GVP A530 PSU - not having any luck

[StompinSteve]

Hi Richard,

The +5V wire on the GVP's mainboard indeed goes to the left hand pin (pin 3) if looking at the female socket from behind/inside.

Btw. the wire colours are different in my unit (compared to that picture on BBOAH). My +5V cable is yellow, +12V is orange and the two middle cables are blue.
Those 4 wires go directly to the HDD's Molex power connector by the way.

Disclaimer: I'm not going to open this GVP A530 again. It's very fiddly to close the case with the RF Shield in place. I gave it a final clean to prep her for the sale and that's it.

[cbm600p-richard]

reminds of me of commodore with their own c64 power supplies, they used to use all sorts of different colour cables on the same power supplies, so you always had to check the voltages and you could never presume the voltages!

theres a couple of sellers , selling a gvp power supply online now, heres one of them,
https://www.ebay.co.uk/itm/166354696998

[StompinSteve]

Originally Posted by cbm600p-richard

theres a couple of sellers , selling a gvp power supply online now, heres one of them

That is them. That is the company the sold me mine!

The Amps specs are correct now. The casing is different this time. I guess they found a PSU with the correct +5 and +12 Voltages and Amps as the base for their plug-modification.

They put a sticker over the original print this time. It clearly states the voltages and amps so that is good.

They also included a picture of their pin-layout diagram this time. If you look carefully, they say that pin 4 (normally -12V) is N/C "not connected".
I bet they will tell you that the A530 will work just fine without -12V.

Not my cup of tea though. I expect a replacement PSU to fully adhere to the original specifications. But maybe that's just me.

[cbm600p-richard]

so are you selling because you cant get a psu ? how much are you looking to sell it for, has it ever been tested before? or did the last seller sell it to you becasue it was broken and untested. there is a lot of ebayers around who 'throw away their psu' and get rid when it tem doesnt actually work. i can send you a pc power supply with the end fitted correctly and -12v if you really want just cover my costs

[Jope]

Originally Posted by StompinSteve

I bet they will tell you that the A530 will work just fine without -12V.

What stops working when you don't have -12V?

[StompinSteve]

Originally Posted by Jope

What stops working when you don't have -12V?

I'm not qualified to answer that question on a technical level. But why would a manufacturer design a product and a PSU for it with -12V, when it is unnecessary.
It makes no business sense to add extra cost and complexity to a product so they must have had a good reason.

[StompinSteve]

Originally Posted by cbm600p-richard

so are you selling because you cant get a psu ? how much are you looking to sell it for, has it ever been tested before? or did the last seller sell it to you becasue it was broken and untested.

It's all in my openening post. Copy-pasting the relevant part here:

Originally Posted by StompinSteve

I have restored a GVP A530. It was sold without a PSU and as "broken / spare parts".
I already have an A530 (restored years ago) in which I put a ZuluSCSI and a FPU. I borrowed its (original GVP) power-supply to get this A530 up and running. Worked fine.

This A530 is completely original. The 120MB HDD works perfectly and it even has the original RF-Shield and cardboard insulator for the Mini-slot. I have never seen an A530 which is so complete.
She was grubby and dusty but after a thorough cleaning, looks beautiful again.
I also upgraded the memory from the 1MB it shipped with, to the full 8MB (A Gentleman in Denmark builds new SIMM's for the A530 and it works great).

I don't intend to keep this A530 (keeping my ZuluSCSI equipped one) so I need a PSU for it. What good is it, without a PSU.

I will be putting it up for sale, incl. my original GVP PSU, on AmiBay when i'm ready (I have a lot on my plate at the moment).

My ZuluSCSI'fied A530 will, from then on, be powered by the modern Amiga 500 PSU i'm converting the plug on. It has all the right volts, amps and oompf's , i just need to swap the square plug for the correct round one and solder the right wires to the right pins.

[Jope]

Originally Posted by StompinSteve

I'm not qualified to answer that question on a technical level. But why would a manufacturer design a product and a PSU for it with -12V, when it is unnecessary.
It makes no business sense to add extra cost and complexity to a product so they must have had a good reason.

Must have been for future expansion that was never made, then they started shipping these with PSUs that only do +5 and +12. :-)

[cbm600p-richard]

>be powered by the modern Amiga 500 PSU i'm converting the plug on. It has all the right >volts, amps and oompf's

check the -12v has enough amperage through it, i think original amiga psu only provided 100ma (for the sound i believe)
i would also more importantly check the +5v and +12v under load on your amiga psu before plugging it in

[StompinSteve]

I'm converting this modern A500 PSU for use with the A530. Should have enough powahh.
(I use one with an A500Plus and GVP A500-HD8+ (with ZuluSCSI) with the "power via Zorro" solder-Mod (no external PSU needed for the HD8+)

https://www.ebay.ch/itm/123973829594?var=424773591392

[levo-ace]

The only answer I can see is for somebody to trace the -12v rail and see if it actually connects to anything . Somebody with one of these must have a meter , and the knowledge to do such .


There are chips that can be discounted from this check as they have no -12v connection .
CPU , FPU , any 74 series logic , memory and SCSI controller .

That should narrow it down quite a bit .

[Lockon]

You have +5V and +12V on the edge connector, perfectly usable for bridging to the power relay near power (DIN) socket. A500 will boot just fine if your storage is either SCSI/SD or SCSI/IDE based one.

[StompinSteve]

Originally Posted by Lockon

You have +5V and +12V on the edge connector, perfectly usable for bridging to the power relay near power (DIN) socket. A500 will boot just fine if your storage is either SCSI/SD or SCSI/IDE based one.

True for the GVP A500-HD8+ (fan removed and with a ZuluSCSI in my case) but when you also have a CPU, FPU, a cooling-fan and all the other stuff in the A530 that the HD8+ does not have, does the edge-connector deliver enough power for all of that?

The power mod on the GVP A500-HD8+ is well documented (bridging two specific solder-points etc.). Can't find similar info about the A530 though.

(always using a beefed up, modern A500 PSU instead of the weak original Commodore PSU)

[Lockon]

I'm away from home, but in next few days I might be able to take some high res shots of PCB side.

It has CPU/FPU/FAN, 2 GVP SIMS, Acard SCSI/IDE bridge, IDE/CF bridge. 4.5A original (heavy power brick) so it was OK for me. IIRC, same PSU actually supported external Yamaha CDRW signaling connected on back side of A530, then A500 clockport with active Subway USB and Dlink USB-to-Ethernet bridge, all in same time.

These pics are from 2008 when I completed all components into fully working setup.



Update:





Red wire is connected to pin#5 and pin#6 to get +5V since that's our major power draw.
Orange wire is connected to pin#10 to get +12V.