It is currently Tue Mar 17, 2020 4:12 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 54 posts ]  Go to page 1, 2, 3, 4  Next
Go to page 1, 2, 3, 4  Next
Author Message
Post subject: Hot Rod Deville - Cracking
Posted: Thu Jul 28, 2011 9:34 pm
Offline
Amateur
Amateur

Joined: Mon Nov 01, 2010 10:31 pm
Posts: 154
Ok here we go... I have a friends 4x10 Deville at the house.. So far we have completed the following in search of a fix for a ghost crackle. Best way to describe it is it sounds like someone crumbling up a piece of paper.. It is noticeable when not playing as well as while playing.. Any volume with any combination of tone, reverb, or channel selected.

What was done:
Complete teardown and rebuild of the amp..
Tightened all screws, nuts and bolts.
Re-shielded the back of the amp..
New tubes and re-biased to 70mV and then all the way down to 40mV..
Changed to upgraded capacitors that were recommended on JH website..
Reflowed solder joints on white 330ohm ceramic resisters.. (no scorching found on circuit board)
Eliminated the possibility of it being the speakers by running a bandmaster head through them.
Did find that the reverb tank has one spring, but this doesn't seem likely to be the culprit..
Different cables and tried input 1 & 2..
Cleaned all pots jacks and push buttons..
Tried different guitars..
Even tried different tubes..
Re-flowed all solder joints on all tube sockets..

Don't know what else it could be... Any suggestions??

Thanks
SFC P


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Hot Rod Deville - Cracking
Posted: Fri Jul 29, 2011 12:39 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
Have you tried isolating the anomaly by testing the pre-amp and power amp independently via the effects loop? Once the problem is narrowed down to a specific section of the amp it'll be that much easier to diagnose and ultimately repair.

HTH

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Fri Jul 29, 2011 3:50 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14050
Location: Province de Québec, Canada
Bad solders on power supply high voltage.

Are you sure your bias is good ? 40 MV or Ma is alright but do you take a good mesurement ? If not sure , put very cold bias and listen.


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sat Jul 30, 2011 4:49 pm
Offline
Amateur
Amateur

Joined: Mon Nov 01, 2010 10:31 pm
Posts: 154
I have played the amp in both channel select on and off. With and without the more drive and still the sound remains. How and or where would I check voltage? Do you mean the joints on the the circuit boards? I took one of the transformers apart and found there wasnt anything I could really check. So I simply put it back together. As for testing the bias, yes I know for certain it is at 40. I am using a fluke meter and it has been calibrated by the Army calibration team. I'm definitely lost on this simple crackle sound and have don't everything I can think of. Where else can I probe??


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sat Jul 30, 2011 4:53 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
Ah yes, good old TMDE.

I was our unit's calibration coordinator for a quite some time.

What's the DA80 sticker on that Fluke read? IIRC, they're on a 270-day cycle.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sat Jul 30, 2011 4:59 pm
Offline
Amateur
Amateur

Joined: Mon Nov 01, 2010 10:31 pm
Posts: 154
Yes good old TMDE!! haha!! The sticker is not on there but I do know I have to take it back in come August.. Man I can't figure out this amp... An also can't figure out how to post pictures in my message without having to do it up as a URL.


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sat Jul 30, 2011 5:16 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Try this... Pull all the small signal tubes (usually 12AX7 and 12AT7) and leave the power tubes in the amp. Turn on the amp. Still have the noise (I'm betting no)? If so... try cleaning the pins and socket of the power tubes. Check for any cold solders in this area---including the power supply (as already suggested by Stratele52).

If no noise... plug in the phase inverter (usually a 12AT7, physically next to the power tubes). Noise? If so... check the inverter area for cold solders and bad circuit board tracings.

Go step-by-step, as Arjay suggested putting each tube into the amp, one-by-one and checking for that noise. This will hopefully narrow the problem area down to one tube.

It maybe a bad cap or resistor, as well as cold solder or bad tube contact with socket. In other words, almost anything and everything. I use the old WOODEN chopsticks method and tap each component and solder point to see if I can change the tone or loudness of the noise. Hopefully, you can find the offending part(s). BTW... WOODEN only, as the amp will be turned on at this point. And DO NOT touch the chassis with your other hand. If this scares you enough (and we are talking 400+ VDC running inside the amp)---a good tech maybe in order.

So a step-by-step approach is best. Prolly, I'd go from power tubes back to the input stage. You'll most likely find the problem area. Then, it's a mattter of going over all the component of that area. A schematic and layout helps immensely.

Good luck. Take your time and keep notes. I like taking photos (of the circuit and not only women :lol: ), to be sure about replacing parts correctly.


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sat Jul 30, 2011 5:59 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
BMW2002Ti wrote:
I like taking photos......and not only women :lol:


Pics, laddie......we need pics!

:P

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sat Jul 30, 2011 6:16 pm
Offline
Amateur
Amateur

Joined: Mon Nov 01, 2010 10:31 pm
Posts: 154
How do I post pics directly to the thread without having to post it through a URL?


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sat Jul 30, 2011 8:48 pm
Offline
Amateur
Amateur

Joined: Mon Nov 01, 2010 10:31 pm
Posts: 154
What is the best or prefered way to clean the tube sockets?


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sun Jul 31, 2011 6:58 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Thu Oct 14, 2010 8:54 am
Posts: 1179
Location: Florida
Retroverbial wrote:
Ah yes, good old TMDE.

I was our unit's calibration coordinator for a quite some time.

What's the DA80 sticker on that Fluke read? IIRC, they're on a 270-day cycle.

Arjay


Fluke? This is what we used to use:
Image


As well as this one:
Image

8)

Art


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sun Jul 31, 2011 8:50 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
I still have my 260 (series 6XL), but it is long retired. The Simpson and other analog meters aren't as forgiving as the newer digital types though, and the circuit loading is hard to overcome, but a great meter in it's day. At first, I resisted the change that we made to the digital Flukes (And the name Fluke conjures up images.... :lol: ). I didn't like the loss of the analog meter movement, especially for checking caps, but now I won't go back.

Image

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sun Jul 31, 2011 8:58 am
Offline
Professional Musician
Professional Musician
User avatar

Joined: Thu Oct 14, 2010 8:54 am
Posts: 1179
Location: Florida
I think they still have their place. And there is just something "magical" about that analog movement. Just like the analog "VU" meters. But yeah, I went digital a long time ago. and as long as you have the range set correctly, it's kind of hard to missread the digital meter by reading the wrong scale, or getting a parallex error. didn't they have a more expensive model with a mirror built into the backing? Or was the only on the powered VOM? Brain fart now, LOL

Art


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sun Jul 31, 2011 9:33 am
Offline
Amateur
Amateur

Joined: Mon Nov 01, 2010 10:31 pm
Posts: 154
Wow!! Those are old school!! But still serve many purposes.. I love working with analog meters.. An your right, there's just something about analog.. On the amp side, I have dome what you instructed me to. In addition, I re-flowed all solder joints on all three circuit boards and tried cleaning out the tube sockets. To be honest, it made things worse. The crackle sound is louder and more defined. I used the "chopstick" method and didn't find anything. When I pulled the tube closest to the power tubes the crackle cut out dramatically, but had a real faint appearance. Installing and removing the next two seemed to have no effect as the noise was very noticeable. How can I check if the power transformers are going bad? Also when I push the channel select button in, it makes a loud POP.. Wasn't doing this before.. This amp is about 9 years old. Also how did you post pictures like that??


Top
Profile
Post subject: Re: Hot Rod Deville - Cracking
Posted: Sun Jul 31, 2011 9:42 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Wed Mar 31, 2010 12:48 am
Posts: 26417
Location: Tombstone Territory
I inherited one of those old Simpson 260's from my Dad......

Image

They're great multi-meters.

I also "liberated" a GI-issue TS-352/U VTVM before I retired which I use for heavy-duty bench work.

Arjay (fond of Roger Miller's line about "every lock that ain't locked when no one's around")

:mrgreen:

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 54 posts ]  Go to page 1, 2, 3, 4  Next
Go to page 1, 2, 3, 4  Next

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: