Crown CE 1000 Worth trying to fix?

[tonecat]

Hello Mark. Thanks again for continuing to help me. I found the exact schematic for my board revision (PWA 102139-8) on pages 555-557 (drawing 102141 Rev. J) of the Crown service manual downloadable through this link: http://www.crownaudio.com/pdf/legacy..._serv_revd.pdf
These parts are on the circuit board and I tested them with my DMM. They are in circuit so I dont know how accurate the tests are. I will work on finding out where the SHORT signal comes from by tracing it on the board. The schematics are confusing to say the least!!
There are 2 diodes in the circuit. One is D216 and the other is D228. They are visible on the schematic I referenced above which I just found late last night. I will wait to here back from you before I unsolder any parts. I am good at soldering and have built several tube amps. Do you have some pointers on replacing SMD parts with traditional tools? I sure would like to finish this thing. I know I have to be close!!

Also, check out page 545, section 9.2 of the Field Modifications chapter of the service manual. It describes a condition similar to what is happening with my amp. Thanks!!!!

I confirmed that U204 (pin 4) SHORT goes into the junction of D216, C221, and R274 (page 556) and then on to the cathode of D228 (page 555) and nowhere else. Also, I have +15V before R277 and +15V at the cathode of D216. While testing today, the odd voltage which was +8.7V yesterday has climbed to +10.6V today (bad part drifting farther out). All other voltages remain the same. I'm thinking comparator since my in circuit tests of the diodes, resistor, and capacitor were similar between channels? I have gotten false readings doing in circuit tests before so I am not 100% on this. What do you think?

[MarkusBass]

What do you think?

I think that you are on a good track to fix this amp. It seemed that the schematic is confusing but it's not. On page 555 you have FAULT label coming from U102-B (pin 1), there is another FAULT label on the input of U5-A on the same page, and on page 556 there is one more FAULT label coming from U202-B (pin 1). They are all tied together. On the output of U5-A (pin 1) you have two diodes: D128 and D228. The cathode of D228 is labeled SHORT and it goes to U204-A (pin 4 if I can see), and the cathode of D128 goes to U104-A (pin 4). This should be marked as e.g. SHORT2 but since there is a direct wire on the schematic, it is not labeled at all. What is important here is that the FAULT signals are common to both channels (pin 2), and also the output of U5-A (pin 1) is common to both channels. It means that it was not needed to check the FAULT signal on U202-B (since the other channel works correctly). Now you see that being able to read and understang schematics helps a lot.
So this narrows the problem to just 4 components or to a power supply. I mention power supply because there is -8.11V on the schematic and you measured only -6.2V on R274. Can you check this once again? BTW, I haven't seen a schematic of this power supply. Which page is it?
If it's not the power supply, it must be either R274 (open or not correctly soldered), or D216 (partly shorted), or C221 (partly shorted), or bad U204-A. If I were to bet which one it is, I'd say that it's R274. And it is the easiest component to be checked. Just look at it if it's not broken and whether it is correctly soldered. And if you won't find anything, just solder another resistor in parallel to it (without desoldering R274). It should be something like 2.2-3.3MOhms. Please check whether this changes the voltage on U204-A (pin 4). If not, you have to learn SMD parts soldering (use an old PC board), and look at two other components, and finally at U204 (hopefully not). There were some good threads on this forum about soldering of SMD components (also available on the internet - google is you friend).

EDIT: and of course you know that measuring components in circuit does not prove anything. If you try to measure a 1kOhm resistor which it in parallel to e.g. output transformer in a valve amp, you will not be able to tell whether it's open or shorted.

Mark

[tonecat]

Hello Again,
Sorry it took me so long to get back on here. I was waiting on parts. The parts have arrived and lo and behold, the amp is fixed!!!!! It was the C221 capacitor. I went ahead and bought all four suspected bad parts direct from Crown ($10.00 total). I started with R274 and it was good. I then moved on to C221 and when I unsoldered it, it just fell apart. Put the new replacement axial (not SMD) cap on and that did the trick!! All voltages are the same in both channels and the amp came out of protect mode. I still have to test it under load once I get it put back together, but as of now, all is well. Mark. I checked the schematic under extreme magnification and the power supply spec is -6.11V not -8.11, so my reading of -6.2V is spot on. I sure am glad it wasn't the comparator. That would of been a trick to change as close to the heatsinks as it is. Whew!! Thank you so much for your help!!!! I am really glad that I decided to fix this thing. It has been a learning experience for me. I now know how to work on SMD stuff. It still is a PITA compared to through hole stuff, but it is doable. I don't think I could of done this one on my own without the help of this forum and especially Mark!! Thank You so much for your help and have a Happy Easter!!

Paul

[MarkusBass]

I told you that you can do it . I think I mentioned looking at these four parts but I forgot to tell you that you should use a magifying glass. Most probably you would be able to see the problem. I think that the amp is OK because it was a protecion (against failure) circuit that failed .
Now, most probably you can say that it was easy and these amps are not that difficult to be fixed as guys say. You can also finally answer the starting question: was it worth?
Happy Easter,
Mark

[Shimp]

I hope I am not in violation for dragging up an old thread.

I have one of these CE1000 amps here that had a bad channel, originally, one of the MJ21194 output transistors, and Q220, Q211, Q204 were bad, and 10 of the .4 ohm current sense resistors in the group that had the one bad MJ21194.

So tinkering with it, I removed the bad MJ21194, took another one from the other side of that channel, and replaced it in same spot, replaced what I had on hand which left me short of Q204, Q211, but figured why not start it up and see what happens. Well, it started alright, after the initial delay the relays kicked on, and then after a short bit, fire from under the board, blew other side .4 ohm resistors and trashed 3 of the MJ21194's. I wasn't thinking that Q204 was a bias transistor for whatever reason and wondering if that's why it blew. The sinks were hot for that channel after the failure, so I guess the transistors went full bore or something. Anyway, eventually I removed the whole channel and removed U202 and now the amp comes on, and Channel 1 (the channel that was still good from beginning) does work fine. But a little concerned about dropping new parts into channel 2 (once they arrive here) without being 100% sure I didn't miss something else besides leaving out Q204 and Q211 like a dummy.

I normally work on car stereo amps, premium stuff that is way more powerful than this "little" crown amp, so I figured it would be easy, but it was a real booger to get apart compared to the car stereo amps, and the protect/fault circuit stuff is overkill. And I really don't think their claim of 500 watts per channel is on par, the car stereo amps that I work on into same load rated at 100-200 watts per channel seem to be about twice the power of this thing. Pretty disappointed, may sell it when repair is complete and look for a easier to work on amplifier for my old DJ gear, that I simply purchased this amp to run some MTX Pro II's just for casual listening at house, little party or whatever. I didn't want to mess with none of those Pyle amps or anything that said a gazillion watts for $100 LOL. So I bought this old Crown thinking it was a "decent" amp. I may should have bought something older, like an old Peavy... Not familiar with the insides of this type of gear, so I didn't know what I was getting into. But either way, I am wanting to get it fixed up, and this thread was pretty helpful going the amp, so figured I'd bump it back up, even though it's old (2011). Hope I don't get in trouble for that.

[Shimp]

Also when I start it up again, going to have to put either a Ammeter clamp on the power input to transformer or use my kill-a-watt on an extension cord to bench to monitor the current draw, that probably would have made me shut it off before damage occurred the first time around... After the initial inrush current it should have settled down, I had no metering on it to know what was going on. When I work on 12V stuff I have meters all over bench monitoring idle currents, etc, but like I said, I normally don't work on "mains" powered gear!

[Enzo]

No violation or anything like that, but you will get better response if you just start a new thread for your repair, instead of tacking onto an old story. Welcome to the forum.

I'd wager the Crown is more honestly rated than the average car stereo, which relies on "peak power" and such. Just an opinion. DOn't confuse power with loudness. It might take a lot more to drive the Crown to its full output than the average car stereo. SO it may not be as loud at some setting than the car amps. But that is a matter of preamp and sensitivity. Some Crown amps - and other brands as well - have a level switch inside to set the amount of signal needed for full out.

If you have the schematic, it would help to post or link it.

[km6xz]

I am with Enzo on this(and most things) that the CE1000 is honest in ratings and is guaranteed to meet published specs. I don't see powerful car amps but see spec sheets on them and wonder how they generate as much power as claimed given that best they could do with 12 volts is use most of the circuitry creating higher voltage using switch mode power supply. Even in quad bridge mode on the power amp, the very high powers claimed don't make sense unless fractional ohm loads are used. What RMS voltage output with undistorted sinewave are you seeing across what load impedance do you measure?

Regarding the CE Crown being worth it. Yes, if it is repaired properly, parts could not be more then $30 at wholesale cost and 1-1.5 hours to repair unless the pc board has been damaged. If the board was damaged it might not be worth repairing unless you can find a junker to rob mechanical parts from. Ask a Crown warranty station for a junker, you might even get one for free but offer $25-50 for it so you can get a good response from them the next time you ask for a favor for them.
I don't work on consumer gear but the electronics is the same, just more concern for lowering production costs and maximizing advertising budgets is the main difference.
The Crown uses a very stable circuit that they call AB/B class which means with very low or no signal the output transistors are not pulling any idle current but the driver it actually driving the load until the signal increases to 1/2 a volt. Anytime outputs are shorted, driver ad bias servo become suspect because they operate at low enough load Z to pull more current in normal operation than conventional AB amplifiers. Check each of those transistors and diodes involved in the driver. You can remove all the power transistors and still drive a load or maybe 50-100 ohms with just the drivers installed. That allows you to make repairs to and analyze the operating conditions of the driver. When it is working well, only then, install the power devices, 1 opposing pair at a time.
Don't put any load until the driver swings full signal open load and there is no DC offset. Using this multi-step repair process will prevent expensive problems from overlooked defects in an earlier stage. Since it pulled current and blew with no signal, it is a good sign that a defect in the bias servo or drivers were turning on both sides of the power stage. The base emitter voltage, at idle on the CE1000 is only .3volts so no current should be conducted in idle through the output transistors. They are operating in Class B so don't even turn on until B-E voltage increases to over .6volts. Since no current is pulled, any bias voltage can be measured even with the output transistors are out of the circuit. Pull all the transistors and with no load, find out what is on the base of both sides of the output section. If it is higher than .3, it points to a problem in the bias servo or one of the drivers. Be sure to check the driver bootstrap doubler on both positive and negative driver supply.
Good luck....remember, no load until any amp is proven stable with no offset.

[Shimp]

No violation or anything like that, but you will get better response if you just start a new thread for your repair, instead of tacking onto an old story. Welcome to the forum.

Thanks for the Welcome and the response.

I'd wager the Crown is more honestly rated than the average car stereo, which relies on "peak power" and such. Just an opinion. DOn't confuse power with loudness. It might take a lot more to drive the Crown to its full output than the average car stereo. SO it may not be as loud at some setting than the car amps. But that is a matter of preamp and sensitivity. Some Crown amps - and other brands as well - have a level switch inside to set the amount of signal needed for full out.

Well, Yes for the 90% part. The problem with the Car Stereo market today is that it's flooded with cheap garbage that is extremely over rated and not well built at all dead giveaway the cheap stuff is made in China, decent stuff made in South Korea. The cheap "peak power" type stuff is not the stuff I work on, it's not cost effective at USA repair labor rates to repair these wannabe so-called 3000-6000 watt amps that are really max of 1200-1500 watts because that's technically all you can squeeze out of your average cars stock electrical system, it's a gimmick, been going on a long time, only gotten worse, the makers just label the amps with whatever power level is "popular" amongst the buyers, but still the amp is the same inside, same board, same parts, may have a different physical arrangement, but it's the same old 1200-1500 watt amp that the previous marketing cycle they labeled as a 3000 watt amp, but the new magic number is 3500 watts or whatever, so they just change the numbers. Again. That's NOT what I work on here. Will post an example later so you can really see what I mean. Just getting into shop this morning need to get some coffee down first.

Also yes, the Crown does need more input drive the sensitivity of the amp won't adjust low enough (even with switch) to match my bench source rig here which is a cheap car stereo and a craptastic signal generator, but it works fine for what I normally do as long as I don't run it into clipping, which it does pretty easy, again, it's craptastic, and I really need to replace it with something better, at the time it was all I had when the last one just died on me after a couple years. Will post again here in a few. Thanks guys for the welcomes and responses.

[Shimp]

Here's a quick example that pretty much sums it up. On left you have a BOSS Audio 1200-1500 watt (in reality) Class D mono amp, that claims to be 3600 watts. The model number is even something-3600, on the right you have a REAL 3500 watt Class D mono amp, which actually will put out over 4000 watts if you keep the supply voltage around 14.4VDC. BOSS = China Sundown = Korea. BOSS price tag around $100-$150, Sundown almost $1000.

[Jazz P Bass]

Here is the CE schematic.

If you can provide the board numbers I can upload a more specific file.
(there is more than one revision.)

CE 1000_2000.zip

[Shimp]

PWA 127452-1

[Jazz P Bass]

Here is what I have.
Pay attention to the resistor mod.

CE 1000_ 127452.zip

These amps can be a real treat when they blow.

There are rectangular ballast resistors (low value) that go open.
Little transistors that also open.

And to make things peachy, most of the components are surface mount.

[Shimp]

Here is what I have.
Pay attention to the resistor mod.

[ATTACH]38582[/ATTACH]

These amps can be a real treat when they blow.

There are rectangular ballast resistors (low value) that go open.
Little transistors that also open.

And to make things peachy, most of the components are surface mount.

Thanks for the help. My amp doesn't yet have the "bootstrap" resistor mod, but could be done no problem, it does have the white wire going to WP6.

As for blowing, yeah it already did, blew out a bunch of .4 ohm surface mount resistors and had a bunch of small failed transistors and some of the big ones. The Surface Mount isn't a problem for me, I work on it every day with hot air soldering gun and tweezers. My complaint about the Surface mount in this amp, is on the board from the OE they have these red dots under where every SMD part goes, once heated it melts and becomes adhesive, it's quite annoying, usually SMD parts come on and off the board quite easy with proper tools, but with that adhesive you practically have to pry them off or get it hot enough that it could damage the board itself before the adhesive turns loose.. A real PITA. I could teach them how to build a better amplifier layout, this thing is like a whole bunch of mixed up methods and technology that could have been done a lot better, even at same costs... Fire that engineer.

[The Dude]

I'm going to go against the grain a bit here. I'm not saying the amp isn't worth fixing in every circumstance. I will point out that you can pick up one of these in working condition for $100-200. Be careful not to get upside down on it if it's a customer unit. I get these in the shop on occasion and have rarely repaired one. Usually the customer refuses the estimate because of the low replacement cost.