Bottlehead Forum
Bottlehead Kits => Eros Phono => Topic started by: Randy morgan on January 12, 2022, 09:25:38 AM
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Hi folks, my first post. I finished building the new Eros kit today. I thought I was careful. The R channel sounds fine, the L is very weak though audible. I visually checked every connection, found a couple of solder whiskers, looked for debris, poor/cold solder joints, replaced the 6922 tube, cables, & more. Check voltages and resistances? I hate to admit I’m a bozo with a multimeter, can’t get correct or reproducible results. I’m don’t have alligator clips. The initial voltages on boards 1 & 2 were fine. I’ve read most of the relevant posts ( I think)
Any ideas? Thanks,
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I would post the following voltages:
+275V pad on PSU board
+6.3V pad on PSU board
-6.3V pad on PSU board
IA, IB, OA, OB, KregA, KregB on the board above the D socket
All labeled pads on the front C4S board
-PB
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I figured out the multimeter, no longer a bozo there. I went through the entire instruction manual step by step. On p. 54 “connect /solder white wire from d8 to A Kreg†Shoot! I had routed both white wires , D3 (correct) AND D8 to kreg B. Couldn’t believe it. Connected D8 correctly and….. no difference. Couldn’t believe it. I replaced the 12au7, nope.
There is one voltage way off: OB on the c4s was 108 while OA was 227. Here they all are:
Shunt: IA 306
IB 304
OA 227
OB 227
KregA. 6.38
KregB. 7.25
C4S: IA. 229
IB 229
OA 227
*OB 108
OC. 101
OD. 101
OkA. 104
B. 101
C. 1.82
D. 1.99
Fingers crossed.
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Oh yes
+275 pad 300
- 6.3 v (set on dc 200) 55.5. (?)
+ 6.3 v pad on psu: 62.1
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The voltage check on page 55 of the manual would have halted the build so this issue could be addressed.
The board above the 12AU7 is producing the correct voltages, so we can move on to the other board.
Can you post a few photos of the wiring around the EF86 and 6DJ8 sockets? It would probably also help to see the board above those sockets too.
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I hope this helps. Had to switch iphoto formats to jpg.
Photos still aren’t accepted.
I can email them
RM
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If they are large files you may just need to post one at a time.
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I tried that as well without success. I did email you 5 pix
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Screen shot of pix have .png extension which is on the allowable list, size is 4 mb, less than the 25 limit, still won’t post. Please refer to your email pix
Thanks again, RM
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It's been about two hours and I haven't seen those images come rolling into my inbox.
-PB
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You have some backwards transistors on the front C4S board.
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Oh my! So you found the photos?
I’ll get to work. Thanks!
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I found them easily enough, 2 are backwards, Doh!
I was able to remove them, but re-inserting was a disaster, I broke leads on both of them. How do I order 2 replacement parts?
Thanks! I’m finally optimistic that it will eventually work
RM
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PN4250A transistor x 2
So funny (now). I stared and stared at all parts & manual photos, I could not see that those 2 were backwards. Thanks for your patience & time.
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You can contact [email protected] to request some new PN4250s.
Doc B. forwarded me your photos.
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I received & installed the 2 transistors today, and….now the left channel is totally silent. Ah well, at
least I got to email-meet Mrs Doc B, Eileen who sent the parts. I had high hopes. Not sure what to do
now, kind of losing interest. It’s Not the kit’s fault. As I said previously, I thought I was being careful, methodical & I didn’t feel like I was in a hurry. I do now realize my 66 year old focus and concentration is Nothing like it was when I was younger. I probably should have kept my work time to 90 min, & not 2-3 hours.
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Did you measure voltages before you tried to listen to your kit? You really have to do that, as bad voltages mean your kit isn't working and could cause unpredictable consequences if you attempt to use it!
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No I did not measure voltages first, thinking the reversed transistors MUST be the (only) problem.
Wrong again. At least readers of this thread can see what Not to do.
Voltages have gone from bad to much worse
The 3 power board #s are the same
Shunt board all essentially the same except OB is 243 (was 227). & kregB 8.2 (was 7.25)
C4S: IA 245 (was 229). The other readings not listed are normal/unchanged.
OA 173 (was 227)
OB 230 (was 108)
OD 60 (was 101)
OkB 58 (101)
OkD 2.51 (1.99)
What a mess. I wonder if I fried the replacement transistors, or even the entire board. I had to apply heat for a long time to wiggle
The new leads into old solder-y holes, though I did spend quite a bit of time trying to clean the holes first.
With so many crazy readings I’m thinking I should start over, buy a new kit , everything except the base and transformer. Costs a bit more but less frustrating. Unless I screw it up again.
Hey I have a great idea! I’d love to have an Eros ii with 1:15 sut (my Shelter 901 is 0.5 mv) BUT built by
YOU. Now that would be sweet. My work is just not that good. I’ve built simple amp kits, but this Eros was much more difficult
Ok ok please advise,
& thanks again PB for your time & effort.
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Or if I remove the c4s board & just build a new one, I can send better pix of the 3 sockets & surrounding connections
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Now you have to go back to the board above the 12AU7 socket and figure out why that has stopped working. The 220V you should have at IA on the front board is determined by proper operation of the board above the 12AU7, which is now no longer functioning properly.
If you remove both the IA and IB wires on the front PC board and let them poke up into the air, what do you see at OA and OB on the C4S board above the 12AU7 socket?
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I’ve read your post 5 times, it’s still confusing. You refer to the ‘front board’, the ‘board above the 12au7 socket’ , the ‘front pc board’ and ‘the c4s’ board above the 12au7’ even though the c4s is above the 6922
I see 3 boards, from back (ac plug) to front (inputs) are power supply, shunt reg, and c4s.
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The shunt reg board is above the 12au7
The c4s board is above the 6922
I think you said the shunt reg board is no longer functioning properly.
You want me to remove IA & IB from the c4s board but ‘what do you see (you mean voltages?) at OA & OB “on the c4s board above the 12au7†Did you mean 6922?
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Remove the IA and IB wires from the front PC board that's above the front three sockets.
Measure OA and OB on the board above the 12AU7 socket.
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OA is 224, OB is 267
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How about Kreg B?
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Kreg B 4.7
Kreg A 3.22
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It's probably best to send this in for repair at this point or to order new PC boards and parts to populate them, as it seems likely that both boards are having issues.
This is also eligible for our repair service at this point if that's something you'd like to take advantage of.
-PB
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I have no confidence in my ability to fix this.
I would like to send it in for repair service. It’s either that or send it to the trash!
Thanks again for your time & patience
Please let me know how to proceed
RM
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You can e-mail queen(at)bottlehead(dot)com and let her know that you've been working with me on the forum and are requesting the repair service for your Eros and she'll get you setup.
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I can’t thank you enough, such a relief. Over & Out
Bottlehead forever!
RM
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I received this kit as a repair and there was a broken wire causing the remaining problems.