840AV - freshly recapped ... seems ok ... started failing ... PSU?

[Apfelklassik.de]

So, I finally was able to procure an 840AV - the seller telling me, he recapped it - to no avail.

No offence, when I did have a look the solder job was not optimal.

De-capping, spending a night in IPA, recapped ... connected - the 840 sprung to life, chimed and presented me with a disc symbol and a question mark .

So far so good ... after that, I noted that it does not boot "each time", sometimes you have to multiple start - recently mostly, it starts to chime for "1/2s" and then stops.

Any ideas other than then PSU? The board actually is very clean and I didn't see any bad traces.

(Which PSU can be used to test? the PM8100 is using the same - any models with maybe the same connector?)

 

[Phipli]

(Which PSU can be used to test? the PM8100 is using the same - any models with maybe the same connector?)

I have an 8500 PSU in mine, and previously had an 8100 PSU in it. The 8100 was the same in terms of plugs, the 8500 has an extra plug, but you just ignore it. The 8500 was NOS so I was pleased.

 

[Apfelklassik.de]

Thanks!

Anyone else seen these symptoms and might have another idea than PSU?

 

[Byrd]

I had the same issue with my 840AV - recapped badly a decade ago, but didn't clean the board very well at all - at least I could blame myself. It wouldn't chime or boot without a couple of starts. PSU checked out fine. Ended up recapping and deep cleaning the custom ICs around the caps which results in a reliable chime and startup. A very soft toothbrush in IPA around these chips might assist.

 

[Apfelklassik.de]

Thanks - just did another inspection via the magnifying glass ... and the only visually "maybe unhappy" ship turned out to be U48, which did get a nice soak & scrub - also the surroundings of the other caps did get the brush again.
What I noticed is that, based on the solder marks, F6 did get replaced by the previous owner ... also also some sorcery around U5.

 

[demik]

It may be not that, but 660av/840av boards do need a stable -12V for booting. If it's not there, you only get no chime/black screen or some variants.

 

[Apfelklassik.de]

To get this out of the way ... just measured, stable +11.9 and -12.1.

And ... surprise, after the latest scrubbing it's right away booting up the ?-disk ... so I might consider another compete IPA bath ...

 

[mg.man]

The 8100 was the same in terms of plugs, the 8500 has an extra plug

Good to know. I've wondered about this, and probably could'a hunted it down, but better to know from real-world experience.

 

[Phipli]

Good to know. I've wondered about this, and probably could'a hunted it down, but better to know from real-world experience.

This was with an 8100 PSU I'd borrowed from my dad to test the 840 after repairs. I gave the 8100 PSU back when I found an 8500 one to replace it, and that is what it has now.

 

[Apfelklassik.de]

Very interesting ... after the soak & brush ... 2-3 times starting from "off" without problems. Last act: fully installing new OS with reboots etc - mo prob.
And then the same story as before started ... starting to chime and stopping after 1/2 second ... so I will most probably
a) get some distilled water and soak a night in there ... brush ... rinse
and
b) do the same again with IPA

Do we somewhere have a maintenance how-to for the CD300 Plus? It does not want to read ... lens already cleaned, laser diode "ok", too ...

 

[joshc]

In addition to cap leakage, 840AV suffer from weak solder joints / detached chips - check the legs carefully of the ICs across the board for any bad solder joints.

 

[Apfelklassik.de]

Update: CD300 Plus disassembled, cleaned, grease replaced with white lithium grease -> working again

 

[Apfelklassik.de]

Update: known good PSU ... No effect