FDP Forum / Fender Deluxe 90 (not DSP)/ 11 messages in thread.

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john mcgoo



United Kingdom

Dec 9th, 2016 03:33 AM        

Hello,<br /> I have bought a Fender deluxe 90 for "spares or repair". Serial number M914104 Type PR 402<br /> The bloke I bought it off said it was working fine, until he smelt a Burning smell coming from the amp.<br /> It was the loudspeaker which he has thrown out, so I dont know if it was upgraded or stock.<br /> I have looked around the PCB for signs of heat, but cant see anything. The fuse has blown, and I havent plugged it<br /> in yet I thought I would try here first for advice.<br /> Has anyone had this problem or similar with this type of amp.?<br /> Thanks John Mc. Warrington England, UK.



willie

Contributing Member
*******

Too Near Atlanta GA

Amp Tech Emeritus
Dec 9th, 2016 08:19 PM        

If the speaker voice coil shorted then the output transistors are likely blown. If that is indeed the case, unless you are quite skilled and experienced with solid state amp repairs, you will need a pro tech to get it up and running. The output circuit is fairly complex in this model amp. <br /> <br /> willie



john mcgoo



United Kingdom

Dec 10th, 2016 01:18 PM        

Thanks Willie, I am able to change transistors, I was hoping to find out how to test which one or all before I ordered, I have sourced replacement output transistors from ebay.



pcalu



usa metro detroit

Dec 10th, 2016 04:12 PM        

Get the schematic.. which will have test points. by testing the points for correct voltage and resistance you will isolate where the problem is.. <br /> <br /> Just take your time



Warren Pederson



Canada

Dec 12th, 2016 10:11 PM        

There's a couple resistors that go on those things like clockwork (I unfortunately owned two of them)



john mcgoo



United Kingdom

Dec 14th, 2016 03:26 AM        

Hi Warren, do you know which resistors ?<br /> I have tested the big ceramic resistors and they seem fine.



willie

Contributing Member
*******

Too Near Atlanta GA

Amp Tech Emeritus
Dec 15th, 2016 07:57 AM        

Our old service records on this amp show mainly bad or fractured solder issues causing most failures. There was only one or two references to resistor failures or issues...the low voltage rail resistors R144, R145 (also their associated zener diodes). Beyond that not much to report other than the usual plastic jack issues. <br /> <br /> willie



john mcgoo



United Kingdom

Dec 17th, 2016 04:07 AM        

SUCCESS <br /> Thanks Willie, I checked R144 R145 and noticed a slightly dryish joint on one of them. I soldered over the joints, switched and hey presto working fine again. Only problem I now have, the replacement speaker is 8 ohm but I think it should be ok.<br /> Thanks to all, and merry christmas.



willie

Contributing Member
*******

Too Near Atlanta GA

Amp Tech Emeritus
Dec 17th, 2016 08:08 AM        

Excellent John....good on ya. <br /> <br /> I do recommend you change out that speaker for a proper 4 ohm one. Solid states amps don't like impedance mismatches too well. :)<br /> <br /> Best to you...<br /> <br /> willie



Warren Pederson



Canada

Dec 23rd, 2016 09:20 PM        

Mr McGoo, no I'm afraid I don't know which resistors. I think the worst culprit was #46?



Warren Pederson



Canada

Dec 30th, 2016 10:28 PM        

Listen to Willie, he's the man



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