Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

Return to Tube DIY Asylum


Message Sort: Post Order or Asylum Reverse Threaded

Re-repair Stories (add your own!)

98.190.181.197

Posted on May 5, 2022 at 08:27:01
Lee of Omaha
Dealer

Posts: 1770
Location: Omaha NE
Joined: September 8, 2006
1. Bought a receiver off eBay to fix or for parts. Seller said it might need repair. Got it in. The seller had added an inline fuse of 25 amps before the primary. Since all home and business circuit breakers are 15 or 20 amps, the fuse couldn't blow. Functionally, it was a piece of wire.

2. Just yesterday, we repaired a Pioneer SX-1280. Someone had used 105 degree Nichicons (nice!) but, to get the receiver to come out of protection, had electrical taped a magnet to the side of the protection relay. That was new to us. Receiver had a couple of bad transistors in a power supply.

 

Hide full thread outline!
    ...
RE: Re-repair Stories (add your own!), posted on May 5, 2022 at 10:02:39
Story
Audiophile

Posts: 6207
Location: NJ
Joined: December 11, 2000
1. Customer brought in his "repaired" Marshall 100 watt Plexi Tube amp for guitar with 1000 mfd replacement caps in the power supply. Needless to say it sounded like a compressed pile of dung. Must have been a Hi-Fi repair guy who though he could make it even better after a routine tube replacement. I put in the standard LCR 50 mfd multi sections and customers blood pressure went back to normal.

wow that magnet rig job is the first time I heard that one



 

RE: Re-repair Stories (add your own!), posted on May 6, 2022 at 16:55:04
triode3
Manufacturer

Posts: 305
Location: Midwest
Joined: August 23, 2005
I have heard of the magnet on the relay before.

The one I always saw was...

Aluminum foil wrapping the fuse.

 

RE: Re-repair Stories (add your own!), posted on May 6, 2022 at 19:26:02
Tre'
Industry Professional

Posts: 16098
Location: So. Cal.
Joined: February 9, 2002
At a show Dave Mason's guitar amp blew a output tube. That took out a fuse. We had a replacement tube but no fuse. I wrapped the blown fuse with the foil from my pack of cigarettes. That amp worked for the whole show and I fixed it later.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Re-repair Stories (add your own!), posted on May 7, 2022 at 17:01:38
Oldbean2
Audiophile

Posts: 131
Location: Midwest US
Joined: March 27, 2022
Yeah, years ago somebody gave me an old Pilot 6L6 mono amp they found while cleaning out a property because they knew I was "into old stereo stuff". 25 amp inline fuse, power trans was blown. All is well that ends well, someone I knew had one that needed an output transformer, so I moved it along.

Back for a bit again. Ignore me if you like.

 

RE: Re-repair Stories (add your own!), posted on May 8, 2022 at 11:12:26
Palustris
Audiophile

Posts: 2294
Location: Cape Cod
Joined: September 12, 2008
I've had my own embarrassing moments when, after some time has passed, I take off the bottom cover of an amp I have constructed and find an unsoldered wire or a bit of loose detritus or tool that I left in the amp somehow.

However, I have held off on this following bit of clever workmanship because it wasn't a repair. But it is too good not to share.

Battery bias:





 

RE: Re-repair Stories (add your own!), posted on May 11, 2022 at 16:24:15
Alpha Al
Industry Professional

Posts: 2863
Location: N. Carolina
Joined: February 16, 2004
Contributor
  Since:
December 3, 2015



This was in a 70's Fender Champ amp I once worked on. The owner said it had been intermittent since it was new. Three other people tried to find the problem unsuccessfully.

It had left the factory with pin 8 of the tube socket never soldered.

 

A farmer brought in an old Realistic STA-220, posted on May 12, 2022 at 13:01:15
Ralph
Manufacturer

Posts: 4381
Location: Minnesota
Joined: April 24, 2002
Which he used to play music in the barn for his cows. It had a lot of flies in it :) and a dirty tape monitor switch. When he picked it up, he asked the front counter guy 'hey- what's this onoff switch for?'

 

I've run into a few of those myself ......................, posted on May 13, 2022 at 16:56:45
Cut-Throat
Audiophile

Posts: 16624
Location: Minneapolis - St.Paul Area
Joined: September 2, 2000
Contributor
  Since:
May 16, 2021
One was on a New Rel Subwoofer. The Power Terminal Wires were never Soldered. Which explained why it was not powering up..... I was looking for a Fuse, when I discovered the Wires on the Terminal for the Power Cord were attached, but not soldered.



 

RE: A farmer brought in an old Realistic STA-220, posted on May 21, 2022 at 09:15:19
DAK
Audiophile

Posts: 2707
Location: PACIFIC
Joined: August 8, 2010
When i was young buck, i used to work in a dairy milking and caring for the dairy cows. But i really don't understand the bit about the on/off switch.

 

Watch out for voltage double circuits!, posted on May 21, 2022 at 09:27:27
DAK
Audiophile

Posts: 2707
Location: PACIFIC
Joined: August 8, 2010
I did an overhaul for a Fisher 500 receiver and per usual hooked it up to the variac for the initial power up. I was up to around 80% or so of full power which is when i check the voltage doubler caps for excessive heat indicating they need to be replaced before proceeding further. So, as usual, i touched the can cap that is not insulated and got zapped by a couple hundred votes. The person who rebuilt it previously had not wired the insulated cap in the first position which made the outside of the uninsulated can fully energized. A whole lotta cussing ensued. cheers, Dak

 

Ouch!, posted on May 22, 2022 at 02:06:24
Triode_Kingdom
Audiophile

Posts: 9424
Location: Central Texas
Joined: September 24, 2006
"The person who rebuilt it previously had not wired the insulated cap in the first position which made the outside of the uninsulated can fully energized."

That's really dangerous. When I build a doubler supply, I always add clear heatshrink over the existing skin of the elevated cap. I do this even when the caps are mounted on a PCB or terminal strips under the chassis. It's just too easy to forget that the can isn't grounded.












--------------------------
Buy Chinese. Bury freedom.

 

Page processed in 0.037 seconds.