1974x PT replacement
Moderators: zaphod_phil, Daviedawg, Graydon, CurtissRobin, colossal
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
Thx. I've emailed Marshall and Dagnell. We'll see what's what after they respond. This PT coming today I'll send back. Someone on the Marshall Forum mentioned a Hammond 290PAZ, At least to compare specs as to what to compare too, though this PT has 140mA
https://www.hammfg.com/files/parts/pdf/290PAZ.pdf
https://www.hammfg.com/files/parts/pdf/290PAZ.pdf
0 x
-
- Verbose poster
- Posts: 1118
- Joined: Mon 01/04/16 3:52 pm
Re: 1974x PT replacement
That looks better at 140mA,is there any specs printed on the PT that failed?
Quote the serial number of the amp when asking Marshall so they know you are a genuine owner.if any of us tried the “reverse engineering” alarm would go off!
Good luck
Quote the serial number of the amp when asking Marshall so they know you are a genuine owner.if any of us tried the “reverse engineering” alarm would go off!
Good luck
0 x
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
I added the amps serial number to marshall. No specs for the bad tranny. it's a a D4909 Dagnall electronics. TXMA 00115 Batch:1294800446
1 x
-
- Verbose poster
- Posts: 1118
- Joined: Mon 01/04/16 3:52 pm
Re: 1974x PT replacement
Keep us posted with your progress on this,will be of interest to me and future reference.the amp is nearly 20 years old now so it might be worth renewing the electrolytics while you are in there.
0 x
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
Marshall responded to my email. Sent a replacement tranny out today. I did not expect that.
I'd appreciate any info on installing a PT. Anything easily confused or that can get wired backwards.
I'd appreciate any info on installing a PT. Anything easily confused or that can get wired backwards.
3 x
-
- Verbose poster
- Posts: 1118
- Joined: Mon 01/04/16 3:52 pm
Re: 1974x PT replacement
That’s good of Marshall,should be just a straight swap regarding wiring,take some pics of the old transformer wiring before you remove it or draw a diagram showing which wires go to which terminal.just ask if you are unsure and post some pics.
2 x
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
OK, so I received a Hammond 290PAZ replacement PT. I'm enclosing some pics before I pulled The Dagnell 4909 PT and then sitting side beside the Hammond. I've got different color wire. I was pretty sure I would.....I'm hoping someones got a spec sheet for the dagnell. As I said, this is my 1st tranny replacement, would like to get it the first time.........Marshall still is sending me a free replacement, but IDK when that'll be here. I've got this one now, I'd like to put it in. Kinda OCD about it now. Any help laying this out would be appreciated.......also, I snipped the wires long from thew tranny
0 x
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
- JMPGuitars
- Super Duper Admin
- Posts: 3998
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: 1974x PT replacement
Click the "Attachments" tab under message post box where I typed all this text into. You click "Add Files" and you can also click "Insert Inline" if you want after uploading them.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
These show the Dagnell 4909 PT before I pulled it
You do not have the required permissions to view the files attached to this post.
0 x
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
You do not have the required permissions to view the files attached to this post.
0 x
-
- Verbose poster
- Posts: 1118
- Joined: Mon 01/04/16 3:52 pm
Re: 1974x PT replacement
note someone has been in there and changed the 91R bias resistor to 200R.
see if you can work out the wiring also do the mounting bolts of the 290 paz match your existing holes?
good luck
You do not have the required permissions to view the files attached to this post.
0 x
- JMPGuitars
- Super Duper Admin
- Posts: 3998
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: 1974x PT replacement
The unused wires get clipped and covered with heat shrink tubing.
Why are you using the Hammond if Marshall is sending you a replacement? I would use the Hammond for another build.
Why are you using the Hammond if Marshall is sending you a replacement? I would use the Hammond for another build.
2 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
Mounting bolts line up perfectly.
No telling when the Marshall replacement might be here. Maybe a couple weeks, IDK, but I've got this one here now
No telling when the Marshall replacement might be here. Maybe a couple weeks, IDK, but I've got this one here now
0 x
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
Does anyone know where I might find a Dagnall 4909 PT drawing? I can't find one anywhere and Dagnall has not responded to emails.
0 x
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
I might wait JPM, but I'd like to be able to install this one If I can. With the Marshall, I'll likely have the same color/location issues with the primary and secondary that I'm having now. A Dagnal 4909 drawing would take most all the mystery away, but I can't find one anywhere and Dagnall hasn't responded
0 x
-
- Verbose poster
- Posts: 1118
- Joined: Mon 01/04/16 3:52 pm
Re: 1974x PT replacement
you won't get any response from dagnall,i've contacted them twice asking about their 18W transformers and had no reply!
You do not have the required permissions to view the files attached to this post.
2 x
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
Thx for posting that geoff 1965. I. I've got this down now. 100%, but now that I do have my head wrapped around it, I'm thinking of waiting at least a few more days to see if the Marshall replacement shows up. I'm more of a purest than pushing this through. At first there, I couldn't leave it alone, because I didn't understand. Now that I do, I can wait a bit......Either way, the extra tranny I have I'll use to build a 18w clone....Love this stuff. Thanks everyone for the help and support........I'll post pics and updates as I move fwd
0 x
-
- Verbose poster
- Posts: 1118
- Joined: Mon 01/04/16 3:52 pm
Re: 1974x PT replacement
Those hand wired marshall’s are a work of art! and I would wait and fit the Marshall PT for originality.check the bias resistor and capacitor and if you don’t have a tube tester I would monitor the bias voltage when you first power on.which brand of ez81 do you have?
0 x
- foreverstrung
- Occasional poster
- Posts: 241
- Joined: Sun 10/10/21 5:53 pm
- Location: Seabrook Texas
- Contact:
Re: 1974x PT replacement
I've got a Tesla EZ81. Old original Tesla, not JJ. I did just order a NOS RCA EZ81. It'll arrive soon.
I don't have a tube tester, but 2 NOS Mullard EL84's.....They were NOS when I put them in after I purchased this amp. Maybe 25 hours of playtime on them.
When you say test the bias voltage, you mean, get the plate voltage and them mA of the EL84's and then do the math, right?
I don't have a tube tester, but 2 NOS Mullard EL84's.....They were NOS when I put them in after I purchased this amp. Maybe 25 hours of playtime on them.
When you say test the bias voltage, you mean, get the plate voltage and them mA of the EL84's and then do the math, right?
0 x