Speakerplans.com Homepage
Forum Home Forum Home > General > Amp Forum
  New Posts New Posts RSS Feed - "ODEP" crown macrotech
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

"ODEP" crown macrotech

 Post Reply Post Reply Page  <1 78910>
Author
Message
EmPro View Drop Down
Registered User
Registered User
Avatar

Joined: 26 June 2020
Status: Offline
Points: 183
Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 19 June 2022 at 10:29pm
Well...i'm a proud owner of 8 MT-s still working flawless,6 of them with all original parts ClapClap ofcourse i did meinteinance on all of them...recalibrated,resoldered,etc etc...the strongest ones are MT2400 folowed by PowerTech 3,after 1200 and last 600,didn't have any use for MT3600vz or 5000vz,i use different amps for bass...maybe just in my head the lateral mosfets sound better for bass,but i love them,MT-s just doing the light mid-hi stuff never in bridge mode,and rarely in 2R/ch on moderate power levels.

Edited by EmPro - 19 June 2022 at 10:39pm
EmPro Audio
Back to Top
EmPro View Drop Down
Registered User
Registered User
Avatar

Joined: 26 June 2020
Status: Offline
Points: 183
Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 19 June 2022 at 10:33pm
Originally posted by opacheco opacheco wrote:

EmPro,
Thanks for comments!

I have changed the bad (5 only) outputs devices in channel one (MA3600VZ) with the 3 Mosfet power supply switching devices too (now new all of them) and now am having a ODEP light turning off indicating some output problem until or PSU failure. I found the MC33079P OTA bad condition, I changed new but the amp is not working until.

Any advise will be appreciated
opacheco 

Are you sure the rest of the outputs are good?? As the amplifier seems to go in protection mode now,and that indicates faulty outputs/drivers (if the psu is good as you fixed the vs mosfets)


Edited by EmPro - 19 June 2022 at 10:40pm
EmPro Audio
Back to Top
EmPro View Drop Down
Registered User
Registered User
Avatar

Joined: 26 June 2020
Status: Offline
Points: 183
Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 19 June 2022 at 10:57pm
So,if your psu,drivers,outputs and biass are good,then you might have a look for ODEP voltages and see how they are,if the odep circuit fails will turn off the ch and you just gonna waste time looking on wrong board for faults Wink

Edited by EmPro - 19 June 2022 at 11:00pm
EmPro Audio
Back to Top
opacheco View Drop Down
Registered User
Registered User


Joined: 09 March 2008
Location: Honduras
Status: Offline
Points: 21
Post Options Post Options   Thanks (0) Thanks(0)   Quote opacheco Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2022 at 4:36am
EmPro,

I tested all the output devices (I pull out every output transistors and they were tested) and changed the faulty units at all!

I am thinking the 555 timer in the regulation channel 1 PSU board could be bad, although as indicated by DjLeco I should change the comparators (+/-V2 versus Output voltages (Black and Red Outout Terminals Votages) in the 555 Timer Trigger terminal as well as changing the source regulation Mosfet (I changed them already!)

Look like, this amp has more than one problem, it wasn't just the damaged outputs devices only, maybe the power supply still has a problem in its regulation system; Do someone know what can I check for tests the power supply for any failure? Any specific voltage test or how I can test the 555 Timer?

Any advise will be appreciated so much!
opacheco 


Edited by opacheco - 20 June 2022 at 4:39am
Back to Top
EmPro View Drop Down
Registered User
Registered User
Avatar

Joined: 26 June 2020
Status: Offline
Points: 183
Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2022 at 7:14am
Morning mate,when the vz mos are gone the 555 holds there hands,Djleco is right saying to change the 555,as the problem now is in the psu,i thought you already did it,that's why i suspected more outputs faulty,btw,did you fit original crown matched output devices? if not...that amp cannot be trusted..is just a timer bomb,for just a blown output i replaced all 16 of them,when outputs fails even the good remaining ones had suffered and the life span is severe reduced unfurtunately.

Edited by EmPro - 20 June 2022 at 7:58am
EmPro Audio
Back to Top
EmPro View Drop Down
Registered User
Registered User
Avatar

Joined: 26 June 2020
Status: Offline
Points: 183
Post Options Post Options   Thanks (1) Thanks(1)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2022 at 9:08am
Some old post from DjLeco,as you can see,just changeing the outputs and vz moss doesn't fix the problem for vz amplifiers,that's why i never bothered with them LOL not such problems with MT2400 and below series.


Edited by EmPro - 20 June 2022 at 9:10am
EmPro Audio
Back to Top
kedwardsleisure View Drop Down
Old Croc
Old Croc


Joined: 20 January 2009
Location: Staffordshire
Status: Offline
Points: 4670
Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2022 at 9:54am
certainly worth checking around the VZ drive ics if the VZ switching fets have failed, although it's pretty rare for them to fail at all.

If the main output transistors failed then the output drivers are suspect, (on the upright aluminium bracket), also any fusible resistors, zero-ohm links and particularly the bias diodes (under the silicone). Check the flywheel diodes for leakage. On the 3600 also check the insulating mat between heatsink and output transistor plates. It rarely fails but it can happen.

If one channel is good, then you have a nice comparison of the readings between the two. Due to the multiple closed loops, I would do cold-checks (unpowered) between the two sides rather than get bogged-down in voltage readings while it's turned on.

Output faults can sometimes travel onto the control card, check the fusible resistors on here and if blown, check the associated drivers.

This line of Crowns rarely fails short circuit across the power rails like some of their competitors, as the grounded-bridge circuit means that if the amp trips into protect, the ground reference is removed from the power supply and no more current can flow.



Kevin

North Staffordshire

Back to Top
EmPro View Drop Down
Registered User
Registered User
Avatar

Joined: 26 June 2020
Status: Offline
Points: 183
Post Options Post Options   Thanks (0) Thanks(0)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2022 at 10:22am
well...when amps like MT-s falling is only from human errors,sc on outputs at full power,poor or inexistent meinteinance etc,and when they do...they do in big style and let you with headache to put them back in order,my mind is set to prevent catastrophic failures and i always keep them clean as new and all my MT-s have all the output boards fully resoldered fom a to z,all the driver boards washed and proper cleaned,bias adjusted and i had no problems with them so far,also like every 2 years i check the psu caps for changes as are old enaugh already,if you take care of them will take care of you Wink almost forgot to mention that i lubricate the bearings on the fans...as i really don't wanna change that fan-transformer ,,thing'' LOLLOL oh,one more thing..i glued the band connectors to the pcb as all the band pressure and the connector was just hanging on the solderings....not quite a good ideea from my point of view....bare in mind when you guys working on MT-s just handle with extreme care the jack inputs sockets as there tend to become ,,glass'' with time,i broke two of them durring meinteinance so far Confused and forced to fit new ones on the blank PIP-cards plates.

Edited by EmPro - 20 June 2022 at 11:08am
EmPro Audio
Back to Top
opacheco View Drop Down
Registered User
Registered User


Joined: 09 March 2008
Location: Honduras
Status: Offline
Points: 21
Post Options Post Options   Thanks (0) Thanks(0)   Quote opacheco Quote  Post ReplyReply Direct Link To This Post Posted: 21 June 2022 at 6:18am
EmPro,

I tested twice ALL the units and I can confirm the output devices are ok! I told in my last comment I would like to test the 555 timer and I would like to know if do you knows a procedure for test this 555 timer in this amp?

Thanks for your comments and response
opacheco
Back to Top
opacheco View Drop Down
Registered User
Registered User


Joined: 09 March 2008
Location: Honduras
Status: Offline
Points: 21
Post Options Post Options   Thanks (0) Thanks(0)   Quote opacheco Quote  Post ReplyReply Direct Link To This Post Posted: 21 June 2022 at 6:27am
Originally posted by <br>If the main output transistors failed then the output drivers are suspect, (on the upright aluminium bracket), also any fusible resistors, zero-ohm links and particularly the bias diodes (under the silicone). Check the flywheel diodes for leakage. On the 3600 also check the insulating mat between heatsink and output transistor plates. It rarely fails but it can happen. <br><br>Output faults can sometimes travel onto the control card, check the fusible resistors on here and if blown, check the associated drivers.<br>  <img src=smileys/smiley17.gif border=0 align=middle /> [/QUOTE
If the main output transistors failed then the output drivers are suspect, (on the upright aluminium bracket), also any fusible resistors, zero-ohm links and particularly the bias diodes (under the silicone). Check the flywheel diodes for leakage. On the 3600 also check the insulating mat between heatsink and output transistor plates. It rarely fails but it can happen.

Output faults can sometimes travel onto the control card, check the fusible resistors on here and if blown, check the associated drivers.
[/QUOTE wrote:



Hi kedwardsleisure,
The drivers of output devices are ok, I tested already.
Do you know where these "fusible resistors" are installed especifilly in the 3600VZ schematic?
Where the "flywheel diodes for leakage" are located?

Thanks
opacheco


Edited by opache

Hi kedwardsleisure,
The drivers of output devices are ok, I tested already.
Do you know where these "fusible resistors" are installed especifilly in the 3600VZ schematic?
Where the "flywheel diodes for leakage" are located?

Thanks
opacheco
opacheco - 21 June 2022 at 6:35am
Back to Top
kedwardsleisure View Drop Down
Old Croc
Old Croc


Joined: 20 January 2009
Location: Staffordshire
Status: Offline
Points: 4670
Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 21 June 2022 at 8:39am
the fusible resistors are usually low value, eg 5.6R or 10R and have a matt finish, obviously due to their nature they can fail without showing external evidence. The flywheel diodes are on the output boards, usually one at each end of the pcb. The bias diodes are around the middle, sometimes obscured by the control card unless you fold it up and there are I think 3 in a row with silicone sealant splurged over them.

If you want to test a 555 timer just stick a new one in, they're about 30p


Edited by kedwardsleisure - 21 June 2022 at 8:40am
Kevin

North Staffordshire

Back to Top
EmPro View Drop Down
Registered User
Registered User
Avatar

Joined: 26 June 2020
Status: Offline
Points: 183
Post Options Post Options   Thanks (1) Thanks(1)   Quote EmPro Quote  Post ReplyReply Direct Link To This Post Posted: 21 June 2022 at 9:11am
You can test 555 just for normal shortages acording to internal schematic,and with special circuits to see if operates,so no point in that,you can buy 3 with one pound,and to be more easy for you just fit a DIP8 socket to be easy in the future,as i'm sure crown didn't fit it on a socket. Cheers
EmPro Audio
Back to Top
 Post Reply Post Reply Page  <1 78910>

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.05
Copyright ©2001-2022 Web Wiz Ltd.

This page was generated in 0.080 seconds.