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Post subject: Blues Deluxe USA Made and Lotsa problems and noob questions
Posted: Fri Apr 04, 2014 12:16 pm
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Hello -

Arrived at this forum after a few weeks of google research, some parts ordered and work done on the amp. I've got a bunch of questions, some are general electronics questions and some specific to the amp. Hopefully, the replies here can help others along with my experience to date.

Amp Issues - Purchased a few years ago, no reverb, presence doesn't work and it cuts out in volume after awhile. After a couple of years of bedroom use, the tubes went out .. or I should say the amp got wicked hot really fast and then stopped making sounds. New output tubes seemed to fix it along with the R85/R86 resistor fix. Sold the amp shortly after to chase (I mean purchase) a more reliable amp.

Bought the amp back from another owner as I kind of missed the tone, felt I had unfinished business with it, and got it back for a great deal.

Current State of AMP - Seems to be working as it sits on my bench (making a noise that's nice). Reverb doesn't work. Seems to be getting really hot, from tubes and the R85/R86 resistors.


Corrective Actions to Date
Replaced 470Ohm Resistors with 330Ohms, back 470 Ohm after traces lifted and more research. Had to go PTP on all 4 legs as pads lifted. Mounted them in "flying formation" about an inch off the board. Also soldered some "stops" on the top end of the board to stabilize them.

Replaced presence pot - it was broken, now it works
Replaced Master Volume with 250k Audio Taper - Amp Works
Reflowed all pots - Noticed the volume was flaky after overdrive was used.
Reflowed all input jacks - shoddy solder all over.
Reflowed all tube sockets - seemed like a good idea after doing research online.
Reflowed other "problem" areas - joints that looked light, cold, dingy got new reflows



To do -

1) Test components/Verify Sound Working condition of amp.
2) Fix Reverb if able to.
3) Replace input jacks with Switchcraft Style plugs

Testing and Things I have tested
I have an ohmmeter, snuffer stick, solder gun, etc, various wires and clips.
I drain the Caps by leaving the Standby in "ON" position and shut the amp off. The unplug from wall, then use the snuffer stick. I attach one of stick to negative on the filter cap and then touch the other end to positive. Test with ohmmeter after

Questions:

What kind of silicon can I use on the board? The stuff I bought from amp supply place is just loctite and says it's rated for 65C. Seems like the amp gets hotter than that.

Ohmeter Basics - I put the Ohmeter on 1000 DCV when testing. Where can I attach the negative? To the chassis? I have been using the negative side of various caps I test, but see in videos its usually attached at one point.


Same question for snuffer stick. When I use it, I attach to negative side of cap and touch to positive for a bit. Is this correct or can attached to a ground point somewhere?

When I turn the amp on to begin testing, I leave standby "OFF". From here I receive the appropriate +16 -16 on the R85/R86 Resistors. C34 and C41 caps give me around 220V to 240V or so. C35 and C42 give me a zero or 1 reading. C45/C46 are around 120-130V. It seems these voltages are half what they should be from the schematic and nothing from C35/C42 seems just wrong.



When I turn standby "ON" I get R85/R86 values of like -200V/-220V respectively.
The other Cap values stay about the same value.

This seems wrong to me. Those resistors get super freaking hot and so do the tubes.

I'm looking for some guidance on the safety questions and where to start troubleshooting next (and how to do it).

I'm new to circuit troubleshooting but am being mindful of safety issues first.

If anyone has any online resources to explain basics, that would be cool too.

I've been up, down, and around the internet doing research and picked this forum since there seems to be a good community response to questions.

Been to BillM's site for hints and tips and the following web resources, which I'll post here for others to find.

I like the sound of the amp and am willing to put some more time in into it to I can get back to playing it.

TIA!

Corby Kissler


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Fri Apr 04, 2014 3:44 pm
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Hi corbykissler,

First of all, R85 and R86 are supposed to be very hot, hot enough to burn your finger should you touch them, that's normal. Same with the output tubes, they get very hot, that is normal, so long as the Plates are not getting red (not the orange from the heaters, which is normal).

A few things that you should check.

Whenever you change output tubes, you should check the bias, and although no adjustment pot on your amp, the bias can be changed if necessary by changing a resistor value in the bias supply circuit. It is very important to be sure that the bias is at a reasonable level, both for sound and tube life.

Check for the +/- 16 volts at pins 8 and 4 of each op amp. You might still have a poor solder joint or broken trace in the supply, either at the large 5 watt white resistors (R85 and R86), or at the Zener diodes right next to the resistors.

Check all test points in the amp indicated on the schematic, and note the readings. The test points indicated in the rectangles are DC voltages, check and compare to the schematic, some variance is normal. For now, ignore the indications in the ovals, those are AC with a signal injected at the amp input.

You can clip the negative meter lead to the chassis, and use the positive meter lead to probe each point for voltage readings.

I am glad that you realized the folly (stupidity really) of changing R85 and R86 to 330 ohms. Those that recommend that change have no idea what they are doing, and should be slapped about the head and face.

A few things to start with anyway.

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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Fri Apr 04, 2014 8:09 pm
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Thank you very much for the reply.

I'll test as suggested and report back. I think the earlier voltages I reported were done incorrectly. I switched my mutimeter to VAC and tested the caps. . . got back values much closer to what the schematic says.

Also, figured out that TP on the schematic means "Test Point" and tried to test at the points. Got confused with VDC and VAC figures and how it works to test those with my multimeter which is a cheapie from Harbor Freight. Working on that.

Put the amp back together and played it for about an hour on the clean setting. No drop outs, but also wasn't pushing it very hard either. It didn't get super hot either. So those are good signs, but I'll continue testing and report back tomorrow.

Thanks!

Corby


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Sat Apr 05, 2014 7:05 am
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Here's the links I promised in my first post. Test values later today - band practice in a couple hours. . .

Rebiasing Original Fender Blues Deluxe
http://forum.ampage.org/forum.php?cmd=vt&tid=22855
Original Fender Blues Deluxe Issues
http://www.tdpri.com/forum/amp-central- ... ssues.html
Blue Deluxe
http://www.duncanamps.com/technical/bluesdeluxe.html


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Sat Apr 05, 2014 7:06 am
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part ii

Green Eagle Amps - Conversion Procesws
http://www.tjadamowicz.com/amps/process.html
Fender Blues Deluxe 1994 - Cutting Out
http://music-electronics-forum.com/t18558/
Fender Hot Rod Deluxe: Sound comes and goes intermittently
http://music-electronics-forum.com/t13363/


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Sat Apr 05, 2014 7:06 am
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Part II

Blues Deluxe ReIssue Failure
http://music-electronics-forum.com/t28233/
Guitar Amp Parts, USA - Turret Boards and AMP Mod Kits
http://www.triodeelectronics.com/gap.html
Blues Deluxe Question - Fender Forum
http://www.thefenderforum.com/forum/sho ... hp?t=29605


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Sat Apr 05, 2014 7:07 am
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Part IV

Hot Rod Deluxe pot 250k log
http://www.banzaimusic.com/Hot-Rod-Delu ... k-log.html
Guitar Amp and Pro Audio Potentiometers
http://www.amprepairparts.com/pots.htm
hot rod mods.doc
http://www.maxxplay.us/img/hrdx/Replaci ... 0Jacks.pdf


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Sat Apr 05, 2014 7:07 am
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Part V

Mods to the Fender Blues Deluxe ReIssue
viewtopic.php?f=13&t=80142
Billm Audio - Fixing Blues Jr Reverb Probvlems
http://billmaudio.com/wp/?page_id=46
Load Plate Capacitors
http://www.thefenderforum.com/forum/sho ... hp?t=29605


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Sat Apr 05, 2014 3:15 pm
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RESULTS OF TESTING

Thanks Shimmilou for the tips - Went through all the VDC Test Points. Noted as below

Test Point/Called For/Actual


TP3 1.67VDC 1.90 VDC
TP5 1.77 VDC 1.90 VDC
TP8 1.71 VDC 1.74 VDC
TP30 >+.6VDC-Clean/<+.06VDC-Drive == 3.13/.05
TP31 -14VDC Clean/14VDC Drive == -15.9/14.68
TP32 +15VDC/-15VDC Drive == 15.43/-14.70

Since these are all within +/- 10% and I played the thing for 4 hours today with no problems (left on the whole time), I may be in the clear.

Tasks tonight are to Silicon the Drive Light in and RTV Copper the resistors. I'll replace the input jacks when they break or when I have more motivation or as my kid reminded me today, "If it ain't broke, don't fix it." I can get my reverb from a pedal for now.


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Sat Apr 05, 2014 3:58 pm
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Here's some pix of inside of the amp ..

Here are the wire stops i put on "top of the board" to secure the resistors.

Image

Back side of the board - you can clearly see it's been scorched like with a blowtorch. The PTP work wasn't mine, but I had to add more on the remaining three legs. One of them was kind of a long run.

[url=http://s1137.photobucket.com/user/Corby_Kissler/media/guitAr%20stuff/IMG_0245_zpse8fc7db3.jpg.html]Image



The offending resistors:
Image


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Tue Apr 08, 2014 5:37 am
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So here's an update on the amp.

I noticed that the number 1 input jack is not making contact when you wiggle the instrument cable a certain way, so that will need to be looked at soon.

The other thing I noticed was that the reverb seems to be getting picked up but no signal sent. When I was tilting the amp forward while it was on, I hit the tank and the spring noise came through the amp, pretty faint, but it was there. Started tapping on the tank and sure enough, kept hearing the boing of the spring. So this would seem to indicate a signal isn't being sent to the tank, or there's a problem with the send side. Will inspect and report back.

Also, does anyone have a "how to" on replacing the input jacks with old style switchcraft? I think the part number for the switches I have is 12A, which seem to be pretty standard jacks. Yes, I'm replacing the PCB jacks.


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Tue Apr 08, 2014 1:21 pm
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For the reverb, you have yet to check pins 4 and 8 on the op-amps for the +/- 16 VDC.

The input jacks are 12A or L12A (longer bushing), and you should use insulating flat and shoulder fiber washers when using traditional Switchcraft jacks, to isolate the jacks from the chassis. This picture might help as to where the wires connect.

Image

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Wed Apr 09, 2014 6:58 pm
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Thanks for the reply!

Here are the voltages of the op-amps

OP Amp - PIN4 - PIN8
U1 -17.4 -- 16.8
U2 -17.16 -- 16.72
U3 -17.08 -- 16.68
U4 -17.13 -- 16.75

I pulled the tank and noticed that on the send end, the two little wires for the transducer (I think) are out of their slotted holder. Maybe a new tank is in order? Most folks, BillM included, suggest replacing the tank.

Any thoughts are welcome.

corbykissler


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Post subject: Re: Blues Deluxe USA Made and Lotsa problems and noob questi
Posted: Wed Apr 09, 2014 9:28 pm
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Good job! Looks like the op-amps are getting proper power, meaning that your supply repair went well and is working properly. A new tank isn't very expensive, look for numbers on the tank, such as 4EB3C1B stamped on the tank, in order to get the same kind from your supplier. I have used the newer MOD tanks, made in Korea and they work well. New Accutronics tanks are also now made in Korea. Before use, be sure to remove any packing used to prevent the tank insides from moving during shipping.

http://www.tubesandmore.com/products/reverb_tanks

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---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


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