Parasound P/HP-850 Preamp Problem - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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
Thread Tools Search this Thread
Old 3rd January 2013, 02:29 PM   #1
diyAudio Member
Join Date: Oct 2009
Default Parasound P/HP-850 Preamp Problem

I have not one but two P/HP-850 preamplifiers that are exhibiting the same problem.

On both units, on all inputs both channels come out the left output.


With both channels plugged in, all audio comes out the left channel, no matter how you turn the balance dial it all comes out the left. If you turn it center it's slightly louder than with it all the way to the left or the right.

With only the left input hooked up if you have the balance knob at center or left the left channel plays, with it turned to the right nothing plays.

With only the right input hooked up if you have the balance knob at center or right the left channel plays, with it turned to the left nothing plays.

This behavior happens whether you're listening from the headphone jack on the front or either of the sets of output jacks on the back.

Here is a download link to a copy of the schematic which I got from Parasound support. I can also take some pictures of the inside of the units if that will be helpful to anyone.

P/HP-850 Schematic

Any help with repairing these units is greatly appreciated.
  Reply With Quote
Old 3rd January 2013, 08:07 PM   #2
diyAudio Member
Join Date: Oct 2009
I tried multiple sources just to rule out the source as an issue, and they all had the same problem.

However I just left the thing on and kept checking it periodically, a few hours later the one that I left on stopped doing it, but it's done it before in the past. The other unit will still do it if I hook it up and try it, so I wonder if the chip that handles the input/output routing is old and flaky or what.

Since it does it over both the headphones and the RCA outs I'm guessing that means it's probably in the input selector chip, volume/balance part of the circuit or in the first gain stage.
  Reply With Quote


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Parasound P/HP-850 Preamp Schematic Request dtm1962 Solid State 0 20th March 2008 04:58 PM
Parasound P/HP - 850 Preamp modifications firekat Solid State 0 10th December 2006 03:36 PM
Help with parasound PHP-850 hiss Howismydriving Solid State 0 19th February 2005 05:26 PM
Parasound P/HP-850 mura Solid State 3 12th January 2005 07:09 AM
What AD Opamp does the Parasound PHP 850 use? G Parts 0 24th September 2002 05:23 AM

New To Site? Need Help?

All times are GMT. The time now is 10:25 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2