So, Hallelujah, it's fixed.  I looked at the tape path and any mechanical issues and I think rather than it being any one thing it was lots of little things that just needed to be cleaned and re-aligned.  The biggest thing, I think, was messing with the pinch wheel.  It had a ton of cruddy grease on the spindle so I cleaned all that up, as well as all the other wheels in the tape's path.  Thanks for the encouragement to give all that stuff another go, it really paid off!


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Thanks for the feedback!  I will Check it over for more mechanical issues tonight, I suppose I gave up on thinking it was mechanical because of how the echo dies so quickly.  I can understand the warble from a mech issue, but the echo decay seemed like it would be something else.  I'll keep y'all updated!


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Hi everyone, you guys successfully helped me fix a Yamaha amp of mine a couple years back and I'm sorta stumped with my new project.  At the very least, documenting my progress on here was helpful in keeping track of my thoughts during that last project.

So, a friend bought this Re-201 in as-is condition for a very low price and wanted me to look at it to check it out once he got it in.  Initially the motor was not turning smoothly and had a bit of a slump mid rotation.  The signal from the output was also moderately noisy and the repeats sounded like warbled garbage.  On some settings you may hear a pronounced initial repeat (still sound like warbled garbage), but then the repeats almost immediately fade out.  You can hear the warbliness in the noise from the unit without having anything plugged in.

The motor not turning smoothly was the most obvious problem with well documented solutions so I addressed that first.  I know the motors on these need serviced all the time so I replaced the top bearing in it and voila, it rotates normally now.  I used the tutorial that the echofix.com guy has shared on his site.  Very helpful walkthrough.

So I plug it back up after motor rotating normally and the warbly garbage is still there.  I can hear my guitar signal fine, the spring reverb works and sounds great, it's just the tape repeats section that is acting wacky.  I also replaced the tape and it did not change the problem.    I also cleaned all the tape heads and made sure they were properly aligned in the tape's path using the procedure recommended by the echofix.com guy.


The service manual linked below has all the maintenance procedures, schematics, pcb charts, etc outlined in it, but most of the maintenance procedures require the use of a scope which I don't have.  The only trimmers I attempted to adjust was the intensity and coil trap because they either didn't require a scope or only needed a DMM.  Both tested fine and did not affect the problem.

http://manuals.fdiskc.com/flat/Roland%20RE-101%20&%20RE-201%20Service%20Manual.pdf

One kinda weird thing is that this is a European model Requiring 220v.  It's hooked up to a converter so it should be getting the voltage it needs.  The seller had also sent a video to my buddy before he bought it and it showed that it essentially had the same issue... so the warbled garbage was there before it got in our hands. 

I'm just not sure what to look for next.  I inspected connections, caps, etc and nothing looks out of place.  The seller of the unit told my buddy that he had it sent off to be serviced by a professional somewhere who specializes in fixing these.  I can tell that most all the electrolytics were replaced, but it's not obvious what else may have been done to it.  Any ideas of what to do next?  Thanks!




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Thanks for the advice everyone, I'll get the new parts and proceed from there.  And yes, I have a light bulb limiter.  I'll give an update once i get the new parts in, thanks!

Quote from: galaxiex on October 22, 2016, 04:11:45 PM
Here's your pics. 

Thank you! :dbtu:

Thanks for the comments guys.  Initially, I was just using my Ohm setting on my DMM to make sure the transistors weren't open.  And now, yes, I have done the diode test.  As far as the driver transistors go-  one is giving me a measurement and the other one is not (it's giving the "1" reading), no matter how I connect the probes to the leads.  That's leading me to believe that the driver in question doesn't work-  unless there's a secret I don't know about.  So-  do I need to replace the pair of to-66 drivers with the MJE15030/15031 combo, or can I just sub in one of those components for the transistor that isn't working?   

As far as replacing the power transistors go-  it looks like I will go ahead and replace them all-  but for testing purposes, just to make sure that the whole thing at least sort of works, can I leave these transistors in?

Here's a couple pictures of the transistors and the PSU.  I'm not really addressing the PS board right now, but it may come up later... probably.   To explain all the red wires, I attached insulated bullet connectors so I can remove the board more easily, instead of having to desolder the whole thing if something else goes wrong.  I also need to replace two of the power transistor sockets at some point (but that's only evident from the other side of the heatsink).  The main problem with the  power board was that one of the traces actually burned through the board.  It was only a single length between two components, so it was easy to solder in a solid jumper.  But I'm wondering what made that happen in the first place...  If y'all want a picture of that too then let me know.

I hosted the pictures on imgur and their embed code isn't working for me... hopefully this link will work for you.

http://imgur.com/gallery/xXWRH

Hey there, so I'm fixing up an ampeg v6-b, 240 watt transistor amp.  It's had a bunch of issues, but right now I'm fixed on messing with the power section.  Here's a service manual and schematic:

http://bmamps.com/Schematics/ampeg/Ampeg_V-6B_Service_Manual.pdf
http://elektrotanya.com/ampeg_v-6b.pdf/download.html

So, the proper output transistors are 2n4348, and there are eight of them.  I received this amp with 4 of those transistors substituted with three SK3297 and one 2N3773.  Now, I don't know a whole lot about the specs on these, and from what I can glean from my own research is that both of these might be a tad under spec'd for this amp.  But, maybe I'm reading the datasheets incorrectly and they're actually fine.  I've gone to alltransistors.com and looked for substitutions and from what I can tell I think other RCA output transistors in the same series, but there's another odd transistor, SK3260 that looks like it would be almost a perfect sub.  Here's a link:
http://alltransistors.com/crsearch.php?mat=Si&struct=NPN&pc=120&ucb=140&uce=120&ueb=7&ic=30&tj=200&ft=0.8&cc=&hfe=15&caps=TO3

Then, there are a problem with the driver transistors.  They're weird and there's little to no info on the internet anywhere about them, especially the one that's broken.  There's zero continuity over the two legs of the one labeled STA8236.  It's in a TO-66 package.  I saw on a another post on another forum someone recommended using an MJE15030, which is in a different package.  I could do this, but I'd love to keep the correct package. 

Any recommendations?  Thanks!!!

Quote from: DrGonz78 on September 20, 2015, 07:28:28 AM
Please check your measurements and describe exactly where you are placing your DMM probes.

On the DC board I've been taking all of my measurements on the legs of the components themselves- since the board is mounted that way to the chassis, with the output board connected via those long pins on the underside of the chassis.  I can try to maneuver it out in order to take my measurements on the solder points, it will just be a bit cumbersome making sure things don't touch things they shouldn't    But oh well, I decided to take on this project, right?

(a few minutes later)

Alright, got the dc board off the chassis, the emitter pin's solder joint on TR203 had broken, so I reflowed that joint.  Looks good.

(Connects everything back together)

WE GOT VOLTAGE PEOPLE.  Before reflowing that joint I measured the pin 1 and 8 on the 4558's and I was getting ~7-9vdc on pins 1 and 8.  Now here are my voltages for them:

Ehh, maybe I'll just plug it in just to see if it works now that I know voltage is getting to all the IC's....

(plugs in signal through input)

IT'S CHRISTMAS!!!

(proceeds to play guitar through input, checks both inputs, fiddles around with all controls, checks direct out, reverb, push/pull pots, etc.)

It works.  It actually works.  Unspeakable joy.

Well gentlemen, it looks like it works!  Now I just need to make these MA board adjustments to make sure all that's where it should be before I box it all back up.
-The idling current is measuring right.
-I don't notice a difference in sound coming from the speaker when I adjust the output waveform when following the directions in the manual.  Is this something I'm just going to need an scope to measure?
-I can't get the center voltage down to ~45v as directed in the manual.  When the trimmer is fully counter-clockwise it only gets down to ~53v.  I'm afraid to turn it fully clockwise because I'm afraid I might blow something, but as it is fully counter-clockwise the amp still sounds great!

I really still am in disbelief that it actually works.  Thank you guys so much for all your help, I wouldn't have figured it out without you.  If you're ever in the Louisville, KY area hit me up so I can buy you a beer!!!

Alright guys, finally got around to doing some testing this evening.  Here's what I've found:

There's no easy way to say this: I am a royal moron. I was doing my readings of those supplies using the 20vdc setting on my DMM and when I clicked it over to 200vdc I got these ratings:
-20 supply = -21.5
-15 supply = -15.7
+20 supply= +21.5
+15 supply= -8.3

So I started looking at that voltage on the +15 supply and did some measuring on the two NPN power transistors feeding that supply (if I'm reading this schematic right), which are TR201 and TR203.  Here are my measurements on those:
TR201 - E: 17.3 vdc
           C: 22.1 vdc
           B: 17.3 vdc
TR203 - E: 16.2 vdc
           C: 16.05 vdc
           B: 16.5 vdc

I took voltages of the other two corresponding power transistors (TR202 and TR204) for the -15v supply and this is what I found:
TR202 - E: -17.2 vdc
           C: -21.9 vdc
           B: -16.6 vdc
TR204 - E: -15.6 vdc
           C: -22 vdc
           B: -16.3 vdc

If you look on the schematic how the transistors correspond to each other then you'll notice that the Collector voltage on TR203 isn't where it should be.  That deduction has no basis in any electronics know-how, I just noticed the pattern.  So should I be looking at that transistor (TR203) perhaps?

I also did a little messing about with a signal, trying to see if the power amp was functioning properly.  The 3rd pin on the board that connects the output circuit board and the DC board is the beginning of the output section.  Applying a signal there amplifies the signal very nicely and it doesn't fade out like it did before.  This leads me to believe the power amp is working just fine.   
I also tried applying the signal to the output of the 4th opamp, which is where it is supposed to then go to the power amp.  The signal came through, although much quieter than when I applied it to the 3rd pin mentioned in the previous paragraph.  The fading thing that I mentioned in a prior post did not happen.  So, I applied the same signal on the output of the second opamp- I got the signal again.  It was a little cloudier, and maybe a tad lower, but pretty much the same as the other opamp signal.  Then I applied it to the output of the first opamp, the pesky one I thought was the problem all along, and there was no sound.  I turned the signal volume up to its maximum on my little usb mixer and I could very faintly hear the signal.... very faintly, and very grainy too.

I'm not really sure where this puts things at the moment.  In summary, the power amp seems to be working as it should, the +15 supply is running at half-ish power, and I still don't know why the signal can't be heard off of that first opamp, but it can be heard everywhere else. 

I skimmed some of Teemu's book, but I haven't been able to really dig into it.  I will definitely be looking into it a little more to see if there's an explanation for all this.  Thanks! 

Thanks a lot phatt!!! 

BTW-  Got some fuses yesterday, popped it in with my limiter and everything worked.  Powered the amp on without the limiter and everything still worked.  I didn't have time to check through voltages, but I'll try to get some of that done tonight.  Thanks!

Sorry guys for not being clearer about my progress last night-  I acknowledge that you guys are being very gracious with your time and patience and I'm trying not to bog you down with details, and only mention things that seems to me as problems.  That being said, I appreciate it a lot and I'll address some of the things you have mentioned...

Quote from: Enzo on September 16, 2015, 12:38:09 AM
Those dual diodes are shown in the schematic as part of the main supply to the power amp.  Not part of the 15v circuits. 

Great to know!  And yes, the 15v supplies are my priority, but I was not understanding why I wasn't getting a reading on the s5151r which led me to believe that it may be a faulty part.  According to Phatt's annotated schematic and what you're saying- because the frame/case of the s5151r and s5151 are carrying different voltage supplies they will not look the same.  That makes a whole lot of sense! 

Quote from: DrGonz78 on September 16, 2015, 01:14:30 AM
Are you having any troubles with reading the schematics?

I'll admit that I do have trouble with schematics, especially ones this complicated.  I'm used to working on pedals which, to me, feel a lot simpler.  I can usually trace an audio signal pretty well, but power supply circuitry is definitely something I lack knowledge in.  So yeah, that's definitely been a barrier and I try to understand things about these individual parts and loops before I post on here so as to not waste your time- but its difficult to clear answers on such specific questions through the internet.

Quote from: phatt on September 16, 2015, 08:23:42 AM
Yes replace the fuse, buy a few. if it blows again straight away you will likely need a lamp limiter before you go any further.

NUMBER 1;
Replace the fuse holder or solder it together then check it,, as mentioned before too much heat can melt the internal connection leaving you with a dead fuse.  better to replace the clip.

Learn to work in *Nodes* see my edit of your Schematic for clues to the idea. Colour coded in this case but you can use numbers. The Red node joins at least 5 components together so at any point on that node you should read the same voltage. So the voltage at the Positive end of D201 will be the same voltage at the Collector of TR201,, same node.
With F3 removed you should still be able to work on the low voltage section and fix that fuse holder.
Phil.

I have built a lamp limiter and will be sure to use it after replacing the fuse.  I also did solder the fuse with the broken clip.  It's making good contact.  Your explanation of working in nodes is very helpful, as is the diagram you provided.  Rather than doing the work for me, is there a resource you can provide (or point me in the right direction of one) that would help me map out the whole DC board like that?  When I'm looking at the schematic I see the parts and connections and have a less than basic understanding of what they do together.  So seeing those networks and their function is very helpful. 

Thanks a lot, once I get that fuse I will post those specific voltages later. 

Alright, so the voltages were showing up as they should in some of those places when I used the appropriate DMM settings.  That was humbling.  :duh

Still wasn't getting any readings on the odd-looking silver diode apparatus (S5151R), so I tried measuring the parts on the under side of the shield. I touched my DMM probe to one of the poles on it, saw a spark, and then the amp shut off completely.  The primary fuse blew, the others on the DC board are fine.  I don't have a 250v 3a fuse at the moment so that's all for tonight- any idea why I couldn't read voltages anywhere on that diode and then when I touch the underside it sparks?  It did read over 100v when the spark hit, but then everything went out. 

Here's a pic of the diode thing for reference:

Quote from: g1 on September 15, 2015, 12:03:59 PM
  It may pass voltage when you are pushing on it with your meter probe, but it may not pass proper current when you aren't touching it.
Try wrapping a small wire around it to hold it tight to the tab, or even solder it if you are careful and quick.  If you take too long with the solder iron you'll melt the solder in the fuse.

I have some bus wire that I can use to wrap it up.  It's funny- watch this thing that I didn't think was a big deal be the problem.   :duh

That tang is in fact totally broken off- it came to me that way- but it's still passing electricity through the fuse.  Any suggestions on how to make it stronger without having to replace the whole holder?  The other side is still able to apply enough pressure to make a good contact, it's never come loose or anything.  It had been kind of a 3rd tier problem for me at this point.   

I'll check some more of those voltages as you all have directed and report back tonight.  Thanks again!   

Quote from: Enzo on September 15, 2015, 12:25:31 AM
If you are missing +20, then there will not be +15.

Look at these voltages right on the DC board.  If they are not there, they won't get to the preamp either.

Yeah, I'm pretty sure the problem is on the DC board given everything I'm reading.  Thanks for that confirmation, it helps to have someone confirm those suspicions.  If you're talking about looking at the voltages on the joint right before jumping to the preamp board- I did that and they are the same as I mentioned before.  So yes, the problem most definitely seems to be on the DC board.

Quote from: phatt on September 15, 2015, 01:19:02 AM
Maybe you trying to read DC with meter set to AC? 8|

Set to ACV before the Rectifier and then switch to DCV after Rectifier.
In both cases rectifiers are full wave bridge so the DC voltage will close to 1.4 times the AC voltage that feeds the diode bridges.
Phil.

Oh gosh, I can't believe I made that mistake.  Duh.  I'll check those voltages on ACV and report back. 

I'm still wondering though about where the voltage seems to be dying on that blue cap- any input on that?  I was measuring those voltages on DCV, and they are after the smaller rectifier.  Thanks again for your help, it is most definitely appreciated!