1974X died.....(but lives again!)
Moderators: zaphod_phil, Daviedawg, Graydon, CurtissRobin, colossal
- Buc McMaster
- Unrated
- Posts: 5
- Joined: Tue 08/02/22 4:56 pm
- Location: Texas
1974X died.....(but lives again!)
....suddenly and completely. Checked fuse....okay. Replaced the rectifier and it came to life once more.......for about three minutes and it went silent again. I intend to deliver it to an amp shop later this week but do any of you have experience with such a failure? What might I expect at the repair shop?
It's a 2004 model, new preamp and power tubes installed about a week ago.
It's a 2004 model, new preamp and power tubes installed about a week ago.
Last edited by Buc McMaster on Wed 08/17/22 7:17 am, edited 1 time in total.
0 x
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: 1974X died.....
Hard to say.. but I do know the original transformers fail often. Marshall usually sends a replacement transformer in those cases. But I think you need an official tech to support that procedure.Buc McMaster wrote: ↑Tue 08/02/22 6:49 pm....suddenly and completely. Checked fuse....okay. Replaced the rectifier and it came to life once more.......for about three minutes and it went silent again. I intend to deliver it to an amp shop later this week but do any of you have experience with such a failure? What might I expect at the repair shop?
It's a 2004 model, new preamp and power tubes installed about a week ago.
0 x
"THIS should be played at high volume..preferably in a residential area"
- Buc McMaster
- Unrated
- Posts: 5
- Joined: Tue 08/02/22 4:56 pm
- Location: Texas
Re: 1974X died.....
I was trained as a radio repair tech in the USAF in the 1970s but I'll admit to not having had much motivation at the time and I certainly did not pursue the field after leaving the military....perishable skills......complete idiot electronically speaking. That said, intuition tells me that a bad transformer would not have been provoked to work with a new rectifier.......if the transformer is blown, it's over, new rectifier be damned.....yes? Would the amp have worked short-term as it did with a new rectifier if it was a blown transformer?
0 x
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: 1974X died.....
Maybe the new rectifier tube is a lemon?
I had a new JJ fail instantly . Stay away from JJ
I had a new JJ fail instantly . Stay away from JJ
0 x
"THIS should be played at high volume..preferably in a residential area"
- Buc McMaster
- Unrated
- Posts: 5
- Joined: Tue 08/02/22 4:56 pm
- Location: Texas
Re: 1974X died.....
Maybe so.....the new one I plugged in was an NOS Mullard.....could have been bad. But still the question: if the transformer was blown would the rectifier replacement have revived the amp for a brief time? Or, if the transformer is in fact blown, would the amp have remained silent? I'm thinking the transformer is okay and the problem is elsewhere, but as I said, I have no skills in this arena....hence my question.
0 x
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: 1974X died.....
There could be a failing winding in the transformer that reveiles itself when enough current is being drawn. But that would be onlu a few seconds.. not minutes. And the fuse should blow from the excess current draw.
Does the amp turn on with all tubes removed?
Does the amp turn on with all tubes removed?
0 x
"THIS should be played at high volume..preferably in a residential area"
- Buc McMaster
- Unrated
- Posts: 5
- Joined: Tue 08/02/22 4:56 pm
- Location: Texas
Re: 1974X died.....
So......the tech called today about the apparently injured 1974X....
It did have a broken leg cap in the tremolo circuit....sussed and fixed. Apparently the real issue was mechanical: someone had installed extra washers on the outside of the tremolo input jacks such that a guitar cord male tip only made intermittent contact. What?! I cannot imagine why this may have been done. And, having been informed of this, I do recall that I had used a curly guitar cord for the first couple of weeks of ownership and had switched to a different straight cord the day it began to act up, leading me to believe the cords interacted differently with the input jacks. Sheesh.
It did have a broken leg cap in the tremolo circuit....sussed and fixed. Apparently the real issue was mechanical: someone had installed extra washers on the outside of the tremolo input jacks such that a guitar cord male tip only made intermittent contact. What?! I cannot imagine why this may have been done. And, having been informed of this, I do recall that I had used a curly guitar cord for the first couple of weeks of ownership and had switched to a different straight cord the day it began to act up, leading me to believe the cords interacted differently with the input jacks. Sheesh.
4 x
- Buc McMaster
- Unrated
- Posts: 5
- Joined: Tue 08/02/22 4:56 pm
- Location: Texas
Re: 1974X died.....(but lives again!)
Retrieved the Marshall from the amp shop yesterday and it is as expected....rippin' and roaring' once again. Had me concerned for a bit.....all's well that ends well.
3 x