Parts list for Quad ESL 63 EHT board

[Thinker]

Hi Everyone,

I recently traded for a pair of Quad ESL 63's (US studio version). The problem one is currently having is that it's playing back at reduced volume, no pops, hiss, crackles, or distortion, just reduced volume. After thumbing through the service manual it seems like it's probably the EHT board. I would like to rebuild it with slightly beefier components and I was wondering if I could get some suggestions from those who are more familiar with the 63's.

I know you can buy pre-done boards but, where's the fun in that? (and I'm a little on the broke side at the moment :-D )

Here's some info from the service manual:

 

[Thinker]

According to the service manual the Caps are 10nf -20 +50% at 2KV
would moving up to a higher voltage rating be worth the extra money, and perhaps switching to metalized polypropylene? or maybe C0G type ceramic?

The diodes are 1AV30's these are the specs I was able to find online for them:
I(O) Max.(A) Output Current 10m
V(RRM)(V) Rep.Pk.Rev. Voltage 3.0k
t(rr) Max.(s) Rev.Rec. Time 300n
@I(F) (A) (Test Condition)
@I(R) (A) (Test Condition)
V(FM) Max.(V) Forward Voltage 15
@I(FM) (A) (Test Condition) 10m
@V(RM) (V) (Test Condition)
I(RM) Max.(A) Reverse Current 2.0u
@V(R) (V)(Test Condition) 3.0k
I(RM) Max.(A) Pk. Rev. Current 5.0u
@V(R) (V) (Test Condition)
@temp. (øC) (Test Condition) 75õ
Semiconductor Material Silicon
Maximum Operating Temp (øC) 80’

Would a GP02-30-E3/73GICT-ND work as a replacement?

And should I change any of the resistors on the EHT board? and if so do you know what wattage I should get, I didn't see it mentioned in the service manual.

Thanks

 

[Thinker]

Here's what I've been able to put together so far, for anyone else that might do this

8 diodes GP02-30 (Mouser part# 625-GP02-30-E3)

14 Capacitors (for the EHT board) 10nF @ 2KV (Mouser part# 594-S103M69Z5UP63K7R)

1 Capacitor (for the neon board) 47nF @250 (I went with Mouser part# 505-MKP4J024703FKSSD)

1 Varistor (Mouser part# 871-B72210S461K101)

Resistors:

2 220K @ 5% (Mouser part# 279-RR02J220KTB)

1 180K @5% (Mouser part# 594-5083NW180K0J)

1 56k @ 5% (Mouser part# 594-5083NW56K00J)

1 10M @ 5% (Mouser part# 594-VR37000001005FA1)

I have the M-12525 ISS 4 version of the board, not the earlier ISS 3 version.

I was able to find this diagram of the ISS 4:

 

[Hawkeye83]

I need to do the same to my 57's...I'm just going to buy the boards though, too many other projects...good luck!

 

[Thinker]

Does anyone know how much power R12 actually dissipates? (I bought a 1/2 watt but, I think the original might have been a 3/4)

 

[audiomagnate]

I would highly recommend against replacing any resistor with one with a lower wattage rating. Leaving the existing one in place if it looks and measures OK is a much better option.

 

[dshoaf]

If rhe old one measures in spec, leave it. There’s little current so little power dissipating.

On high voltage, you really need a high voltage probe. Disconnect the panels, measure open circuit voltage then add one panel back at a time. Each should load down the PS at the same rate.

If the panels are approaching 20 years of age, replace ‘em. You’re chasing your tail otherwise.

Cheers,

David