Author Topic: Finally motivated to fix my 464  (Read 406 times)

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Offline Blurredman

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Finally motivated to fix my 464
« on: 22:58, 28 December 18 »
Hi guys,

My 464 (revision D) has the dreaded grey box in black border after I put in 18v around 10 years ago. When I was soo.... stupid.


From looking through this forum for a few days, researching what to do (with that rarely used item in forums the Search button) I find first most to look at the ram.

In the picture I have attached, the banks with red marker on them are too hot to touch, the other ones are not, warm- but cannot rule them out, for now.

I take it I should start there- cut out the legs and pull those hot chips off (obviously there is no point un-soldering them neatly) and fit some IC beds and new RAM- What's best? The ones on the machine are as far as I can make out MN4164P-20 (does the 20 indicate ns?). What are the best/cheapest replacements on the 'net?

Thanks guys.
« Last Edit: 23:00, 28 December 18 by Blurredman »

Offline llopis

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Re: Finally motivated to fix my 464
« Reply #1 on: 23:32, 28 December 18 »
I take it I should start there- cut out the legs and pull those hot chips off (obviously there is no point un-soldering them neatly) and fit some IC beds and new RAM- What's best? The ones on the machine are as far as I can make out MN4164P-20 (does the 20 indicate ns?). What are the best/cheapest replacements on the 'net?
Definitely start replacing those. Frankly, I would use that as practice to try to remove ICs correctly. It's not very difficult, just get a reasonable 10€ solder sucker and you'll be fine. It'll let you desolder other chips later that you're not sure you really want to destroy or not.


As for memory, just about any 4164 will do. This is the cheapest one that I've been using
This is the cheapest one that I've been using with good results.

Offline rpalmer

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Re: Finally motivated to fix my 464
« Reply #2 on: 01:06, 29 December 18 »

.... MN4164P-20 (does the 20 indicate ns?).

Thanks guys.

The-20 means 200ns. There were no commercially viable 20ns chips in the eighties. If i recall there were 100 ns DRAMs.

rpalmer

Offline Bryce

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Re: Finally motivated to fix my 464
« Reply #3 on: 11:30, 29 December 18 »
Replace all the RAM, not just the hot ones. The non-hot ones probably got damaged too, they just don't have a short inside like the hot ones.

Bryce.

Offline Blurredman

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Re: Finally motivated to fix my 464
« Reply #4 on: 01:56, 30 December 18 »
Definately a possibility.

My original thread was here..
http://www.cpcwiki.eu/forum/general-discussion/broken-6128/msg25902/#msg25902

which Bryce made this interesting topic in relation to..:

http://www.cpcwiki.eu/forum/other-retro/anatomy-of-an-8-bit-over-voltage/msg26393/#msg26393

I've already removed all chips and awaiting sockets and replacement ram. But will likely want to test the non 'hot' ram on reconstruction.


Thanks guys.

Offline Blurredman

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Re: Finally motivated to fix my 464
« Reply #5 on: 19:11, 31 December 18 »
Will the M5K4164NP-20 work in conjunction with the original MN4164P-20 if I wanted to test the suspect chips in the replacement IC sockets, before I just chuck them?Looking through this sheet: http://www.minuszerodegrees.net/memory/4164/4164_list_3.jpg I can see there is a difference in mw. Plus I cannot find a 'non-N' (in NP) variant. What does the N stand for ?

Sorry for the naive question. Unfortunately my forte is engine mechanics not electronic.  :laugh:


Offline Bryce

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Re: Finally motivated to fix my 464
« Reply #6 on: 13:55, 01 January 19 »
The N has designates what type of package it has, the chips should be identical inside and fully compatible.

Bryce.

Offline Blurredman

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Re: Finally motivated to fix my 464
« Reply #7 on: 23:19, 12 January 19 »
Great..

8x chips on the 464. All fixed. Also fixed a few Chips from the 6128 with the same problem as well as some broken traces. So that's two CPC's fixed tonight.. As well as fixing the disc drive for the 6128 that didn't work, too!! :D

I feel very happy..!








« Last Edit: 23:20, 12 January 19 by Blurredman »

Offline llopis

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Re: Finally motivated to fix my 464
« Reply #8 on: 23:45, 12 January 19 »
Fantastic! Good to see them working again.  :)

Offline Bryce

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Re: Finally motivated to fix my 464
« Reply #9 on: 14:06, 13 January 19 »
A successful evening!

Bryce.