Transformer Conundrum: 1965 Gibson GA15-RVT

[Leo_Gnardo]

If the trans is bad.

^^^ yes right there is a pertinent observation: IF. So far we have only the opinion of a so called "tech" who doesn't seem to be able to get anything straight. It would save us ALL a lot of flailing around if the condition of the original PT would be verified by a tech who does know how to check it proper-like.

[Bloomfield]

Unfortunately it requires a CT HV secondary and that 290XX doesn't have one.

Good catch Chuck, I missed that. Looking at that schematic sideways didn't help.

[drewl]

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The amp in question has 300Vp using a diode rectifier. A Deluxe Reverb PT would push it to about 460Vp It's also a laydown type mount rather than upright.

Agh, I was thinking of a different Gibson.

[Chuck H]

I guess I'd ask if it was your amp what transformer do you think would be the optimal choice?

If it were mine I would probably:

1) Get the Heyboer if they have it on file and don't charge too much for the custom order. They often don't. They're easy to talk to and work with. You don't get anything if you don't ask.

2) If that didn't pan out "I" would probably measure the existing hole and see if I could cram the Hammond 270DAZ in there. The specs for mounting the Hammond are on line in the specs. The 270DAZ will probably raise your B+ 30V to 40V. The tubes will handle that with no trouble. I can't say about the OT, but it'll probably be fine with an extra watt or two.

[widget2640]

I had a hard time reading that schematic, but maybe this Hammond 290XX or another Blues Jr. replacement might do the trick. The stated voltage is after rectification so seems reasonable. I'm not sure if the Gibson transformer is horizontal or vertical mount; the Blues Jr. is horizontal.

http://www.nextgenguitars.ca/product...ansformer.html

Thanks for responding Blooomfield - the tech confirmed it's a "flat mount" based on this chart: https://mercurymagnetics.com/pages/_...klTM80C5OFzPy8

Yeah the schematic is brutal. Incomplete, and inconsistent.

[widget2640]

Hoffman also has a list of recommended techs: https://el34world.com/service.htm

Don't neglect the not too far away New Hampshire zone.

Hey Leo - thanks. I sent an email to the fella in NH seeing if he could help. We shall see.

[widget2640]

If it were mine I would probably:

1) Get the Heyboer if they have it on file and don't charge too much for the custom order. They often don't. They're easy to talk to and work with. You don't get anything if you don't ask.

2) If that didn't pan out "I" would probably measure the existing hole and see if I could cram the Hammond 270DAZ in there. The specs for mounting the Hammond are on line in the specs. The 270DAZ will probably raise your B+ 30V to 40V. The tubes will handle that with no trouble. I can't say about the OT, but it'll probably be fine with an extra watt or two.

Sincerely, thanks again for providing so much info Chuck. - couple follow ups

1.) Regarding Heyboer - I followed the link and read the thread - I am baffled as to what to ask Heyboer or what to look for? The thread doesn't mentioned specifics or specs of the custom PT they did for that fella. What would I ask that they had on file? I've put so much time and effort into getting this amp up to speed that I would spend a little bit extra for the best possible replacement. Do I simply call and ask what? Do you have a Drop in replacement PT for a 1965 Gibson 16 RVT? Do they "rewind" the original PT?

2. The 270DAZ from Hammond is mentioned a couple times, as is this EDCOR on several similar threads... (EDCOR: Power transformer for a 120V, 60Hz. or 240V, 50/60Hz. line to 510V (255-0-255) at 125mA center tapped and 6.3V (3.15-0-3.15) at 4A center tapped. https://www.edcorusa.com/xpwr013 ) If Heyboer doesn't pan out - you would choose the Hammond over the EDCOR?

Thanks again,

MJL

[DrGonz78]

So if the power transformer is found to be faulty there is another place that does rewinds. It seems that TRS (Transformer Rewinding Services) has recently been sold by the original owner. I am pretty sure BlueGlow is the same one I have watched on youtube. Now I don't think they are taking in any rewinds until later in 2019, but who knows maybe by summer. Still good to know there is someone out there offering the services of rewinding transformers. The original website for TRS shows all the Gibsons that they will rewind and the GA15-RVT is on the list. I guess this is more for the future but it's out there.

Old owner's website: Lists all Gibson amps that they will re-wind. Too bad since he was working in Maine...
http://members.tripod.com/tubes_tube...vice/id69.html

New owner's website:
https://blueglowelectronics.wordpres...mer-rewinding/

[Chuck H]

Sincerely, thanks again for providing so much info Chuck. - couple follow ups

1.) Regarding Heyboer - I followed the link and read the thread - I am baffled as to what to ask Heyboer or what to look for? The thread doesn't mentioned specifics or specs of the custom PT they did for that fella. What would I ask that they had on file? I've put so much time and effort into getting this amp up to speed that I would spend a little bit extra for the best possible replacement. Do I simply call and ask what? Do you have a Drop in replacement PT for a 1965 Gibson 16 RVT? Do they "rewind" the original PT?

2. The 270DAZ from Hammond is mentioned a couple times, as is this EDCOR on several similar threads... (EDCOR: Power transformer for a 120V, 60Hz. or 240V, 50/60Hz. line to 510V (255-0-255) at 125mA center tapped and 6.3V (3.15-0-3.15) at 4A center tapped. https://www.edcorusa.com/xpwr013 ) If Heyboer doesn't pan out - you would choose the Hammond over the EDCOR?

Thanks again,

MJL

I'd probably still choose the Hammond if only because it's a lay down mount like the original. The Edcor is not. I don't know what the interior geometry of parts fit is though or how much retrofitting would be necessary for either. At face value I would expect the Hammond to be easier to retrofit.

[guitman321]

Weber W025130, The secondary voltage is only slightly higher and it's a lay-down. About 50$.

[Chuck H]

Weber W025130, The secondary voltage is only slightly higher and it's a lay-down. About 50$.

A good alternative, but...

It's 20V higher than the Hammpnd, larger and has an ancillary secondary winding that the Hammpnd doesn't