# NAD Old Traynor YGM-1 (1967?)



## ook ook (Jun 3, 2021)

Hi everyone, I just recently got an old Traynor YGM-1 and I figured I would find some bona fide Traynor experts on here that can tell me, more or less, exactly what I'm looking at. The amp is serial number GR-549.

I have plenty of pictures and can always take more if need be.

I haven't played the amp much so I haven't really gotten to know it yet but I think it sounds nice for the most part. I'll have to keep playing around with it to coerce some great tones out of it, but I don't have any complaints right now. 

I believe what I have is either a decently modified or some sort of transitional-era Guitar Mate. It doesn't seem to exactly follow the YGM-1 circuit schematic that I've found online and looks to have some characteristics of the later YGM-3 models. I attempted to follow the circuit and draw up a rough schematic which I will put up soon.

I'll hide the pictures in a bunch of spoilers so this post isn't a mile long.

Here's the speaker. It's labelled "jensen" and has other writing; maybe serial/model numbers? I'm not exactly sure. It also has some markings on the cone. My brief research tells me that this is an RSC (I think) speaker and RSC later became Marsland. Marsland speakers are apparently no good, but these RSC ones that were produced by Jensen are much better. I'd really like to know a rough power rating for this speaker if anyone's familiar with it. I just want to know that it's not going to blow up if I really get the amp going. I also lean towards more British-flavoured speakers so replacing it is something I'll be looking into. Not sure if the reverb tank is anything special or interesting, but here's a picture of it as well.


Spoiler: Speaker and Reverb Tank

































Here are the tubes it came with. We're looking at what looks to be an RCA 12AX7A with the RCA logo mainly faded away, an EH 12AX7, a Haltron 12AX7A, and some 12AX7 made in Yugoslavia. The tube chart calls for a 12AU7 in V1 where the RCA tube is. The power tubes seem to both be Westinghouse 6BQ5s although one of the tubes has no apparent branding on it. They both say "GT BRITIAN" and look similar in construction so I'm assuming they're both the same.


Spoiler: Tubes
























I'm not sure about how original all of the transformers are. The OT and reverb transformer are both Hammonds that look really old so I'm assuming they're original or at least of the era. The PT was replaced with a Peavy transformer which I wasn't too pressed about but I'm not sure what sort of reputation Peavy gets when it comes to their transformers. You'll also see some discolouration around the power tube sockets and the (old and disconnected) filter caps from the power tubes running hot.


Spoiler: Transformers

































And finally, here's what she looks like inside. Replaced electrolytics, 3-prong power cord, death cap removed and ground switch completely unused, and maybe some other various modifications. Looks like there are two additional diodes added? Lots of singed wire ends from a soldering iron wielder.


Spoiler: Guts















I have closeup shots of the circuit as well but I'm getting close to my 10-image limit here, so I'll leave them out.

As I said before, this doesn't exactly match the YGM-1 schematics that I've found. Following the circuit, I drew up what I think to be a good schematic, although I did leave some stuff out. I'll get that drawing up soon.

I know it's very common for people to mod these old Traynor amps so if anyone has some mod ideas for me, I'm all ears. I won't be getting into the modding side of things until I really have a feel for the amp and what I like/dislike about it.

Also, I'm not exactly an expert on any of this stuff so any and all information is appreciated.

Thanks guys.


----------



## Frenchy99 (Oct 15, 2016)

Some pictures would help !


----------



## greco (Jul 15, 2007)

Frenchy99 said:


> Some pictures would help !


Click on where it says "Spoiler *__*"


----------



## Frenchy99 (Oct 15, 2016)

thanks @greco ! Got the pictures now.

Speaker is dated Nov 1967 

i would research the new power transformer to make certain its equivalent.

aren’t the new caps replacing 40uf 450 volt caps?


----------



## butterknucket (Feb 5, 2006)

Email Yorkville Sound with the model and serial number and they'll help you out.


----------



## ook ook (Jun 3, 2021)

Frenchy99 said:


> thanks @greco ! Got the pictures now.
> 
> Speaker is dated Nov 1967
> 
> ...


Yeah, the schematic calls for 40uF. They've been replaced with 33uF caps. Not sure how detrimental that is to the amp.

I really can't seem to find any info on the PT, unfortunately. If anyone is familiar with it, that'd be great. Maybe I'll have to contact Peavey themselves


----------



## Latole (Aug 11, 2020)

To know if it is the right power transformer, it is not difficult.

Two voltage measurements to take: the right voltage and the right power.

You just have to measure the voltage at the output of the rectifier diodes, at the first filter cap
You should have around 400 volts DC. A variation between 365 and 425 is very acceptable and normal.

*WARNING; very dangerous voltage, do not measure if you do not know how*.
Depending on the voltages obtained, it may be necessary to replace the 10 watt bias resistor of the 6BQ5 to get the right bias.

To be sure that the transformer is of the right power, just measure the voltage of the filaments of the lamps. Theoretically it will be 6.3 volts AC but it can vary between 6.1 and 6.6
Less than 6.1, the transformer is not powerful enough.
More than 6.6, the transformer is too powerful.

Schematic; 



https://el34world.com/charts/Schematics/files/Traynor/Traynor_guitarmaterev_ygm1.pdf


----------



## tomee2 (Feb 27, 2017)

Transformer is from a Peavey Bravo.

There is schematic in this thread...


+++need schematic peavey bravo 112+++ - Music Electronics Forum



Looks like 3 preamp tubes and a pair of EL84s.


----------



## ook ook (Jun 3, 2021)

Latole said:


> Schematic;
> 
> 
> 
> https://el34world.com/charts/Schematics/files/Traynor/Traynor_guitarmaterev_ygm1.pdf


I've seen this schematic but you might be able to tell from the picture of the circuit that this isn't exactly what I'm dealing with. At least it doesn't look like it to me.



tomee2 said:


> Transformer is from a Peavey Bravo.
> 
> There is schematic in this thread...
> 
> ...


Thanks, I couldn't find anything about this specific transformer.

I drew up what I believe this amp's schematic is. I left out the transformers and filter caps and such. It's a little bit rough but readable, I think. If anyone sees anything really strange, point it out to me. I found some things strange but I've double checked and this is what I see.

EDIT: Or if it seems like my drawing is equivalent to the other schematic and I'm just not seeing it, that's fine too


----------



## Latole (Aug 11, 2020)

ook ook said:


> I've seen this schematic but you might be able to tell from the picture of the circuit that this isn't exactly what I'm dealing with. At least it doesn't look like it to me.


Picture is too small to help
Peavey Bravo PT have non center tap at hi voltage secondary winding. It is you PT ? 

What you need to know about the PT is reading the voltage ; answer # 7


----------



## ook ook (Jun 3, 2021)

Latole said:


> Picture is too small to help
> Peavey Bravo PT have non center tap at hi voltage secondary winding. It is you PT ?
> 
> What you need to know about the PT is reading the voltage ; answer # 7


Opening the picture in a new tab might help. 

I will get the PT measurements at some point. I'm having a little bit of trouble understanding what you're saying but I have contacted Peavey and I'll go in there myself to see what's up.

I have more pictures of the circuit as well that I'll upload in case anyone wants a closer look


----------



## Latole (Aug 11, 2020)

I open it in a new tab.
From picture to see if it is the right schematic....good luck


----------



## ook ook (Jun 3, 2021)

Some more gut shots


----------



## ook ook (Jun 3, 2021)

Oh, another thing. When taking out the chassis, all of the nuts came loose. Anyone have any good methods of securing them or am I just gonna have to reach into the cab and tighten them?


----------



## Latole (Aug 11, 2020)

ook ook said:


> Oh, another thing. When taking out the chassis, all of the nuts came loose. Anyone have any good methods of securing them or am I just gonna have to reach into the cab and tighten them?



I use teeth washer like Fender do


----------



## Latole (Aug 11, 2020)

ook ook said:


> Some more gut shots


The peavey PT high voltage winding don't have center tap like original Traynor PT
The mod done with a full wave solid state rectifier ; add 2 SS black diodes to ground

The mod :









The "original " Traynor rectifier circuit:


----------



## Latole (Aug 11, 2020)

ook ook said:


> Some more gut shots
> View attachment 371078
> 
> 
> ...



Now we need time to check..........Are there any volunteers?


----------



## Paul Running (Apr 12, 2020)

Is the objective to return to an original YGM-1?


----------



## tomee2 (Feb 27, 2017)

Pretty sure Hammond makes a drop in replacement for the YGM3, it should work in the 1? If that's the goal....


----------



## ook ook (Jun 3, 2021)

Paul Running said:


> Is the objective to return to an original YGM-1?


Not necessarily. I just want a reliable, great sounding amp. I'm open to mods. I may clip the bright cap on the volume pot and I'm considering moving to log pots.



tomee2 said:


> Pretty sure Hammond makes a drop in replacement for the YGM3, it should work in the 1? If that's the goal....


Hammond makes transformers for the YBA-2B that are modern equivalents for the transformers originally found on the YGM-1, if I'm correct. The OT model number matches what's in my amp but obviously I don't know for sure that the PT does. Looking at the specs, it seems like the PT matches. I believe it's the 1750S or something similar. Again, not necessarily the goal. If the Peavey works fine, I don't see a real reason to replace it

Woops, 1750S is the OT. PT is 290TRB



Latole said:


> Now we need time to check..........Are there any volunteers?


Yeah if anyone's actually interested and has time that'd be cool


----------



## ook ook (Jun 3, 2021)

Frenchy99 dated the speaker, so thanks for that, but does anyone have any other info about it? Power handling specifically is important to me if I'm gonna be cranking this thing


----------



## Frenchy99 (Oct 15, 2016)

ook ook said:


> Frenchy99 dated the speaker, so thanks for that, but does anyone have any other info about it? Power handling specifically is important to me if I'm gonna be cranking this thing



OK, just had a look again. The ext large can caps are dated DEC 1967 so I would put your amp early 68.

The insides looks stock apart from the replaced ( smaller valued caps that would worry me a bit ) and the added two diodes for some unknow reason ?!? why add two diodes there ??? Its not on any schematics...

The amp is rated at a conservative 17 watts and has tremendous good reviews.


----------



## tomee2 (Feb 27, 2017)

Frenchy99 said:


> OK, just had a look again. The ext large can caps are dated DEC 1967 so I would put your amp early 68.
> 
> The insides looks stock apart from the replaced ( smaller valued caps that would worry me a bit ) and the added two diodes for some unknow reason ?!? why add two diodes there ??? Its not on any schematics...
> 
> The amp is rated at a conservative 17 watts and has tremendous good reviews.


The replacement Peavey power transformer is not center tapped, so they made a full wave bridge rectifier out of it. That's my guess...


----------



## ook ook (Jun 3, 2021)

Frenchy99 said:


> OK, just had a look again. The ext large can caps are dated DEC 1967 so I would put your amp early 68.
> 
> The insides looks stock apart from the replaced ( smaller valued caps that would worry me a bit ) and the added two diodes for some unknow reason ?!? why add two diodes there ??? Its not on any schematics...
> 
> The amp is rated at a conservative 17 watts and has tremendous good reviews.


Yeah, I noticed the added diodes; full wave bridge rectifier seems like the most logical explanation.

I also noticed the filter caps were only 33uF instead of 40uF but I figured this would be close enough? I'll admit I'm not exactly sure how detrimental this is and what sort of issues it could introduce. Should this be something I look into fixing? Swap out those caps for the proper 40uF?

Edit: I did notice a little bit of hum. Maybe this is part of the reason


----------



## Paul Running (Apr 12, 2020)

The capacitance of electrolytic caps drifts from the nominal value as time passes and they have large tolerances, typically ±20%, the early models were sometimes +40%, -60%. This means that an aluminum electrolytic cap with a nominal capacitance of 40µfd will have a measured value of anywhere between 32µfd and 48µfd. A 32µfd cap will stress the diodes less than a 40µfd


----------



## tomee2 (Feb 27, 2017)

Paul Running said:


> The capacitance of electrolytic caps drifts from the nominal value as time passes and they have large tolerances, typically ±20%, the early models were sometimes +40%, -60%. This means that an aluminum electrolytic cap with a nominal capacitance of 40µfd will have a measured value of anywhere between 32µfd and 48µfd. A 32µfd cap will stress the diodes less than a 40µfd


Do full bridge rectifier circuits need less capacitance for the same level of hum?


----------



## Paul Running (Apr 12, 2020)

tomee2 said:


> Do full bridge rectifier circuits need less capacitance for the same level of hum?


That's an interesting question. I've not compared that on a bench test myself. I do prefer the full wave rectifier configuration myself with the center-tapped secondary. When you compare the two types, the bridge uses 2 more diodes which in theory would generate more noise...I should set that up and do a comparison test.


----------



## ook ook (Jun 3, 2021)

I've emailed Yorkville and the only info they gave me was "yeah YGM-1s have 3 inputs and a reverb transformer, so if your amp has those, then it's a YGM-1." Okay thanks, I already knew it was a YGM-1.

Anyways, anybody know some worthwhile mods for this circuit? Would it be a good idea to modify the tone stack so it has more fender-like values? I'm wondering if the 1M treble pot is a little much...

Still haven't had the chance to get in there with a multimeter and check the PT, but I'll get around to it soon


----------



## ook ook (Jun 3, 2021)

Hey guys, I didn't electrocute myself; I'm still kicking. I had to get a set of alligator clips and I kept putting off the trip to home depot, but I finally got around to it.

I took the following measurements with the power tubes pulled so I'm not sure how much of an impact that would have on the readings. The voltage at the output of the rectifier is 422VDC. I measured the voltage across the pilot light and it read 6.72VAC.



Latole said:


> A variation between 365 and 425 is very acceptable and normal.
> 
> Theoretically it will be 6.3 volts AC but it can vary between 6.1 and 6.6
> Less than 6.1, the transformer is not powerful enough.
> More than 6.6, the transformer is too powerful.


So the PT is too powerful? It's from a Peavey Bravo which is a 25 watt amp. I figured that would be alright


----------



## Frenchy99 (Oct 15, 2016)

Your amp (YGM-1) was 20 Watts and the following models were upped to 25 watts so you might just have the extra 5 watts now due to the PT.


----------



## ook ook (Jun 3, 2021)

Frenchy99 said:


> Your amp (YGM-1) was 20 Watts and the following models were upped to 25 watts so you might just have the extra 5 watts now due to the PT.


Maybe. The OT, at least assuming it's more or less 1:1 with it's modern replacement part, is rated for 25 watts. The Hammond 1750S/A-1339


----------



## ook ook (Jun 3, 2021)

Also just another note for dating purposes, the pots seem to be dated the 39th week of 1967


----------



## ook ook (Jun 3, 2021)

Wow! I held off on cranking it up until I was sure things were in good working order but damn. I got it just over half way on the volume and it really sings!

Surely the speaker reputation comes from later speakers since this one sounds so sweet.

I just need a foot switch for the reverb and trem now. 

What a great sound


----------



## ook ook (Jun 3, 2021)

Actually, I do notice a high-pitched noise while playing. This becomes more apparent as I turn the volume up and as I increase the tremolo intensity. Maybe something to do with the tube?

I'm also running 4 12ax7s while the base schematic calls for a 12au7 in v1, but my amp doesn't exactly follow the schematic anyways...


----------



## Paul Running (Apr 12, 2020)

ook ook said:


> Actually, I do notice a high-pitched noise while playing.


An indication of instability, probably due to the increased gain from the 12AX7. Try subbing a 12AT7, 12AY7, 5751 or other pin compatible tubes with a lower gain, sometimes a different 12AX7 may work however, the instability could creep back in as the tube ages. Otherwise, circuit alteration would be required if you wish to stay with the 12AX7.


----------



## Frenchy99 (Oct 15, 2016)

ook ook said:


> I'm also running 4 12ax7s while the base schematic calls for a 12au7 in v1, but my amp doesn't exactly follow the schematic anyways...


I`m with @Paul Running on that, the 12AX7 is much more high gain. 

You could also look at doing some of the more popular moods and remove the bright cap.


----------



## ook ook (Jun 3, 2021)

Paul Running said:


> An indication of instability, probably due to the increased gain from the 12AX7. Try subbing a 12AT7, 12AY7, 5751 or other pin compatible tubes with a lower gain, sometimes a different 12AX7 may work however, the instability could creep back in as the tube ages. Otherwise, circuit alteration would be required if you wish to stay with the 12AX7.


Yeah, I figured that would end up being an issue. Out of curiosity, what kind of circuit alterations are we talking here?



Frenchy99 said:


> I`m with @Paul Running on that, the 12AX7 is much more high gain.
> 
> You could also look at doing some of the more popular moods and remove the bright cap.


I do intend on clipping the bright cap on the volume control. Also swapping the RCA jack for a 1/4 inch, but I'd be open to hearing about commonly done mods for this amp


----------



## ook ook (Jun 3, 2021)

Swapped in a 12AT7 and the issue was less noticeable but still there. The RCA 12AX7 that was in there seems to be bad. I moved it to the phase inverter and it made all kinds of funky noises when I played certain notes.

I put in a 12AY7 as well and I think the issue still remains, although barely perceptible. Might try a 12AV7 before giving up and moving down to the proper 12AU7.

I'm also considering just swapping all of the tubes. None of them are microphonic as far as I can tell, but I don't have a tube tester so I don't know for sure how good the tubes are. The RCA tube seems to have gone bad so maybe others have gone as well.


----------



## ook ook (Jun 3, 2021)

Alright, I think this thread has served it's purpose. I got a 12au7 in V1 now, haven't powered it up yet since I'm planning on doing some very simple mods. Just built a rangemaster clone and an l-pad attenuator. Clipping the bright cap for the rangemaster and swapping the RCA jack for a 1/4 inch for the attenuator. Just want to be certain I'm not gonna blow up the speaker.

I guess I'll be starting up a new thread in the technical/repair section for discussion of mods and such. Here's a picture in the mean time. Never snapped a full shot of the amp


----------



## Latole (Aug 11, 2020)

ook ook said:


> Yeah, the schematic calls for 40uF. They've been replaced with 33uF caps. Not sure how detrimental that is to the amp.


I'm late ; 
33 mfd will work fine, no need 40 mfd


----------



## Latole (Aug 11, 2020)

"....and swapping the RCA jack for a 1/4 inch for the attenuator. Just want to be certain I'm not gonna blow up the speaker. " 
-ook ook

What is the relationship between replacing the jack and blow up the speaker, because I do not see.


----------



## ook ook (Jun 3, 2021)

Latole said:


> "....and swapping the RCA jack for a 1/4 inch for the attenuator. Just want to be certain I'm not gonna blow up the speaker. "
> -ook ook
> 
> What is the relationship between replacing the jack and blow up the speaker, because I do not see.


I built an attenuator that uses 1/4 inch jacks. I don't know the speaker's power rating so backing off a few dB seems like a pretty good idea if I'm cranking the amp. In order to use the attenuator, I'd need either RCA to 1/4 inch adapters or just change the jack and speaker cable

hope that makes sense


----------



## Latole (Aug 11, 2020)

I understand you are afraid to blow a speaker with 2/1 jack, I se now it is not what you mean


----------

