Penta electricity disaster!

9 replies
pepps
pepps
GoldModerator
481 posts
Posted January 4, 2024 at 04:56 GMT ? Edited May 5, 2024 at 19:16 GMT
#688454
Dear Beoworlders, I have a shameful confession to make. I recently wanted to extend the power cord on my Penta mk2 to help hide the cable. Instead of soldering a new length of flex from the Penta amp itself I used a junction box. The junction box was new to me and of a style I wasn't used to. In my haste I connected live and neutral to the same binding post! When I applied power the Penta amp remained lifeless (no LED and no display) and the ring main for all first floor sockets tripped on the house consumer unit. I have since had no luck getting the Penta amp to work. With your varying levels of expertise, can anyone imagine what might have happened inside the Penta and how I should go about tracing the problem(s)? I've been running the pair of Pentas from an MCL2P but the power is way off and I really miss the displays. If anyone has any ideas please let me know. And please, feel free to mock me for the stupidity of my blunder. Julian

Location: Kent, UK

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filip_kbh
filip_kbh
Bronze
332 posts
Posted January 5, 2024 at 00:00 GMT
#706605
First, check the fuse(s). There is one where the power chord comes in (you need to unmount the bottom of the amp. I don't remember if there is more than one fuse.

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pepps
pepps
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481 posts
Posted January 5, 2024 at 10:53 GMT ? Edited January 5, 2024 at 10:55 GMT
#706617

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lesbart
lesbart
Silver
13 posts
Posted January 5, 2024 at 14:47 GMT ? Edited January 5, 2024 at 15:02 GMT
Hi Julian, Is this what your fuse board looks like? There are 2 of them: one for the small transformer and the other for the larger one. /Les

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pepps
pepps
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Posted January 5, 2024 at 16:33 GMT
#706635

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pilatomic
pilatomic
Silver
93 posts
Posted January 11, 2024 at 09:33 GMT
Hi pepps, If you shorted live and neutral, there should have been no voltage applied to your Penta, so no damages. Did you check the continuity of the Penta power cord ? Is it possible that the cable was damaged during your modification ? Regards,

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pepps
pepps
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Posted January 11, 2024 at 10:24 GMT ? Edited January 11, 2024 at 10:24 GMT
#706830

Location: Kent, UK

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pepps
pepps
GoldModerator
481 posts
Posted February 6, 2024 at 15:53 GMT
Update: I found the 5A fuse in the mains plug to be blown. Continuity in the mains cable is good. I replaced the 5A fuse and connected to the mains. Red light. All good. I connected the + and - speaker leads from the amp to the binding posts and the powerlink connector. Put everything back together. Connected the mains once again and "POP!". The little 2A fuse blew inside the amp. So I'm still trying to suss out what's wrong. Is a 5A mains fuse ok for a Penta amp?

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pepps
pepps
GoldModerator
481 posts
Posted February 10, 2024 at 20:37 GMT
#707498
Update and closure! Dear all, thank you for your contributions and suggestions. Today I had some spare time (at last) so took both my Penta amps off the towers and set them out on the kitchen table. Took them both apart (only to the power supply stage) and compared the working one to the not working one. I resoldered some rather bad looking connections and swapped out both fuses in the Penta (the 2A and 150A (140A was not available but read on here that 150A would be ok)) before resoldering in a new mains power lead. Reassembled and tested. Everything works perfectly!!

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