My recently acquired EAD TheaterMaster Classic Pre/Pro often stops operating when turned on. It always powers up, but it seems to freeze and won't fully turn on. Then again sometimes it will. I use it only as a 2-channel preamp and the sound is truly stellar.
Schematics apparently are unavailable. Could be a PS cap, but it's pretty complicated in there and while I have successfully recapped vintage amps, this is another animal altogether. Plus, no bottom access cover, so a major disassembling would be needed.
Not sure if it's worth the $$ to have it serviced by Noble Electronics, who are comprised of some of the original EAD staff, plus it's heavy and shipping will add another $100 to the cost.
Has anyone had a similar issue with one of these units?
Thanks!
Schematics apparently are unavailable. Could be a PS cap, but it's pretty complicated in there and while I have successfully recapped vintage amps, this is another animal altogether. Plus, no bottom access cover, so a major disassembling would be needed.
Not sure if it's worth the $$ to have it serviced by Noble Electronics, who are comprised of some of the original EAD staff, plus it's heavy and shipping will add another $100 to the cost.
Has anyone had a similar issue with one of these units?
Thanks!
Attachments
Thanks for looking so closely. Actually that's from the wires that go to a cooling fan mounted in the middle of the top cover (the two wires can be seen in the pic). Sometime during the life of this unit it was upgraded with Black Gate caps (on the Teflon Boards to the right) and the wires from the fan to the mother board must have been cut and the wire nuts installed.
When I took the cover off to take the pic I pulled the wire and knocked the wire nuts off.
But thanks again for looking so intently, and please let me know of anything else that catches your eye.
When I took the cover off to take the pic I pulled the wire and knocked the wire nuts off.
But thanks again for looking so intently, and please let me know of anything else that catches your eye.
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Sometimes it just won't turn on completely from a cold start. Would that still indicate a heat issue? You can see that one of the heatsinks for the voltage regulators (or power transistors or whatever they are) is a little different color but when it is running and I feel the sinks it doesn't seem like one is substantially hotter than the others - for whatever that observation is worth.
I'll try the spray - any particular place you would suggest?
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No then. Color change is common and not related, just different dye depths in the anodizing process.
I would start with the most stressed area, the PS and its output. Without a schematic, try seperating all boards, even unsoldering them for inspection, taking pics so you don,t lose your way. Clean all connections with Deoxit
A powerful lens of some kind for visual inspection with plenty of light for starters where any high temp areas might have created minute cracks in a pcb trace etc.
I would return the mods mentioned back to the original starting point if possible. That might have been the tipping point
A case in point.
A HK citation 7.0 processor I had would occasionally cut in and out in hot ambient temps but not in cold room temps. What was happening, even though you turn off the unit, the designers left the PS on at all times ( actually a good idea ) but the transformer pins got hot enough to seperate and lose contact...The design "knee" was exceeded just enough to tip the balance..
After removing all solder and reflowing with plenty of new solder, and keeping the back panel switch off and cool, meaning really off electrically, never had a heat issue again.
Regards
David
I would start with the most stressed area, the PS and its output. Without a schematic, try seperating all boards, even unsoldering them for inspection, taking pics so you don,t lose your way. Clean all connections with Deoxit
A powerful lens of some kind for visual inspection with plenty of light for starters where any high temp areas might have created minute cracks in a pcb trace etc.
I would return the mods mentioned back to the original starting point if possible. That might have been the tipping point
A case in point.
A HK citation 7.0 processor I had would occasionally cut in and out in hot ambient temps but not in cold room temps. What was happening, even though you turn off the unit, the designers left the PS on at all times ( actually a good idea ) but the transformer pins got hot enough to seperate and lose contact...The design "knee" was exceeded just enough to tip the balance..
After removing all solder and reflowing with plenty of new solder, and keeping the back panel switch off and cool, meaning really off electrically, never had a heat issue again.
Regards
David
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I appreciate yours and AVWERK's (and all) responses. I got the the beast under a magnifying lamp and decided to pull all the cables and apply some DeoXit Gold to the pins and reinstall. The white cloth covered cables (2 of them) were somewhat suspect as the top one appeared to come off with almost no effort. (They were custom made by EAD as an upgrade to the unit and I think they are teflon/silver with the linen cloth jacket.)
It appears that you're also suggesting I do the same with the ICs? Is there a puller available for those?
It turned on today, but further testing is needed.
Maybe pulling the ICs is excessive. Anyway, there are pullers available, though a lot of the time a small flat screwdriver works well enough. The main thing is to lift the chip as evenly as possible so as to avoid bending pins. The square chips can be removed using a couple of jeweller's screwdrivers, but great care must be taken to not crack the socket, so I don't recommend that.
Cables which unplug too easily are a concern. Perhaps they weren't even plugged in all the way?
Cables which unplug too easily are a concern. Perhaps they weren't even plugged in all the way?
I think there may be a couple of issues. One may have been oxidized connections at the connectors. If you look at the 5th picture (I think), you can see the upgraded irregular looking white cables to the right - with the loose linen-like cable covers. These just slip on and do not snap into place like the multi-colored ones. It easily moves off and on the pins with little effort at the daughterboard, though it snaps onto connectors at the motherboard.
So far, after cleaning and reinstalling these, it has been starting up OK but since that has been an intermittent issue I'm not ready to call that fixed just yet.
I've also noticed that after sitting for a while in the on position that it still freezes up and that turning off and on will work to re-set it. There still seems to be the lack of a pattern here so further observation is needed, but that could be a heat issue or perhaps something else?
So far, after cleaning and reinstalling these, it has been starting up OK but since that has been an intermittent issue I'm not ready to call that fixed just yet.
I've also noticed that after sitting for a while in the on position that it still freezes up and that turning off and on will work to re-set it. There still seems to be the lack of a pattern here so further observation is needed, but that could be a heat issue or perhaps something else?
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