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Marcin
Joined: 02 Jan 2005
Posts: 8519
Location: Poland
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 Posted: Thu Nov 21, 2019 4:01 am Post subject: |
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| ph4nt0m wrote: | | Weller WECP-20 with the longest conical tip, that's 1" ETS probably. Desoldering done with a help of another Weller, a Magnastat WTCP-S, and two pieces of a thick copper wire. The soldering process is routine, the most important part is to position the chips properly. |
Well alligned and clean job ! I use WTCP-S but at that work I would use hotair with a lot of flux. I understand you mounted thick copper wire and heated memory chip from two sides at same time ?
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ph4nt0m
Joined: 01 Jan 2018
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Location: Europe
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| Posted: Thu Nov 21, 2019 4:02 am Post subject: |
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| thehinac wrote: |
ph4nt0m's board with the replaced SRAM is 100Mhz 10ns SRAM. So I'd be interested in seeing if he could run a PF110 in bus sync mode. |
Well, if I had a PF110 or just any PF and an NxPCI board to test. If anyone has one to sell for a good price, I'm open to offers.
This mod has been done to an NxVL board with a P80 running 87MHz. It runs at this speed since I've got it in the 1990's.
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ph4nt0m
Joined: 01 Jan 2018
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| Posted: Thu Nov 21, 2019 4:04 am Post subject: |
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| Marcin wrote: | | I understand you mounted thick copper wire and heated memory chip from two sides at same time ? |
Yes, thick wire with flux and solder. SOJ chips can be desoldered easily this way.
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Marcin
Joined: 02 Jan 2005
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| Posted: Thu Nov 21, 2019 4:08 am Post subject: |
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| ph4nt0m wrote: | | Yes, thick wire with flux and solder. SOJ chips can be desoldered easily this way. |
Never heard of this but sounds very easy to use. I must get second soldering station and try this method. Thanks.
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ph4nt0m
Joined: 01 Jan 2018
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| Posted: Thu Nov 21, 2019 4:18 am Post subject: |
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I have also replaced many small capacitors around the cache which were on 5V and 4V, the latter for the processor and NxVL. Those ceramic ones were about 200nF each, put 10uF/10V instead. Tantalum and electrolytic 10uF/16V have been replaced with KEMET T494 47uF/10V industrial low ESR.
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feipoa
Joined: 08 Mar 2011
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Location: Canada
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| Posted: Thu Nov 21, 2019 4:34 am Post subject: |
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Weller ETS tips, yes that is what I generally use as well. Of all my tips, the coating doesn't last as long on this particular tip, although I use ETH most of the time.
I don't quite follow how you are desoldering these SOJ chips using thick copper wire and two soldering irons simultaneously. You are getting the solder from the SRAM module to flow off onto the thick copper rod, which is soaked in flux, by heating up the rod and placing it near the leads? Sort of like solder wick? And what's the other soldering iron for? To heat both sides of the rod? What gauge is the copper rod?
The tightest spacing IC I have desoldered and replaced was a TSOP-40 or -44 from an E28F002BC EEPROM. I haven't seen any IC's with any tighter spacing, but to desolder that, I just placed fresh solder on all the leads in a giant bridge. Did this to both sides, then kept heating both solder bridge pools up in a back-and-forth sequence until the chip would just pull right off. Not sure if this method can be done with the SOJ's on this board.
But what I have noticed when replacing SRAM on other boards with 1024K, if the system timings are just barely acceptable for stable with only 256K, then using 1024K causes instability. In which case, the FSB had to be reduced. I'm not sure if this situation can happen to a PF110 chip with 1024K, and is another reason why I'm hesitant to try this mod. Is the SOJ spacing such that sockets can be used instead?
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ph4nt0m
Joined: 01 Jan 2018
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| Posted: Thu Nov 21, 2019 4:52 am Post subject: |
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| feipoa wrote: |
I don't quite follow how you are desoldering these SOJ chips using thick copper wire and two soldering irons simultaneously. You are getting the solder from the SRAM module to flow off onto the thick copper rod, which is soaked in flux, by heating up the rod and placing it near the leads? Sort of like solder wick? And what's the other soldering iron for? To heat both sides of the rod? What gauge is the copper rod? |
The wires are covered with solder and flux in excess. Aligned on both sides of a chip and heated with both soldering irons until the chip comes off. I think a 1.2mm / 0.05" diameter wire is sufficient.
| feipoa wrote: | | Is the SOJ spacing such that sockets can be used instead? |
Not without trimming them on sides. These sockets may reduce performance though.
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thehinac
Joined: 08 Aug 2014
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| Posted: Thu Nov 21, 2019 8:40 am Post subject: |
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| feipoa wrote: | | Is the SOJ spacing such that sockets can be used instead? |
Not without trimming them on sides. These sockets may reduce performance though.[/quote]
Yeah I haven't found the smaller sockets, I've seen pictures of them but couldn't find them. So they would have to be trimmed or drimmel the areas of overlap with the other parts on the board.
I've read about that specific performance issue. It can add a couple nano seconds of latency. Also read an old report on 72 simms tin versus gold on the socket and simm. That the connection has less latency with gold. It got real techinical, read a long time ago don't remember much. So I could see it having more latency from socket versus soldered on. I had forgot about that until you mentioned it.
So I guess I'll be soldering. But I have access to a nice hot air work bench at work. But I did watch a youtube video on the copper wire approach, looks like it works very well.
Just ordered 16 chips from mouser, 8 for the pci and 8 for the vlb. Then I can compare my numbers with you apples to apples. |
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thehinac
Joined: 08 Aug 2014
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| Posted: Wed Nov 27, 2019 6:46 am Post subject: |
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Parts are in. Soon as I get a chance to solder. 
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feipoa
Joined: 08 Mar 2011
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Location: Canada
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| Posted: Wed Nov 27, 2019 7:36 am Post subject: |
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Quantity: 16. There are 2 boards. Didn't order a spare to account for goof up?
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thehinac
Joined: 08 Aug 2014
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| Posted: Wed Nov 27, 2019 7:46 am Post subject: |
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| feipoa wrote: | | Quantity: 16. There are 2 boards. Didn't order a spare to account for goof up? |
lolz yeah I did. I posted about it think on page 3 or 4. A co-worker in the engineering department ordered me one after I asked him to confirm that the pin out and properties matched and would work on the two part's PDF white pages. Before ph4nt0m posted up that they had already done this with the same part number.
The 17th part is what I plan on test soldering with. I have a Nx PCI board that's already damaged. I'm doing a test run on it by removing all the sram and soldering the one sram ic. Before I botch my working system's board. |
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thehinac
Joined: 08 Aug 2014
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| Posted: Wed Nov 27, 2019 7:55 am Post subject: |
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| I'll post up some pics while I'm doing a horrible job goofing up. lolz. Your joking happens to be right my soldering skills are shi# |
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thehinac
Joined: 08 Aug 2014
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| Posted: Fri Nov 29, 2019 6:31 am Post subject: |
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It begins.
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feipoa
Joined: 08 Mar 2011
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Location: Canada
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| Posted: Fri Nov 29, 2019 7:34 am Post subject: |
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anticipation...
Do you think doing the 1024K modification adds to the collection value (adds more cache), subtracts from it (because it was modified), or equals out in the end?
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| Posted: Fri Nov 29, 2019 11:55 am Post subject: |
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| feipoa wrote: | anticipation...
Do you think doing the 1024K modification adds to the collection value (adds more cache), subtracts from it (because it was modified), or equals out in the end? |
I'd say it depends. Being fictional in the first place is one. Being functional and can run under load for a long period with out crashing is another point for old hardware. I know for systems like Amiga's that having had a full capacitor replacement already adds to the value. If there is a proven speed change by doing the mod it may change the value is such a way that modded boards are the ones that are worth the money. But this hardware is so niche in the first place it's hard to place value on it. I have 6 nexgen boards and I'd pay 100$ extra not to have to do the sram cache switch myself. Being I'm a board purchaser myself. So I'd say it would add to the value. So long as you can prove burn-in testing on the auction. |
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