need a little help with an HK solo2 tube receiver - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 18th November 2011, 03:23 PM   #1
ke4mcl is offline ke4mcl  United States
diyAudio Member
 
Join Date: Apr 2009
Location: miami, fl
Default need a little help with an HK solo2 tube receiver

this old receiver started as a labor of love and has now become a personal challenge. i'm two steps away from gutting it for the iron but i'm stubborn and with every tube repair i learn something new.

its been recapped with all new coupling caps and lytics. i left the ceramics alone. the two 1k resistors in the pic get REALLY hot at 110v on the variac. the caps are new and do not get hot so i am assuming they are ok.

could the value on those have drifted down causing them to pass more current? the resistors are r27 and r28 in the schem.

Click the image to open in full size.
Click the image to open in full size.
Click the image to open in full size.
__________________
certified packrat
  Reply With Quote
Old 18th November 2011, 04:13 PM   #2
diyAudio Member
 
artosalo's Avatar
 
Join Date: Feb 2010
There are voltage readings (320 V and 292 V) given at both sides of R28/27.
If the readings are correct, then the power dissipated by both resistor is some 0,78 W/resistor. What are the existing voltages ?
Obviously at the left side the voltage is much less than 292 V. Since the schematic is not complete, it is difficult to say more.
  Reply With Quote
Old 18th November 2011, 04:47 PM   #3
ke4mcl is offline ke4mcl  United States
diyAudio Member
 
Join Date: Apr 2009
Location: miami, fl
full schem here down loadable as a pdf about 3/4 way down the page
Harman Kardon - Product Support - TA12 (Solo II)
__________________
certified packrat
  Reply With Quote
Old 18th November 2011, 10:22 PM   #4
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
R27 and R28 are more likely to overheat if they rise in value, which is quite possible if they are carbon composition.
  Reply With Quote
Old 18th November 2011, 10:56 PM   #5
ke4mcl is offline ke4mcl  United States
diyAudio Member
 
Join Date: Apr 2009
Location: miami, fl
sure enough they were both way off from each other and way over 1k. i replaced them and the new ones still get hot even at 100v on the variac. amp plays ok on aux and AM but fm is out.

i've heard that HK initally made lower end stuff. this receiver uses a pc board in 1957. the iron is of decent size and the tubes are well chosen but the rest leaves much to be desired. i wonder if the rest of the carbon comps are shot as well?

i put the covers back on and put it on the shelf for now. i'm almost about to give up on this one and just break it down for parts.
__________________
certified packrat
  Reply With Quote
Old 18th November 2011, 11:05 PM   #6
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
You are likely to find that many, although not all, of the carbon comp resistors have changed value. Don't worry too much about small changes - in most cases 20% does little harm.
  Reply With Quote
Old 19th November 2011, 06:38 AM   #7
diyAudio Member
 
artosalo's Avatar
 
Join Date: Feb 2010
Quote:
sure enough they were both way off from each other and way over 1k. i replaced them and the new ones still get hot even at 100v on the variac.
Can't you simply measure the voltages at both end of R27 and R28 ???
If the voltage drop is too high, then excessive current goes somewhere. This kind of fault must be located by measuring.

I can not find the schematic. The link you gave goes the HK country selector page only.

Last edited by artosalo; 19th November 2011 at 06:49 AM.
  Reply With Quote
Old 19th November 2011, 07:53 AM   #8
rmyauck is offline rmyauck  Canada
diyAudio Member
 
Join Date: Apr 2009
Default SOLO II (TA12)

I found it under Canada, support, all products, and it's too big to upload.
  Reply With Quote
Old 19th November 2011, 10:36 PM   #9
ke4mcl is offline ke4mcl  United States
diyAudio Member
 
Join Date: Apr 2009
Location: miami, fl
while i can get in there to measure, those resistors are notoriously close to the bare power switch leads. to add to the annoyance all the wire is brittle. in order to fit the new resistors in i had to stick a shim of fish paper in. the leads on the power switch are that close. a little face flex and it would be a sparking good time!

i'm a collector at heart but at the end of the day if i get it going right its an unremarkeable mono receiver. i'm setting it aside for now in the "trade it off or strip it down pile". the tubes and iron alone in this unit would make a real nice setup for a great mono amp or guitar amp. other projects await.

thanks all
__________________
certified packrat
  Reply With Quote

Reply


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
Need Service Manual for HK SR400B Receiver tjet Forum Problems 0 24th January 2010 05:25 PM
transformer hum on my beloved HK 3270 receiver, help! gychang Solid State 9 4th March 2008 02:22 AM
Re: HK Receiver 590i Mayank Vendor's Bazaar 0 8th June 2007 02:38 PM
hk 930 receiver latala Solid State 2 8th February 2006 08:27 AM


New To Site? Need Help?

All times are GMT. The time now is 08:30 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright 1999-2015 diyAudio

Content Relevant URLs by vBSEO 3.3.2