair an A3010 IFEL 4Mbyte RAM upgrade

Postby Trapper » Thu Sep 14, 2017 1:00 pm

Did you ever repair this? I'm having an issue with my 4MB upgrade board (the other version with the 10 smaller RAM chips)


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