Author Topic: Plasma hell! CF82E75, E74 and E73 cards! Please help!  (Read 2321 times)

cleartrack

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Plasma hell! CF82E75, E74 and E73 cards! Please help!
« on: November 04, 2021, 03:55:54 AM »
I'm failing to find the fault with these cards. It all started with my Atomic supply going down and then a spare SSL PSU with some issues seemed to tank my cards. I think I've managed to fix the E75 (HT card) since it's fairly simple and just needs to push 83v x6.

I've checked whatever I possibly can but at this point would rather send these cards to someone who's more familiar with them.

Does anyone have any for sale or would know someone reputable who I can send these to?

skipburrows

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #1 on: November 04, 2021, 07:40:19 PM »
Hi there, what are the symptoms of the failures? That would help a lot…
Cheers

MarconeMusic

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #2 on: November 05, 2021, 12:24:09 AM »
Ouch.
I’ve dealt with these and have a few spares. But not sure what ones.

What are the issues?

cleartrack

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #3 on: November 06, 2021, 01:11:19 PM »
E75 card: I have a working one for one of my consoles but the other card heats up so fast and so hot it starts melting the PCB within seconds. The large resistor especially. That one also kills every HA2-2645 op-amp in it. I'm going to stay away from that card completely and would rather replace it.

E73: I think this is the culprit who's preventing the meters from rising? The meters show level no higher than a cm from the bottom.

E74: I have a card that doesn't react to the switching in the center section.

I could of course get all of the chips necessary to completely re-chip these. I'm not good at checking transistors but could those likely have crapped out after the power hell hit them?

Considering I have 2 consoles with plasmas I definitely would like to get a known working set of spares.
« Last Edit: November 06, 2021, 01:13:45 PM by cleartrack »

amillar

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #4 on: November 08, 2021, 04:52:04 PM »
Quote
E73: I think this is the culprit who's preventing the meters from rising? The meters show level no higher than a cm from the bottom.

So is it just going up 4 segments? If so that means phase 4 isn't working (or if e.g. it's just going up 3 segments then phase 3 isn't working). So if that's on all bargraphs a faulty 2645 or faulty FETs on the '75?

I am so pleased that it's probably 35 years since I last had to try fixing these. Horrible things. They bite.

Good luck,

Andy
 
co-designer and project manager G series analogue 1987
channel strip designer J series 1992-93
design "caretaker" 4000/6000 1985-93
analogue team leader ARC/Bertha 1988-92

cleartrack

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #5 on: November 11, 2021, 03:05:57 PM »
It never goes any higher than 1 segment on any meter.
As the audio signal gets hotter the 1 segment just gets brighter and brighter but never lights any more segments.

cleartrack

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #6 on: December 06, 2021, 07:10:56 PM »
I changed out some 2645's and managed to get the card working temporarily. Then by simply by unplugging and/or turning the system off/on some of the 2645's stopped working.

Are the newer HA2-2645-5's on ebay junk? counterfeit? or just lesser quality or is there something in my system that is causing them to die?

Also, can I used the HA7-2645-7 if I apply a DIP8 heatsink? They seem to have the same specs. I'm very close to throwing in the towel and going with VU meters, yet that'll probably cost me much more money than getting these plasmas going.

I wonder if the older/original 2645's were of better quality and where I can find some.

amillar

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #7 on: December 08, 2021, 02:49:57 PM »
Then by simply by unplugging and/or turning the system off/on some of the 2645's stopped working.

How are you turning the system on/off? If you are using the miniswitch under the patchbay (the one with the channel bay power switches), don't! The 250V contact is very likely welded closed. Just mentioning because I had a very small memory somewhere that this used to cause card failures - and nasty shocks.

Have you checked that you are getting 83V across D7? (Or at least somewhere between 75 and 85V.) I'd be surprised if that's a problem, the 85V regulator is more likely to fail altogether than to give too high voltage, but it's just possible that it's giving a high voltage above, say, 85V. Please be careful while checking this!!!!

Personally I wouldn't expect the DIL packages to work, but someone here may have made them work.

I did check my spares box because I thought I had some original 2645s from SSL I'd have happily sent you, but sadly not :(

I quite understand you wanting to chuck these and fit VU's, I know the feeling...the plasma technology was the best available at the time, but was always a bit agricultural. Very clever, particularly the storage part, but when LCDs came along they were always going to be way more reliable.

Let us know how you get on,

Good luck,

Andy
 
co-designer and project manager G series analogue 1987
channel strip designer J series 1992-93
design "caretaker" 4000/6000 1985-93
analogue team leader ARC/Bertha 1988-92

cleartrack

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #8 on: December 13, 2021, 02:17:21 AM »
Then by simply by unplugging and/or turning the system off/on some of the 2645's stopped working.
Have you checked that you are getting 83V across D7? (Or at least somewhere between 75 and 85V.) I'd be surprised if that's a problem, the 85V regulator is more likely to fail altogether than to give too high voltage, but it's just possible that it's giving a high voltage above, say, 85V. Please be careful while checking this!!!!

Personally I wouldn't expect the DIL packages to work, but someone here may have made them work.
Most of the time I had turned on/off the 250v independently after the 674 switch was on, but I think I may have missed it a few times and turned it all on/off together, but I was careful with the last set of 2645's.

I'm getting about 83-84V off D7 on all of the 3 E75 cards I have in total (few spares).

Any particular reason the DIP8 packages wouldn't work? I don't have the knowledge or experience to know one way or another, but the specs seemed the same according to the datasheet.

Thanks for your help! Fingers crossed the next batch of 2645's work.

amillar

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #9 on: December 13, 2021, 12:58:37 PM »
I'm getting about 83-84V off D7 on all of the 3 E75 cards I have in total (few spares).

That sounds good.

Quote
Any particular reason the DIP8 packages wouldn't work? I don't have the knowledge or experience to know one way or another, but the specs seemed the same according to the datasheet.

Actually the datasheet shows the ceramic DIP as better  for thermal resistance than the metal can

     Thermal Resistance (Typical, Note 1) θJA (oC/W)    θJC (oC/W)
     CERDIP Package. . . . . . . . . . . . . . . . . 135            50
     Metal Can Package . . . . . . . . . . . . . . . 165            80

But the problem is coupling the package to the heatsink, which works much better with a metal can. But worth trying a DIP with good heatsink adhesive, just not straight before an important session!

Let us know how you get on!

Cheers,

Andy
co-designer and project manager G series analogue 1987
channel strip designer J series 1992-93
design "caretaker" 4000/6000 1985-93
analogue team leader ARC/Bertha 1988-92

cleartrack

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Re: Plasma hell! CF82E75, E74 and E73 cards! Please help!
« Reply #10 on: December 13, 2021, 08:20:53 PM »
I just put some new 2645-5's (just arrived today!) in 2 different E75 boards and I'm getting about 68v off each one when all powered on except for the "reset" one. I'm getting about 13v off that one. I've tried 2 different E75 cards and 2 different E7E cards all producing the same result. Still only getting no more than 1 segment on the plasmas.

UPDATE:
I can't get any of the "new" HA2-2645-5's to work worth a damn, but I did try 2 "HA7-2645-5" DIPs and some vintage HA2-2645-5's and am getting more action compared to the "new" ones. Something's not right with any of the new "metal can" packages. I have some more of the DIP's on order and hope those do the trick, though, those are pretty hard to find.
« Last Edit: December 13, 2021, 09:30:16 PM by cleartrack »