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GAS Son of Ampzilla problem

47.156.137.5
Posted on July 10, 2017 at 07:26:26
docw
Audiophile

Posts: 8115
Location: So. California
Joined: July 23, 2004
Contributor
  Since: November 29, 2004
 Recently set up my old Son of Ampzilla in a simple 2 ch stereo.
Turned it on after using it for a couple of months, and 7 amp slo blo fuse blew.

Does anyone remember what may have led to this and how to proceed?

Old unit w Upgrade and a couple of transistors replaced, vg condition and sounded great with Fulton FMI 80s. See my profile under Retired system.

 

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RE: GAS Son of Ampzilla problem , posted on July 10, 2017 at 15:55:31
Coner
Audiophile

Posts: 3703
Location: S.W. Washington state, USA
Joined: November 17, 2001
 I'd try a new fuse first before assuming other things. But it could
be time for new PS capacitors if 20+ yr. old.

 

RE: GAS Son of Ampzilla problem , posted on July 10, 2017 at 21:15:23
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 The Son of Ampzilla is at the age were the electrolytic capacitors are questionable. Replace them all and then you don't have to worry.


Dave

 

RE: GAS Son of Ampzilla problem , posted on July 11, 2017 at 06:36:08
docw
Audiophile

Posts: 8115
Location: So. California
Joined: July 23, 2004
Contributor
  Since: November 29, 2004
 Both you and the other respondent suggested PS filter caps. If I tried the fuse, would I risk damage? Read some repair shop ads and websites, one is very reasonable.

Maybe call around LA/OC and ask?

 

RE: GAS Son of Ampzilla problem , posted on July 11, 2017 at 06:56:56
Coner
Audiophile

Posts: 3703
Location: S.W. Washington state, USA
Joined: November 17, 2001
 No, it should not hurt anything to try a new fuse. Check to make
sure old one was correct amps and slo-blow. If new one blows,
then there obviously is a problem inside.

 

RE: GAS Son of Ampzilla problem , posted on July 11, 2017 at 07:18:10
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 When did you have it upgraded and a few transistors changed?

How many hours of listening did you get out of it before it blew again?

If the second fuse blows it sounds like it's time for a full overhaul. Transistors shouldn't "need replacing" unless something else is causing a problem.

 

RE: GAS Son of Ampzilla problem -fuses do go bad..., posted on July 11, 2017 at 10:19:55
jaynemo
Audiophile

Posts: 1881
Location: Connecticut
Joined: February 7, 2003
 After constant use fuses do go bad. Try another one like the other poster said and take it from there.

 

A fuse caution, posted on July 11, 2017 at 10:46:04
M3 lover
Audiophile

Posts: 6605
Location: SW Mich
Joined: May 29, 2005
Contributor
  Since: July 4, 2007
 Hi doc,

Some months ago I discovered the first owner had installed the wrong value fuses in a pair of monoblocs I had. However after buying the correct value at a trusted electronics parts store two of those blew upon turn-on. After driving up to Chino for a factory check out/repair we discovered the fuses were apparently mis-labeled. I'd never seen that before but installation of factory supplied fuses worked without a problem.

The brand was NTE Electronics and the store took them back, but they had not had reported any similar problem. Point is strange things can happen even with anything as simple as a fuse.

Good luck.

"The secret of life is honesty and fair dealing, if you can fake that you've got it made." Groucho

 

RE: GAS Son of Ampzilla problem , posted on July 11, 2017 at 12:45:10
docw
Audiophile

Posts: 8115
Location: So. California
Joined: July 23, 2004
Contributor
  Since: November 29, 2004
 Air, purchased from Karen Richardson in Lincoln NE 1977, upgraded with GASworks Level 1, 1978 long ago.

Unit took out some transistors, my relative (tech) figured it out and fixed it with some Military transistors, repaired PS, 1986 or so. Excellent sound.

Stored a while, then decided to use it sporadically for my office from about 2007 (guessing) to 2015, when I retired.

Back home, loaned it semi permanently to my friend in April this yr.
No abuse, no loud volume, simple setup.

 

RE: GAS Son of Ampzilla problem , posted on July 11, 2017 at 13:07:33
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 I'd box it and have it restored if it means anything to you.

 

RE: GAS Son of Ampzilla problem , posted on July 11, 2017 at 14:10:42
docw
Audiophile

Posts: 8115
Location: So. California
Joined: July 23, 2004
Contributor
  Since: November 29, 2004
 OK. I decided to replace the Son with a reliable backup amp, and advise him to buy a pre owned integrated if he wants.

My friend recently returned from living overseas, and lives pretty near me now. His uncle designed and built the speakers.

Do you know of a good and reliable restorer?
Mike Bettinger wants a lot more than I wish to spend.
The original designer did upgrades, but is in Heaven.
There are a few out there on the 'net, and I live in LA and can fish around.

 

RE: GAS Son of Ampzilla problem , posted on July 11, 2017 at 14:11:29
docw
Audiophile

Posts: 8115
Location: So. California
Joined: July 23, 2004
Contributor
  Since: November 29, 2004
 I posted to myself. Any good restorer whom you've used?

 

RE: GAS Son of Ampzilla problem , posted on July 11, 2017 at 17:24:53
fredtr
Audiophile

Posts: 1987
Location: Phoenix
Joined: January 4, 2005
 If you don't find someone you are comfortable with, try the ham radio community. You can meet people by going to a ham fest, which is also a good place to buy tubes and equipment. My experience is that a higher percentage of hams are techs than people into HiFi. Like a lot of us they tend to be older, and work on equipment more as a hobby than a business.

 

"We discovered the fuses were apparently mis-labeled.", posted on July 12, 2017 at 06:27:15
FenderLover
 How did the factory determine they were mislabeled?


Thanks!

 

RE: "We discovered the fuses were apparently mis-labeled.", posted on July 12, 2017 at 07:10:18
SpotcheckBilly12345
 I don't have a horse in this race, but I do have some experience with "mis-labeled" fuses.

It's pretty much common knowledge in the automobile service & repair industry that there are various brands of Chinese knock-off fuses floating around that don't meet the specs that they are claimed to meet. Like so-called 20 amp fuses that don't blow until over 50 amps are fed through them. I've personally witnessed this.

So my advice is to stay away from bagged bulk assortment fuses that you might encounter in dollar stores and the like.

Cheers,
SB

 

RE: "We discovered the fuses were apparently mis-labeled.", posted on July 12, 2017 at 10:10:42
M3 lover
Audiophile

Posts: 6605
Location: SW Mich
Joined: May 29, 2005
Contributor
  Since: July 4, 2007
 Note I said "apparently mis-labeled".

After discovering the wrong fuses had been installed in the monoblocs, I bought replacements of the correct values per the owner manual. Two new fuses blew upon turn on. I had a separate issue to have checked so took the amps to the factory for service. When the tech installed their regular fuses they worked fine.

So upon reflection, either my replacement fuses were mis-labeled or defective. There was no problem in the amps to cause that failure.

"The secret of life is honesty and fair dealing, if you can fake that you've got it made." Groucho

 

RE: GAS Son of Ampzilla problem , posted on July 14, 2017 at 22:42:47
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 hi, look no further than Mike Bettinger. I doubt that anyone can do a better job.

 

RE: GAS Son of Ampzilla Update , posted on July 15, 2017 at 10:00:06
docw
Audiophile

Posts: 8115
Location: So. California
Joined: July 23, 2004
Contributor
  Since: November 29, 2004

sorry for the big image (don't know how to shrink it)

I switched out the Son with a Hafler XL 280, circa 1987, used lovingly and intermittently stored for the last 10 yrs. Rock stable, mildly hot (same as new), excellent powerful sound.

The Son 7 amp fuse was burnt, mildly black on the glass, not severely black (someone suggested this means it was a "violent" action).

Between my wife's rec (who would trash it or give to Mrs Berdan for the late Brooks' museum), and my researching for a tech in LA, I will think about it.

Again, who would you use? Tom at Brooks Berdan? Any tech who could repair or restore for under $500?

Thanks.

 

RE: GAS Son of Ampzilla problem , posted on July 16, 2017 at 11:34:16
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 It is possible, but on gear of that age, I don't think it is likely that the caps are that bad.

Dave

 

RE: GAS Son of Ampzilla problem , posted on July 16, 2017 at 13:32:31
docw
Audiophile

Posts: 8115
Location: So. California
Joined: July 23, 2004
Contributor
  Since: November 29, 2004
 So it's the transistors themselves, like what happened before?

 

RE: GAS Son of Ampzilla problem , posted on July 20, 2017 at 14:21:12
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
 Transistors can be tested. That is what you should do. If you don't have the knowledge, it is time to take it to a shop.

Dave

 

RE: GAS Son of Ampzilla problem , posted on August 1, 2017 at 16:23:47
llwhtt
Audiophile

Posts: 192
Location: SOCAL
Joined: October 28, 2008
 I'm fairly well versed in SAE, GAS and SUMO, that's what I collect. I'm in SoCal also. Click my name and send me an email.

Craig

 

RE: GAS Son of Ampzilla problem , posted on August 4, 2017 at 09:55:08
llwhtt
Audiophile

Posts: 192
Location: SOCAL
Joined: October 28, 2008
 Have you found anyone to repair your SON? I can repair or rebuild it for you no problem.

Craig

 

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