solving my old radiogram sound issues - help - Page 2 - 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 February 2014, 12:26 PM   #11
diyAudio Member
 
azazello's Avatar
 
Join Date: Aug 2008
Location: Bulgaria
Needles for 78 and 33, 45 are different, but they must sound on "wrong" records. I had the same problem with "keepers" for needle in cartridge....
__________________
Projects: OTL-OCL 6AS7 Gen. Electric, SEs 2A3 RCA, 300B JJ, 6S4S, 4P1L, EL11 Telefunken, 6AS7 RCA, 6S33S, 6S41S, 6S19P, E84L Siemens, E236L Telefunken, headphone ampl. OTL Loftin White 6AS7 RCA,... PPs 6005 Gen. Electric, EL34 Mullard, 6L6....
  Reply With Quote
Old 18th February 2014, 12:33 PM   #12
diyAudio Member
 
Join Date: Feb 2014
Quote:
Originally Posted by Refugee1 View Post
A photo of the under side of the chassis where the 6M8 valves are would be very helpful so that I can identify the type of capacitors that are fitted in the C21 and C22 positions.
I will then be able to see if they are types that need to be changed out or not.
If they are faulty the 6M8 valves and the transformers could overheat and burn out. The sound does not distort until it is too late.
It looks very much like you will need a new cartridge as these fade with time and not use.
The later types that need a preamp ire very different and do not fade like the early types.
Hello !
i've attached a photo, i hope the resolution is enough for understanding..
thanks again
Attached Images
File Type: jpg chassis1.jpg (974.6 KB, 40 views)
  Reply With Quote
Old 18th February 2014, 12:49 PM   #13
diyAudio Member
 
Join Date: Feb 2014
and another close up to 6v4 , 6m5
Attached Images
File Type: jpg 6v4-6m5.jpg (933.5 KB, 38 views)
File Type: jpg 6v4-6m5-clear.jpg (382.3 KB, 43 views)

Last edited by uuzai; 18th February 2014 at 01:16 PM.
  Reply With Quote
Old 19th February 2014, 12:25 PM   #14
diyAudio Member
 
trobbins's Avatar
 
Join Date: Feb 2009
Location: Melbourne, Oz
With all the power off, and the switch set for phono, do you have an ohm meter to measure the resistance from the top of the volume pots through to the jacks J1 and J2 and then to the 2.2M resistors going to the cartridge? This would indicate if the switch and jack switch contacts are ok, and that the 2.2M resistors are ok.

Are you proficient enough to take voltage measurements - that is a basic checking operation to check operation (not only HT1,2,3 but also the voltage across R25 and the bias 2 level, which will indicate the 6M5 idle current, plus the 12AX7 cathode bias).

Note that the schematic doesn't show any fusing, so the radiogram is dangerous at the moment to use.
  Reply With Quote
Old 19th February 2014, 01:04 PM   #15
Keit is offline Keit  Australia
diyAudio Member
 
Join Date: Feb 2014
Location: Australia
Check the aforementioned 2.2m resistors. These sometimes go open circuit, unless they are Philips CR series - which in your case they are not.

I have come across a few stereograms of this vintage and using the same cartridge still in use by the folk (now old age penioners) who purchased them new. There is a batch of faulty stylii on the market that have the saphire point mounted incorrectly, so that the stylus arm sits on top of the record without the point penetrating the groove. This gives weak distorted sound. In each case I have bent the end of the stylus so the the point is at the correct angle, whereupon the sound volume and quality becomes normal.

It's nothing to do with the symptoms you described (low volume of record play only, radio ok), but I notice your unit has blue Ducon electrolytics. These are notorious for random failures, and they always completely fail eventually. I would pre-emptively replace them. If you want to keep an authentic apearance, obtain NOS Philips blue electrolytics from eBay. The Kriesler factory sometimes used Philips, sometimes Ducon. The Philips caps rarely fail completely, but slowly increase their internal series resistance (which does not matter much), leaving the capacitance unchanged. You may be surprised by a notceable improvement in gain and sound quality.

Check all the 1/2 watt carbon resistors and the audio cathode bias resistors. These tend to slowly drift up in resistance over time. Replace any that have gone up more than 20 or 30% - again you may get a small increase in sound quality.

Tube based Kriesler stereograms were carefully designed to a low manufacturing cost, but the sound quality is never the less pretty good considering when all parts are good. Niot quite as good as some of the classier HMV's but pretty good.

Keit

Last edited by Keit; 19th February 2014 at 01:09 PM.
  Reply With Quote
Old 19th February 2014, 02:35 PM   #16
diyAudio Member
 
azazello's Avatar
 
Join Date: Aug 2008
Location: Bulgaria
Take off "the head" from ton arm, take sewing needle and try to touch one of contacts in ton arm....If there is big hummm, the problem is in the head. If there isn't, go to another end of wire in radio box, and touch again with the needle.
__________________
Projects: OTL-OCL 6AS7 Gen. Electric, SEs 2A3 RCA, 300B JJ, 6S4S, 4P1L, EL11 Telefunken, 6AS7 RCA, 6S33S, 6S41S, 6S19P, E84L Siemens, E236L Telefunken, headphone ampl. OTL Loftin White 6AS7 RCA,... PPs 6005 Gen. Electric, EL34 Mullard, 6L6....

Last edited by azazello; 19th February 2014 at 02:41 PM.
  Reply With Quote
Old 21st February 2014, 12:55 AM   #17
diyAudio Member
 
Refugee1's Avatar
 
Join Date: Jul 2012
Location: Worksop
From the photos C21 and C22 look like Mulladr Mustard types and will be fine.
There are three tone correction capacitors that look like the old wax types and these will go leaky and make the sound tinny.
They are C25 and C26. Also C28 in the tone control bias.
They will not do any very nasty damage if they are a bit leaky but they could get very bad and burn a resistor if the set is run for too long with them faulty. Replacing them will improve the tone control operation.
All the others are good types and should be fine.
Those 2.2M resistors will make the gram sound low and very tinny if they have gone open circuit.
  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
HELP - Sound quality issues silentcropduster PA Systems 12 3rd December 2013 09:17 PM
Kriesler Radiogram refurbishment questions lhalha Tubes / Valves 10 4th November 2013 09:36 PM
Turntable sound output issues old skool junkie Analogue Source 1 21st November 2011 07:03 AM
Degraded sound issues amt Chip Amps 0 4th September 2010 07:48 PM
Sound Issues. Carm2K Everything Else 5 12th July 2009 06:25 PM


New To Site? Need Help?

All times are GMT. The time now is 03:22 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2