need help repairing a beautiful Power Designs 2005A power supply - Page 1
Forum section: electronics / repair

author: crazyhog
author_rank: Regular Contributor
timestamp: November 23, 2016, 05:34:41 am
content: Hi all,I got a broken Power Designs 2005A (see 2005A.jpg) power supply off ebay. I found the component that was fried to a crisp on the circuit board. The markings on it is unreadable. I also could not find the schematic for 2005A. Note the design has changed a lot from PD 2005.Can someone help identify what this fried component is (see magic smoke.jpg)? The picture is taken of the bottom of the 2005A, view from the front. The fried component is circled in red. If you have a 2005A, just remove the 4 screw from the bottom plate and you'll see it.Also, if some one can share their 2005A schematic that would be much appreciated.Thanks again.

author: crazyhog
author_rank: Regular Contributor
timestamp: November 23, 2016, 09:22:55 am
content: Cool, thank you!

author: CatalinaWOW
author_rank: Super Contributor
timestamp: November 23, 2016, 10:40:19 pm
content: Strangely, I also have a Power Designs 2005A. At least it says it is on the front and back panel. And the board layout is the same as in the Power Designs Technical Data document which comes from either of Blueskull's links. Which doesn't look like your supply at all. The first attached picture is the closest matching view I could make, while the second is a broader view of the whole board. Q8 is to the back of the board, near the end of the fuse.You may need to keep searching for a schematic and layout for a later version of the 2005A

author: timb
author_rank: Super Contributor
timestamp: November 24, 2016, 12:33:53 am
content: If you need *any* PD parts, let me know. I have all the original parts for the 2005 and 2005A including resistors, transistors and diodes. (I had a couple broken beyond repair that I disassembled into parts. I've also got meters, knobs, front panels, etc.)

author: crazyhog
author_rank: Regular Contributor
timestamp: November 27, 2016, 11:35:57 pm
content: Hi Catalina,Thank you for posting photos of your 2005A and you are right. The manual and board layout (dated 1969) found online doesn't match my power supply. From the capacitor date code, my power supply is a 1974. Strangely, the revision marking on the circuit board is Rev A and it matches the schematic!When I get a chance, I will try to reverse engineer the schematic of the circuit board. If any one with a later year 2005A, can you take a look see of the marking on the fried component on my board? I am guessing it is a TIC47 (mfr code CR24) a SCR.Thanks!

author: CatalinaWOW
author_rank: Super Contributor
timestamp: November 29, 2016, 02:16:30 am
content: Quote from: crazyhog on November 27, 2016, 11:35:57 pmYou must have gotten a very early version of the revised design. Mine has a tag which says it was purchased in 1973, and matches the 1969 documentation. That will at least narrow the date range for you as you search for updated schematics.

author: vindoline
author_rank: Unknown
timestamp: December 28, 2016, 02:29:01 am
content: Quote from: timb on November 24, 2016, 12:33:53 amHi Timb, my beloved 2005A just let out the magic smoke from the reference oven. At this point I suspect one of the transistors but don't know yet. Is there any chance you have one left over from your projects? Also, I've removed the oven from the supply and gotten the red outer cover off, but I haven't figured out how to get the reference board out of the oven tube. Do you know the trick? Thanks.

author: bitseeker
author_rank: Super Contributor
timestamp: December 28, 2016, 04:12:46 am
content: Crazyhog, that is in beautiful condition. Congrats and looking forward to hearing about your successful repair in due time.