Hi all,

I just got hold of another Kriesler, This one is the 11-103. I have replaced all the electrolytic caps and a great deal of resistors in the pre-amp and output section of the unit.
But it still has problems with the way it sounds, The left channel sounds a bit muddy but does not distort, The right channel seems to have a fair bit more tone and higher volume but it has distortion.

The tubes are fine and it makes no difference if swapped around, If anyone has encountered this sort of problem can you please help me out with this?

The other thing is that the speaker grill cloth is falling apart and I am not sure how I could replace the cloth.

Any help with these things will be greatly appreciated

Kind Regards,
James

Maybe a cartridge problem? Try swapping the input connections and see if the problem moves channels.

Re grille cloth, there are some selling it online, for instance:

http://www.soundlabsgroup.com.au/p/Speaker-Cloth-Colour/Acoustic+Speaker+Grille+Cloth

Thanks for that , but the cartridge is not at fault as it does it on all inputs.

Thanks for the link, it will come in handy..

Some of the usual suspects include corroded valve pins, bad solder joints, dud paper or mica capacitors.

For the more intractable distortion cases (and assuming circuit voltages have been checked with a meter), I usually involve the CRO. Helps when it's a stereo circuit as you can compare similar test points. (The usual caution applies about high voltage here.)

Even though paper caps were not listed in the parts list I did find two of them. (Both replaced)
Other than that the only types I found in the pre-amp and output are ploy and styroseal caps.

It was suggested that there might be bad contacts on the switches, I will need to investigate that and get some cleaner.

Also I thought I seen a cracked styroseal cap, Is that even possible? This was attached to the volume pot along with a resistor,

I have experienced an intermittent attenuation problem associated with a radio/gram switch on an Airzone radio. Had me going around in circles until it dawned on me to clean that with contact cleaner.

I've come across cracked old Ducon styroseal type caps (clear plastic case).

The styroseal caps are the clear type ones in this unit. I feel the problem is in the pre-amp stage?

I'd go ahead and clean the switch contacts as a matter of course.

If you suspect the preamp, as a rough check you could try swapping the connections on the balance pot and see if the problem moves channels.

What test equipment do you have? My approach would be to check the voltages at various valve element points: They should be the same in both amps.

Resistors also fail and need checking.

When checking for distortion in amplifiers, I find a tone generator and an oscilloscope quite useful.

Marc

GTC,

Yes that is on my to do list and thanks for tip of swapping the connections I never thought of that.


Marc,

As of now I only have a DMM, I did have a oscilloscope but that went up in smoke (It was old)
I have replaced resistors that have been way above spec. Most have been replaced, All that remains is caps, all are original except the electrolytic caps.


Regards,
James

James, re caps you did say earlier:

"Even though paper caps were not listed in the parts list I did find two of them. (Both replaced)
Other than that the only types I found in the pre-amp and output are ploy and styroseal caps."

Also, I did mention in post #4 above that circuit voltages should be checked. I gather that you have the schematic?

There is no other paper caps, only the ones I found, even though they were not listed in the schematic part list.
The voltages were checked and appeared fine.

Output transformers are shot

Hi James, et al,

an old post but was wondering if you managed to remove the speaker grill panels to change the cloth. I am restoring an 11-103 but after a quick look, the panels appear to be glued in? I cannot see any screws from the rear.

Regards,
Steve

The screws are there, covered by the grille cloth. Try using a magnet to find them.