Help needed with troubleshooting a dead GVP A530 Turbo sidecar please

[Magic]

I recently picked up a GVP A530 Turbo side car as not working with the hopes of getting it running. When I connect it to my A500 the machine boots fine from a floppy with the A530 Turbo switched off. With the A530 Turbo switch turned on the A500 will not boot. The power LED on the A500 stays dark but all the LEDS on the 530 work fine and the HD spins up too. During this time the CAPS lock light is the only thing lights on the A500 - but it only lights when the caps lock button is pushed. It is not flashing. I measured the voltage at the inside of the power connector on the GVP mainboard and it is 12.20 volts and 4.97 volts with the Turbo switch in both positions. Does anyone have an idea of what to do next? I have a pretty complete shop with a scope, soldering tools, etc. The GVP is configured with 4 megabytes and all of the jumpers look correct. I have also tried a different A500 with the same results. I tried with the HD disconnected too. It seems to be a hardware fault with the GVP mainboard.

Thank you
Jeff

 

[mjnurney]

The first port of call is to check that the board has no damage at all. burnt , missing or fried parts? Are all the socketed chips clean and fitted properly ? Then id probably strip out all the parts not required for booting.

Have you taken the board out to inspect it?

I don't have a 530 or i would offer to take a look for you.

mike.

 

[Magic]

Several minutes with a multimeter in the power section of the board and I found component FC6 was open, it looks like a 47uf 16v smd capacitor. I replaced it with a radial cap of the same value and it started right up! Time for a good cleaning now

[EDIT] I guess I should have searched here first! The answer was already here if I would have searched a little better. This must be a common problem with these.

 

[Cryton]

Glad you found it mate these are lovely things and I'm quite jealous lol.

It would be good to try and get a data base with equipment and their associated faults and how/if people have managed to solve them. Maybe add list of parts etc and have links to modification and upgrade projects ..... wow that sounds like a big job

 

[CodePoet]

Several minutes with a multimeter in the power section of the board and I found component FC6 was open, it looks like a 47uf 16v smd capacitor. I replaced it with a radial cap of the same value and it started right up! Time for a good cleaning now

[EDIT] I guess I should have searched here first! The answer was already here if I would have searched a little better. This must be a common problem with these.

did you test the cap in-place, or did you desolder and test? My system "clicks" but doesn't do anything, and no LEDs light up

 

[CodePoet]

There are 4 of those same capacitors on the board - using just simple resistance probe, 3 out of 4 would beep my multimeter, but FC6 was infinite/open - just like the OP saw. I'll also try a radial cap that I have on-hand and see what happens

 

[Dale423]

There are 4 of those same capacitors on the board - using just simple resistance probe, 3 out of 4 would beep my multimeter, but FC6 was infinite/open - just like the OP saw. I'll also try a radial cap that I have on-hand and see what happens

Is it the relay? Those often fail.

 

[CodePoet]

Is it the relay? Those often fail.

not sure yet, but i also read up where FC6 fails and can be replaced. I'll start with FC6 (its cheap), and if that doesn't work i'll order a relay (about $15 with shipping)

 

[Dale423]

I have a DOA A530 that also has FC6 open. Can you guys share what part you replaced it with? I am not that good with sizes and such.

 

[CodePoet]

I have a DOA A530 that also has FC6 open. Can you guys share what part you replaced it with? I am not that good with sizes and such.

let me get back to you on Sunday? I'll have an update by then

 

[Dale423]

let me get back to you on Sunday? I'll have an update by then

Any update @CodePoet ?

 

[CodePoet]

Any update @CodePoet ?

I let you know the part from Mouser over on Discord / Acill. Mine should arrive tomorrow, but i have little hope. Replacing with a radial that I had on hand didn't resolve things. I have the relay coming this weekend and will try replacing that as well. I'm suspicious of my PSU/etc as well, as it isn't the original GVP PSU