WIP Danelectro Challenger 89 amp restoration

PunchySunshine

PunchySunshine

Well-known member
My buddy gifted me this old danelectro amp. I've got plans to restore it. Looks all original inside including the rather large amount of mouse turds. Speakers only had a small tear. Cabinet is made out of particle / chip board. Makes for an incredibly lightweight but not particularly strong box. The canvas doesn't want to clean up but I'm going to keep on trying to see if I can get that gold back. I took the handle off and tried to polish the mounts for it but they were apparently only brass plated. Steel underneath so I may try my hand at electroplating. I've always wanted to try it. It's a crazy circuit so I'm glad I've got the schematic. New caps are coming next week!

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I'll be watching this closely too. I have a late 50s Ampeg and an early 60s Kay to rehab, so this should be a good preview.

Are you replacing all of the caps, or just the electrolytics? What about the carbon comp resistors? Some of the CC's in my amps have drifted way out of spec.
 
keevohn said:
I'll be watching this closely too. I have a late 50s Ampeg and an early 60s Kay to rehab, so this should be a good preview.

Are you replacing all of the caps, or just the electrolytics? What about the carbon comp resistors? Some of the CC's in my amps have drifted way out of spec.
Click to expand...
I'm gonna shotgun all of the caps. I don't know why but I feel like Sangamo caps are shit. This is only my second tube amp but I've got the schematic and I feel really good about that. I'll be checking every one of the carbon resistors along the way. There is one (R25) that was mega crispy and in researching I found a few different solutions but I'm just going with a good ole 10watt instead of the puny 1/4 watt that came from the factory.
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Close, so close. In typical fashion I missed the cap order by two. I'm just not gonna worry about how I wound up with two extra .0022uf and I needed two .022uf.
The tubes were all RCA, so that's great. Except for the 12ax7s which are sylvania.
I've already ordered the .022uf with a few extra to be safe and a few different LEDs and jewel combinations to try out for fun. I replaced the pilot light assembly as this one was too crusty to change the bulb easily. I replaced all caps but the two aforementioned as well as the two tone caps. They're mica and should be fine but I have replacements if needed. I also changed that burnt ass 2.2k with a 2k 10watt. I had to add solder to every single connection in order to get it to flow for the solder wick to work. This certainly used up my wick faster than expected. I've wired in a 3 wire power cable, 86d the death cap and I was happy to see the small speaker patch worked like a charm. I'm going to run a new speaker cable. I would like to add a jack for the speaker but I may not. I'm not sure of the safety ramifications tbh, seems like it would be fine.... Also there are a lot of rubber mounts in this amp and they all need replaced due to dry rot.
The cabinet tightened right up with some clamps and glue. The amp was originally blonde tweed but best we can figure is someone recovered it with an old bassman tolex. Savage.
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IMG_1524.jpeg She's alive! Not happy about it, but shes alive. Terrible sputtering then oscillating. I've done a spreadsheet for the BOM and then checked the resistors, marking the actual value on the spreadsheet as well. Three were so bad I couldn't even get a reading! Five or six were over 50% off. And there were two possibly switched from what the schematic has. So now I've got a resistor and tube order in. I'm only going to start with the B+ and anything out of spec. I ordered enough to shotgun the whole thing if needed.
 

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Can you explain your test setup there? I think I see two DMM's and what appears to be a current-limiting light bulb. What's connected where in the circuit?
 
That's the setup. Simple 150 watt current limit bulb after a variac. I just had the two meters hooked up to each of the transformers primary for the first power up to make sure I don't smoke em. Once it's up and stable I take plate voltage readings with the amp plugged into a wall outlet. I am using a crappy mixer stand for the chassis mount while I'm working on it. Works way better than the mixer I had on it!
 
Installed new grommets on the preamp 12ax7 mount.
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Plugged into the current limiter to make sure I didn't have a short. Fired up good so I plugged into the wall and it sounded great just on the bench!
I'll assemble in the morning and hopefully post a sample of the sweetness!
 
I put everything back in the cab and made a short video sample. The power strip being turned off is a great start. :rolleyes:
https://photos.app.goo.gl/uzsU3u9qX9N1pefp6
The vibe isn't working...yet. I tried a different tube and still nothing. I'm not terribly concerned as I've got the schematic but I've gotten spoiled lately with 100% out of the box. There is a hiss and crackling that I believe to be old, crusty resistors somewhere. I'll do some actual voltage checks once I open it back up for the vibrato.

Also, not a good pedal platform AT ALL. I may mod some of the plethora of input channels for this purpose.
 
So if I lower R30 from 2.2 Meg to 100k~220k, I'm pretty sure it'll turn channel two into a low gain pedal input? Any thoughts are appreciated!
 

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