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Rick S.

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  1. Well, my cord delivery got delayed so I temporarily wired up my short cord and the speaker to the amp just to start initial testing. I did the tests w/o tubes, then with rectifier, then with all tubes. Voltages are good with right at 165 on the plates of the 12AX7 and 370 on the plate of the 6V6. At idle, the cathode of the 6V6 was at 22. I just now realized I forgot to check cathode voltages of the 12AX7, but I know the resistors measured correct earlier on so hopefully that was good as well... I'll check at next power up. I did check the coupling capacitors for leakage at idle. the preamp coupler was a few millivolts DC and the output coupler was at about .5V DC. This was less than 1 volt, so I thought I'd see what it sounded like. One word -- BAD. The amplifier is in a bad sounding distortion at all volume levels especially with a guitar plugged into input 1. The Low's are especially distorted. From what I've read, the sounds I'm getting are indicative of leaking coupling capacitors. So, I have now replaced them with the .022uF 600V orange drops I had in my parts box. Unfortunately, I can't power the amp up right now without waking the rest of the house :D. I'll power it up tonight and see if that makes an improvement. Here's a couple of photo's of the new orange drops installed.
  2. This morning I replaced the 10K & 22K power supply resistors as well as the Bias Resistors and bypass Caps on the 12AX7 & 6V6. My power cord should arrive tomorrow so I'll likely install it Friday morning. Then will come initial power up and test time. Assuming that goes well, I'll just need to secure the power supply caps and put everything back together. I'm getting excited to hear what it sounds like now...
  3. I've now replaced the multi-cap with Sprague Atoms. I haven't fastened them down yet, but the wiring is done on them. Before: After: I used some cloth covering from extra wire I had to cover and color code the leads of the caps. I used the original cap wires to connect to the amp. I'll post more as I go.
  4. I've started the repairs. I removed the two prong cord and death cap. I added a 3 way terminal strip and wired the fuse inline with the power switch. My cord should come in later this week. I thought I had a long one laying around to use, but only had 6 ft long ones and I want a longer cord so I ordered one today. I'll wire the black of the cord to the open terminal on the fuse. The white will attach directly to the transformer on the terminal strip. The green will go to the terminal strip center/chassis ground. I figure this should make this section wiring pretty clean. Before: After: I'll post more as I go.
  5. I don't have a tube tester, though I've thought of possibly getting one. I wish I had known in the 80's that I'd get into tube amps. I worked for Radio Shack back then and while I worked there we literally threw away the tube testers that were in the stores. I've ordered Sprague Atoms for all the electrolytics and should get them in early next week. I'll replace them all, as well as the power supply and bias resistors. I'm going to leave everything else as is. I've checked all the resistors and they all appear within spec. The two coupling caps also checked within spec with a meter. Where do I find Paul Ruby's startup procedure? Is it here on these forums?
  6. Did a little more research, and based on the Volume Pot code, the Speaker code, and Output Transformer code, This appears to be a 1960 model. I also checked the coupling caps with a meter and they both appear to be within tolerance and several sites I read said to leave them in to keep it as original as possible and maintain original tone. So I will leave them in circuit. I've always wanted to play but as of now, I don't... At age 50 though, I'm getting the bug strong enough that I plan to begin lessons in the spring. I have built up a small amount of equipment over the past several years. This however is my first True vintage amp. My other amps include a home built Champ Using a PCB from TubeDepot, a VibroChamp XD, and an 80 something Peavy tube amp. Instrument wise, I have a Takamine Acoustic/electric, and an Ibanez electric. I'd like to learn to play music similar to the Eagles, and Kansas. I also love the Bluesy / Jazz guitar sound and would love to figure out the instrument / amp combination that would give me that.
  7. Yeah, I was kind of surprised to see it there since it wasn't on the schematic. It's definitely leaving the circuit though. I was thinking this morning, should I replace the .02uf coupling caps as well as the electrolytic caps or would they typically be OK? I have a couple of new .022uf 630V Xicon Metalized Polypropylene caps in my parts box I could probably use if need be.
  8. I purchased repair parts from Tubedepot.com. I went with 25uf/50v Sprague atoms for the bypass caps and 500V Spragues for the Power Supply filter caps. I ordered new Power supply resistors (2w 10k & 22K) and a new output bias resistor. Here's a few photos in case anyone would like to see it. I see this amp has a cap on the AC line to ground that isn't on Gibson's Schematic. I also noticed it's cracked. This could have been a shocking amp had I plugged it in :D
  9. Hello everyone! I'm new to the forum. I just purchased a Skylark GA-5 that appears to be 100% original right down to the Gibson branded tubes. The person I purchased it from said it sounded staticy. I haven't plugged it in, because I don't want to do any more damage. I did plug the tubes into a Champ clone I have and I think the 6V6 is bad - it crackles on occasion especially when turned up and hitting bass notes. Also, I tapped (lightly) on the 6V6 and the crackles occur at each tap. How do I find out what year this amp was manufactured? Is there a chart somewhere to lookup the serial number? I figure I'll have to do a complete re-cap, also the 10K resistor in the power supply looks like it's been quite hot and has darkened in the middle. I figure replacing both the 10K & 22K in the power supply, and the 470 ohm in the Output bias. Also, I'm having a hard time finding the 20uf 25V caps for the output and 1st stage bypass would 25uf be OK?? or should I look harder? Any other suggestions or thoughts of areas for possible repair before I power this up?? Thanks so much, Rick
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