Rocket PT issues discovered during troubleshooting

[DaveMon]

All,

I am seeing a very strange issue, while troubleshooting my Rocket build, here is a rundown:

Amp was with built with RJ supplied aluminum reverse chassis, RJ-PAC-PTW and A470 transformers
- after completing the build, I had an issue with very low output from the amp, at every setting, all controls on 10, the amp was not louder than a clock radio ( but sounded good ) I posted about that issue here:

https://ampgarage.com/forum/viewtopic.p ... 17#p387617

I never resolved that issue, and put the amp aside for awhile and worked on Express builds...….then I decided to try it again.
I removed the potentiometer grounding wire from the back of the pots and replaced it with individual star washers that have a solder lug attached ( these things are great and have solved lots of headaches ) I also found a bad solder joint and corrected that....put it all back together.....nice sweet tone....but only at grandma volume....played it for about 20 minutes....(since I wasn't bothering anyone)….back to drawing board.

Started troubleshooting again.....I came to TAG, and printed out the rocket voltage chart, and began taking readings.... all voltages are within 5-20% of the listed "expected ' values on the chart except the last one......

On the V8 - GZ34 Recto tube, I measured 533 volts AC on pins 4 and 6 (plates) ....... I was expecting 250 !!
I don't recall what that value was previously, when troubleshooting, or during the initial build......but I think 533 would've got my attention!!
Anyway, I went back to check this seemingly impossible value again, when I touched the probes to the contacts the amp buzzed like a brownout...... then the #3 power tube redplated ( this had never happened before, I had never seen a redplate before till this)
Anyway, I removed all the tubes, measured 535AC then fuse blew. ( I thought that was weird also ) I have ordered a resettable 2 A circuit breaker.
I cut yellow/green wires going to the rectifier socket, and measured 535AC on the yellow/green and then checked the yellow/yellow pair and measured 625 volts AC, neither pair connected to socket

Any idea what could be going on ?? I figure one of 3 things:

A) PT always output 533 VAC and I overlooked it ( doesn't explain why its redplating now )
B) PT was normal and something occurred in the PT around the time I took the reading and it now outputs > 500VAC forever ( like Incredible Hulk? )
C) PT was normal but something is now shorted, somewhere? causing the > 500 condition ( I have not cut all PT wires loose yet to rule out amp circuit)

I have no reason to suspect anything wrong with components I got from RJ...…they have been functioning for a year until I started "poking around"...…..In fact, if not for RJ , I wouldn't have a Rocket at all!


I will go cut remaining PT wires from socket and see if that changes anything....

[norburybrook]

isn't a regular Rocket PT 265-0-265 ? that would equate to around 530V. Is your center tap wired correctly to ground ?



M

[DaveMon]

Yes, an intermittent grounding issue was causing the strange behavior....I apologize for the really dumb questions......my skills have grown by leaps and bounds , thanks to TAG. But despite that..... I have huge gaps in my knowledge, that I am working to close.....I have books....I watch uncle Doug on youtube.....I will get there!!!
...