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Re: General Stuff(tm)
Posted: 09 Oct 2022 18:25
by Icky
stephen_usher wrote: 09 Oct 2022 08:17
I’ve ordered another add board for the RGB2HDMI, £35 quid via SellMyRetro.
Our hobby is an expensive one when things go wrong. Just read this thread and something you would never expect to see 25V p-p in these machines.
Glad it’s not fried the lot.
Re: General Stuff(tm)
Posted: 10 Oct 2022 09:29
by mrbombermillzy
That was really bad luck. :(
Like you say though, it could have been worse.
Re: General Stuff(tm)
Posted: 10 Oct 2022 09:45
by rubber_jonnie
stephen_usher wrote: 09 Oct 2022 08:17
I’ve ordered another add board for the RGB2HDMI, £35 quid via SellMyRetro.
An expensive thing to have to replace, but it could have been a lot worse I guess.
Also good to show other people this sort of thing can happen to anybody.
Re: General Stuff(tm)
Posted: 12 Oct 2022 17:48
by stephen_usher
The replacement 12 bit board for the RGB2HDMI arrived today and thankfully that's fixed the problem. *phew!*
The main board is getting problematic due to it using a CPLD.
IMG_2820.jpg
Re: General Stuff(tm)
Posted: 16 Oct 2022 17:14
by stephen_usher
Designing a 6 pin DCC adapter board for old (late-70s/80s) locos.
Forget most of those pins as they'll just be wires.
No bigger than the old Zero-1 modules.
Hornby-Ringfield-DCC6-Adapter.jpg
Re: General Stuff(tm)
Posted: 19 Oct 2022 14:44
by stephen_usher
Impressive delivery speed from RS Components today.
Last night I put in an order for a load of PCB sockets, diodes and spade connectors. This was done at about half eight, so I didn't expect anything to be dispatched until today. At 10:30pm I got a dispatch e-mail and today at lunchtime the stuff arrived!
Re: General Stuff(tm)
Posted: 22 Oct 2022 13:27
by stephen_usher
The DCC decoder adapter PCBs are in Oxford now and so should be delivered on Monday.
Having got the DCC decoders themselves I can see that I could make the PCB quite a bit smaller, maybe for Mk.II if I do one.
Re: General Stuff(tm)
Posted: 23 Oct 2022 14:37
by stephen_usher
As I had it on the bench and I had an oscilloscope handy I thought I'd investigate the voltage output from my old Hammant & Morgan Duette model railway controller, given that one of the manufacturers of a new train advised against using such old controllers.
Well, I see why now.
The unit is merely using a bridge rectifier. The nominal 12V DC is actually unfiltered full wave rectified 24V, giving an average of 12V but with 100Hz 24V sinusoidal peaks.
Testing using a 440uF cap on the tracks shows that adding a cap would flatted this out, you just can't stick an electrolytic on the line as the voltage can be reversed. So, any fix would have to take place on the inside... But the case is fully steel and pop-riveted together. *sigh*
I may drill out the pop rivets and find some small self-tappers to replace them. Then I can look inside to see if I can fit some big caps to smooth out the voltage.
Re: General Stuff(tm)
Posted: 23 Oct 2022 14:39
by rubber_jonnie
stephen_usher wrote: 22 Oct 2022 13:27
The DCC decoder adapter PCBs are in Oxford now and so should be delivered on Monday.
Having got the DCC decoders themselves I can see that I could make the PCB quite a bit smaller, maybe for Mk.II if I do one.
Nice, I should have my Aquarius composite mode PCBs on Monday too :)
Re: General Stuff(tm)
Posted: 23 Oct 2022 14:41
by rubber_jonnie
stephen_usher wrote: 23 Oct 2022 14:37
As I had it on the bench and I had an oscilloscope handy I thought I'd investigate the voltage output from my old Hammant & Morgan Duette model railway controller, given that one of the manufacturers of a new train advised against using such old controllers.
Well, I see why now.
The unit is merely using a bridge rectifier. The nominal 12V DC is actually unfiltered full wave rectified 24V, giving an average of 12V but with 100Hz 24V sinusoidal peaks.
Testing using a 440uF cap on the tracks shows that adding a cap would flatted this out, you just can't stick an electrolytic on the line as the voltage can be reversed. So, any fix would have to take place on the inside... But the case is fully steel and pop-riveted together. *sigh*
I may drill out the pop rivets and find some small self-tappers to replace them. Then I can look inside to see if I can fit some big caps to smooth out the voltage.
I'd be interested to see the inside of the controller if you do decide to pull it apart.