Apple Performa 460 won't start

[Mr Fahrenheit]

I've got a beige G3 that won't power on without a PRAM battery. If I used the machine more, I'd probably replace it with a Lithium-ion rechargeable and fit one of those cheap charging controllers on it.
Similarly, my Performa 6200 is a brick without a PRAMattery.

I also have experienced beige G3's not booting without a good PRAM battery. In fact, when a battery goes flat, and you attempt to boot, it seems it can corrupt the on-board power management unit, necessitating a CUDA reset.

Power Macintosh g3 All in One Beige boot … - Apple Community

discussions.apple.com

 

[3lectr1c]

I remember hearing some other people having issues, maybe something to do with a certain board revision? It certainly isn't all of them.

 

[tonata]

I have put a brand new SAFT battery (identical to the original) and the only thing I get is some noise from the speaker after a few seconds.
The voltages are of the power supply (not connected):

+ 5.33 (instead of +5)
+ 11.1 (instead of +12)
- 3.3 (instead of -5)

I am trying to find the schematics for the power supply. I am not sure if replacing the capacitors will be enough to fix the power supply.

 

[Mr Fahrenheit]

I have put a brand new SAFT battery (identical to the original) and the only thing I get is some noise from the speaker after a few seconds.
The voltages are of the power supply (not connected):

+ 5.33 (instead of +5)
+ 11.1 (instead of +12)
- 3.3 (instead of -5)

I am trying to find the schematics for the power supply. I am not sure if replacing the capacitors will be enough to fix the power supply.

Two things:
1. These 'LC' boards really do need a recap these days.
2. The PSUs in the LC Macs are basically all failing by this point. Recap or replace.

In regards to replacing the PSU in the LC Macs, the Mean Well RPT-60a is the best option for a simple, cost-effective, working replacement for the guts inside the PSU housing. You can either solder the leads directly into the PSU, or you can source some connectors and solder those onto the original wiring harnesses (AC side and DC side going out to logic board).

There is a forum post over at 68kmla where a user there has successfully done it:

Replacement Power Supply in Quadra 605

the power supply in my souped up Quadra 605 died, and i am too lazy to recap it. (Q605 is recapped with tantalum, HD replaced with SD card, pretty new VRAM, 128MB RAM, and a full 68040) Following knowledge from a thread on TinkerDifferent I searched out a MeanWell RPT-60A, a small power supply...

68kmla.org

The Mean Well PSUs can be sourced on AliExpress, eBay, Amazon, and are on backorder with Mouser (quoting May delivery). Cost is somewhere around $30-40 USD which is pretty reasonable considering the cost of recapping the original, with mixed results.

 

[Mr Fahrenheit]

I remember hearing some other people having issues, maybe something to do with a certain board revision? It certainly isn't all of them.

Reseating the personality card, and the power regulator, often also helps. I've found once I can get mine to boot, it boots perfectly every time. If the battery dies or has been removed, getting mine booted is a painful experience of trying multiple things before it works again. And this is on a recapped G3 board, with a good, working, ATX PSU (with proper jumper set on the logic board).

 

[tonata]

Two things:
1. These 'LC' boards really do need a recap these days.
2. The PSUs in the LC Macs are basically all failing by this point. Recap or replace.

In regards to replacing the PSU in the LC Macs, the Mean Well RPT-60a is the best option for a simple, cost-effective, working replacement for the guts inside the PSU housing. You can either solder the leads directly into the PSU, or you can source some connectors and solder those onto the original wiring harnesses (AC side and DC side going out to logic board).

There is a forum post over at 68kmla where a user there has successfully done it:

Replacement Power Supply in Quadra 605

the power supply in my souped up Quadra 605 died, and i am too lazy to recap it. (Q605 is recapped with tantalum, HD replaced with SD card, pretty new VRAM, 128MB RAM, and a full 68040) Following knowledge from a thread on TinkerDifferent I searched out a MeanWell RPT-60A, a small power supply...

68kmla.org

The Mean Well PSUs can be sourced on AliExpress, eBay, Amazon, and are on backorder with Mouser (quoting May delivery). Cost is somewhere around $30-40 USD which is pretty reasonable considering the cost of recapping the original, with mixed results.

Thank you! I think I am going to do that!
I see that RPT-60a costs 22 euros (tax not included I suppose) on the site of Mouser fr:

Tension de sortie - canal 1:	5 VDC
Tension de sortie - canal 2:	12 VDC
Nombre de sorties:	3 Output
Alimentation en sortie:	46 W
Courant de sortie - canal 1:	4 A
Courant de sortie - canal 2:	2 A
Longueur:	101.6 mm
Largeur:	50.8 mm
Hauteur:	29 mm
Courant de sortie - canal 3:	500 mA
Tension de sortie - canal 3:	- 5 VDC

Sorry if it is in French.
5V is 4A instead of 4.75A as it is the original. Would this be a problem?
It also fits in the original case. Nice!

 

[GiGaBiTe]

5V is 4A instead of 4.75A as it is the original. Would this be a problem?
It also fits in the original case. Nice!

I wouldn't go under the current limit of the original PSU. Those pizza box PSUs were already on the knife edge of being enough, especially on the higher power 68040 machines. There's also derating to worry about from heat.

You may get away with it if you ditch the SCSI hard drive and use a BlueSCSI or other solid state media.

 

[Mr Fahrenheit]

Thank you! I think I am going to do that!
I see that RPT-60a costs 22 euros (tax not included I suppose) on the site of Mouser fr:

Tension de sortie - canal 1:	5 VDC
Tension de sortie - canal 2:	12 VDC
Nombre de sorties:	3 Output
Alimentation en sortie:	46 W
Courant de sortie - canal 1:	4 A
Courant de sortie - canal 2:	2 A
Longueur:	101.6 mm
Largeur:	50.8 mm
Hauteur:	29 mm
Courant de sortie - canal 3:	500 mA
Tension de sortie - canal 3:	- 5 VDC

Sorry if it is in French.
5V is 4A instead of 4.75A as it is the original. Would this be a problem?
It also fits in the original case. Nice!

The LC475 had a beefed up power supply, compared to the Performa 450/460 (basically LC3). What does the PSU that you have show? Does it show 4.75A? Because earlier LC models used a lower spec PSU than the LC475 model.

 

[tonata]

The LC475 had a beefed up power supply, compared to the Performa 450/460 (basically LC3). What does the PSU that you have show? Does it show 4.75A? Because earlier LC models used a lower spec PSU than the LC475 model.

My computer is Performa 460.
The original power supply is:

Dyna Comp 614-0028
Max continuous power output: 36W
+5 is 4.75A
+12 is 1.0A
-5 is 0.075A

 

[Mr Fahrenheit]

My computer is Performa 460.
The original power supply is:

Dyna Comp 614-0028
Max continuous power output: 36W
+5 is 4.75A
+12 is 1.0A
-5 is 0.075A

I think using the Mean Well power supply with 4A on 5v is only a concern if you install a PowerPC processor upgrade in a 475 and use this power supply, or if you install a PDS card that is very power hungry.

There are many people using the Mean Well RPT-60a inside an overclocked 475/Q605 machine, with full FPU, and everything "works fine". That being said, it's possible the pool of users isn't big enough to be 100% sure that it won't cause an issue. Generally speaking, people say this power supply is "just fine" as a replacement, without issue. I have some, but haven't installed them yet inside any (lack of time).

 

[tonata]

I changed all the radial capacitors and there was no change in the voltages:

+ 5.33 (instead of +5)
+ 11.1 (instead of +12)
- 3.3 (instead of -5)

There are 3 transistors that might be worth replacing.

 

[tonata]

Actually my fault. I was measuring the voltages without load.
When connected the power supply it worked as expected. The Mac is starting without problem. Next step is replacing the HDD.