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

Solid State Talk all about solid state amplification.

Marantz PM7200 - No Sound
Marantz PM7200 - No Sound
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 12th April 2019, 04:50 PM   #1
Passmore is offline Passmore
diyAudio Member
 
Join Date: Dec 2018
Default Marantz PM7200 - No Sound

Hey All,

Thanks in advance for any help you can offer.

I have a Marantz PM7200 which Iím struggling to get working. It powers on and lights up on the front, you hear the relay click in the power supply, but the relays on the amplifier board do not click and there is no sound. One can flip between input channels on the front of the device, but nothing happens internally.

This device has known problems with some of the capacitors on the power board and protect board going bad and falsely tripping the amp into protect mode. I tested them all with my atlas ESR and they seemed fine, but Iíve replaced anyway to be sure - no difference. I replaced the four caps on the protect board and caps 2304, 2302, 2305, 2210 on the power board.

I have tested the main voltages going from the power board to the amp board. My measurements are
VB+: 44.8v
B+: 44.8v
VB-: -44.8v
B-: -44.8v

These values are much too low, they should be +/- 56v according to the service manual. I suspect this is why the amp board isnít switching on. Problem is - I cannot figure out why these values are low. The 12000uf filter caps are measuring within range, so it doesnít seem to be that. Any ideas? Iím getting the same values even if I disconnect the board from the amplifier board.

Thanks!
  Reply With Quote
Old 12th April 2019, 05:31 PM   #2
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by Passmore View Post
It powers on and lights up on the front, you hear the relay click
in the power supply, but the relays on the amplifier board do not
click and there is no sound.
Is the DC at the output (before the speaker relay) zero, or a high DC voltage?
An output device (and more) could be shorted.
  Reply With Quote
Old 12th April 2019, 06:35 PM   #3
Passmore is offline Passmore
diyAudio Member
 
Join Date: Dec 2018
Quote:
Originally Posted by rayma View Post
Is the DC at the output (before the speaker relay) zero, or a high DC voltage?
An output device (and more) could be shorted.
0.025vdc measured at the amp side of speaker relays, specifically at t012 and t018.
  Reply With Quote
Old 12th April 2019, 08:16 PM   #4
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
diyAudio Member
 
JonSnell Electronic's Avatar
 
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
The rail voltages depend upon the model suffix; N or U.
Don't get caught looking for a fault that is not there.
If you had shorted output transistors, you would have a buzzing mains transformer/lots of het or smoke.
Don't get bogged down, it is only an amplifier!
Check for DC on 5351 and 5352, if at zero, the amplifier is probably OK and you need to check for signal on those points.
All will become clear after those check as to which area your fault lies.
__________________
Support for Fender, Marshall and all Valve Equipment; Audio Innovations, Audiorama FU29, Quad and Leak. www.jonsnell.co.uk
  Reply With Quote
Old 12th April 2019, 08:50 PM   #5
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by Passmore View Post
0.025vdc measured at the amp side of speaker relays, specifically at t012 and t018.
That sounds within the normal range.
  Reply With Quote
Old 12th April 2019, 11:08 PM   #6
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
Measure on the cathode end of the diodes that are across the relay coils, to ground (NOT across the relay coil or the diodes!) - do you get 24V there ? Do you get 24V at the emitter of transistor 7203 ?
  Reply With Quote
Old 13th April 2019, 04:32 PM   #7
Passmore is offline Passmore
diyAudio Member
 
Join Date: Dec 2018
Quote:
Originally Posted by JonSnell Electronic View Post
The rail voltages depend upon the model suffix; N or U.
Don't get caught looking for a fault that is not there.
If you had shorted output transistors, you would have a buzzing mains transformer/lots of het or smoke.
Don't get bogged down, it is only an amplifier!
Check for DC on 5351 and 5352, if at zero, the amplifier is probably OK and you need to check for signal on those points.
All will become clear after those check as to which area your fault lies.
I'm really sorry - i'm probably being stupid, but I cannot find 5351 or 5352 anywhere, i've searched the schematic and boards. Can you advise?

Quote:
Originally Posted by jaycee View Post
Measure on the cathode end of the diodes that are across the relay coils, to ground (NOT across the relay coil or the diodes!) - do you get 24V there ? Do you get 24V at the emitter of transistor 7203 ?
Measuing 0.025vdc on the diodes to ground!
NOT getting 24v at the emitter of transistor - getting nothing!
  Reply With Quote
Old 14th April 2019, 06:08 PM   #8
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
Quote:
Originally Posted by Passmore View Post

Measuing 0.025vdc on the diodes to ground!
NOT getting 24v at the emitter of transistor - getting nothing!
Thats your problem. The protection circuits run from this voltage, so they won't be activating even though everything else is OK. Check the resistor at 3203, it's a fusible resistor and may have blown.

Personally I dont like the way Marantz implemented this - they would have done better to use a 7824 regulator.
  Reply With Quote
Old 15th April 2019, 09:10 AM   #9
Passmore is offline Passmore
diyAudio Member
 
Join Date: Dec 2018
Quote:
Originally Posted by jaycee View Post
Thats your problem. The protection circuits run from this voltage, so they won't be activating even though everything else is OK. Check the resistor at 3203, it's a fusible resistor and may have blown.

Personally I dont like the way Marantz implemented this - they would have done better to use a 7824 regulator.
I'm afraid r3203 seems to be fine any other suggestions?

Thanks so much for your help!
  Reply With Quote
Old 15th April 2019, 11:22 AM   #10
Passmore is offline Passmore
diyAudio Member
 
Join Date: Dec 2018
Quote:
Originally Posted by Passmore View Post
I'm afraid r3203 seems to be fine any other suggestions?

Thanks so much for your help!
AC is coming in at 1503 to the tone circuit, but it goes no further because the fuses 1202 & 1201 are both blown. Diodes following these fuses don't seem to be blown, so i'm guessing there's a short somewhere after.
  Reply With Quote

Reply


Marantz PM7200 - No SoundHide 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
Marantz PM7200 re-cap question Dave Lillis Solid State 16 17th February 2019 07:42 PM
marantz Pm7200 reddish75 Solid State 2 5th February 2019 07:51 PM
marantz PM7200 dead east electronics Solid State 1 7th December 2010 12:21 PM
Marantz Pm7200 Amp jjbmon Solid State 3 22nd February 2009 08:46 PM
marantz pm7200 preamplifer jules_gerfault Solid State 0 16th February 2007 08:00 AM


New To Site? Need Help?

All times are GMT. The time now is 07:03 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki