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Author Topic: Amstrad PCW let out the magic smoke! (CRT Board Repair)  (Read 1602 times)

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Offline BlueAppleTopic starter

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Amstrad PCW let out the magic smoke! (CRT Board Repair)
« on: August 30, 2022, 09:43:56 pm »
I found an Amstrad PCW 8256 at an estate sale. When I got it home and powered it on smoke came out. Looking at the board one capacitor is bulging. There also is no power on the 12v rail.

Can capacitors let out smoke without it being visible?
« Last Edit: August 31, 2022, 11:37:40 am by BlueApple »
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Offline Rasz

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #1 on: September 02, 2022, 05:31:07 pm »
to amateur eye? definitely
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Offline BlueAppleTopic starter

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #2 on: September 02, 2022, 06:55:36 pm »
Quote from: Rasz on September 02, 2022, 05:31:07 pm
to amateur eye? definitely
Ok. I'm gonna go ahead and buy a new cap.
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Offline Rasz

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #3 on: September 02, 2022, 07:32:17 pm »
singular cap? so you did find the culprit? afaik there are a couple of electrolytics on pcw
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Offline BlueAppleTopic starter

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #4 on: September 02, 2022, 07:38:42 pm »
Only the one cap is bulging and tests bad with my multimeter. I just desoldered it to test it out of circuit and it still tests bad. It was leaking too.
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Offline BlueAppleTopic starter

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #5 on: October 08, 2022, 07:08:17 pm »
I replaced that cap, turned it on, and a few transistors blew up.  :-BROKE
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Offline Rasz

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #6 on: October 08, 2022, 08:37:46 pm »
haha thats awesome!
looking at https://www.cpcwiki.eu/index.php/PCW_Mainboard_Versions#PCW_8256.2F8512 I dont see any transistors
is there a rifa capacitor in the power supply?
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Online Audiorepair

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #7 on: October 08, 2022, 08:38:34 pm »
I think prisoners should be given such tasks whilst incarcerated.
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Offline T3sl4co1l

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #8 on: October 08, 2022, 11:51:51 pm »
Quote from: Audiorepair on October 08, 2022, 08:38:34 pm
I think prisoners should be given such tasks whilst incarcerated.

What?  Vaping electrolytics?

Tim
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Offline Gyro

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #9 on: October 09, 2022, 01:26:42 pm »
Quote from: BlueApple on October 08, 2022, 07:08:17 pm
I replaced that cap, turned it on, and a few transistors blew up.  :-BROKE

Quote from: Rasz on October 08, 2022, 08:37:46 pm
haha thats awesome!
looking at https://www.cpcwiki.eu/index.php/PCW_Mainboard_Versions#PCW_8256.2F8512 I dont see any transistors
...

It seems likely that the 'transistors' may actually be Tantalum bead capacitors. Those are what I would expect to blow up in a noticable fashion on something that old that has been stored in unknown conditions.
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Offline BlueAppleTopic starter

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #10 on: October 10, 2022, 02:48:06 pm »
Quote from: Gyro on October 09, 2022, 01:26:42 pm
Quote from: BlueApple on October 08, 2022, 07:08:17 pm
I replaced that cap, turned it on, and a few transistors blew up.  :-BROKE

Quote from: Rasz on October 08, 2022, 08:37:46 pm
haha thats awesome!
looking at https://www.cpcwiki.eu/index.php/PCW_Mainboard_Versions#PCW_8256.2F8512 I dont see any transistors
...

It seems likely that the 'transistors' may actually be Tantalum bead capacitors. Those are what I would expect to blow up in a noticable fashion on something that old that has been stored in unknown conditions.
Do they have 3 legs? And also they are on the power board not the computer board.
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Offline BlueAppleTopic starter

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Re: Amstrad PCW let out the magic smoke! (CRT Board Repair)
« Reply #11 on: November 16, 2022, 07:38:34 pm »
I figured out why the transistors blew up, I forgot to connect the power to the motherboard and they must've overloaded.  :palm:
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