Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

PA Systems A forum for discussion of all parts of a sound reinforcement or DJ system: loudspeakers, mixers (desks) etc.

blowing fuse - Peavey CS-800
blowing fuse - Peavey CS-800
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th December 2017, 06:11 PM   #1
Andyman001 is offline Andyman001  United States
diyAudio Member
 
Join Date: Dec 2017
Location: IDAHO
Default blowing fuse - Peavey CS-800

Newbie here,
I've learned a lot reading past threads, as title says, I have acquired a Peavey CS-800, 2nd version i believe, (4 ohm min, 400 watts per channel, Wind tunnel)
had a open main fuse, replaced, blew pretty quick (with sparks from under the main (output ?) board; upon inspection I found the large resistor on the power supply board loose and overheated - re soldered; and the triac (SAC-187) on the "A" channel shorted, and the trace on one of the legs blown open.
Questions:
1. Where do I check rail voltage? (like I said newbie). i have reinstalled the power supply and hooked up the fan, it powers up and fan comes on.
2. I should be able to hook up the "B" channel to test, Correct? or should I just wait for the replacement Triac and test both?

any and all advise welcome.

Andy

(I have about 15 years as an industrial electrician, so know how to be safe around electricity)
  Reply With Quote
Old 9th December 2017, 06:58 PM   #2
indianajo is offline indianajo  United States
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
There are various versions of these. On the version B schematic I have, the triac on the channel is the DC protection triac, that detects DC on the output and blows the main fuse to protect your speaker from burning the coil insulation or tearing the suspension. So the triac is the last thing you want to replace, after everything else is perfect. That means no DC on the output and passes sound okay into a trash speaker through a 50 uf plastic cap. (to protect the speaker from dC).
If your this new, lesson one is don't ever measure voltage with two hands. Current across your heart over 24 v can stop it. Use a clip lead on the negative probe to speaker ground. (On the back). The speaker ground of the channel you are working on. Many Peaveys have different returns for the two channels : version B probably is not since it is quasi comp.
Next safety tip, use safety glasses desoldering, solder can splash. Also powering up, metal can transistors can blow the tops off at these voltages. Also E-caps can blow their tops and squirt hot borax water.
Likely somebody has pulled a 1/4 phone plug part way out, and blown the output transistors. With the triac out of the circuit, put on a light bulb box, replace fuse and measure for DC on the output. A light bulb box has a 100 W bulb in series with the power plug, to limit the current. If everything is okay, the bulb stays out and all the transistors power up and draw no current.
It is also possible, at this age, a DC power supply cap has shorted or a bridge rectifier has shorted. No +-50 on the mains caps (81 without the light bulb box) something is wrong around there.
The schematic I think I got from this website, so search around & see if you can find it. The CS800s and CS800x are pretty different, don't download those if you don't have one.
See also this repair thread: vintage amplifier repair/upgrade manual - diyAudio
In Idaho, your nearest full line distributor w/o counterfeits is digikey in Minnesota. I use Newark in SC but digikey has seemed to be okay the one time they had something unique.
These aren't worth a lot, but do have decent sound and can play 400 W/ch all day and night if the output plug is not shorted and the fan doesn't quit. You'll learn a lot by repairing it. I did my PV-1.3k. More fun than crossword puzzles and warmer in December than restoring cars or tractors.
Have fun.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300

Last edited by indianajo; 9th December 2017 at 07:10 PM.
  Reply With Quote
Old 9th December 2017, 07:41 PM   #3
Andyman001 is offline Andyman001  United States
diyAudio Member
 
Join Date: Dec 2017
Location: IDAHO
Thanks for the reply.
I have downloaded schematics for the CS800;CS800s & CS800x, trying to figure out which matches mine. I already sent a request to Peavey support (day before yesterday) for correct schematics.
thanks for safety tips, will probably start tomorrow afternoon or so.
how I remove the triacs from the circuit? other than physically removing them?

thanks, Andy
  Reply With Quote
Old 9th December 2017, 10:01 PM   #4
indianajo is offline indianajo  United States
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
An S or X model will say it on the front cover. At least my S does and there is an X for sale on e-bay now, with picture. S & X have op amps on the input, and full complimentary output transistors. If yours has quasicomp output transistors, all the output transistors have the same part number. Full complementary, one is one digit off from the other in pairs. In the early days Peavey didn't highlight model changes, like changing from quasi-comp (early ) to full complementary (late).
You disable the triac by removing the gate lead which is the right lead with the lettering up and the leads towards you. Alternately you can remove the diac next to it which triggers it, shown as sac187 on the schematic. Probably it should come out anyway, as if the triac shorts they blow up too, often. The diac breaks over at 7 to 8 volts, so you put a 12 v power supply in series with it, a 1k to 470 dropping resistor, and see what you measure, 7 to 8 if good. Of course if it is shorted it's bad without digging out the battery charger.
Sorry about any redundant safety tips, but this is the USA and people giving advice can be sued.
I found a replacement for the diac as Powerex bs08d, at Newark. Various people get huffy about names for the sac187, expect some argument.
Alternately you can buy them, plus all parts from Peavey. You have to call them though, they don't respond to email for parts. Or didn't 2 years ago. Peavey fans are probably better than any you can buy elsewhere. Also if you buy complete sets of output transistors, they've matched them at the factory already. If the OT's are blown, usualy some drivers predrivers & other stuff is blown one. The musicians won't quit plugging the amp in and turning it on just because it blew the fuse once.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300
  Reply With Quote
Old 10th December 2017, 12:13 AM   #5
Andyman001 is offline Andyman001  United States
diyAudio Member
 
Join Date: Dec 2017
Location: IDAHO
looks like it is later than i thought; 4 opamps on each board 2-5532; 1-TL072CP; 1-70487478;
output transistors - 8 pairs 70483180 & 2 pair 70481180.

according to this thread Peavey op-amp sub
i can use schematic for CS800x -correct?
  Reply With Quote
Old 10th December 2017, 04:23 AM   #6
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
Yes, wind tunnel is CS800X.

CS800S has a switching power supply and is totally different. The old CS800 series is one rack unit taller than the wind tunnel guy, and is also totally different.

If the triac is shorted, remove it. For testing, you don't need the triac. Work with NO LOAD until the amp is working.

Look at the schematic, the main rails are on the collectors of the power transistors, the cases.
  Reply With Quote
Old 10th December 2017, 05:03 AM   #7
indianajo is offline indianajo  United States
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
I don't think it is a CS800x. I just downloaded that schematic, and it is fully complementary, that is 4 70483180 and 4 70473180 per channel (Mj15024 & 25). If your output transistor board is all 70483180 it is quasi-comp. The 1180s are drivers, should be on a driver baord.
5532 and tl072 op amps are pin compatible with rc4580 & rc4560, and somebody might have substituted over the years.
One implication of emitters tied together to the speaker return, it is "flying ground" which means you work on one channel at a time with the negative probe if dvm clipped to speaker ground. The two channels do not have the same ground and speaker ground is not the same thing as case ground. The transformer has two windings to make the channel speaker grounds independent. This is done to make bridging easier. The op amp supplies derive from the rails, unlike other amps.
Does your unit have a DDT switch & light on the front? If not, definitely not an X. The DDT op amp has a weird pinout and drives a J174 jfet. It is hard to buy, hope yours is not blown.
The ebay cs800x does say that on the front. In big bold letters.
Next thing after defeating triac protection, is build a light bulb box or use a element from a dead room heater to put in series with the AC power, so you can test for DC on the output without blowing the fuse.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300

Last edited by indianajo; 10th December 2017 at 05:16 AM.
  Reply With Quote
Old 10th December 2017, 11:48 AM   #8
Andyman001 is offline Andyman001  United States
diyAudio Member
 
Join Date: Dec 2017
Location: IDAHO
Thanks. to clarify, front panel "CS 800" (no "X"); 3 rack space "wind tunnel" design cooling; it has the DDT speaker protection.
The plan for today is to repair the blown out trace on the power board and remove the bad SAC187. I will build the light box also. Should I test the output transistors since i have it apart? The only thing in the case ATM is the power supply.
  Reply With Quote
Old 10th December 2017, 12:39 PM   #9
indianajo is offline indianajo  United States
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
The light bulb box DC on output test is the first test of the power transistors. If they are not messed up, don't pull them. I make enough solder mistakes to leave things alone that work. My CS800s only had a blown input and power supply problems, so I haven't monkeyed with the output transistors yet. Yours are likely blown, but blowing fuses means you seriously need the light bulb box. Problem could be power supply caps or rectifier, instead. (change rsil electrolytic caps anyway for reliability at 30 years, but not until you identify what is wrong and fix that first. Later when working right you can change all the other electrolytic caps two at a time between tests).
Warning, the light bulb box would not provide enough power for my PV-1.3k to pass +-16v to the op amps, so I had to use a dead room heater element instead. Other problem with light bulb boxes, 100W tungsten filament bulbs are rare beasts these days in the USA. The halogen ones have a diode or something in them and don't work.
With DDT, the CS800x schematic on eserviceinfo.com should be good enough to work on it unless there traces melted off the driver board or vaporized parts you can't identify by color code. There was a 18 month period when Motorola/ON Semi made the MJ15024 and not the MJ15025, so Peavey may have stayed quasi comp while that was going on. MJ15024 would have been seriously more reliable at 81 v rails than MJ15003 or whatever previous version was. But fully complementary output could sound slightly better at low volumes than quasi-comp. These have HD rated at full power and as PA amps should mostly be used at 100 W/ch or above, but I listen to my CS800s at 1.5 W/ch today, and sound is superb.
Remove one leg of both sac187, you want the triacs disabled during testing. Or remove the triac gates. TO92 legs are easier to desolder.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300

Last edited by indianajo; 10th December 2017 at 12:51 PM.
  Reply With Quote
Old 10th December 2017, 01:00 PM   #10
Andyman001 is offline Andyman001  United States
diyAudio Member
 
Join Date: Dec 2017
Location: IDAHO
thanks.
I'll re assemble and do some tests after i repair that trace.
it will have to wait till after Church though (playing bass today)
  Reply With Quote

Reply


blowing fuse - Peavey CS-800Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Crown M 600 blowing the 1.2 amp fuse - not the 20 amp fuse srinath Solid State 7 11th September 2014 02:59 AM
Peavey 400 blowing fuse on power up Barnacle Instruments and Amps 11 2nd February 2009 10:49 AM
Fuse housing melting but fuse not blowing, ppi amp rawadia Car Audio 21 2nd August 2008 10:39 AM
Blowing B+ fuse trombone Tubes / Valves 5 1st July 2008 02:05 PM
Blowing my fuse (s) Jimlondon Chip Amps 7 7th March 2005 06:03 PM


New To Site? Need Help?

All times are GMT. The time now is 06:08 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki