71 Princeton NR transformer

[BigPlay]

First of all I am new at this but figured I would give it a go and try to learn something. I am in the process of replacing the output transformer with a Classic Tone.( Recommend this was my original problem) Most of the wires were straight forward so I soldered them in but the replacement transformer has a Green 4 ohms and yellow 8 ohm option. I have a 8 ohm speaker so I solder the yellow in place. I left off the green 4 ohm but have no sound to the speaker. Does it need to be attached somewhere? I do realize I may have another problem. Thanks for any help or suggestions of what I may can trouble shoot next.
Ray

[olddawg]

First of all I am new at this but figured I would give it a go and try to learn something. I am in the process of replacing the output transformer with a Classic Tone.( Recommend this was my original problem) Most of the wires were straight forward so I soldered them in but the replacement transformer has a Green 4 ohms and yellow 8 ohm option. I have a 8 ohm speaker so I solder the yellow in place. I left off the green 4 ohm but have no sound to the speaker. Does it need to be attached somewhere? I do realize I may have another problem. Thanks for any help or suggestions of what I may can trouble shoot next.
Ray

Did the amp have sound before you changed the transformer? Did you take a picture of the unmolested amp before you started? If it worked before the upgrade I would put the old transformer back in and see if the amp still works. Normally you just tape up or cap any speaker taps you are not using.

[BigPlay]

I have had the amp for a few years and it stop working with no sound. I would also get shocked if I touched the chassis. I was recommended this was probably the problem. I no longer get shocked so that's a plus but still no sound. I change all the tubes and have power going to each.

[olddawg]

I don’t want to sound condescending... but have you checked the speaker? It sounds like there may have been no problem with the old transformer. I would put it back stock and troubleshoot the amp. Throwing parts at something (especially expensive ones) usually creates more problems than it solves imhe. There are many techs here that will help you troubleshoot your amp. But we don’t want you to hurt yourself. There are potentially lethal voltages even in a Princeton so you need to be familiar with basic electronic repair safety protocols . A few pictures and a schematic would help. Then we take voltage measurements. No output doesn’t necessarily mean bad OT. In fact it usually doesn’t.

[Justin Thomas]

Transformers are absolutely the LAST suspects in order of suspicion. And there are LOTS of tests that can be done quickly & easily without replacing them.

As always, I recommend R.G. Keen's Geofex page...

Justin

[BigPlay]

I don’t want to sound condescending... but have you checked the speaker? It sounds like there may have been no problem with the old transformer. I would put it back stock and troubleshoot the amp. Throwing parts at something (especially expensive ones) usually creates more problems than it solves imhe. There are many techs here that will help you troubleshoot your amp. But we don’t want you to hurt yourself. There are potentially lethal voltages even in a Princeton so you need to be familiar with basic electronic repair safety protocols . A few pictures and a schematic would help. Then we take voltage measurements. No output doesn’t necessarily mean bad OT. In fact it usually doesn’t.

No worries for having me check the simple things. I did check the speaker already a d it is in good working order. I got the amp from the other guitar player in my band who has done some wiring and trouble shooting. The schematic I am using is AA964 I have the old OT but the new one is installed so I leave it as is for now. The OT I put in is a classic tone 40-18045. I am familiar with the voltage risk by reading up on these and watching some you tube. I will see of I can find the page listed below. If I can firgure out how to post pics I will do that. This amp was all original other than the now new OT.