Bass Master XM100 Type:100B

[redkurn]

Hmm, that is possible I put it in backwards even though I did the opposite since these sheets show they are flipped.

https://www.mouser.com/datasheet/2/3...-D-1801440.pdf
https://www.mouser.com/datasheet/2/3..._D-1811481.pdf

I'm not getting a positive voltage on the base of Q10, it's supposed to be + 38v, but I am getting a little over - 36v.
My common lead is on the chassis ground when probing.

Is it possible they intended the fet to be orientated in the same manner as the original? they specifications do seem opposite of the original part, this one I chose because they listed at the part to use on yorkville...

[g1]

Side note, the J111 is reverse of the original 2N5638, I did make sure to check all of my parts against the originals datasheet and should be fine as they all tested good. (Flat face of J111 is GSD, the 2N5638 is DSG)

The datasheets I have show both to be DSG (looking at flat face with legs pointing down). See attached. (The J111 is GSD when looking at the back.)
If it's in there backwards you will have volume problems.

[redkurn]

I’ve proved around the board and the voltages where I was able to get a reading seem fine, Q10 is about 1.5v lower than the schematic shows, but that shouldn’t be the problem.

If it is the fet, do I just jump it or leave the drain or source detached?

When I turn the volume up it does distort, so I’m kind of thinking it’s not the new parts, but could it be something else?

[g1]

The 1.3A is when putting out full power. You don't need to be running any signal on the bulb so at idle the 60W should be just fine. The higher wattage bulb you use, the less protection it offers to the amp. The whole point of the bulb is protecting the amp and especially the expensive new components.

As far as the power output, it's very difficult to judge by ear. You really need to measure into a load. Then you can get an idea of whether it is getting to full power with a normal input level.
The Fet is for muting. If there is any question about it at all, you can just disconnect the drain or source leg and see if the volume level changes.
edit: see post #46

[redkurn]

Found out this amp requires 1.3a and with a watts calculator it shows 156w, wish I found a 75w now I suspect the 60w will still be good enough.
Thanks be to all of you that helped me get this far, now I am going to power it on the limiter and multi meter the output, if it's clean sweet!, if not then maybe someone here will have an idea of what's next.

Side note, the J111 is reverse of the original 2N5638, I did make sure to check all of my parts against the originals datasheet and should be fine as they all tested good. (Flat face of J111 is GSD, the 2N5638 is DSG)

Update: 1
Output jack started at 1.358v when connected to the limiter and slowly fell to 1.2v and was continuing to do so, powered off and it spiked to over 2v.
Took it off the limiter, tested TP1 and TP2 and it measured .16mV.

Now I am going to do a sound check and see if it is actually as it appears, repaired.

Update: 2
It makes guitar noises now instead of broken sounds, but at max volume it is very low on the cab and headphones aren't overwhelmingly loud, but definitely fairly good volume, but probably half what it should be.

Good start though, pots need cleaned for sure.

[redkurn]

Not sure that I would want to, just basic maintenance.
have a set of JJ tubes on the way. 6L6 and ECC83S.

Can’t be worse than the originals, maybe better, but I hope the sound doesn’t change much as I like it and don’t see why the complaints.

[g1]

The 60W should be fine to get it up and running with idle voltages and no signal. Once all is well and you have no DC on output, you can get off the bulb and run signal.
I think we have some infinium schematics on the forum. I would not recommend anyone who is not at advanced level repairs try to work on one.
Tube replacement should not be a problem, as bias is all automated.

[redkurn]

I’ve got a knot in the cable, used a step bit to make a clean hole and heat shrink to buffer the shielding.

just hoping the 60w is enough for this 100w output amp and the parts that arrive tomorrow do the job.

I did find and buy a Bugera V55HD Infinium all tube amp for $250, so I’m not as stressed over this project getting done, but want to see it through.

also wondering if I posted looking for a schematic if a authorized repair person would have one available, probably mostly the same as the V55 with the infinium change. I will need to change the tubes on that one, think I have an idea how to take it apart, but would rather use a small screw driver instead of a full tear down.

[Helmholtz]

Don't forget to protect the mains cable from sharp edges and use some strain relief.

[redkurn]

Home Depot only had 60w and 150w, went with the 60w as suggested and for $25 I have a working dim bulb tester.
Checked it with my MM first, then created a short to see the bulb turn on, plugged in a old 10w bass amp i was given and no light, but amp works.
Tomorrow the parts come and the real test happens, but if it doesn't work at 60w I was told Ace Hardware nearby has incandescent bulbs and I ended up with a brand called Original by Feit Electric... a vintage looking bulb which is kind of cool when you think about it.

Followed these guides if anyone comes along looking for one.
https://audiokarma.org/forums/index....how-to.808399/
http://www.geek-tips.com/2015/11/22/dim-bulb-tester/

This is the bulb, might want to bookmark the page as they seem to manufacture these still.
https://www.feit.com/product/60-w-21...scent-vintage/

[g1]

So this one is a no go?
https://www.mouser.com/ProductDetail...SBPZK7Bg%3D%3D

That should be fine. You should be ok with your order. However, in the future, if you upgrade the NPN to the 200V version, you might as well also use the 200V version for the PNP, for better matching.
So the MJH11019 would be considered the complement to the MJH11020.

[redkurn]

I don't see why those wouldn't work.

Awesome, dropping the order in now and then we will see if there is more to fix. XD

Thank you

[The Dude]

I don't see why those wouldn't work.

[redkurn]

I missed that. Yes, that will work! It's just rated higher voltage, which matters not.

Awesome!
so the part I originally chose to sub the BC550C is BC550CBU and BC550CTA is in stock, should be ok right?
Hoping the BC560C sub is correct as well, BC557ATA.

Updated the list aswell.

[The Dude]

I missed that. Yes, that will work! It's just rated higher voltage, which matters not.