Crown Power Amps

[tbonuss]

Howdy all,

So after a brief hiatus to study jazz guitar, I'm back at it fixing stuff for people. I got two graveyard-dead Crown amps, and before I do anything, I thought I'd ask for some opinions.

CTS 600
CDi 1000

1. Is it "worth it" -- not just $$$ (although that is important), but are they going to be anti-fun to work on
2. Any experience for typical problems with these that you may have experienced. There is absolutely no sign of life from either one--visually or aurally. Nothing.
3. Most important--any specific safety concerns for either of these

I can split these into two different threads if I move forward on them and need any help, or if anyone has any interest.

Thanks in advance,

Steve

[Chuck H]

Even if the amps are "dead" that doesn't mean there's anything major wrong with them. In fact it might be a good sign. It's VERY hard to fix an amp that sort of works or almost works because symptoms in these cases can be difficult to trouble shoot. With a dead SS power amp I might suspect something easier like a blown output transistor taking out the fuse. Much easier to fix than many possibilities in the former scenario.

My only reservation might be if either or both amps are loaded with obsolete and hard to source amplifiers. Many of which seem like they are being reintroduced from overseas, but don't perform well enough in actual use. Crown amps are known performers so I wouldn't expect any such parts to perform adequately. This probably wouldn't be a problem for someone like Juan. He'd just choose a modern equivalent and adjust the circuit values. More of a problem for a silicon illiterate like me.

I can't say what the service difficulty level is, but both amps are still common and command good prices on the used market. That could be an indicator of overall serviceability and usefulness I think.

[nickb]

Howdy all,

So after a brief hiatus to study jazz guitar, I'm back at it fixing stuff for people. I got two graveyard-dead Crown amps, and before I do anything, I thought I'd ask for some opinions.

CTS 600
CDi 1000

1. Is it "worth it" -- not just $$$ (although that is important), but are they going to be anti-fun to work on
2. Any experience for typical problems with these that you may have experienced. There is absolutely no sign of life from either one--visually or aurally. Nothing.
3. Most important--any specific safety concerns for either of these

I can split these into two different threads if I move forward on them and need any help, or if anyone has any interest.

Thanks in advance,

Steve

With switch mode PSUs of various types, complex protection circuitry, DSP and so on these could potentially turn into a real PITA to work on. But, like Chuck says, it might be something simple.

[nevetslab]

CT400 Schematics....lower power version of the CT600

With switch mode PSUs of various types, complex protection circuitry, DSP and so on these could potentially turn into a real PITA to work on. But, like Chuck says, it might be something simple.

I checked to see what I had in my Crown files, and while I didn't have the CT600 schematics or service manual, I did have the schematics of the CT400, which would be using the same PCB as the CT600 if memory serves. This one doesn't use SMPS or Class D output stage, both of which you'll probably find on the CDi1000.

ct400_main.pdf

I've worked on a couple of the I-Tech series amps for a post production studio here in town, and was able to cure the issues on one, it being solder joint issues preventing the digital control system from setting up the amp. Probably an evolution to the CDi1000. SMPS, DSP control, Class D output, and the long list of electromagnetic Compatability standards is staggering as to how Crown met all the applicable standards so they could be sold anywhere on the planet. Nothing conventional about these amps, other than the rack mount hole pattern they use to mount them in an installation.

[Jazz P Bass]

Oh are you going to have fun!

[Chuck H]

Erg!.. Still, at used values of over $500 each it's sure worth looking into whether a repair is practical. Some guys that like to tinker get nerdy with such things using loupes, tiny soldering pencils and such just for the challenge and satisfaction. Not my game at all. I can do it, but I prefer not to.

[tbonuss]

Thanks Chuck! Do those concerns generalize to other parts outside of amplifiers? I think you're saying that components need to be within tighter tolerances because its so "exotic / high performance" that "close enough" might throw it into protection mode, or whatever...

[tbonuss]

With switch mode PSUs of various types, complex protection circuitry, DSP and so on these could potentially turn into a real PITA to work on. But, like Chuck says, it might be something simple.

Thanks Nick--I found a bad electrolytic cap, so *maybe* that'll be it. I haven't replace it yet.

[tbonuss]

I checked to see what I had in my Crown files, and while I didn't have the CT600 schematics or service manual, I did have the schematics of the CT400, which would be using the same PCB as the CT600 if memory serves. This one doesn't use SMPS or Class D output stage, both of which you'll probably find on the CDi1000.

[ATTACH]53255[/ATTACH]

I've worked on a couple of the I-Tech series amps for a post production studio here in town, and was able to cure the issues on one, it being solder joint issues preventing the digital control system from setting up the amp. Probably an evolution to the CDi1000. SMPS, DSP control, Class D output, and the long list of electromagnetic Compatability standards is staggering as to how Crown met all the applicable standards so they could be sold anywhere on the planet. Nothing conventional about these amps, other than the rack mount hole pattern they use to mount them in an installation.

Thanks Nevetslab--I found the full service manual, but the site here says its to big for me to upload. Hey, at least it'll fit in the rack! Hollow it out and make a tray...

[tbonuss]

Oh are you going to have fun!

[ATTACH=CONFIG]53257[/ATTACH]

[ATTACH=CONFIG]53258[/ATTACH]

Haha, my drummer says: All that does is make stuff loud? Shouldn't you just turn it into, you know, a time machine or something?

[tbonuss]

I checked to see what I had in my Crown files, and while I didn't have the CT600 schematics or service manual, I did have the schematics of the CT400, which would be using the same PCB as the CT600 if memory serves. This one doesn't use SMPS or Class D output stage, both of which you'll probably find on the CDi1000.

[ATTACH]53255[/ATTACH]

I've worked on a couple of the I-Tech series amps for a post production studio here in town, and was able to cure the issues on one, it being solder joint issues preventing the digital control system from setting up the amp. Probably an evolution to the CDi1000. SMPS, DSP control, Class D output, and the long list of electromagnetic Compatability standards is staggering as to how Crown met all the applicable standards so they could be sold anywhere on the planet. Nothing conventional about these amps, other than the rack mount hole pattern they use to mount them in an installation.

Any chance you've got the CDi 1000 schematic? I may take a look at it while I'm waiting for parts for the other one. Thanks!

[nickb]

Ta da! Crown_cdi_1000_schematics_en.pdf

[tbonuss]

Wow. Thanks!

[Chuck H]

Ta da! [ATTACH]53263[/ATTACH]

Wow. Thanks!

You sure

[tbonuss]

No sir; I am not