Hammond cv with Leslie 21h --issue with distortion

[hammondcv]

I recently brought a Hammond CV with a leslie 21H. The CV has a Trekii ssp-3a, Reverb, and an add percussion unit. the CV also has a kick switch attached to the swell pedal to control the leslie. I'm experiencing distortion when I play 2 and 3 notes at one time. there is no distortion when I play single notes. I noticed the distortion when i got the organ home. My thoughts are leslie tubes and or 21h amp. I ordered the 21h amp kit and I'm ready to attempt a rebuild. The issue is that all of the resistors are old with a messy solder job. The color patterns are a little off from whats inside the amp. I can match up most, but not all parts In the kit, there is a blue resistor. Where does that go. Note: there was no paperwork giving the value of each resistor. Does anyone have a 21H Inside Picture with new parts, that i may use as a Guide? Am I in the right neiborhood with my thoughts.about the distortion issue. The distortion is not massive but noticeable on triad chords. I've also noticed that the bass pedals are no where as loud as the manuals.
After I pulle the amp out, I found that I had (4) mismatched 6v6 tubes.(I'm thinking about replacing the tubes.. any recommendations). As far as the cv, I oiled it and cleaned the contacts but thats it.

Your Thoughts

[DanielP]

The issue is that all of the resistors are old with a messy solder job

I just finished rebuilding an amp and had the same symptoms as you describe above with distortion on notes played at 2 or 3 at a time. I had swapped out the caps and electrolytics but not the old resistors. After further inspection it turned out to be one failed resistor. As soon as I replaced it the distortion was gone, there was loads more volume, and it sounded 110% better.

Leslie amps are really quite simple, there is nothing extra in there, and something so small as a single resistor can make the difference of it sounding great or terrible! Check those resistors one by one and make sure the solder joints are solid. If the distortion remains then at least you know the problem is not there. I've spent money replacing tubes and other parts which are more expensive and later found the problem was a bad solder joint!

Good luck!

[DanielP]

21H amp photos

Here are photos of the underside of my 21H amp. Also, if you have any questions about resistors there is a website where you can type in the colors of the stripes and it will tell you the value of your resistors, it may be of help if you are like me and don't know offhand what values the colors of the stripes signify. Here is the url: http://www.csgnetwork.com/resistcolcalc.html

[hammondcv]

Thanks I will begin the work and let you know how it turns out. I noticed that my 6v6 tubes are mismatched in brand name. does that make a difference?

[jimmywilliams]

Johnny,

Look here: http://www.captain-foldback.com/Lesl...schematics.htm

and make sure you locate the correct schematic based on the serial number. There were several variants of the 21H amplifier.

It appears there was work done on this amp - the newer "orange drop" coupling, etc. capacitors are not original - unless you did that from your kit parts.

Did you replace the large filter capacitor can?

I took a look at your photos briefly ... For the striped resistors - yes consult the resistor stripe code website you were given, if you are not familiar with how to read teh resistor codes. I guess the peole who put the kit together assume whoever buys the kit already knows how to do this. Most of the striped resistors look like 1/2 watt but there are some that look like they could be 1 watt, and one even higher. There are also several of those high power "dog bone" resistors in there too. Sometimes these are hard to "decode" without a schematic in front of you (the markings may get old and worn). Your "blue resistor" is probably of a different type than the rest - possibly higher wattage or different material. If tou take a photo of that resistor from your kit some of us can probably tell you its value.

[jimmywilliams]

Johnny ... sorry - just noticed the 21H photos were not yours; they were Daniel's.

[DanielP]

jimmy was right about my 21H amp, the caps have been replaced, I should have mentioned that so as not to create any confusion! Aside from the caps though everything else visible under the chassis is original, nothing rewired or tampered with (to my knowledge!).

Hope that helps

[hammondcv]

I didnt start the work yet. I took pictures of the amp and parts kit. i tried to get different angles so that you can get the whole picture. bare with me as it may take a couple of post to complete.

outside of amp

[hammondcv]

schematics on the side

[hammondcv]

Inside of 21H

If you see something strange let me know

[hammondcv]

Inside of 21H continued #1

[hammondcv]

inside of 21H Continued #2

[hammondcv]

Inside 21H #3

[jimmywilliams]

Inside of 21H[ATTACH=CONFIG]2980[/ATTACH][ATTACH=CONFIG]2981[/ATTACH][ATTACH=CONFIG]2982[/ATTACH][ATTACH=CONFIG]2983[/ATTACH][ATTACH=CONFIG]2984[/ATTACH]

If you see something strange let me know

Your fifth photo here shows a burned resistor in the power supply stage - the large resistor coming from one of the filter capacitor can socket terminals. Do not operate the amp until it is repaired as you may damage the power transformer. I would recommend you take a close look at the power supply stage in the schematics (that would be all the way to the right on the pasted schematic - I didn't see a close up of that in your photos). I would GUESS that the filter capacitor can went down and took out the resistor but it is hard to say with absolute certainty; other things may be wrong that caused the problem as well. If your repair parts kit only included resistors and capacitors (i didn't see photos of the kit) you may want to also look into replacing the power supply diodes.

The captain-foldback.com site does have printable schematics but as I said the variant of the amp depends on the serial number. Maybe some others here are more familiar with the 21H (typo in last message) than I am and can tell you right away from the photos which revision of the amp you have.

I assume you have an ohmmeter. If not you should get one right away. If you have problems identifying the resistor values in your kit based on the color stripes, you can just measure them out with the meter. Then you can match them up as per the schematic to where they need to go in the amp. Don't try measuring the resistors in the amp because (1) they are in circuit and (2) they are most likely out of spec.

[jimmywilliams]

ALso from the looks of things your amp was worked on at one time - your coupling/bypass capatitors look newer than what would have originally been in the amp.