Hi Robert, Great job with the video man. Here's some wisdom for you from a long time tech. Try adding some solder to your de-soldering iron to prevent heat transfer & actual solder removal next time, I think you will pleased with the results.
I have an old 1982 Peavey Backstage making a similar noise I've been trying to figure out. I just got done changing the filter caps but I left the 9 other smaller electrolytics alone until my parts order gets here. Now I'll have to check the speaker terminals for voltage - thanks! One question: My amp is a solid state and I *think* I can power it without the speaker connected and no dummy load, but juuuuust to be sure: when you found 40v at the speaker wires, did you have a dummy load connected? Was the amp plugged in for your measurement? Or were you using a benchtop supply? In the video it looks like you just disconnected the speaker, hooked up the DMM, plugged in the amp and switched it on until you got your reading.
No Dummy load connected is needed for solid state amps. The amp was on and connected for that measurement. I just used the amp supply. You are right. I connected everything. Then turned on the amp and got my reading and then turned it off. You will normally get 5-20 millivolts. but since it is an old amp, those might get 50 millivolts. In this video there was a look resistor that was sending a large amount of voltage, which is not good for speakers. You can message me on Instagram. If you have more questions. @brokensoundz I will reply back when I can.
hi. tks for the video. mine has the normal channel doing distortion. i plugged the guitar into the return input and the distortion is there. I suppose that the problem is on the power section, right?
@@bitcoinbreakout2918 not a lot. all the forums that i read point to the IC's. the board has 6 IC's. 2 big ones, 2 mediums and 2 small ones. I have a cheap reader and a multimeter and I'll try to make some readings having some tips from the forums. I cant get a decent schematic to identify wich ICs are the preamp ones and the power amp. the 2 major ones are MJW21192 and MJW21191, the 2 medium size ones are A1306A and C3298A. the 2 smaller ones have no visible identification
When noting the 40 volts dc across the speaker you claimed the 50 watt test speaker could handle the power. But power = voltage squared over resistance. Most 8 ohm speakers have about 7 to 7.5 ohms dc resistance. So, 40 volts across the speaker means it's dissipating over 200 watts.
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I have the same amp except it got wet and I let it dry out now it sounds really bad like almost sounds busted and buzzy and it plays but it’s not good for playing at all
Hi Robert, Great job with the video man. Here's some wisdom for you from a long time tech. Try adding some solder to your de-soldering iron to prevent heat transfer & actual solder removal next time, I think you will pleased with the results.
Yes!! When I recorded this, I was not doing that. But I practice that now. Thanks for the tip. Hopefully people will read this comment.
2:17 you were checking the transistor, with amp power on?
That sound though..... It just sounds very satisfying...
It is totally satisfying ✌️
It's a Boogie without tubes !
Hey, do you remember how you fixed the pushed in jewel light? My Frontman has the same issue and I want to secure it properly
I have an old 1982 Peavey Backstage making a similar noise I've been trying to figure out. I just got done changing the filter caps but I left the 9 other smaller electrolytics alone until my parts order gets here. Now I'll have to check the speaker terminals for voltage - thanks! One question: My amp is a solid state and I *think* I can power it without the speaker connected and no dummy load, but juuuuust to be sure: when you found 40v at the speaker wires, did you have a dummy load connected? Was the amp plugged in for your measurement? Or were you using a benchtop supply? In the video it looks like you just disconnected the speaker, hooked up the DMM, plugged in the amp and switched it on until you got your reading.
No Dummy load connected is needed for solid state amps. The amp was on and connected for that measurement. I just used the amp supply. You are right. I connected everything. Then turned on the amp and got my reading and then turned it off. You will normally get 5-20 millivolts. but since it is an old amp, those might get 50 millivolts. In this video there was a look resistor that was sending a large amount of voltage, which is not good for speakers. You can message me on Instagram. If you have more questions. @brokensoundz I will reply back when I can.
hi. tks for the video. mine has the normal channel doing distortion. i plugged the guitar into the return input and the distortion is there. I suppose that the problem is on the power section, right?
Smart. Yes. Is there noise too?
@@bitcoinbreakout2918 not a lot. all the forums that i read point to the IC's. the board has 6 IC's. 2 big ones, 2 mediums and 2 small ones. I have a cheap reader and a multimeter and I'll try to make some readings having some tips from the forums. I cant get a decent schematic to identify wich ICs are the preamp ones and the power amp. the 2 major ones are MJW21192 and MJW21191, the 2 medium size ones are A1306A and C3298A. the 2 smaller ones have no visible identification
@@bitcoinbreakout2918 the noise or hum happens when the volume is on (more than 0) and when a jack is plugged in. otherwise is dead silent.
Hi Robert, I have a Fender Frontman 25R that hums when I simply turn it on. No pedals being powered and no guitar plugged into it. Any thoughts?
When I check my resistors do I have the board plugged in.
No. Inspect it unplugged first. Then plug it in and check voltages.
Please more amp repair videos.
Well done!
When noting the 40 volts dc across the speaker you claimed the 50 watt test speaker could handle the power. But power = voltage squared over resistance. Most 8 ohm speakers have about 7 to 7.5 ohms dc resistance. So, 40 volts across the speaker means it's dissipating over 200 watts.
That desoldering iron needs to go right in the trash! Lol good video on the Frontman's problem though!
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I have the same amp except it got wet and I let it dry out now it sounds really bad like almost sounds busted and buzzy and it plays but it’s not good for playing at all
Replace the resistors and elevate the new ones off the board to try to keep them cool.