HRD on the bench

[rzenc]

Hi forum, I need help 
A friend of mine brought me his Fender HRD 112. He was playing it at a gig and suddenly the amp stopped working and started to produce an annoying buzz and crackling noises. He uses the amp regularly, 3 to 4 times weekly.
I fired the amp and checked the following symptons:

1) The amp buzzes - kind of high pitch stuff, pretty annoying;
2) Took one tube out at a time, first preamp tube - buzz stayed the same. Second preamp tube - buzz stayed the same. P.I. tube buzz stayed the same. By this time, It was only power tubes in and buzz kept the same...;
3) Took both power tubes out - there were no tubes on the amp and I could clearly hear buzz coming from the power supply board
4) Changed power tubes to known good ones and buzz kept as annoying as before. However there was less junk like crackles and other noises;
5) Installed all known good tubes and tried to play it, buzz still going strong, but them I noticed something different. There was a tremolo like effect, changing the amplitude of the notes being played. When a note was sustained it whoobled and there is noise behind every note. I have never seem this happening before;
6) In addition to the tremolo like disturbance, even with the reverb control down there seems to be something boingging  and interacting with the tremolo like effect;
7) Tried a different speaker to rule it out and the same happens with every speaker enclosure used, althought less pertinent;
8) Someone was previously inside the amp and did an awful job converting the PCB power tube sockets to chassis mount;
9) I will take voltages measurements and post them.
10) Sticker inside the amp says it is from 2002, so maybe a cap job is in order????

I have never seem such strange problem as the tremolo like effect and I have no clue where to start on this one.
The buzz coming from the power supply board is pretty bad too. 
I have a schematic of the Fender HRD dated from 1996 but there seems to be some differences between the amp I have in front of me. Are you aware of production changes?
The picture below shows the 'beautiful' work done converting the PCB mounted sockets to chassis mount...

All help is greatly appreciated!!!  Many thanks in advance!!!

With Respect
Best Regards

Rzenc

[LooseChange]

Check those two 470 ohm - 5 watt resistors in the middle off the main board. Can't miss them.
Very strange things happen when these go bad or have bad solder connections.
Just replace them and see if all is good.

[jjasilli]

I suggest you methodically check all voltages in the amp:  note that the schematic shows a number of TP's or testing points for specific voltages.

The amp was modded so it makes sense check all the modded connections.  BUT, no doubt both PCB boards were pulled to mount the tube sockets to the chassis.  It is easy to flex these boards in that process; and every connection in that anmp is techinically a cold solder joint. So there could be a problem literally anywhere; and possibly multiple problems.

[rzenc]

Check those two 470 ohm - 5 watt resistors in the middle off the main board. Can't miss them.
Very strange things happen when these go bad or have bad solder connections.
Just replace them and see if all is good.

Ok, I will take a trip downtown and ee what I can grab in the local electronic store.

I suggest you methodically check all voltages in the amp:  note that the schematic shows a number of TP's or testing points for specific voltages.

The amp was modded so it makes sense check all the modded connections.  BUT, no doubt both PCB boards were pulled to mount the tube sockets to the chassis.  It is easy to flex these boards in that process; and every connection in that anmp is techinically a cold solder joint. So there could be a problem literally anywhere; and possibly multiple problems.

I'm willing to take both boards out and reflow all solder joints.

I will report back.
Thanks
Best regards

Rzenc

[rzenc]

What do you recommend as a retube???
All tubes will be replaced.

Thanks in advance
Best Regards

Rzenc

[jjasilli]

I'm willing to take both boards out and reflow all solder joints.  You're a trooper! 

Note that the flat computer cables don't like to be flexed; the individual wires can be broken internally.  So check their pins for voltage or continuity.

[jojokeo]

and every connection in that anmp is techinically a cold solder joint. So there could be a problem literally anywhere; and possibly multiple problems.

If that isn't the truth! Most of Fender's stuff is that way and I re-solder as much as I can when inside one, many other amps too for that matter. I encounter a lot of this also in non amplifier related electronics as well. In outside environmental conditions inside of enclosures, like our amps, things can get very hot as we well know and things cool at fairly cold night time temps. This ongoing condition over time expands and contracts solder joints and other components creating many bad contacts to where you can see them plainly w/ "circle cracks" around many joints. Sometimes a little manual flexing helps to see them too.

[rzenc]

I'm willing to take both boards out and reflow all solder joints.  You're a trooper! 

Note that the flat computer cables don't like to be flexed; the individual wires can be broken internally.  So check their pins for voltage or continuity.

I will not forget your advice

Do you think it would be prudent to change these pesk ribbons with stranded wire?

and every connection in that anmp is techinically a cold solder joint. So there could be a problem literally anywhere; and possibly multiple problems.

If that isn't the truth! Most of Fender's stuff is that way and I re-solder as much as I can when inside one, many other amps too for that matter. I encounter a lot of this also in non amplifier related electronics as well. In outside environmental conditions inside of enclosures, like our amps, things can get very hot as we well know and things cool at fairly cold night time temps. This ongoing condition over time expands and contracts solder joints and other components creating many bad contacts to where you can see them plainly w/ "circle cracks" around many joints. Sometimes a little manual flexing helps to see them too.

Take these boards in and out several times s@#K$.... I prefer, once I take them out, to reflow all joints...does not take more then 5 minutes to do so...

Also, I was considering upgrading to metalfilm resistors everyone that I can. My friend uses it a lot - he makes a living out of it - and it would be bad for "business" if the amp collapses again.
Sticker inside the amp says it was made in 2002. He bought it used and he agreed to change PS caps and the other e-caps too. I explained to him that these parts have a working life and he would like them to be changed.... in order to avoid near future troubles...
I will need to wait P.S. caps and tubes and some other itens.
I will keep you posted about how it turns out...
BTW, have you ever seem the chips going south??

Thanks
Best Regards

Rzenc

[rafe]

I had one of those and it was a great sounding amp. There is (was) a site that dealt in those amps specificaly Justin XXXX don't remember his last name. I replaced three bad resistors ...you will see a dark discoloration on the board where the joints are soldered ..they get so hot, they melt the solder ...When I replaced mine I kept them up off the board it seems to help.....remove the boards ever so carefully as mentioned before= the computer ribbons suck......also they are usually biased cold and they like a hotter situation and it really opens up the sound ...good luck

[jojokeo]

I will keep you posted about how it turns out...
BTW, have you ever seem the chips going south??

Generally no, chips take a lot of abuse inside and out of circuits really. They have reverse voltage and overheat protection built into them normally. I have encountered bad ones on what seems like rare occasions as compared w/ other components and especially solder joints. When I open something up that's for repair and I've given it a visual inspection, I power it on and start to feel for things heating up. This is a dead giveaway for bad chips before any testing is required.
(FYI, On solid state amps, it's pretty common to find the power transistors w/ bad contacts and/or compromised heat sinking too.)

[jjasilli]

Do you think it would be prudent to change these pesk ribbons with stranded wire?  Personally, I'd say if it ain't broke, don't fix it. 

However, I do not like the stock tone of this amp.  I find it to be both muddy & sterile.  I did a number of mods from the now defunct Justin site -- the Unnofficial HRD Homepage:  particualry orange drops (or quality caps of your choice) in the tone stack & signal path.  I now love the tone of this amp, though due to these PCB's I think it's risky to gig with.

[jojokeo]

This has some ideas to try regarding V1 cath bypass cap and tone stack stuff

http://www.blueguitar.org/new/schem/fender/modnotes/hrd_mod.htm

[Fresh_Start]

Have you put a DMM on the bias voltage and watched it over time?  That tremolo effect could be a bias issue, either with the power tubes or one of the three triodes with solid state stuff hanging off the cathodes.

Is this the correct schematic?
http://support.fender.com/schematics/guitar_amplifiers/Hot_Rod_DeVille_Schematic.pdf

If so, that .1uf bass cap (C5) may be odd combined with a .022 mid cap (C6).  The 130K slope resistor is different.  Play around with Duncan's Tone Stack Calculator.

Normally, I wouldn't replace 8-year old electrolytic caps unless they were known bad or I wanted to change the value (like the 47uf cathode bypass cap on the first stage... 4.7uf might be better).  Given the noise with all tubes removed, I probably would replace the power rail filter caps.

"Winged C" Svetlana 6L6 power tubes sounded really good in a Super Reverb build.

If your buddy is willing to experiment, I'd suggest trying several types of new 12AX7s:  Tung Sol and Chinese 9th generation (best one I've found was a re-labelled "Penta") to start with?  A couple of each and try 'em in each spot to see where they sound good.  Electro Harmonix 12AX7s are kind of sterile to my ears but reliable - not bad for a phase inverter.  IMHO don't waste money on "matched triodes" but YMMV.  JJ 12AX7s are too dark to my ears for the amps I've experimented with, but some amps need a bit of furry warmth.  I have found that tubes which sound like crap in one amp may be just the ticket for a different amp (or player for that matter).

Not even 2CW

Chip

[rzenc]

I would like to thank everybody for the tips

I will poke inside the amp today and record voltages.

The "unnofficial HDR" which was Justin Holton experiments with HDR is not online anymore. However, I found a guy who made PDF's with all the information and I have them here. Unfortunatly, the whole .zip file is too big to post... if you guys want it, p.m. me and I will sent ya!!

BTW, are you aware of a Turret board to sub in the HDR??? Do you think it would be worth the effort o make one??

Thanks in Advance
Best Regards

Rzenc

[phsyconoodler]

If you decide to go hand-wired,try using another circuit.There is no board that can incorporate all the crap the HRD has on it and why would you want all that crap anyway?
  I suggest you find the issue with the amp,which is likely a cold solder joint or a bad resistor,and move on.

[rzenc]

I suggest you find the issue with the amp,which is likely a cold solder joint or a bad resistor,and move on.

Yeah!!! 

If you decide to go hand-wired,try using another circuit.There is no board that can incorporate all the crap the HRD has on it and why would you want all that crap anyway?

Sure I don't want... I asked because that what my friend asked me... if I knew a handmade board for the amp...

Thanks
Best Regards

Rzenc

[bmack]

As far as tubes go, I installed the TAD short bottle 6L6WGC in several of these amps I've worked on.   I thought it was a big improvement- bigger and tighter bottom end. 

[rzenc]

I finally had time to go inside the amp today. Visual inspection revealed 2 PS caps - screen supply and P.I. supply pouring out goo. I took a pic but it's blurry - blackberry cam s@#$% - Also noticed burnt marks around the pesky 470/5W (R78 & R79) and diode CR13.
Voltage measurements showed very low voltages around reservoir cap (318VDC instead of 431VDC shown on schem.) and these voltages showed up along the supply rails....
Bias is rock solid @ -41VDC, however steady current is 11.3mV - I suppose it's this low since H.T. is also very low.
So, I will take my time to bring it to life again.
Thanks for all help.
I will report next steps!!

Best Regards

Rzenc

[Fresh_Start]

You might want to visually check each of those quick connectors too.  Several around the AC power switch and OT in my Blues Jr. had scorched insulation.  Don't know the reason but thought it best to do solid, solder connections in those spots.

Chip

[jjasilli]

Those caps do not seem old enough to die of old age.  Is maybe some other fault causing them to overheat, boil & ooze?

[rzenc]

Thanks for the tip Chip!

I took the main board out and there are some serious burn marks on the soldering pads around the 470/5W. It's the third time I found this marks on HDRx. I'm sure Fender knows this stuff...what concerns me is the fact that these amps sells here - Brazil - for around US$2800 . El cheapo stuff going so high isn't fair with customers....Saidly, it seems to be the current trend with big names...And even knowing this, some folks still clains it's a "fender" and it immediately shuts all arguments off.... :occasion18:

Those caps do not seem old enough to die of old age.  Is maybe some other fault causing them to overheat, boil & ooze?

I will replace them and see what happens...
My friend said he went to the gig, sound was checked and when he was playing it just went buzzzzz and noisesssssss.


Time to heat the soldering iron!!

Best Regards

Rzenc

[VMS]

Hi,

you can still find the unofficial HRD page here:

http://www.justinholton.com/hotrod/

and there is a FAQ about that site here:

http://www.justinholton.com/

[phsyconoodler]

I'm a Fender warranty tech and we replace filter caps once in a while on HRD's.Not that often,but it does happen.It's like any mass-produced item these days.It's considered acceptable if there is some failure rate on components,as long as it doesn't exceed a cetain percentage.

[jjasilli]

Thanks VMS! I thought Justin's site was gone forever.  He had it hosted on his school's site when he was in college, and then it vanished.  I guess he graduated.  That HRD site is what started it all for me.

[PRR]

> these amps sells here - Brazil

Just FYI:

Me, I think the Constellation is the best airplane ever, the DC3 the best little plane. Last I flew it was a 707 with about a billion hours on it.

My gal had to fly last week and took an Embraer 170 (made in Brazil). She says it is a wonderful ride. So smooth. Fast too: I had to drive to the airport before she took off because it went 500 miles while I went 30 miles.

[6G6]

I heard on another site that the 5W 470s were prone to get hot enough to unsolder themselves.
If you replce them with 10Ws, they run cooler.

[rafe]

keep the leads long and up off the board ,that helps too.....

[rzenc]

I heard on another site that the 5W 470s were prone to get hot enough to unsolder themselves.
If you replce them with 10Ws, they run cooler.

Would it be reasonable to replace them by 2 x 250 Ohms @ 5W in series?? Or it would be wiser to solder 2 x 1K @5W in parallel??The 10W resistors I have are too huge to be inserted.

Thanks in Advance.
Best Regards

Rzenc

[rzenc]

Quick question:

The ceramic capacitors located on the H.T. bridge recto is marked: Z5U 822M 1KV. Is it 8200pF of capacitance?? I tried to discover it thru cap codes but I'm doubt.. Can someone point it to me?

Thanks in advance,
Best Regards

Renc

[phsyconoodler]

Don't change the value of those resistors and you don't need 10 Watt ones! Just lift them off the board a bit and use some silicone between them and the board so they don't transfer the heat to the PC board.
 

[rzenc]

Don't change the value of those resistors and you don't need 10 Watt ones! Just lift them off the board a bit and use some silicone between them and the board so they don't transfer the heat to the PC board.

Thanks for the Tip phsyco!! I have already done that. Lifted them away from the board, around 15mm. Also lifted the zeners since they were showing heat marks too. I did not change values.

About the ceramic cap... is it 8200pF??

Thanks Best Regards

Rzenc

[phsyconoodler]

Yes it's 8200pf and 1kv(1000v)

[rzenc]

Yes it's 8200pf and 1kv(1000v)

Many Thanks man

Best Regards

Rzenc

[rzenc]

All went well replacing power supply caps, resistors and diodes.. Changed the sloppy mod someone did while replacing PCB octal sockets to chassis mount sockets. Worked like a charm. New tubes in, got it biased. Tryed clean channel, works ok. Tryed O.D. channel, works ok. Tryed mode drive into O.D., works ok.

Before calling my friend to pick it up, I decided to take the amp to a rehearsal, you know, just in case... Thanks Lord I did so. Out of the blue the O.D. channel went very down on volume and then mute. no sound at all. Nada. When clean channel is engaged it works perfect, however, when O.D. in engaged the amp goes mute.
LED lights on and change it's color depending on settings. So, I  presume it's power supply is running alright. Have you ever faced this situation? As far as I understand the circuit, it seems that the relays are not doing their job...
Any tips?

Thanks in Advance.
Best Regards,
Rzenc

[jjasilli]

Yes.  I had the same issue.  For giggles and kicks try inserting a phono plug in and out of the input jacks -- see if the channels switch intermittently !

Anyway, in my case, the problem turned-out to be no solder in the 3 holes where the panel Channel Select SW is mounterd to the PCB board.  I tried everything & then noticed arcing at that location.  It's worth a look-see.  (These amps are a million cold solder joints waiting to go bad.)

[rzenc]

Yes.  I had the same issue.  For giggles and kicks try inserting a phono plug in and out of the input jacks -- see if the channels switch intermittently !

I did it, unfortunately, it's not an intermittent problem. However I noticed a delay when I turn on/off O.D. I use Omron's relays on my builds and they do no exibit such delayed action. I will try to reflow the solder joints around the relays and O.D. circuit and check voltages on test points 31 to 36.
Also, there is something new... Master Volume pot is now dead too makes no action. it's always at full blast  Man, this amp makes me wanna die...
I have penty of 5V omron's but none 24V... Does mouser have them?

Any other tips?

Thanks in Advance.
Best Regards,
Rzenc

[phsyconoodler]

It's almost never the relays that go bad in those amps.It's usually a bad solder joint or even a bad footswitch jack.And don't forget the second preamp tube.That's your overdrive.And then the pots where they contact the PC board.If you removed the PC board you may have bent the pots a bit to get it out,possibly breaking one of the connections.

[plexi50]

I have found as well little problems with the HRD boards. One is the heater pins soldered to the the board. I have seen 3 of them in the last 4 months where the solder had worked it's way away from the heater pins leaving a barley connected pin. Intermitant cut in and out of the power tubes heater voltage. Very little solder on most all of the tube sockets. Very thin. Another thing is the screen resistors burning up and the PI 82K/100K resistors being really far off values and or either open. I will have to make a list.

[phsyconoodler]

Quote:"leaving a "barley" connected pin."
 
 I don't usually fix amps when I've had too much "barley" in me.

[plexi50]

Quote:"leaving a "barley" connected pin."
 
 I don't usually fix amps when I've had too much "barley" in me.

Now thats got to be one of the worst typing errors i have ever done. I didnt even notice it. I think theres Barley on my keyboard  

[rzenc]

Thanks guys!

I have re-soldered lots of suspicious joints, but I guess I should have done them all...

By now it has new B+ caps, ceramic caps, diodes, bias caps, zeners and those pesky 5W 470 are new too. I installed G2 resistors directly on the socket, as well as G1 stoppers. O.T. leads are directly connected to pin on socket and heaters are tightly twisted on power tube sockets. I cleaned the area since it was a mess - check first post to see before my intervention.

Finally arrived home and hope to have some time to investigate if test points are close... :violent5:

And don't forget the second preamp tube.That's your overdrive.

V2 is a new tube - china labelled PENTA 12AX7 - which I know is/was working good until this moment. 

Gotta check it too....

I will try to report back soon..

Thanks.
Best Regards,

Rzenc
 

[dude]

Well, glad I saw this tread. A friend brought one of these over yesterday said he didn't know what was wrong but it wasn't working right (guess it was a friend of his).

I don't fool with PCB boards too much but said I'd give it a shot. I think my shot is done before I even opened it.

Good luck and I hope you find the problem.

al

[rzenc]

Well, it took me long hours of hard looking with magnifier under sunlight, looking for suspicious joints... resoldered almost all joints inside the amp. :whip2:
By now, O.D. came back to life  and everything seems to be alright... however something is making me scratch my head....may sound silly, but I really need to know...does the master volume controls clean volume channel too? I ask this because when operated in clean mode, master does not affect clean volume at all, when O.D. is engaged then master becomes active...

Also had 2 bad 12AX7 - china tubes labelled penta - going microphonic.

Thanks in advance.
Best Regards,

Rzenc

[LooseChange]

Master is for OD only.

[rzenc]

Master is for OD only.

THANKS MAN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I highlighted the clean path on the schem...indeed, master is for O.D. only...

Many many thanks for all help you guys gave me.... :icon_thumleft: :icon_thumright:

Amp is ready now... hope no f****** gremilins decide to mock inside again!!!!

Best Regards,
Rzenc

[chabby-ao]

I'm willing to take both boards out and reflow all solder joints.  You're a trooper! 

Note that the flat computer cables don't like to be flexed; the individual wires can be broken internally.  So check their pins for voltage or continuity.

Just make sure and use an irritatingly cold iron or you'll toast those weld pads on the HRD board........ They built them to throw away, but not to repair.

[rzenc]

The amp is up and running for almost a month, gigging regularly for about 3 - 4 hours/ 3 times per week.
Everything is alright....or at least seems to be

They built them to throw away, but not to repair.

Yeah, however, it's kinda hard to explain something like this to someone who bought the amp from a 'friend' and the damn thing was modded by an 'expert'...
Well, check the first post and the pic which has the 'expert upgrade' on the power tube sockets...

Removed all that s*** did it as it is really supposed to be...

Best Regards
Rzenc

[Platefire]

Boy what a trouble shooting ride! Glad it's going good now. The HRD was my entrance back into the tube world in 1999 after using transistor/Hybreds for a decade. In fact it was the first USA Aniversery model HRD fender made---I think 1996?. It had sat in the music shop a couple of years before I bought it. I loved the clean channel but didn't like the drive channels. I finally decided to move it before I started having problems about 3 years ago. This post makes me glad a did  

[rzenc]

Boy what a trouble shooting ride! Glad it's going good now. The HRD was my entrance back into the tube world in 1999 after using transistor/Hybreds for a decade. In fact it was the first USA Aniversery model HRD fender made---I think 1996?. It had sat in the music shop a couple of years before I bought it. I loved the clean channel but didn't like the drive channels. I finally decided to move it before I started having problems about 3 years ago. This post makes me glad a did 

It gave a hell lotta work to make it run again. I hope he gets rid of it soon. 

Best Regards,
Rzenc

[Platefire]

Yeah! Key word is GAVE   If you really charged the going rate for all the labor you put into it you could buy a couple of new HRD's----of course then you wouldn't want a couple of HRD's!!!