Maybe of interest for German (any maybe other European) users: finally I received the thyristors and can now offer five remaining sets of Rik's pcb board with parts for 12€ each, plus shipping costs.

#HP9825

Hi Martin, did you receive my e-mail some days ago? Cheers Chris

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I built up one of my earlier revision boards today with an added-on capacitor. I also uploaded the current revision of the board (with cap included) to Oshpark, shared as "HP 9825/35 Crowbar". Oshpark

#HP9825

Hi Martin, as a nice coincidence, I am living in Germany too (in the Ammersee region, likely not tooooo far away from you). It would be awesome if you put me on the list for two boards, I will contact

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In order to upgrade my 9825s I had 10 PCBs manufactured (minimum order), but I only need 3-4. So I have 5 boards avaialable, but currently unpopulated. I have most of the parts and am currently waitin

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Hi Chris, No, I'm sorry but all boards are used or spoken for. -Rik -Rik

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Hi Rik, are there any of your crow bar PCBs available? A 9825A will arrive in my lab tomorrow and I'd love to see it being well protected before I fire it up the first time! Cheers Chris

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Thanks Rik, This is my first time ordering a PCB from a file (pretty non-commercial if I'd say so). I'm having some trouble finding the size of the board/number of layers etc from the file. Any help w

#HP9825 #VintageHPComputers

Rhys, I uploaded a slightly optimized gerber, you’re free to use it non-commercial 😉 -Rik Van: VintHPcom@groups.io <VintHPcom@groups.io> Namens Rhys Lowry Verzonden: donderdag 4 maart 2021 19:15 Aan:

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I just ordered new filter caps as well as a new 2N4398. I'll let you know if that fixes things or if I need any more help. I'll make sure to test it safely this time. Rik, is your crowbar circuit avai

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The 2N4398 is the pass transistor for the +5V supply if it failed short (mine did too) it will put +20V in places it really should not be. I am afraid the damaged trace would suggest the fuse did not

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The trace that burned some of the solder mask off is the leg of the transformer feeding the +20 unregulated. I am surprised it did not blow the fuse before doing that damage, maybe there is a nail in

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By head I say it's the AC return line to the transformer. So it seems your very lucky. -Rik

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If you haven't already, download a copy of the service manual: http://www.hpmuseum.net/document.php?hwfile=1808 Also two sets of schematics are available, one are the hand drawn ones by Tony Duell: ht

#HP9825 #VintageHPComputers

I was measuring the 12V rail when it happened and was confused as to why it wasn’t changing the voltage when I turned the pot. As for dead components, the 2N4398 is shorted and it looks like some sold

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12.43 V was within the spec and probably didn't need adjustment immediately. Did you look at the schematic before you turned the potentiometer? Doing so without understanding what you were adjusting o

#HP9825 #VintageHPComputers

Hi all, I'm a newish vintage electronics repair enthusiast having recapped and done basic troubleshooting and the such in the past. No expert, although I aspire to be. After picking up this HP 9825A l

#HP9825 #VintageHPComputers

I don't think the exact SCR used is that critical but it will need to withstand a pretty heavy current pulse when it trips. Blowing the fuse will be nothing for it, but it will effectively short the b

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The choice of brexit is pure nonsense, but at least in the UK they have a true democracy that respects the choices of the people, which is not the case in all countries including France.... Don't worr

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I've all the parts except the thyristors RS is moving it's stock from GB to Germany ( they told me) and that seems to take some time. So I'm waiting for those. The stupid thing is most of the time I h

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