Digi 003 Controller- Issues with power sequence- Too Many Relay Clicks

Link555

Well-Known Member
Joined
Mar 31, 2007
Location
North Vancouver
This baby came in for a little inspection this week. The owner was worried that it was a ticking time bomb, as the start sequence would randomly take longer some days and not others. He mentioned, when cold, the unit could take 7-to 15 relay clicks to start. When warm and operating normally he would hear 3-5 relay clicks.

I was able to experiences this extended start up the first time I turned it on, I counted 7 clicks, but it did start. I turned it off and back on, and it took three clicks to boot.

I took it apart, and have to say it is a pretty well thought out design. Clearly significant thought went into the manufacturability and repair of the unit. Someone had already been inside, as I found a broken screw and several stripped machine screws.

Inside this is what I saw:


IMG_9480.JPG


Lots of ribbons and tight interconnection wiring. The clicks were coming from two relay control boards.
IMG_9491.JPG

I could not tell exactly what relays were clicking in by ear, but certainly the wiring was tight.
IMG_9483.JPG


I removed the ribbons one by one and inspected the pins, no really signs of oxidation or corrosion. I reseated them a few times. I restarted the unit cold and no real change, it still started slow.

I then removed the cable interconnects and inspected the connectors, nothing clearly visible. I reseated the connectors a few times. And retried the unit. 4 clicks to start...hum maybe it was warm. I let it cool down a bit. My garage is not heated so 15 mins later I tried it, 4 clicks again. Could that be all it was?

I am not sure if that is truly all it was, but I put it back together. And will try again today...
 

Boswell

Moderator
Joined
Apr 19, 2006
Location
UK
Did you manage to check what the power rails were doing during the abnormal clicking start-up?
 

Davedog

Well-Known Member
Joined
Dec 10, 2001
Location
Pacific NW
I'm not a repair guy but I play one when I have to crawl around under the console furniture....Isn't it ALWAYS the ribbon connections? LOL
 

Link555

Well-Known Member
Joined
Mar 31, 2007
Location
North Vancouver
I measured the rails, 54Vdc, 17VDC, -17VDC, 5VDC, 3.5VDC and I think 3.3VDC during start up, nothing sagged or ramped up. The second relay click seems to turn all rails on everytime. I can't see any cap issues physically either...
 

Boswell

Moderator
Joined
Apr 19, 2006
Location
UK
That all looks reasonably OK.

Can you reproduce the condition that had the irregular number of start-up clicks? Maybe it simply did require re-seating of connectors, although that wouldn't be the first time that going though a re-seating process has cured mysterious irregular and intermittent problems.
 

Link555

Well-Known Member
Joined
Mar 31, 2007
Location
North Vancouver
On the first start up I did, but the rails behaved the same as they did in a "normal" start up sequence. After it warmed up I could not get more then 4-5 clicks. It's strange that the relay click sequence seem to change with every start up.
 

Link555

Well-Known Member
Joined
Mar 31, 2007
Location
North Vancouver
Found it! It took along time and a lot of power cycles to find but it was a bad cap as Boswell suggested! it was hiding well working 9 times out of ten. Now with the single cap changed, it starts up in the same sequence every time.
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