Ampeg B-80N Repair

Ampeg_Jet-70My dad recently dropped off his guitar amp, an Ampeg B-80N from the late 70′s or early 80′s, for repair saying that it wasn’t working. It was behaving oddly, then just stopped working one day. Figuring it should be easy to fix, I gladly said I would take a look. First thing was obviously pulling it apart and seeing if anything obvious was wrong. The trick to taking these apart is to remove the speaker grill, then the 9 screws that hold the speaker on, drop it down and unplug the spade connectors on the driver. Then unscrew the amp on the back, and pull it straight off, and then pull the speaker wire out of the hole that it threads through down to the sound box. Make sure to note which lug plugs into which spade on the speaker, btw. I just snapped a quick picture with my phone.

Anyway, pulling the amp, there was nothing obvious wrong other than being a rather old design of a, I believe, class AB amp. It uses a diode pair (STV4H) to bias the output transistors, and unfortunately, that diode pair is at this point, unobtanium unless you want to spend $60 on ebay.

Okay, anywho, after the initial look, I contacted Ampeg (or rather, loudtechinc) to get the schematics, and manual for the amp. Sadly, they don’t post schematics on their site like Fender, but if you contact them, you can ask, and they’ll send you back an indemnity clause that you agree to not electrocute yourself, then they’ll send you the info. Took about 2 business days to get the schematics1.

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  1. btw, I find these old schematics funny given they use the old symbol for polarized capacitors []

Dell ATI/AMD 5870′s in Mac Pro 1,1

Dell 5870I have a couple Mac Pro’s at work (well, 3) that sit behind my desk doing render jobs, and running BOINC. They’re Mac Pro 1,1′s, so they date back to late 2006, but I’ve upgraded them with dual quad core processors, so they do okay. I’ve been keeping an eye out for ATI 5870′s to put in them for some GPU grunt, but they generally sell on eBay for $100/each. A couple weeks back, I saw someone was selling 2 for $75 total, and snagged them up. Once they got here, though, I realized an issue. They were made for some Dell, and have a weird bracket on them that you can see in the picture. It’s angled off to no doubt fit into some holder that those specific Dell’s have. Anyway, just thought I’d post that they DO work in the Mac Pro, you just have to grab a Dremel (or hacksaw) with a cutoff wheel, and after unscrewing the 12 or so screws that hold that bracket on, remove it, and cut the angled part off. Seriously, don’t try to put it off while it’s attached to the card… metal filings/dust are not great for electronics. The card then looks like a stock ATI reference card, and fits perfectly.

Make sure to throw the aluminum (aluminium) in the recycle bin. =)

Robin Williams

Robin-Williams-robin-williams-32089715-2798-2239It’s been a long time since I’ve posted anything not related to reviews, work, projects, etc, but given the news today, I thought I would post something short.

For those that don’t know, or for posterity (for myself), Robin Williams was found dead today of apparent suicide. A stereotypical comedian in many ways, he battled depression and what I would imagine was some form of bi-polarism, and for years took a lot of drugs that no doubt self-medicated. He cleaned up years ago, and since then has talked about the years he was on drugs, how he got off them, and how he was doing since.

Growing up, Bill Cosby and Robin Williams were probably my two biggest comedic influences, and certainly made me laugh more than any other people save my father. He stars in what is probably, pound for pound, my favorite Disney movie (Aladdin), and a couple of my favorite dramas (Dead Poets Society, and Good Will Hunting). And while Bill is still kicking, and is still funny, Robin will be sorely missed by a lot of people. Maybe not since Richard Pryor has the comedy world lost someone more prolific, and so influential (certainly not to me). I only hope that he knew how much he meant to so many people, and that he had some form of peace in the end.

You will be missed Robin.