Film-Tech Forum ARCHIVE: Panastereo CSP1200 Power Supply Blowing Fuses

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Posted by Joshua Waaland (Member # 287) on 12-03-2008, 04:15 PM:

I bought a used Panastereo CSP1200 about a year ago and it needed a new front panel. I replaced the front panel and powered it up and it worked fine. A few nights ago I powered the processor up again and it blew a fuse. It was a specialty time delay fuse that I didn't have laying around so I bought a few and tried again last night.

I tried replacing the cord, disconnecting the front panel, different 115V outlets and taking the power supply out of the processor all together, but it still kept blowing fuses. I have not hooked it up to anything since I have had it so I know it is not something else causing the problem.

I am at a loss here. I hope Norm is still fixing these so I can get it working again. Anyone have any ideas to try before I ship it off? I inspected it visually and it appears to be free of any noticeable burns or defects. Thanks.

Posted by Steve Guttag (Member # 268) on 12-03-2008, 04:54 PM:

Josh...yes, Norm is still fixing them. Odds are, you've lost a power regulator (the guys exposed and screwed to the heat sink).

The other highly likely suspect would be the bridge rectifier(s). When one blows a main fuse on most any power supply immediately upon turn on...start with the bridge rectifiers and work your way out...odds are it is something early in the circuit.

BTW...do you have a CM410 (linear) or a CM510 (switch mode). They look nearly identical but they will have a suitable silk screen identifing what they are.

One thing to help with a CSP1200 is to ensure it has good air flow...always give the CSP1200 a rack space above and below the unit and I also tend to filter and blow a rack to ensure a positive pressure of cool, clean air is going across the equipment. It has resulted in much cleaner racks and the equipment tends to last much longer.

Steve

Posted by Gordon McLeod (Member # 33) on 12-03-2008, 05:28 PM:

I have had several csp1200 loose the bridge rectifier

Posted by Joshua Waaland (Member # 287) on 12-04-2008, 06:56 AM:

Thanks guys. I have the CM510 model. It is in an open relay rack with plenty of airflow around it and I haven't hooked it up to any amplifiers or anything yet or used it. It has just been sitting in there and I turned it on to try and learn the functionality of it. I have powered it up at least 3-4 times since I have had it with no problems. It seems to be in really good shape and well taken care of except for the front panel that had glue on it that I had to replace.

I will contact Norm about getting it fixed. Thanks.

Posted by Mark Gulbrandsen (Member # 72) on 12-04-2008, 08:17 AM:

Actually Carl at Quality Presentations is in the process of taking over ALL Smart Devices and Panastereo repairs in the USA. Smart's repair facility is no more. Its a super simple repair so just take it to a competant local audio electronics tech as he can easily repair it for you in about an hours time! And yes! Its just a blown bridge rectifier... a VERY common problem with both types of the supplies. The 510's also have another problem with PC traces but that doesn't cause a blown fuse.
BTW: We also have all the CSP-1200 modules in stock and can do an RA or repair on any of them for you.

Mark

Posted by Joshua Waaland (Member # 287) on 12-04-2008, 11:49 AM:

Is the bridge rectifier board mounted? We have simple ac to dc step down power supplies that we use in our equipment but they don't have this much circuitry in them so I was a little timid about working on it.

Posted by Steve Guttag (Member # 268) on 12-04-2008, 12:48 PM:

The CM510 is a switch mode supply...

As to Norm, what Mark said is false...he WILL repair Pana stuff (I've spoken with him in the last 48-hours). I have also spoken with Quality...while they will attempt repairs on SMART stuff, no mention of Pana as of yet and it isn't like they are "taking over" just providing an alternative repair facility for out-of-warranty items.

There are Pana units still within the 2-year warranty...the last ones came off the line in June 2008.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 12-04-2008, 01:25 PM:

Yes, the bridges are on the board. They are about one ana a quarter inches long by a quarter inch wide by perhaps one inch high.

Steve... The 510 is not a switch mode power supply, the switch mode supply idea was abandoned long ago. If you'd like I can post pictures of the insides of a 510.

Mark

Posted by Steve Guttag (Member # 268) on 12-04-2008, 02:20 PM:

I dunno Mark...that was the claim for the CM510...changing it over to switch mode to, among other things, reduced the heat generated as compared to the CM410 (which got very hot). The CM510 started out fanless...they eventually added a fan.

I've never verified the switch mode claim.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 12-04-2008, 03:24 PM:

Yea, that was their intention but it just ended up being a re-designed regulated supply instead.

On the 410 bridge replacement... I don't install an exact replacement on the pcb... I re-locate a bit beefier metal encased bridge on the inside of the metal cover so it can efficiently dissipate the heat it gives off. They never fail a second time...

Mark

Posted by Joshua Waaland (Member # 287) on 12-13-2008, 09:44 PM:

Well, I shipped it off to Norm this past Friday so we will see how things go. I'll let you know what I find out.

Posted by Oscar Neundorfer (Member # 458) on 12-15-2008, 06:01 AM:

Best I recall, the CM510 was indeed switch mode regulation, at least some of the supplies. I may have a schematic somewhere. If I find it, I will let you know some details.

Posted by Mark Gulbrandsen (Member # 72) on 12-15-2008, 10:50 PM:

Humm... I am pretty sure it was you that told me it wasn't. Could have been Ray too... someone said it was going to be pure switch mode but that in the end it didn't actually run any cooler and was "noisy" so they left it as a standard although updated regulated device. Anyway there were pcb problems with them as well. And the cheapo plastic bridge rectifiers just don't cut the amount of heat they generate over the long trem... They were also problematic in other units, especially in the MOD 2C's power supply.

I sort of look back and chuckle at the whole Panastereo thing... a good processor it was and very reliable in the beginning... but when Norm told me he that his power supplies could fail because Dolby's also had a history of failing... well, that was the last batch of Panastereos I ever sold. Switched to the CP650 and have yet to have a power supply failure with any of them... or a single failure for that matter.

Posted by Oscar Neundorfer (Member # 458) on 12-16-2008, 05:36 AM:

It has been a while, and the memory fades a bit on some of the details. As I recall, the input stage was good old fahioned transformers, bridge rectifiers, etc. It was definitely not pure switch mode, as in rectifying the line and using isolated switching buck regulators to get down to the required voltages. However, and as I recall, at least 2 of the supplies, the + and - 15V supplies for the analog circuitry, were switch mode regulated. These were the heaviest loaded supplies and would benefit most in terms of heat reduction by using switching regulators.

I think all the other supplies used standard analog regulators, but I am fuzzy on that detail also.

You are correct about the bridge rectifiers being a weak link.

As far as comments about Pana vs Dolby power supplies, sometimes it is amazing how a few ill-chosen words can make such a difference.

Posted by Gordon McLeod (Member # 33) on 12-16-2008, 08:56 AM:

Bridge rectifiers are often the weak link
On the Mod2c powersupplies I had the solder melt around the bridge on some of them

Posted by Steve Guttag (Member # 268) on 12-16-2008, 09:30 AM:

You know Mark...the CP650 failure rate on the power supplies to the Panastereo CM410/510 is a no contest...the CP650s have been quite unreliable for their power supply. I've had maybe 2 or 3 Panasupplies die and never took a show down.

I've seen a great many CP650 supplies die though. Two last month alone! Christ, Dolby is up to the 5-version of that supply now too. I good supply doesn't need to constantly be revised. In fact, power supplies have been Dolby's long legacy of problems, except for maybe the CP100. The CP50's supply was woefully underpowered and would often hum up, depending on the cards installed...the Cat 114C did better but still...voltage sag down to 11-volts on the +/- 15V rails are common....the CP200...via the PS1 and PS1B...again voltage sag...loose capacitor leads and blown bridge rectifiers...one thing we do when we reissue a CP200 is rework that thing....CP55...Cat 249...generally burns up...have a CP55? Pull the Cat 249 and look at the PCB...it going to be charred bit. Many of them failed...leading to the Cat 249A...no real complaints there and there are nice big caps on it (finally). DA10...constant supply failures, if not from the supply, the molex connector...DA20...same molex connector problems and again numerious power supply failures...CP500...the power supply wasn't too bad but we've had several of them go...CP650...the single biggest point of failure we've had has been the power supply...in fact, we just had to change a Cat 794...because the power supply went and took it with it!

One thing we have done with all of our Panastereos is to leave 1U of space above and below AND we pressurize the rack (blow in via filter at the bottom and have nice cool clean air flowing)...the Power supply and other boards don't over heat...problem solved and the rack stays nice and clean too.

So Pana versus Dolby power supplies? Pana seems to be doing at least as well. If you want to complain about the Pana supply...pick on something simple...like LOCK the F-in thing in the card cage!

Steve

Posted by Mark Gulbrandsen (Member # 72) on 12-16-2008, 09:55 AM:

We do a similar thing with racks but it didn' t stop the bridge failures. Some CSP-1200's have never failed, but only the older units. All of the Smart produced supplies failed at least once and some twice prompting me to install a better quality bridge off the pcb and onto the heat sink that's screwed to the inside of the case. These have never failed.

Mark

Posted by Louis Bornwasser (Member # 3063) on 12-16-2008, 12:33 PM:

What I appreciate(d) about Oscar is that he always told the complete truth. No so with "others." I CAN handle the truth.

Finding out later that somethings are not quite true is worse than knowing up front. When I dealt with oscar, I always felt more secure in what I was doing. Louis

Posted by Joshua Waaland (Member # 287) on 12-22-2008, 08:19 AM:

I just went to the Smart Devices website so I could get the phone number to call them about the repair and the website did not come up. Either their website is down or they have gotten rid of it because it is only a generic page now.

Posted by Steve Guttag (Member # 268) on 12-22-2008, 08:53 AM:

Try going to www.panastereo.com In their "important announcement" link...they give you a phone number.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 12-22-2008, 09:47 AM:

I suspect that we have alot more Panas in this area than you do. We also have an equivelent number of 650's and have not had a single 650 go down in this neck of the woods since the 650 was introduced. Just several software issues that were easily corrected. Quite the opposite for the Panas where every single 410 supply and almost all the 510's have failed, indeed some 410's have failed multiple times. Although there is one Aussie built Pana that still chugs along since day one. All those failures is what led me to instaling the larger bridge... they now do not fail. As Oscar truthfully mentioned the bridges have always been and will always be a weak link in the power supplies that came from Smart. Many 510's failed because the PCB's were not properly designed and have to be modified... after the mod they are however very reliable. Our customers frankly got tired of the power supply issues and since Norm wasn't willing to stand behind them we discontinued the sales of Panastereo all together. Now I do still love the unit in spite of this, it is still the best sounding Cinema processor ever built. The rest of the unit has been reliable for us... just not the supplies.

P.S. Getting the supplies repaired by Norm is just going to get you another 10 cent bridge rectifier installed... Why bother? Instead, fix it the right way, its what Ray Derrick would have done!

Mark