bjwil1991 wrote:

Roman555 wrote:

Yes, it would be better to remove caps from the board temporarily. And with a bottom preheater you could decrease temperature o […]
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ahtoh wrote:

I now noticed that I burned some electrolytic capacitors with the hot air so they leaked some black thing.

Yes, it would be better to remove caps from the board temporarily.
And with a bottom preheater you could decrease temperature of hot air.
Although the pads look good (not overheated, IMHO)

My suggestion for SMD chips and capacitors would be to use an SMD soldering/desoldering iron.

I agree there's special mini-wave tips to ease soldering of PQFP chips.
But it's pretty tiresome to desolder pin by pin a PQFP-160 chip with an ordinary soldering iron. With hot air soldering/desoldering is much faster.
Of course it can be done if hot air isn't in hand.

Good to know. However, removing the caps and other chips adjacent to that chip should be removed or shielded using tin foil (except for the caps) to prevent them from burning up.

You will also need some sort of low melting solder alloy like chip quik for that.
Especially if the board is lead free. not sure if PB450 is lead free though

I put some foil shield to protect the capacitors but it did not help
anyway, the new chips are arriving Friday and I will replace both chip and the caps

Any electronic used the lead solder for stronger joints. I use lead-free solder on PCB boards when I repair them, such as sound cards (fixed the NX Pro and it's still playing without issues), remote entries for cars (fixed 2 for my dad's car, one for my mom's van, but, that broke), and speaker headphone jacks.

Fixed the board today
L12 was at fault.
Probably I was too lazy checking all passives before replacing the chip
But now I have PB450 with Cirrus logic GD5429!

Congrats, man!

Brilliant - is that L12 just a link or does it perform some other function / operate as a fuse?

bjwil1991 wrote:

The L2 cache requires the following: […]
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Thermalwrong wrote:

bjwil1991: It's worrying that you've had so many issues with the L2 cache, I've been trying to get that working too but I've only got the 128KB cache and TAG RAM chip, not the DB ram chip it apparently also requires(?) Right now, it either doesn't boot with the cache fitted or doesn't detect it.

The L2 cache requires the following:

4x 32K x 8 (or 256Kb) 20ns 28-pin or 4x 128K x 8 (or 1Mb) 20ns 32-pin
1x 32K x 8 (or 256Kb) 15ns 28-pin TAG
1x 64K x 1 15ns 22-pin DB

The cache chips must match in order for it to successfully work, and I believe it goes by the BIOS string of which chips will work with it.

I'm still not able to get the cache working, I've got these chips fitted right now:
4x 32K x 8 (or 256Kb) 20ns 28-pin or 4x 128K x 8 (or 1Mb) 20ns 32-pin - 4x IS61C1024-15N
1x 32K x 8 (or 256Kb) 15ns 28-pin TAG - IS61C64AH-15N
1x 64K x 1 15ns 22-pin DB - CY7C187-15PC

The PC still can't detect any cache, and/or locks / fails to boot with the cache & tag installed. You mention that the chips should be matched, or that they need to match a specific specification, what should I look at for getting this working? Polarities are all correct to my knowledge, no burning smells on power on and the cache chips themselves are 128KB each so no issues with 28-pin chips in 32-pin sockets. Should they be the W241024AK-20 instead?

It is an Inductor

Thermalwrong wrote:

Brilliant - is that L12 just a link or does it perform some other function / operate as a fuse? […]
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Brilliant - is that L12 just a link or does it perform some other function / operate as a fuse?

bjwil1991 wrote:

The L2 cache requires the following: […]
Show full quote

Thermalwrong wrote:

bjwil1991: It's worrying that you've had so many issues with the L2 cache, I've been trying to get that working too but I've only got the 128KB cache and TAG RAM chip, not the DB ram chip it apparently also requires(?) Right now, it either doesn't boot with the cache fitted or doesn't detect it.

The L2 cache requires the following:

4x 32K x 8 (or 256Kb) 20ns 28-pin or 4x 128K x 8 (or 1Mb) 20ns 32-pin
1x 32K x 8 (or 256Kb) 15ns 28-pin TAG
1x 64K x 1 15ns 22-pin DB

The cache chips must match in order for it to successfully work, and I believe it goes by the BIOS string of which chips will work with it.

I'm still not able to get the cache working, I've got these chips fitted right now:
4x 32K x 8 (or 256Kb) 20ns 28-pin or 4x 128K x 8 (or 1Mb) 20ns 32-pin - 4x IS61C1024-15N
1x 32K x 8 (or 256Kb) 15ns 28-pin TAG - IS61C64AH-15N
1x 64K x 1 15ns 22-pin DB - CY7C187-15PC

The PC still can't detect any cache, and/or locks / fails to boot with the cache & tag installed. You mention that the chips should be matched, or that they need to match a specific specification, what should I look at for getting this working? Polarities are all correct to my knowledge, no burning smells on power on and the cache chips themselves are 128KB each so no issues with 28-pin chips in 32-pin sockets. Should they be the W241024AK-20 instead?

The first 4 chips should be 20ns, and the rest are correct, yes.

Most likely you have fake Chinese cache chips

ahtoh wrote:

Most likely you have fake Chinese cache chips

Given where I got them from, that seems plausible, so I'll test with some from another board. The Db chip was the most troublesome to get hold of, is the one I got correct?

The flux on that L12 chip looks a bit odd, good to know

Thermalwrong wrote:

The Db chip was the most troublesome to get hold of, is the one I got correct?

any 64Kx1 chip should work

I bought my chips here
1. https://www.ebay.com/itm/1-AT-T-ATT7C187P-15- … =item4ab6180cca
2. https://www.digikey.com/product-detail/en/idt … 3674-ND/2011023
3. IS61C1024 on ebay from china (you will need some luck finding working chips)

If you order from digi-key make sure you order 1225 battery holder
https://www.digikey.com/product-detail/en/BH5 … BH501-ND/557808

ahtoh wrote:

If you order from digi-key make sure you order 1225 battery holder
https://www.digikey.com/product-detail/en/BH5 … BH501-ND/557808

Good to know. Planning on doing just that as my temporary solution is a 2x AA battery pack that serves as a CMOS battery soldered to the board (the pack is far away from the board in case the acid leaks out). Also, someone on eBay is selling that type of board with the battery holder and in fantastic shape as well. Glad you got the system working, man.

that's me on ebay
I have two working boards now
Selling one of them

ahtoh wrote:

Fixed the board today L12 was at fault. Probably I was too lazy checking all passives before replacing the chip But now I have P […]
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Fixed the board today
L12 was at fault.
Probably I was too lazy checking all passives before replacing the chip
But now I have PB450 with Cirrus logic GD5429!

Good news 😀 I'm glad to know!
Now I see the thick trace goes from the choke L12 to the cap C76 and further under the graphics chip.
I guess the chip didn't have power supply.

Now when I upgraded the graphics chip I'm thinking about upgrading to Intel DX4 100
I believe I would need to do a 3.3v mod for that. the board is supposed to support that voltage, but the LDO components are not soldered.
Has anyone tried that with this board?

I haven't done that yet, but, I purchased a DX4-100 OverDrive that supports 5V. Next to the CPU socket would have the voltage regulator on there, but, I believe it requires resistors for it to function.

Overdrive chips are expensive, LT1085 LDO chip is not ($7 at digi-key), there is also a fixed variant LT1085CT-3.3 that does not require resistors.
So you would only need a chip and a few smd tantalum capacitors that I can scavenge from some other board.
The only problem is to get proper isolation because the case of the chip is connected to the output, and the pad on the board is connected to the ground. So it will require some isolator and a bolt to get proper heat dissipation.

Good to know. I paid $20 for mine last year. Maybe I should put the voltage regulator on the motherboard. Are the capacitors, isolator, bolt, and the other chip (LDO) only required if, for example, I'm making a voltage regulator that goes between the CPU and the motherboard, or am I wrong about that?