Is anyone building the DIY Pass F-5

Russellc · « **Reply #120 on:** 24 Mar 2011, 01:30 pm »

Quote from: parodielin on 22 Mar 2011, 08:14 pm

If I want to do Mono, do I need two power supplies and two transformers?

do you mean mono or dual mono? If dual mono or monoblocks is what you mean, then yes you will need two transformers and two power supplies. If you are wanting dual mono in a stereo (single) box, you would also need two transformers and two power supplies for it to be dual mono. My amp in the gallery is dual mono in a single box, you can see the double PS boards and two transformers.

Russellc

Russellc · « **Reply #121 on:** 24 Mar 2011, 01:33 pm »

Let me stare at mine when I get home, yours looks like the drawing of the FirstWatt schematic as far as I can see.

Russellc

sts9fan · « **Reply #122 on:** 24 Mar 2011, 01:35 pm »

It is exactly that except its a CRC in place of a CCRCC. I also do have the 0.033uF cap between the mains

Russellc · « **Reply #123 on:** 24 Mar 2011, 06:59 pm »

Mine is C-R-C also, as I used the Daniels power supply boards, and on his new ones he only uses four caps instead of eight, but twice as big, uF wise. I'm kind of stumped, your power supply looks fine.

Are you trying to fire up JUST the power supply, or board and all? When I first fired my power supply up, I measured it (incorrectly) from the V+ and V- and thought it was screwed upbecause I was reading double what I should have been getting! Then someone showed me it was good, I should have not measured both V+ and V- together, but V+ and ground, then V- and ground.

I believe you are getting 24 volts when you measure V+ and V-? Is that right?

Thanks, we'll figure it out,

Russellc

sts9fan · « **Reply #124 on:** 24 Mar 2011, 07:20 pm »

I have not attached it to the circuit yet. I will take more measurements tonight. I guess it confuses me because without the circuit attached its not really a return/pwr gnd. Each set of two caps are sort of the same and without attaching the pwr gnds of the two rails. As I am testing it I don't think they areall are gnds. I am confusing myself.

Russellc · « **Reply #125 on:** 24 Mar 2011, 09:05 pm »

I do that all the time!

I'l be on here this eve to see whats happening with your build. Its got to be something simple if the boards arent hooked up to it yet.....

Russellc

sts9fan · « **Reply #126 on:** 24 Mar 2011, 09:31 pm »

I know it's something simple! I am for sure getting 24v accross the rails

Russellc · « **Reply #127 on:** 25 Mar 2011, 01:18 am »

Well, looking at mine its a little different, but basically the same layout. The Daniels power supply boards I'm using use 4 caps.

Where you have your schematic labeled across the bottom: V+ V- V+ V- where my schematic is: V+ G G V-.

Now, assuming the juice coming from the diode bridges is coming in on your V+ V-V+ V- side, and I measure from your A to your D, I get in the vincinity of 47 volts or so, about 23.3 or so if I measure from V+ to ground, or from V- to ground. By ground that would be your inside set of V- V+, my G G.

Hope this makes sense!

Russellc

sts9fan · « **Reply #128 on:** 25 Mar 2011, 03:16 am »

So my EE friend was just over. He could not find anything wrong. He thinks it's the large caps and inrush current. He suggested two more thermistors on the rails.

strider · « **Reply #129 on:** 25 Mar 2011, 12:44 pm »

With the help of my father in law we got the cause of my problem figured out. A bad solder joint at the ground connection to the amp PCB coupled with mis-reading a 35 amp fuse as 3.5

allowed both the MOSFETs to stay on long enough to cause mayhem. The MOSFETs appear to be toast, they show extremely low resistance in circuit and I'm surmising once I pull them from the board they'll be confirmed as blown. Kind of bummed about the MOSFETs, I opted for the Fairchilds that Tech DIY was offering as an upgrade to the Vishay, looks like the Fairchilds are no longer available.

Because of the Fairchilds no longer being available, I'm assuming that in addition to replacing the blown side I should replace the other channel's as well so both channels have the exact same devices. I've not ordered from Mouser in a day or two, and I can get the Vishays from there cheapest, but I can also pay a bit more and have a pair matched to VGS +/- .01 VDC. Is the matching a good idea?

sts9fan · « **Reply #130 on:** 25 Mar 2011, 01:15 pm »

I think I am going to throw some CL60s or 70s on the rails and see if that helps. Plus I got some sloblo fuses.

Russellc · « **Reply #131 on:** 25 Mar 2011, 08:52 pm »

Quote from: strider on 25 Mar 2011, 12:44 pm

With the help of my father in law we got the cause of my problem figured out. A bad solder joint at the ground connection to the amp PCB coupled with mis-reading a 35 amp fuse as 3.5 allowed both the MOSFETs to stay on long enough to cause mayhem. The MOSFETs appear to be toast, they show extremely low resistance in circuit and I'm surmising once I pull them from the board they'll be confirmed as blown. Kind of bummed about the MOSFETs, I opted for the Fairchilds that Tech DIY was offering as an upgrade to the Vishay, looks like the Fairchilds are no longer available.

Because of the Fairchilds no longer being available, I'm assuming that in addition to replacing the blown side I should replace the other channel's as well so both channels have the exact same devices. I've not ordered from Mouser in a day or two, and I can get the Vishays from there cheapest, but I can also pay a bit more and have a pair matched to VGS +/- .01 VDC. Is the matching a good idea?

I hope this isnt violative of the rules, it is not profit motivated. I have a set of the Fairchild output devices I got from Tech-diy. Myself, I would advise the Toshiba mosfets, but if you want these give a PM as I will not be using them. Again, I would get Toshibas if they are to be replaced. PM if you just got to have Fairchilds!

Russellc

strider · « **Reply #132 on:** 26 Mar 2011, 02:29 am »

Quote from: Russellc on 25 Mar 2011, 08:52 pm

I hope this isnt violative of the rules, it is not profit motivated. I have a set of the Fairchild output devices I got from Tech-diy. Myself, I would advise the Toshiba mosfets, but if you want these give a PM as I will not be using them. Again, I would get Toshibas if they are to be replaced. PM if you just got to have Fairchilds!

Russellc

Thank you very much for the offer. Are there Toshiba MOSFETs floating around for the F5? A quick Googling didn't turn up the IRFP240pbf or IRFP9240pbF.

Russellc · « **Reply #133 on:** 26 Mar 2011, 11:14 am »

Over on DIYAUDIO. Look for members "Blues", "Spencer", or ZhouFang. I think all of them have something in the Swap thread, or in their signature at bottom of their posts.
Get a few spare J-fets if any are still available, blues is out of J-fets for F-5, last I checked Spencer and Zhoufang still did.

If nothing else, use the IRF devices. I used them in my build and it sounds fantastic.

Russellc

strider · « **Reply #134 on:** 26 Mar 2011, 02:18 pm »

Ok, think I found it now. Those FS threads of ZhouFang's are a bit tough to wade through. Saw your post, did he ever come through with the 2SJ74BL?

Russellc · « **Reply #135 on:** 26 Mar 2011, 05:17 pm »

They are shipped, but have not received.

Well known source.

Russellc

Russellc · « **Reply #136 on:** 26 Mar 2011, 05:22 pm »

I have also gotten the mosfet outputs by Toshiba recently from Blues

strider · « **Reply #137 on:** 26 Mar 2011, 06:05 pm »

Quote from: Russellc on 26 Mar 2011, 05:22 pm

I have also gotten the mosfet outputs by Toshiba recently from Blues

I ordered Toshiba MOSFETs and Jfets from ZangFhou, along with some of the insulators. Basically copied your order from a couple posts above.

We're headed to my in-laws in a few, my father inlaw is going to check it over and we'll see if we can get the one channel operational so I have a reference for the second when I get my parts. I may also order the Vishays from Mouser while I'm waiting on the good stuff from Singapore.

Russellc · « **Reply #138 on:** 27 Mar 2011, 02:43 pm »

Quote from: strider on 26 Mar 2011, 02:29 am

Thank you very much for the offer. Are there Toshiba MOSFETs floating around for the F5? A quick Googling didn't turn up the IRFP240pbf or IRFP9240pbF.

Just for the record, the IRF devices are available and being made. there seems to be a fairly good supply of the Toshibas around, but they too will dry up. Its the J-fets that are getting increasingly difficult to source. The SK170-BL part is still around, and usually the SK370 will usually work, but not always. The 170 will always work where the 370 is called for, but not always the other way around. The 170 part takes a little more abuse than the 370. It will work for the F-5 fortunately. Also, I think its Linear that has come out with a new version of the SK170-BL, but not the complementary part, which is really getting in short supply.

Hopefully those who have made the replacement for the SK170 part will get on the band wagon with the replacement for the 2SJ74!

That part, either 2SJ108 or the 2SJ74-BL that is the dickens to source, and tons of fakes are out there! Kits can still be purchased from Tech-diy.com, and I have ordered from them on several occassions. With kits like these with tons of tiny parts, please go through the bags and make sure everything is there and everything is correct. I've gotten bags missing the pots once, another time I had double sets of one fet and none of the others. These parts are tiny and the writting on them is even smaller. VERY easy to mix up. Corrections were mailed out in fast order. Other times, all is well. You just dont want to wait until build day to discover you are missing something!

Russellc

strider · « **Reply #139 on:** 28 Mar 2011, 12:34 pm »

My FIL spent a lot of time helping get mine sorted out the other night. It's nice to have someone local I can sit down with and is obligated by my marriage to his daughter to help; someone that actually understands how the circuit works. I grab the manual and start reading, he grabs the schematic and starts telling me what does what. Turns out the problem that caused my failure wasn't the ground after all, I misinterpreted the manual and the direction in which to have the trimmer pots turned on initial start up. I had the full voltage of the rails getting sent directly into the output devices. They, of course, didn't stand a chance and the power resistors (R11 and R12, IIRC) blew afterwards. Good news is the amp boards still look good. After we got the one channel that still had viable MOSFETs up and running, we looked over data sheets and he showed me how the Toshiba and IRF devices, while having different part #'s, did similar things.

He chastised me for using solid core wire, and having runs of it parallel from the IEC inlet to the switch. Also said the double fuses were unnecesssary and could cause oscillation under heavy load. I'll re-wire the power input and mount the amp boards to the heatsinks while I have everything apart. In the long run, I'll have a better constructed amp and an actual understanding of how it works. The only regret I have is rushing the assembly of a project I've been collecting parts for for over a year and a half.

Russell - Did you get my PM?