Turbo repair - The Nightmare Begins

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Richard Hull
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Turbo repair - The Nightmare Begins

Post by Richard Hull » Tue Jun 23, 2020 6:20 am

After two months of gathering parts and diagrams, I am finally ready to attack, with a vengeance, the repair of my turbo controller.

A thanks to Dan Knapp for the schematics and troubleshooting manual.

Sadly, it seems 6 IC's are no longer available, (discontinued) I hope one of these is not the problem.
Blessedly, all IC's are socketed!
I am making up the board jumpers that will allow the system to be spread out for easy access during repair and testing. I will give this my best shot in order to retain the pump for the "real" fusor V effort where there will be 0.000 arcing, by design. A fail here will have me drop the concept of a turbo pump in any future system and a return to the "plug and go" Leybold diff pump of fusor IV fame.

I include three photos of the work area and set up to attempt repair and testing. Wish me luck, I already have the skills, a bit of luck is always a plus.

Richard Hull
Attachments
Turbo repair (2).JPG
Turbo repair (3).JPG
Turbo repair (1).JPG
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

John Futter
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Re: Turbo repair - The Nightmare Begins

Post by John Futter » Tue Jun 23, 2020 6:52 pm

Richard
Send me a list of the ics you need
I have quite an extensive pile of logic and analog leaded ics

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Re: Turbo repair - The Nightmare Begins

Post by Andrew Seltzman » Tue Jun 23, 2020 10:19 pm

May be worth it to buy another controller, they're pretty cheap:

[url]https://www.ebay.com/itm/133173568909/url]
Andrew Seltzman
www.rtftechnologies.org

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Richard Hull
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Re: Turbo repair - The Nightmare Begins

Post by Richard Hull » Wed Jun 24, 2020 10:29 am

FIXED!!

Yes, the shotgun approach worked. I have spent the last two months and about $90 in orders from Jameco, Digi-key and Mouser ordering every IC in the turbo's controller system that was still made. DIPs (N package ICs of the 70s-80s) are going away fast! Fortunately, between the 3 suppliers, I found all the DIPs needed. Whew! Some, only offered in SOIC. There were about 5 ICs that were obsolete and no one had them. The controller used about 23 ICs over the 3 boards. While waiting for the IC's I checked all the transistors in-circuit and all were good. About 30 transistors were in the controller.

I have a stock, here, of about 3000 IC's Most are TTL and variants, CMOS, and a lot of linear. All from the 70's through the early 2000's. My stock yielded about 5 of the 15 ICs needed. Determined not to really trouble shoot until I shotgun blasted all the ICs I had accumulated into the 3 boards and give it a whirl.

It worked!! Now, which IC or ICs were defective?? Who cares? I have a working turbo again! I am pretty sure it was one of the many, CMOS, CD4000 series logic ICs that the discharge destroyed or the two odd ball SG3525 PWM chips in the power board electronics.

I loaded all the IC pulls in a bag and marked them "pulls TCP-40 ??" I also stuffed all the spare ICs I ordered, which are known good, into another bag marked NEW ICs for TCP-40. I put both of the bags, the four custom board jumpers, which I manufactured, and the Pfeiffer manual into a flip top box and marked it "TCP-40 Turbo ICs and manual". I put it with all my vacuum hoard up in the loft of the lab. Hopefully, I will never need that stuff again. ( ordered about 4 of each IC needed.)

I am glad I didn't have to troubleshoot as Pfeiffer put a lot of CMOS logic snaking all about the system to check for startup issues and feed or receive signals from about 8 op amps. Typical 70s electronics, but very serviceable as most of the parts are still floating around without any custom programmed ICs, thank goodness.

I ran the turbo in the old, soon to be dismantled, fusor V setup and it ran for 2 hours, no problems....

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Dennis P Brown
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Re: Turbo repair - The Nightmare Begins

Post by Dennis P Brown » Wed Jun 24, 2020 6:26 pm

Good idea - overwhelm the problem! Still, anyone with such a unit now knows who to buy required spare electric parts from.

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Richard Hull
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Re: Turbo repair - The Nightmare Begins

Post by Richard Hull » Wed Jun 24, 2020 11:50 pm

It seems the nightmare began and ended in one day, once all the materials needed were amassed. This might be the shortest nightmare I have experienced on the tech front for a while. The time spent ferreting out the needed DIPs on the computer and on the phone, it turns out, was the real nightmare.

Now on to the real fusor V construction as I rip up the abortive first pass.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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