So many problems with my DRRI !

[Wil]

If you go the PTP route, do you know someone with experience doing this? PTP isnt without potential problems either. Lead dress and grounding are really important.

Yes, luckily there's someone here near my town but he asks a lot for not much... I have a uncle who's engineer in electronics, if I buy all the things I need to go PTP, he could easily help me assemble everything. Who's making the best boards around the web ? I saw a couple of sellers on ebay but did not find any review. The choice of component is also quite important isn't it ? I may try to save a little on capacitors by taking the ones I put on the PCB of my DRRI which are all Mallory 150 (a bit pricey here)...

[Jazz P Bass]

The PTP route is a sound concept.
However, if you do not have what it takes to repair the amp that Fender designed & has proven, how are you going to troubleshoot a new build?
Just a thought.
You may be heading for a lot more trouble.

[J M Fahey]

But there's something wrong I can't fix and that's invisible to the naked eye.

*That's the point*
I would get the service manual, or al least the schematic+layout and carefully set the clock back to zero, meaning leaving it *exactly* as factory fresh.
No Mods, no nothing, because I bet there's where the problem lies ... and nobody can guide you in uncharted waters, only when the original "map" is valid.

[Wil]

Last News , I plugged a speaker, played the amp, and it wasn't even as loud as a single watt amp... B+ oscillates between 410 and 385V depending on the bias pot position.

[Wil]

http://ampwares.com/schematics/65_Deluxe_Reverb_RI.pdf
I'm going to check every test points of the schematics, I may find something wrong that could make us discover a starting point.

[JoeM]

.. B+ oscillates between 410 and 385V depending on the bias pot position.

That doesnt by itself indicate a fault. As you increase or decrease the idle current by changing the bias, the B+ will vary due to the change in loading.

You really need to have someone who understands troubleshooting to look at your amp. So far it just looks like you're shooting in the dark.

[Wil]

That doesnt by itself indicate a fault. As you increase or decrease the idle current by changing the bias, the B+ will vary due to the change in loading.

You really need to have someone who understands troubleshooting to look at your amp. So far it just looks like you're shooting in the dark.

I am. That's why I'm here. I understood the relation between bias pot, b+ and idle current but voltages measured look right for this part.
Now I'm measuring the 39 test points that are in the service manual but I'm having problems with AC voltages... values indicated are weird. (for example TP11 should be 2,7VAC, I get 503...) but no problem for DC voltages.

[Wil]

For all DC voltages, here's what I measured : *(TP value)
TP1 : 393V (396) OK
TP2 : 393V (394) OK
TP3 : 327V (311) OK
TP4 : 288V (261) OK
TP5 : -58V (-49)
TP10 : 0.86V (1.3)
TP13 : 1.2V (1.3) OK
TP18 : 17.2V (7.1)
TP22 : 1.32V (1.4) OK
TP 27 ON : 0.7V (1.8)
TP28 : 21<VDC<23 (11)
TP29 465VAC (300)
TP33 : 70V (68) OK
TP36 : -43V (-37)
TP37 : 394V (391) OK

I hope this means something to you, haha!

[J M Fahey]

I'm having problems with AC voltages... values indicated are weird. (for example TP11 should be 2,7VAC, I get 503...)

You need a real multimeter, like those which have 200mV AC scales; those which typically have only 2 AC scales (say, 200VAC and 700VAC or so) are no AC voltmeters at all but DC ones with a series diode.
They measure plate DC (say, 250VDC) and display it as impossible over 500VAC ... which do not exist.

Besides that; I repeat my suggestion to leave that amp back to stock, otherwise the "map" does not match the "terrain".
Not forgetting that the original untouched amp is a *killer* one; don't understand why anybody would Mod it.

[Wil]

But I did not mod it, I just changed some component that I though were defective. (okay I admit, I put a negative feedback variable resistor, haha).
Tomorow I'll remove every cables, rewire everything and resolder everything, if that doesn't work... I'll have to go PTP !

[J M Fahey]

But I did not mod it

I forgot to say that I'm running my amp with the "Pull V1 mod", so there's no tube in the V1 position.

I changed all the capacitors, tubes, optocoupler, etc...

But after that, I don't know why, maybe this amp only wants to p*$$ me off but it was way weaker and thin sounding than before...

My newer JJ power tubes made a very strange noise when I was switching the standby off. The amp was squealing during half a second and it happened to be the power tubes... So I put older groove tubes that sound like... you know what!

the amp sounded nice for a week or two, before I changed the optocoupler and probably broke something

[Wil]

I don't consider changing component with the same value is a mod. The Pull V1 mod is simply removing V1 so there's more gain on the vibrato channel because I don't use the normal channel.

[pdf64]

If V1 isn't in place then some of the VDC TP values won't match the corresponding Fender values on the schematic.
Pete

[Wil]

Hello everyone.
I started this thread a couple of weeks ago. I rewired everything. I added bias testing points. My JJ's GZ34 burnt a fuse so I put a old Ruby 5AR4 that's making a lot of noise. But that's not the problem, I can buy another one.
My multimeter reads at Pin 3 of each power tube 400V. The problem is, with the bias test points, I only read 0.006A. I guess normally it should be around 0.025A. The minimum I can set is 0A, no sound.
The bias range resistor is ok. (22ohm).
Still have no clue what's going on.. Plus, now, it is noisier (a bit of motorboating).
Any idea ?
Thank you.

EDIT : The previous owner added a 1.5k resistor between PIN 1 and 5 on each power tube. And 2 resistors in paralell (2x1K) between Pin 4 and 6 (still on each power tube). I know PIN 1 and 6 aren't use. I solder the wired from the PCB at Pin 4 and 5, so those resistors are useless, right ?

EDIT 2 : Grid voltage can go from -60V to -40V.
Plate voltage goes from approx 430 to 403V.
I noticed the first quarter of the pot rotation doesn't affect the reading. Plate voltage only start decreasing after approx. a quarter of its rotation (I hope you can understand this sentence, haha!)

EDIT 3 : Screen grid resistors look OK (both reading 470ohm)

[Wil]

I tried to measure with the power tubes removed... big flash and fuse blown... badly burnt !