Blizzard 1230 IV running at 1/3 clock speed (16.7 MHz instead of 50 MHz)

pyksy · 13 May 2015, 17:14

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!

eXeler0 · 13 May 2015, 18:55

Have you tried it with another oscillator just make sure the one you have is working properly..

pyksy · 13 May 2015, 21:12

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).

voyager_1701e · 14 May 2015, 14:42

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.

pyksy · 14 May 2015, 15:13

Quote:

Originally Posted by voyager_1701e

seems to be an SMD cap missing next to the SCSI board connector.

Ooh, thanks! Could you help me pinpoint it? I compared my board to this image http://www.bigbookofamigahardware.co...0mk4_9_big.jpg but I'm unable to locate the missing capacitor. Maybe crop my original image and circle the missing component?

Thanks again,
--pyksy

14 May 2015, 17:27

I can't see differences either, except missing RTC battery...

Dunny · 14 May 2015, 20:25

Quote:

Originally Posted by U96

I can't see differences either, except missing RTC battery...

Missing? It looks like it's been torn off!

D.

cpiac64 · 14 May 2015, 20:55

one chip is under xtal, remove xtal and verify if all ok

voyager_1701e · 15 May 2015, 16:51

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!

hese · 15 May 2015, 18:01

The two PCBs aren't identical, the "missing" capacitor hasn't been torn off or removed.

8bitbubsy · 17 May 2015, 16:06

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.

BarryB · 17 May 2015, 17:28

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'?

pyksy · 17 May 2015, 23:09

Quote:

Originally Posted by BarryB

Has anyone noticed the tracks on the 27C256 EPROM?

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!

BarryB · 17 May 2015, 23:49

stachu

Jope · 18 May 2015, 08:07

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. :-)

BarryB · 18 May 2015, 14:31

See, if you don't shout no one knows who you are! PM incoming!

Jope · 18 May 2015, 14:41

Hehe, there's always lots to do, so making noise will only clog up the calendar. :-)

roy bates · 18 May 2015, 18:33

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.

pyksy · 18 May 2015, 19:18

Quote:

Originally Posted by roy bates

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.

I am worried too, but according to my trusty multimeter all the traces still work.

They sure do look nasty, with exposed copper and all... :-/

pyksy · 10 September 2015, 16:30

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.

13 May 2015, 17:14	#1
pyksy Registered User Join Date: Jul 2013 Location: Finland Posts: 24	Blizzard 1230 IV running at 1/3 clock speed (16.7 MHz instead of 50 MHz) 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!

15 May 2015, 16:51	#9
voyager_1701e Registered User Join Date: Feb 2014 Location: Maitland / AUSTRALIA Posts: 205	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! Attached Thumbnails Last edited by voyager_1701e; 15 May 2015 at 16:55. Reason: added details

10 September 2015, 16:30	#20
pyksy Registered User Join Date: Jul 2013 Location: Finland Posts: 24	Fixed 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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13 May 2015, 18:55	#2
eXeler0 Registered User Join Date: Feb 2015 Location: Sweden Age: 50 Posts: 3,002	Have you tried it with another oscillator just make sure the one you have is working properly..

13 May 2015, 21:12	#3
pyksy Registered User Join Date: Jul 2013 Location: Finland Posts: 24	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).

14 May 2015, 14:42	#4
voyager_1701e Registered User Join Date: Feb 2014 Location: Maitland / AUSTRALIA Posts: 205	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.

14 May 2015, 17:27	#6
U96 Posts: n/a	I can't see differences either, except missing RTC battery...

14 May 2015, 20:55	#8
cpiac64 Registered User Join Date: Apr 2010 Location: Italy Posts: 1,136	one chip is under xtal, remove xtal and verify if all ok

15 May 2015, 18:01	#10
hese Registered User Join Date: Sep 2008 Location: Somewhere Posts: 223	The two PCBs aren't identical, the "missing" capacitor hasn't been torn off or removed.

17 May 2015, 16:06	#11
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,725	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.

17 May 2015, 17:28	#12
BarryB Amigaholic Join Date: Dec 2009 Location: UK Posts: 4,759	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'?

17 May 2015, 23:49	#14
BarryB Amigaholic Join Date: Dec 2009 Location: UK Posts: 4,759	stachu

18 May 2015, 08:07	#15
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,955	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. :-)

18 May 2015, 14:31	#16
BarryB Amigaholic Join Date: Dec 2009 Location: UK Posts: 4,759	See, if you don't shout no one knows who you are! PM incoming!

18 May 2015, 14:41	#17
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,955	Hehe, there's always lots to do, so making noise will only clog up the calendar. :-)

18 May 2015, 18:33	#18
roy bates Registered User Join Date: Apr 2011 Location: birmingham Age: 55 Posts: 2,827	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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