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Before you jump to the transformer, check the solder joints on the IEC connector. It could be as simple as a poor connection issue.
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"I took a photo of my ohm meter... It didn't help." Enzo 8/20/22 -
My comment was in regard to being able to measure above 200vac on your meter. I was rushing getting ready for work earlier in my post and just realized you were trying to measure the AC voltages on the secondary (not the primary). Sorry I did get confused... I even said it in my post too. "Uh... I am a little confused here... "Originally posted by Kidderman View Post
When the going gets weird... The weird turn pro!Comment
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Maybe, but the mains switch illuminates but worthwhile double-checking everything.Originally posted by The Dude View Post
Your fuse is good - the reading you get is the resistance of the leads and is fluctuating because you don't have 100% contact. The reading you get on the mains inlet tells me the primary is open, or the leads connecting the primary are not making good contact.
You can check the primary resistance just to be entirely certain - I'll get a transformer out of stock later this morning and let you know what it should read.Comment
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The primary is tapped;
0v - Brown
100v - Black
117v - White
230v - Blue
With the amp disconnected from the mains, take a resistance reading between the brown and blue leads. You should get around 46 ohms. Then take a reading between brown and black. This should read 10 ohms. If it reads open there's a high probability that the internal thermal fuse has blown. This cannot be replaced.
A tip on resistance readings - always short your probes together to make sure your meter reads zero, or close to zero (your lead resistance) before taking any measurements.Comment
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Thanks again, Mick. Tried tests as advised in your last reply. Readings appear open, so I've decided to order a replacement transformer. Replacing it looks to be pretty straightforward, as long as I'm careful to make the same connections as in the current setup.
The transformer should arrive tomorrow. I'll post the outcome. Cheers.Comment
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Oops. I missed that part.Originally posted by Mick Bailey View Post"I took a photo of my ohm meter... It didn't help." Enzo 8/20/22Comment
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The replacement transformer arrived this morning. After making careful notes about which wires connected to which areas of the two boards, I fitted it. Surprisingly easy (for someone who hasn't got much of a clue). The amp works perfectly. I now own a pristine, fully-working AS50D which cost me about one third of the retail price. Big thanks to those of you who took the time to reply to my original post.
Your advice enabled me to carry out the various tests and eliminate a number of possibilities before going ahead with replacing the transformer. I'm very grateful. Cheers.Comment
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FYI, on the Marshall AS50D amp
FYI, on the Marshall AS50D amp. I ran into a similar situation with no voltage to the rectifier. When I ohmed out the transformer it checked out ok. I discovered the crimp connectors on the wires were defective on at least 2. Resoldered all the crimp connections including the ones on the switch and it took care of the problem.Comment
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I've had these amps where the wiring hasn't been stripped at all - just inserted into the connector and crimped around and through the insulation. Kind of works like an IDC connector for a while until it eventually fails. The last few Fender Excelsior amps I've worked on had this problem as well.Comment
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Got the same problem. Where did you get the transformer from please?Originally posted by Kidderman View PostComment
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Try Marshall themselves - ring the main number and ask for spares. Whereabouts in Cheshire are you?Comment
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Have one, myself, and its the same description. No sound out, and lights up. Found the dual pushbutton switch on the right side of the front face of the amp, is defective. Mirrors, your same description. Now, looking for the part number to the switch, as it a dual pushbutton, (one piece, two switches stacked on top of each other) SW2Comment
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Since the job of the amp is to make sound, about half the parts in it could make it go silent if any failed.Education is what you're left with after you have forgotten what you have learned.Comment
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Ireaize this is an old thread, but...... I have a similar problem with my AS50%. Thanks to all the contributors here, I have the following information, and if nyone can get me moving further toward repair, it would be greatly appreciated.
I started by troubleshooting teh power supply section. All seems fine, as I have 32VDC at LT1 ansd LT2. I then tried what DRGonz recommended, I plugged my guitar into Channel1, then connected the effects send to another amp. The pre-amp is working fine, as I got sound. I then connected teh line out jack to the external amp, and not only did I get ound, teh reverb and Chorus circuitry works as expected. At this opint, I've hit a dead end, and not sure what to try next, or what direction to turn to. Thanks in advance for taking the time to read this, and thanks in advance again for any info that may help me!!!
DonComment
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I realize this is an old thread, but...... I have a similar problem with my AS50%. Thanks to all the contributors here, I have the following information, and if nyone can get me moving further toward repair, it would be greatly appreciated.
I started by troubleshooting the power supply section. All seems fine, as I have 32VDC at LT1 ansd LT2. I then tried what DRGonz recommended, I plugged my guitar into Channel1, then connected the effects send to another amp. The pre-amp is working fine, as I got sound. I then connected the line out jack to the external amp, and not only did I get sound, the reverb and Chorus circuitry works as expected. At this point, I've hit a dead end, and not sure what to try next, or what direction to turn to. Thanks in advance for taking the time to read this, and thanks in advance again for any info that may help me!!!
DonComment
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