Peavey CS 800 Blows fuse

[arambharose]

Hi Guys,
This is my first post.I just came into A peavey CS800 commercial type.It blows the main fuse when I power on.I have read all previous since 2007.I am just glad to know this is where I can go If I need help.Any updated help will be appreciated.Thank you for all the help you have provided so far.

[gtrplayr1976]

Hi Guys,
This is my first post.I just came into A peavey CS800 commercial type.It blows the main fuse when I power on.I have read all previous since 2007.I am just glad to know this is where I can go If I need help.Any updated help will be appreciated.Thank you for all the help you have provided so far.

You know the complete model / serial #....pictures would help. I have some schematics I could post.

[arambharose]

Peavey cs800

Hi thanks for the speedy reply.I took this directly off the sticker on the bottom of the amp.Model -CS-800* 6A-02519720 86b. It says commercial in front and weighs a ton.Will post pics later.Have to run out to work.Thanks again.

[gtrplayr1976]

Hi thanks for the speedy reply.I took this directly off the sticker on the bottom of the amp.Model -CS-800* 6A-02519720 86b. It says commercial in front and weighs a ton.Will post pics later.Have to run out to work.Thanks again.

This is what I have. Hope they help.

[arambharose]

Peavey cs800

Thank you very much for the schematics.I will match them up to my model.Will send some pics later.If you can please point me in the direction of the latest diagnostic and repair steps for this model.
Thanks

[gtrplayr1976]

Enzo ,and Jazz are two of the best on here. If you search the forum you will see some posts on here with the same problem ,and they will tell you what to do. Keep us updated. I'm working on one myself.

Good luck.

[Jazz P Bass]

The very first thing that I would do is document exactly where every cable & connector is presently located in the amp.
Now you can start to narrow down where the short is (it is blowing fuses, so there is a short somewhere)
There are duplicate boards.
The power output boards & the driver boards.
You can disconnect them from the power supply.
Check the rectifier diodes of the power supply.
If nothing appears shorted, see if just the power supply will hold a fuse.
If it does, then you have to start checking the output transistors for a short.
I would advise draining the power supply before going any further into the amp, as there is not a load on it to drain it.
There are small bypass caps on the back of the output transistor board that sometimes short.

[arambharose]

Didn't think about isolating the power supply from the rest of the amp.Great idea. Will give it a shot.Thank you.

[Enzo]

From your serial number I am thinking the olde style like the schematics in post #4. The CS800 C series is most likely, though they are all similar from that era.

The top off, there should be two large heat sink modules. Four screws each loosens them, and there should be enough wire slack that you can lift them off and stand them on end to either side. Stick a magazine or a towel between module and hte chassis wall to prevent shorts when powered up. On the underside of each module ther is a four-wire molex connector. It carries the two main power supply voltages, ground, and the output to the speaker terminals. Unplug both of them. They are how to isolate the power supply as Jazz suggested. Now power up. I bet it holds fuses.

If fuses STIIL blow, then check the main rectifier bridge down in the bottom - look for a shorted side on it. SHorted filter cap? Possible, but in my 25 years as a Peavey repair shop, I have not seen one.

But I am betting your powr supply is fine. I am willing to bet my lunch money you simply have a blown amp channel. Power off. SO, pick one power amp module, and plug the power cable back on it. And fire up the amp. If the fuses now blow, that is a was power amp, needing repair. If it fires up OK, unplug that one and plug in the other one, and I bet it is the bad one.

Once we have determined which module is bad, we need to disconect it, and go down the row of transistors looking for shorted ones. It may be as simple as replaacing the shorted transistors, or it may be that the driver card perched on the underside is also troubled.

Now why are we blowing all these fuses? Look up "light bulb limiter" and make one and use it. VERY simple thing to make. And it will not only reduce stress to the amp, but save a lot of fuses.

[arambharose]

Thanks for all your help Enzo.Will try this tomorrow after work.

[gtrplayr1976]

BTW. These light bulb limiters are great to have. Saved me some extra headache.

[arambharose]

What is a light bulb limiter?Thanks.

[arambharose]

Sorry found it online. Thanks.

[gtrplayr1976]

What is a light bulb limiter?Thanks.

You use the light bulb to draw more of the current to protect your equipment in case there's an issue. It's kind of like a fuse that you can see work. Receptacle , and bulb ,and light switch in series. Someone else could explain it better. Do a search on here, or google it. A must have for repairs.

Check one of these.

http://www.youtube.com/results?searc...t+limiter&aq=f

[Jazz P Bass]

Here is another link: http://www.geofex.com/Article_Folders/SPO_Test.htm