SGI: Hardware

Not SGI related but I need to hack in a battery to a Dallas DS1235YW thats throwing checksum errors in my HP 54501A digital oscilloscope. The datasheet I found puts pin 14 as GND and pin 28 as Vcc +5v. There is no Vbat or Vgnd pins as in the 1397. Am I screwed?

find a creative way to always keep it powered (5V) from a Li-Ion or something, it will "think" the Scope is always on, so won't lose its contents. This probably draws 0.1W, so any 5V Li-Ion will probably work for months. Do you think you can't source a "new" DS1235YW?

This Scope is top-notch though, so please don't ever throw it away.

Is it a "tophat" type similar to the other Dallases and MOSTEK units? If so, then there's probably a crystal and battery in the tophat and a little creative excavating will allow you to get at one of the two batteries (and since it claims to automatically switch it should ignore the dead batt).

I'd look at either of the two "end" sides for hidden pins. X-ray would work great (are you friends with a dentist?), but you might be able to track it magnetically too (or just take a guess based on how the potting compound goes).

@mia, I found I can replace it with a DS1230Y, problem is it's not socketed and I don't have a de-soldering tool. Keeping it powered as you suggest might be the easiest solution, and yes, it's a great piece of equipment.

@saq, It's the 28-pin black encapsulated package, I'll give the magnet trick a try.

I did order a DS1230 but it's coming from Hong Kong and no telling when it will arrive, so I don't want to screw around with the 1235 until it gets here. The scope still works, I just have to re-calibrate it every time I turn it on and if I do all four channels it takes about 35 minutes to calibrate.

I did a quick fix the other day, hacked in a bank of AA NiMh batteries in a holder, seems to be doing the job. I have a Dallas DS1230 on order from Hong Kong but no telling when it will arrive. SAQ, I tried your magnet trick on the old one, no dice. I also tried getting the old DS1235 out without any luck, my de-soldering bulb and wire rope doesn't seem to be cutting it. I didn't want to f**k up the PCB and stopped for now. What's the best way to get this thing out?

Too bad you're not here ... every little shop in the computer 'burbs has a three-axis chip-remover and resolderer. About a third of them have microscopes. They can't be very expensive ... is there a market for such things in the US ?

I've ended up taking a dremel directly to a Dallas chip on an IO4 while it was still soldered to the board.
Talk about sweaty fingers.

I hear many roflcopters flying overhead

Unfortunately the hack didn't work, two hours later it was throwing checksum errors again and the batteries were dead. So I'm left with dremeling out the old one or replacing it Guess I'll try the $20 solder sucker next.

I take it that's a no

I'm wondering why tho ? People don't fix things in the US ? It seems like every little computer place in baoshan has one of these - simple x-y table and some sort of heating element to remove and replace chips. They can't be very expensive. If I hadn't been so lazy I'd have taken the Fuel mainboard over to do a pinball enviro-chip replacement.

With the time and effort involved its not worth repairing consumer gear. Would you really spend two hours troubleshooting and reflowing chips on a motherboard that costs $60? Although you could probably make decent cash by reflowing Xbox 360s.

So kshuff gets to throw out his HP digital oscilloscope because a $2 chip died.

Now that is a forward-looking sensible economic model.

This reminds me of a place which was throwing away managed 24-port ethernet switches every couple of months because a single capacitor overheated and died

It worries me that people today would rather waste $300 on a new switch than spend five minutes to desolder a capacitor and solder in a $0.15 replacement.

Might even work on a Fuel mainboard. But these things don't work for thick PCBs with many layers and thick ground planes (like the IO4 'pentium' mentioned). I really tried, and with proper, professional equipment (we have a decent lab at $WORK). Either you put enough power/heat into the PCB to melt the solder, but also cause enough thermal stress to crack a couple of VIAs in the process, or you they keep the PCB intact, but you're unable to remove the component.

I can think of two ways to remove a Dallas from an IO4: you put the entire board in a reflow oven *or* simply cut all the legs of the component and then use a precision drill and/or desoldering equipment to remove the remains.

IMHO, if you want to keep your equipment for a little longer than the warranty period, these Dallas chips are fundamentally flawed:
* They run out of battery before I'm ready to give up on the equipment
* Removing them from a PCB often is a pain
* If you're lucky and they still manufacture the one you need, the problem is going to come back in a couple of years ...
* ... and by they you almost certainly won't be able to buy a compatible Dallas and you'll need to find another solution anyway.

Better bite the bullet and fix this problem *right now* (i.e. CR2032 mod).

BTW: I opened my IBM TotalStorage DS4300 (SAN server) the other day to clean the FC backplane connectors after I bought some new disks. Thickest PCB I've ever seen.

If you zip all of the legs off of the chip, why can't you just desolder the pins one at a time and clean up the holes with a wick? That's what I would do... Or is that what you were implying with "precision drill and/or desoldering equipment"

in fairness, not too many people keep a 54000 series o-scope around. People are much more impressed when you are able to replace the battery in their ipod in exchange for beer and pizza money

Never going to happen, I'll get something to work, I love this scope and my little Tektronix 211's. I finally let go of my old Tek 549 though, it found a good home.

Heh - you guys should invite Tony Duell from classiccmp to chime in, but I'm not sure how well nekochan works when you're using an ASCII-based web browser...

Fixed, it's happy again. The new DS1230 arrived today. What a PITA getting the old one out but the crappy chinese solder sucker did the trick, had to go over each pin three times to get all the solder out. Soldered in a socket, popped in the new Dallas, working again Holds calibration now.