Amp tinkerers and people who aren't afraid of 700 volts or so in here....

Moderators: Slowy, Capt. Black

#751050
The jewel light is intermittent & appears to be some form of LED.
I can't see any obvious way to remove it. Is it possible to do so, or do I have to replace the complete assembly?

Ramparte Jewel Light.jpg
Last edited by H671 on Wed Aug 09, 2017 4:57 pm, edited 1 time in total.
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BY H671
#751057
Jellybelly wrote:
Molly wrote:I think this is the part you need:

https://www.rockshop.co.nz/shop/marshal ... ition.html


Best get two so you have a back up :D


:problem: Hmm! I'll need to find a couple of strong Irishmen to turn the stack while I hold the retaining cap.
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BY H671
#751065
Jellybelly wrote:Failing that give these guys a yell
https://fendershop.co.nz


Thanks, I'll try them yet again, but they are useless!
I gave up waiting for them to get back to me about a pickup for my Squier.
BY tubeswell
#751124
Yep its a LED. I haven't inspected the lamp close up in one of these yet to determine whether you need to replace the whole lamp holder assembly or whether you can just remove the bit inside that's giving you grief - there's no useful information in the service manual and the part number is not listed.

https://fmic1.zendesk.com/attachments/t ... agrams.pdf

The LED voltage is maintained by a simple diode shunt regulator (D1 and R29 on the schematic in the linked service manual), which is powered from the heater winding.

If the LED is blinking a bit, it could be because its not supplied with enough voltage to switch it on properly (although this is just my theory at this point). If this is the case, one possible solution could be to try and increase the LED supply voltage slightly by changing out D1, e.g. replacing it with a couple of 1N4007 in series. This would give you 1.2V instead of 0.6V at the LED. (Red LEDs should be able to handle 1.2 to 1.6V - but if you blow up the LED, WTF, you were wanting to replace it anyway right?). D1 is located next to R29 on the main board - refer to the layout diagram in the service manual. If you're not sure about doing this mod yourself, take it to a techy person. If you have a go and it works out favourably, feel free to report back. (or likewise, feel free to feck up your amp at your own risk)
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BY H671
#751127
Thanks for that -I'll get in touch with a local tech up here.
#751891
H671 wrote:Thanks for that -I'll get in touch with a local tech up here.


I was playing around with this today & noticed that every time that I touched the LED, it came on & every time that I screwed the jewel back, it would go out. So, in a moment of inspiration, I fitted an O'Ring around the outside of the LED, screwed on the jewel & "viola" - it works!