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#1 |
Registered User
Join Date: Jul 2013
Location: Finland
Posts: 24
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Hello everyone,
I recently acquired some Amiga hardware and among the stuff was a Blizzard 1230 IV with a 32MB SIMM. It seems to work well, except for one thing: it runs at 16.7 MHz instead of 50 MHz, ie. at 1/3 clock speed. (Yes, it really runs at 16.7 MHz, as reported by both SysInfo and WhichAmiga. SysInfo benchmark reports some 3100 dhrystones; according to Google, the result should be around 9200. The card has a 50 MHz CPU and a 50 MHz oscillator.) The board seems to have had some minor damage: the battery is missing and I can see a scratch and some repaired lines on the card, but according to my multimeter the repairs seem to work fine. The 60ns/70ns memory speed selection also works. I get higher results in AIBB memory test benchmarks with the jumper set to 60ns mode. I've also tested the card with a different SIMM but it didn't help. Does anyone have any idea what could be causing the low clock speed? Here's a picture of the card: https://farm9.staticflickr.com/8768/...340e792c_o.jpg As you can see, it has been scratched and there are some lines fixed near the EPROM. Other than the clock speed, the card works just fine. Thanks in advance for your help and suggestions! |
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#2 |
Registered User
Join Date: Feb 2015
Location: Sweden
Age: 50
Posts: 3,002
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Have you tried it with another oscillator just make sure the one you have is working properly..
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#3 |
Registered User
Join Date: Jul 2013
Location: Finland
Posts: 24
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Hi,
no I haven't, as it's soldered to the board and also I don't have a spare. I guess I could take it to someone with a scope and verify the oscillator frequency (for non-intrusive testing). |
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#4 |
Registered User
Join Date: Feb 2014
Location: Maitland / AUSTRALIA
Posts: 205
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It is probably not relevant...but seems to be an SMD cap missing next to the SCSI board connector. I compared your photo to that on BBH, and the BBH photo shows a cap in that place.
Good luck rectifying the issue. |
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#5 | |
Registered User
Join Date: Jul 2013
Location: Finland
Posts: 24
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Quote:
Thanks again, --pyksy |
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#6 |
Posts: n/a
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I can't see differences either, except missing RTC battery...
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#7 |
Registered User
Join Date: Aug 2006
Location: Scunthorpe/United Kingdom
Posts: 2,168
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#8 |
Registered User
Join Date: Apr 2010
Location: Italy
Posts: 1,136
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one chip is under xtal, remove xtal and verify if all ok
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#9 |
Registered User
Join Date: Feb 2014
Location: Maitland / AUSTRALIA
Posts: 205
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Here.....
Edit...you are right! In your linked photo it is missing also! This one http://amiga.resource.cx/photos/phot...res=hi&lang=en ... has it there! Last edited by voyager_1701e; 15 May 2015 at 16:55. Reason: added details |
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#10 |
Registered User
Join Date: Sep 2008
Location: Somewhere
Posts: 223
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The two PCBs aren't identical, the "missing" capacitor hasn't been torn off or removed.
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#11 |
Registered User
Join Date: Sep 2009
Location: Norway
Posts: 1,725
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As hese pointed out: You guys didn't pay enough attention to the pictures. :-)
That "missing" capacitor is most likely intentional, it looks perfect on the solder pads. Also I think it's a spot for a 0 ohm jumper resistor, not a capacitor. I know there's only two capacitors on his cards and three on the other picture, but it was probably removed/added in a different revision of the card. Look closely and you will understand what I mean (look at the traces, they differ): ![]() Conclusion: These are two different revisions of the card. |
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#12 |
Amigaholic
Join Date: Dec 2009
Location: UK
Posts: 4,759
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Has anyone noticed the tracks on the 27C256 EPROM? On the top, 3rd track in from the left, has what looks to be a bodged link to the pin, maybe the track was damaged? Also on the top left corner some more tracks seems to have a similar 'repair'?
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#13 |
Registered User
Join Date: Jul 2013
Location: Finland
Posts: 24
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Sure. I've measured them with a multimeter and the repaired lines are ok. Also haven't found any shorts, even though the repair job looks a bit ugly.
I'll probably send the card to a certain someone more skilled in soldering and with proper diagnostics equipment. Thanks for your help, everyone! |
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#14 |
Amigaholic
Join Date: Dec 2009
Location: UK
Posts: 4,759
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stachu
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#15 |
-
Join Date: Jul 2003
Location: Helsinki / Finland
Age: 43
Posts: 9,955
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I don't think this one is going to Poland.. We have repairmen in Finland too, they just don't make noise about their services. :-)
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#16 |
Amigaholic
Join Date: Dec 2009
Location: UK
Posts: 4,759
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See, if you don't shout no one knows who you are! PM incoming!
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#17 |
-
Join Date: Jul 2003
Location: Helsinki / Finland
Age: 43
Posts: 9,955
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Hehe, there's always lots to do, so making noise will only clog up the calendar. :-)
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#18 |
Registered User
Join Date: Apr 2011
Location: birmingham
Age: 55
Posts: 2,827
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i would be more worried about the scratch on the board.
from the pictures its goes through some traces quite deep,a couple look broken but i cant see them properly. |
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#19 | |
Registered User
Join Date: Jul 2013
Location: Finland
Posts: 24
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Quote:
They sure do look nasty, with exposed copper and all... :-/ |
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#20 |
Registered User
Join Date: Jul 2013
Location: Finland
Posts: 24
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So I finally handed the card over to this certain someone last weekend. He desoldered the oscillator and found a broken pcb trace underneath it.
He fixed it and the card is now running at 50 MHz again. ![]() |
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