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leof
2nd March 2015, 18:53
I have a Marpet MP605 clock module: http://amigakit.leamancomputing.com/...roducts_id=595 (http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=595)
It must be used together with a MP604A memory expansion: http://amiga.resource.cx/exp/marpet604 (http://amiga.resource.cx/exp/marpet604)
I do not have such a RAM expansion. So I wondered if this clock module can be modified to work with
any other memory expansion for the A600 (or A1200).

BLTCON0
2nd March 2015, 20:15
I have a Marpet MP605 clock module: http://amigakit.leamancomputing.com/...roducts_id=595 (http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=595)
It must be used together with a MP604A memory expansion: http://amiga.resource.cx/exp/marpet604 (http://amiga.resource.cx/exp/marpet604)
I do not have such a RAM expansion. So I wondered if this clock module can be modified to work with
any other memory expansion for the A600 (or A1200).

Not the module itself - it's the other RAM board that will need the modification.

From a quick look at the module and the Marpet RAM board, it seems that the Marpet RAM board doesn't have any partial circuitry for the RTC module and simply acts as a pass-through for the RTC-related signals present on the trapdoor connector.
The complete RTC circuitry seems to be present on the module.

Therefore you simply need to feed it the RTC-signals, and of course Vcc and GND. Take a look at the schematics for the A600 to see what is what on the expansion connector, then solder wires to the appropriate contact points on your RAM board and route them to the RTC module.
You'll need schematics for the RTC too - namely the A601 schematics (but I bet the A501 schematics will do just as well).

leof
3rd March 2015, 08:04
Thanks! Appreciate your help.
I found some schematics: the first one is from the A600 memory expansion bus and the second is taken from the A501.

84092 84091

I don't yet see the connections between these two. Can you assist?

BLTCON0
3rd March 2015, 11:46
See the photo of the OKI chip diagram. Use the A501 schematic to match the OKI pins to the connections on the 2x7 module connector.
Since there are 14 pins there, they must be: 4 + 4 for address + data on the OKI chip, three lines for read, write, select on the OKI chip (= total 11 lines so far) and +5V, +12V and GND (another 3 lines, total 14).
So it's logical to assume that the 14 connections on the 2x7 module connector match the above.
Use continuity test to match the 2x7 connector pins to the RTC pins.
As per naming, on the P6 A600 trapdoor connector the correspondence should be:

A501 RTC name ----- A600 P9 trapdoor connector name

XD 0-1-2-3 (OKI pins 14-13-12-11) ---- D 0-1-2-3
XA 2-3-4-5 (OKI pins 4-5-6-7) ---- A 2-3-4-5
_XCLKRD (OKI pin 8 ) ---- _IORD
_XCLKWR (OKI pin 10) ---- _IOWR
_XCLKCS (OKI pin 2) ---- _RTC_CS

Pin 9 of the OKI chip is ground
Pin 18 of the OKI chip is power (+5V)
The common end of the two diodes should be connected to +12V through a resistor (supposedly the resistor seen on the RTC module).

leof
3rd March 2015, 12:49
Wow! That's great!
I will need some time to study and perform this. Will provide feedback how it goes.
Many thanks!

BLTCON0
3rd March 2015, 13:10
You're welcome.
To make things easier, first make a correspondence table between the 14 contacts on the 2x7 connector and the 11 OKI pins + 5V + 12V + GND (use the OKI schematic and the multimetre to determine the correspondence), i.e.
2x7 pin --- OKI pin# or 5V/12V/GND
1 - ?
2 - ?
...
13 - ?
14 - ?

Once you've filled the 2nd column with the correct values, insert a 3rd column and use the correspondence table I wrote to match OKI pins to P9 names.
And finally insert a 4th column where you'll write next to the P9 names the relevant P9 pin#, based on the P9 connector schematic.
Then you can ignore the inner columns - the 1st and 4th columns will directly provide you with the correct matching between the contacts on the 2x7 module connector and the A600 P9 connector pins.

Good luck!

leof
4th March 2015, 14:21
Thanks again!
I have several memory expansions one of which is http://amiga.resource.cx/exp/baseboard601
Description says it even has a battery backed up clock! The PCB seems to have the circuitry, but no components.
Would it be easier to move parts from the clock module to the expansionboard?
84139

BLTCON0
4th March 2015, 16:04
Maybe (see photo). You'll need an extra diode and to not damage the oscillator while desoldering. But on some photos of the RTC version of the card, the oscillator is not installed, I don't know what's with that.

leof
4th March 2015, 16:28
Where is the battery supposed to go?

BLTCON0
4th March 2015, 16:43
Blue double arrow. It's where the OKI chip should be. Of course the battery will be installed on the other side of the PCB.

leof
4th March 2015, 17:22
OK. Thanks a lot!

leof
5th March 2015, 07:56
One last question: I need an extra diode as far as I can tell from your arrows in the picture.
Do I need the same type as the one already on the clock module?

roy_bates
5th March 2015, 08:59
someone could probably confirm there the right ones.

http://www.ebay.co.uk/itm/20-x-1N914B-1N914-Small-Signal-Diodes-/281589291602?pt=LH_DefaultDomain_3&hash=item4190079a52

BLTCON0
5th March 2015, 10:47
One last question: I need an extra diode as far as I can tell from your arrows in the picture.
Do I need the same type as the one already on the clock module?

Use an 1N914 or 1N4148 diode. Also, double check with the schematics that the components on the RTC circuitry on the PCB are at their expected places (connectivity wise), as my diagram is just an educated guess and not exact knowledge.
Since photos of the board with an RTC don't show the oscillator and the two nearby capacitors installed, you might as well initially leave them out and only install them if all else fails.

bagpuss22
5th March 2015, 13:00
OR

I think I have the, 1Mb populated, Marpet MP604A in my 600HD.
If you want I will swap it for one of your 1Mb A600 expansions?

Then you can have the matching board and I will still have a 2Mb A600 :D

Russ

leof
5th March 2015, 14:38
Hi Russ,

Seems to be very heavy, putting strain on the edge connector.

BLTCON0
5th March 2015, 14:50
But the strain can be relieved by padding the underside with some support material (rubber, foam, folded piece of paper etc) to keep the marpet board straight. I wouldn't worry too much about it.

leof
6th March 2015, 13:11
OK. So I moved the components except the oscillator and two capacitors. (These 2 caps didn't survive desoldering.)
The time is being preserved, but doesn't advance when the Amiga is shut off.
Time to move the other components as well?
84326

BLTCON0
6th March 2015, 13:29
That would be the logical step.
It didn't anyway make much sense that on those web photos the oscillator wasn't installed, as the schematics are very clear on its presence, but oh well.
One of those capacitors, according to the schematics, should be a variable 6.8 to 45 pF capacitor (to allow calibration of the clock period) and the other a 22 pF capacitor, but installing fixed capacitance won't matter much, worst that can happen is you might want to readjust the clock every couple of weeks or so.
So, before you install the two capacitors, to follow the schematics you should determine some stuff.
Spot pin #16 on the OKI chip. It should have continuity with one of the oscillator holes and with one hole from one of the two nearby capacitors.
Spot pin #17. It should have continuity with the other oscillator hole and with one hole from the other nearby capacitor.
If all's ok, proceed to install the oscllator and the capacitors (which should be in the aforementioned pF range).
Hopefully all will be OK now.

leof
6th March 2015, 14:07
Continuity as you say is OK.
As I do not have any suitable replacement capacitors, the mod is on hold.
I will order one of those variable capacitors if I can get them somewhere.
Thanks so far!

leof
7th March 2015, 12:53
Installed the oscillator and one of the capacitors and it is already working fine now.
Thanks a lot!
84386

BLTCON0
7th March 2015, 17:37
Excellent :)
Take note of time slips over, say, a week's period. I'd suggest you still install the 2nd 22pF capacitor.

bagpuss22
10th March 2015, 21:35
What did you do with the old board that was stripped?

leof
11th March 2015, 07:40
I have that PCB here.

bagpuss22
11th March 2015, 09:05
Just wondered if it would be worth 'resurrecting' it for my MP604A? :D

Russ

leof
11th March 2015, 15:14
Hi Russ,
You can have it for postage. PM sent.
Leo

bagpuss22
11th March 2015, 16:10
Hi Russ,
You can have it for postage. PM sent.
Leo

Sent you some postage monies :thumbsup:

Russ

leof
11th March 2015, 17:30
Monies received and items sent! :)

bagpuss22
17th March 2015, 18:21
Item received.

Does anyone have a complete circuit diagram for this item?

I have the following info, please correct/add as required:

IC1 - MSM6242B
X1 - 32.768Khz Crystal ?
C1/C2 - 22pf Capacitor
C3 - ?
C4 - 47uF 16v ?
D1/D2 - BAT85 Diode
R1 - 560 Ohm resistor
CR2032 Holder and Battery


84959

BLTCON0
17th March 2015, 20:39
100 nF would make it for C3 (it's standard decoupling for the RTC IC).
The frequency for X1 is correct.
C4 seems right too, leof can certainly verify the value.
The diodes type is 1N914 or 1N4148 (I do however have a clockport RTC module that uses one 1N914 and one Schottky ( BAT48 ) diode).

bagpuss22
17th March 2015, 21:34
100 nF would make it for C3 (it's standard decoupling for the RTC IC).
The frequency for X1 is correct.
C4 seems right too, leof can certainly verify the value.
The diodes type is 1N914 or 1N4148 (I do however have a clockport RTC module that uses one 1N914 and one Schottky ( BAT48 ) diode).

Thanks for the help.

The only reason I used BAT85 is that is what is written on the PCB under where the component was.

Russ

BLTCON0
17th March 2015, 23:33
The only reason I used BAT85 is that is what is written on the PCB under where the component was.


If it says BAT85 and you have them, use them of course :) but as I can't see the design deviating from the standardised one, my guess is the standard silicon diodes are just fine as well.

leof
18th March 2015, 09:47
X1 has "KD5E" written on it
C4= 16V 47nF
C3 has "104" written on it

BLTCON0
18th March 2015, 12:00
C3 has "104" written on it

= 10 x 10^4 pF = 10^5 pF = 100 nF

bagpuss22
8th July 2015, 20:04
Quick question about this module. I have repopulated it except for the crystal, which arrived today. Does it matter about the size of the crystal? I have the right frequency but I have ordered the smaller 2mm x 6mm. I am assuming this will not matter.

Thanks

roy_bates
9th July 2015, 00:53
Quick question about this module. I have repopulated it except for the crystal, which arrived today. Does it matter about the size of the crystal? I have the right frequency but I have ordered the smaller 2mm x 6mm. I am assuming this will not matter.

Thanks

it wont matter,its only the frequency that matters.

bagpuss22
9th July 2015, 08:05
Quick question about this module. I have repopulated it except for the crystal, which arrived today. Does it matter about the size of the crystal? I have the right frequency but I have ordered the smaller 2mm x 6mm. I am assuming this will not matter.

Thanks

it wont matter,its only the frequency that matters.


@roy_bates, I thought as much but thanks for the confirmation...

bagpuss22
22nd July 2015, 16:50
OK, this is now built! Header added to the A604B card and it works!!!