I just picked up a second st70 amp that was covered in 1/2 of dust. I thought it was all original. After cleaning it I noticed it does not have a PA060 power transformer. It is a Dynaco transformer PT0062. The laminations are slightly shorter.It seems to work ok. Anyone know if this transformer is ok for the ST-70?
2 posters
ST-70 transformer question PT0062?
richtp- Posts : 49
Join date : 2011-11-18
Location : Sterling MI
stewdan- Posts : 231
Join date : 2010-03-07
Age : 85
Location : Houston Texas
Hi --
There are several Dynaco Transformer Catalogs on the Web that are pdf files and are google-able. Your "PTO062" Power Transformer is not listed in either of them.
I have several Dynaco Mk III's, and most have the Standard P-782 (output) and A-431 (power) Transformers.
But I also have one Mk III that has an PTO186 (Power) and a ZTO165 (Output) Transformer.
I believe that PTOnnn and ZTOnnn type designations are for either very early or very late production runs of the Dynaco Amps. I say this because there was a very late version of the Mk III Amp that used a 1N400n type diode in place of the Selenium Rectifier and also used a "Z-216 Output Transformer".
Hope that this info helps, maybe Roy or Bob or others can provide additional info!!
Stew
There are several Dynaco Transformer Catalogs on the Web that are pdf files and are google-able. Your "PTO062" Power Transformer is not listed in either of them.
I have several Dynaco Mk III's, and most have the Standard P-782 (output) and A-431 (power) Transformers.
But I also have one Mk III that has an PTO186 (Power) and a ZTO165 (Output) Transformer.
I believe that PTOnnn and ZTOnnn type designations are for either very early or very late production runs of the Dynaco Amps. I say this because there was a very late version of the Mk III Amp that used a 1N400n type diode in place of the Selenium Rectifier and also used a "Z-216 Output Transformer".
Hope that this info helps, maybe Roy or Bob or others can provide additional info!!
Stew
richtp- Posts : 49
Join date : 2011-11-18
Location : Sterling MI
Thanks for the response stew. I found the transformer catalogs as well and could not find the transformer in them. It very well may be an early part number.
I think it has been changed, it looks like something fried in the chassis at one time and the transformer looks older than the output transformers so it may have been salvaged.
It is a little smaller than the PA060 in my other amp and I was a little concerned about that. But I played it a lot today and it seems to work fine.
I haven't checked any voltages yet.Other than the bias voltage.
Thanks again
Rich
I think it has been changed, it looks like something fried in the chassis at one time and the transformer looks older than the output transformers so it may have been salvaged.
It is a little smaller than the PA060 in my other amp and I was a little concerned about that. But I played it a lot today and it seems to work fine.
I haven't checked any voltages yet.Other than the bias voltage.
Thanks again
Rich